2012 -->

The Facts in Sequence of the Accident
of the Fukushima Daiichi Nuclear Power Station
Released in 2011 by the Government of Japan.

Unofficial Translation. Dates and Times are shown in Japan Standard Time, or UTC + 9.
Data released by TEPCO (The Tokyo Electric Power Company), the utility that operates the Fukushima Daiichi Nuclear Power Station, are also included.

March 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
14:46 The 2011 Earthquake off the Pacific coast of Tohoku, 9.0 on the moment magnitude scale, occurred.
14:46 Automatically Shut Down*.
* This fact was made public by TEPCO on May 16.
  "The Control Room of Unit Nos. 3 and 4 was filled with white smoke as if a smoke screen had exploded*."
* This information was made public on June 18 by TEPCO.
Not in operation.
14:47 The Main Steam Isolation Valves were shut.
External powers were lost. Two diesel generators started. According to the record of the Alarm Typer, they supplied electricity through 15:17*.
* This fact was made public by TEPCO on May 16.
Automatically Shut Down.
External powers were lost.
The Main Steam Isolation Valves were shut*.
* This fact was made public by TEPCO on May 16.
Automatically Shut Down.
External powers were lost. Two diesel generators started*.
* These facts were made public by TEPCO on May 16.
 
14:48   Two diesel generators started*.
* This fact was made public by TEPCO on May 16.
The Main Steam Isolation Valves were shut*.
* This fact was made public by TEPCO on May 16.
 
14:49 The Japan Meteorological Agency announced a Major Tsunami Warning.
14:50   Manually started the Reactor Core Isolation Cooling System, which automatically stopped at 14:51 because the water level was higher than the one for the system to continue operation*.
* This fact was made public on May 23 by TEPCO.
   
14:52 The Isolation Condenser System automatically started*.
* This fact was made public by TEPCO on May 16.
     
14:54     Confirmed nuclear chain reaction had stopped.
* This fact was made public on June 18 by TEPCO.
 
15:00   Started one of the pumps of the Residual Heat Removal System at 15:00, as well as other pumps by 15:07. The pumps failed at 15:36 when tsunami hit the Power Station.
* This fact was made public on May 23 by TEPCO.
← The other pumps of the Emergency Core Cooling Systems of Unit No. 2, such as ones of the High Pressure Core Flooder System and the Low Pressure Flooder System and the other pumps of the Residual Heat Removal System, did not start then, because the water level was higher than the one for the systems to activate themselves.
The Residual Heat Removal System failed when the all AC powers were lost. After the loss of powers, the Low Pressure Flooder System was unable to work. The High Pressure Core Flooder System was unable to work after the batteries were submerged.
* This information was made public on May 23 by TEPCO.
15:01   Confirmed nuclear chain reaction had stopped.
* This fact was made public on June 18 by TEPCO.
   
15:02 Confirmed nuclear chain reaction had stopped.
* This fact was made public on June 18 by TEPCO.
Manually started the Reactor Core Isolation Cooling System, which automatically stopped at 15:28 because the water level was higher than the one for the system to continue operation*.
* This fact was made public by TEPCO on May 16.
   
15:03 Stopped (temporarily?) the Isolation Condenser System*.
* This fact was made public by TEPCO on May 16.
     
15:05     Manually started the Reactor Core Isolation Cooling System, which automatically stopped at 15:25 because the water level was higher than the one for the system to continue operation*.
* This fact was made public by TEPCO on May 16.
 
15:06 TEPCO set up the Headquarters for Emergency Disaster Control at office in Tokyo.
15:07 Manually started one of the pumps of the Containment Spray System at 15:07, as well as the all pumps by 15:10, in order to cool the Suppression Chamber*.
* This fact was made public on May 23 by TEPCO.
← The other pumps of the Emergency Core Cooling Systems of Unit No. 1, such as ones of the High Pressure Coolant Injection System and the Low Pressure Coolant Injection System, did not start then, because the water level was higher than the one for the systems to activate themselves.
The Containment Spray System failed when the all AC powers were lost. After the loss of powers, the Low Pressure Coolant Injection System was unable to work. The High Pressure Coolant Injection System was unable to work after the batteries were submerged.
* This information was made public on May 23 by TEPCO.
15:10
- approx. 15:30
One of the two lines of the Isolation Condenser System is supposed to have been working by manual operation, as the data of pressure and temperature in the Pressure Vessel suggest*.
* This fact was made public on May 23 by TEPCO.
← The Isolation Condenser System was unable to work after the batteries were submerged.
Approx. 15:30 Tsunami began to hit the Power Station.
The primary wave arrived at 15:27, and the secondary one at 15:35.
15:37 According to the Handover Log, the all AC powers were lost at 15:37*.
* This fact was made public by TEPCO on May 16. The record of the Alarm Typer suggests the AC powers had been lost at 15:17.
One of the two diesel generators failed due to Tsunami*.
* This fact was made public by TEPCO on May 16.
   
15:38 → The Residual Heat Removal System and the Low Pressure Flooder System of Unit No. 3 were unable to work due to loss of AC powers.
* This information was made public on May 23 by TEPCO.
The two generators failed, resulting that the all AC powers were lost*.
* This fact was made public by TEPCO on May 16.
According to the Handover Log, the all AC powers were lost*.
* This fact was made public by TEPCO on May 16.
15:39
- 13:25, March 14
  Manually started the Reactor Core Isolation Cooling System, which kept working through 13:25, March 14*.
* This fact was made public on May 23 by TEPCO.
   
15:40   The other generator failed, resulting that the all AC powers were lost*.
* This fact was made public by TEPCO on May 16.
   
15:42 TEPCO informed the government that the all AC powers had been lost.  
* The following information was made public on June 18 by TEPCO:
After the AC powers were lost, the room lights and the panel lights in the Control Room faded out. The alarm sounds also stopped. While the No. 1's side of the Control Room was lit with emergency lights, the No. 2's side was totally blacked out.
Operators checked the conditions of the Isolation Condenser System and the High Pressure Coolant Injection System of Unit No. 1, both of which could work with batteries. The operators recognized that they were not able to confirm the status of the valves in the IC System. They thought they were not able to start up the HPCI System, as they saw the panel lights of the system had faded out.
Operators recognized they were not able to confirm whether or not the Reactor Core Isolation Cooling System of Unit No. 2 was working.
Mobile phones were disabled.
* The following information was made public on June 18 by TEPCO:
After the AC powers were lost, the Control Room was lit with emergency lights. Operators used flashlights.
15:45 The petroleum storage tanks for emergency diesel engines were swept away by Tsunami.
15:50 The power to monitor the water level in the Reactor Core was lost*.
* This fact was made public by TEPCO on May 16.
     
16:03
- 11:36, March 12
    Manually started the Reactor Core Isolation Cooling System, which kept working through 11:36, March 12*.
* This fact was made public on May 23 by TEPCO.
 
16:36 TEPCO was not able to confirm that the Emergency Core Cooling Systems were working.    
Approx. 16:40 * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuel Rods had begun to be exposed above water at a certain time between 16:40 and 16:50.      
16:45 TEPCO informed the government of the malfunctioned ECCS.    
Approx. 18:00 * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuels had begun to be damaged at a certain time between 17:50 and 18:20.
The Agency estimates that hydrogen began to be produced approximately at 18:00.
     
Approx. 18:10 * TEPCO released an analysis on March 12, 2012, that the Fuel Rods had begun to be exposed above water approximately at 18:10.      
Approx. 18:20 TEPCO asked another utility, the Tohoku Electric Power Company, to send high power supply vehicles to the Power Station*.
* This fact was made public by TEPCO on May 16.
Approx. 18:50 * TEPCO released an analysis on March 12, 2012, that the Fuels had begun to be damaged approximately at 18:50.      
Approx. 19:30 According to the analysis released by TEPCO on May 16, the Fuel Rods were totally exposed above water, and the Reactor Core began to melt down*.
* This estimate was made public by TEPCO on May 16.
     
Approx. 20:00 * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Reactor Core (Fuels) had melted down approximately at 20:00.      
20:07 A worker entered the Reactor Building and confirmed that the pressure gauge of the Reactor Core showed 6.9 MPa*.
* This information was made public on June 18 by TEPCO.
     
20:30 Blackout in the Control Rooms. Metal Clad Switchgears were submerged.
Unit No. 2 had priority for power supply vehicles to come.
20:49 Temporary lights were installed in the Control Room with (a) small generator*.
* This fact was made public on June 18 by TEPCO.
   
20:50 The local government of Fukushima Prefecture advised people within 2 km of the Power Station to evacuate the area.
21:00 Started fire pumps, preparing to inject water to the Reactor Cores when the pressures dropped.  
21:19 Confirmed the water level (+200 mm) in the Reactor Core for the first time since the batteries had been submerged*.
* This fact was made public on June 18 by TEPCO.
     
21:23 The Prime Minister ordered local governments to advise people within 3 km of Unit No. 1 of the Power Station to evacuate the area, and people within 10 km to stay indoors.
21:50   Confirmed the water level (+3,400 mm) in the Reactor Core for the first time since the batteries had been submerged*.
* This fact was made public on June 18 by TEPCO.
   
21:51 The plant manager forbad workers to enter the Reactor Building because of high radiation*.
* This fact was made public on June 18 by TEPCO.
← According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, most of the radiation leakage from Unit No. 1 were:
· Leakage from the Contaiment Vessel on the morning of March 12,
· Released radiation when the Containment Vessel was vented.

The Agency estimates approximately 0.7 % of iodine and 0.3 % of caesium were released to the atmosphere.
21:54   A water gauge was restored.    
21:58     Temporary lights were installed in the Control Room with (a) small generator*.
* This fact was made public on June 18 by TEPCO.
22:00 Confirmed the water level in the Reactor Core was +550 mm*.
* This fact was made public on June 18 by TEPCO.
The facts and estimates of Unit No. 2, according to the Nuclear and Industrial Safety Agency:
Fact14:47 15:02*Started the Reactor Core Isolation Cooling System. / * The time was corrected by TEPCO on May 16.
Fact20:30The Reactor Core Isolation Cooling System failed, resulting loss of means to inject water to the Reactor Core.
* The RCIC System had been working, which was confirmed at 02:55 on March 12.
Fact21:50A water gauge was restored. The water level in the Reactor Core was approximately 3 m above the top of fuels.
Estimate22:50The Fuel Rods will be exposed above water.
Estimate23:50Part of the Fuel Claddings will be damaged.
Estimate0:50, March 12Part of the Fuel will begin to melt.
Estimate3:20, March 12The pressure in the Containment Vessel will rise to the Maximum Working Pressure, or 527.6 kPa.
Will begin to vent the Containment Vessel, releasing radioactive materials.

* According to a document made public by the Nuclear and Industrial Safety Agency on July 1, TEPCO had reported to the agency that the water level in the Reactor Core of Unit No. 2 would drop to the Top of Active Fuel at 21:40, that the Reactor Core would begin to be damaged at 22:20, and that the Pressure Vessel would be damaged at 23:50. These estimates were premised that the Reactor Core Isolation Cooling System had failed. An operator confirmed later, at 02:55 on March 12, that the RCIC system had been working, which denied the estimates.
23:00 Radiation increased in the Turbine Building.
(The radiation levels varied from 0.5 mSv/h to 1.2 mSv/h, which was made public on June 18 by TEPCO.)
* The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Containment Vessel had been damaged before 23:00.
     
21:50   Confirmed that pressure in the Drywell was 0.141 MPa (absolute).    
As of 23:45 Three power supply vehicles arrived at the Power Station. One from the Self-Defense Force at 21:22, another from TEPCO at 21:30, and the other from the city of Iwaki at unknown time. Other fifty power supply vehicles were heading for the Power Station.
According to TEPCO's record made public on May 16, the first power supply vehicle arrived at the Power Station around 11:00.
According to TEPCO's press release on June 18, officials of the utility considered bringing power supply vehicles to the Station with aircraft, but they were too heavy for aircraft to carry.
00:30 23:50 A suspect that the pressure in the Drywell exceeds 600 kPa, as the design pressure is 427 kPa.
Operators connected a bettery, which had been connected to the level gauge of the Rector Core, to the pressure gauge of the Drywell, and found out that the pressure was 600 kPa (absolute), as the design pressure is 427 kPa*.
* Corrected by TEPCO on June 18.
     
March 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:00 Cooling the steam from the Reactor Core with the Isolation Condenser System.
* According to the report released by TEPCO on May 23, the time when the IC System resumed is not confirmed. Photographs of handwritten records on the whiteboards in the Control Room taken on March 11 suggest that workers restarted it at 18:18 and stopped at 18:25, and then resumed at 21:30 (through 01:48, March 12).
Confirmed, with temporary AC power, that the water level in the Reactor Core was high and safe. Injecting water to the Reactor Core with the Reactor Core Isolation Cooling System.  
00:49 * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the pressure in the Drywell of the Containment Vessel had exceeded the design pressure.      
00:57 Unusual high pressure in the Containment Vessel.
Informed the government of the high pressure.
     
01:48 The Isolation Condenser System completely failed*.
* This fact was made public by TEPCO on May 16.
     
Approx. 01:50 * TEPCO released an analysis on March 12, 2012, that the Pressure Vessel had been impaired approximately at 01:50.      
01:55   Suspended working to connect (the Reactor Building) with AC power, fearful of another tsunami.    
01:57 Radiation continued rising in the Turbine Building.      
02:00   Before 02:00, an operator, carrying a self-contained breathing apparatus and a flashlight, had entered a room where the pumps of the Reactor Core Isolation Cooling System were installed. He was not able to confirm wheter or not the pumps were working. He reported that the room was submerged almost as deep as the height of his boots. Mobile phones were disabled.
Another operator went to the room approximately at 02:00. He found the water in the room had increased, and was not able to see the pumps either. Based on the readings of the pressure gauges on site, he concluded the pumps were working, which he reported to other operators when he was back to the Control Room*.
* This fact was made public on June 18 by TEPCO.
   
02:29   Planning to vent the Containment Vessel.
* This information is not consistent with others, although recorded in a document released at 05:30, March 12 by the headquarter of the government.
   
04:00 02:30 A suspect that the pressure in the Drywell rose to 840 kPa, as the design pressure is 427 kPa.
The pressure in the Drywell reached 840 kPa (absolute), as the design pressure is 427 kPa*.
* Corrected by TEPCO on June 18.
     
02:45 The pressure in the Pressure Vessel was 0.8 MPa.      
03:33 02:55   Confirmed that a pump of the Reactor Core Isolation Cooling System had been working.
* The time was corrected by TEPCO on May 16.
* This information is based on a report of an operator who went to see the readings of the pressure gauges in the RCIC room, which TEPCO made public on June 18.
   
03:00 Planned to vent the Containment Vessel at 3:00. The result would be a Serious Incident.
Capacity: 5,600 m3, Pressure: 8 atm to 1 atm
     
03:06 Kaieda Banri, the Minister of Economy, Trade and Industry, and Komori Akio, a junior executive vice president of TEPCO, held a joint press conference at the Ministry in Tokyo to announce that TEPCO was going to vent the Containment Vessels and release radioactive materials into the atmosphere.
Approx. 03:45 Workers opened the double door of the Reactor Building for survey of radiation, in preparation for other workers to enter the Building to manually vent the Containment Vessel. But they were not able to measure the radiation because they found white steam in the Building and soon shut the door*.
* This fact was made public on June 18 by TEPCO.
     
04:20   Changed resevoirs of the Reactor Core Isolation Cooling System from the Condensate Storage Tank to the Suppression Chamber.    
04:23 The radiation level in the Power Station rose, from 0.069 μSv/h at 04:00 to 0.59 μSv/h at 04:23 near the Main Gate*.
* This fact was made public on June 18 by TEPCO.
Approx. 04:50 The plant manager ordered workers to wear a full face mask when they worked outdoors.
The manager also ordered operators in the Control Rooms to wear a full face mask approximately at 05:00*.
* This fact was made public on June 18 by TEPCO.
05:14 Operators reported to the Government that radioactive materials were leaking from the Reactor*.
* This fact was made public on June 18 by TEPCO.
     
05:44 The Prime Minister ordered local governments to advise people within 10 km of the Power Station to evacuate the area.
05:46 Began to inject freshwater into the Reactor Core with a pump of fire truck*.
* This fact was made public by TEPCO on May 16.
* The Nuclear and Industrial Safety Agency supposes possibility, in the analysis released on June 6, that the water was not delivered to the Reactor Core.
     
06:30 Injected 2 m3of freshwater into the Reactor Core with a pump of fire truck*.
* This fact was made public by the Nuclear and Industrial Safety Agency on July 1.
     
06:50 According to the analysis released by TEPCO on May 15 after the utility confirmed the water gauges had shown false data, most of the Fuel had melted down on the bottom of the Pressure Vessel by 06:50, March 12.
Unit No. 1 as of November
Click the figure for a larger one.
According to the report submitted to the Ministry of Economy, Trade and Industry by TEPCO on November 30, the utility estimates:
  • Most of the Fuels of Unit No. 1 melted down from the proper place to the bottom of the Pressure Vessel.
  • Most of the fuel debris on the bottom melted through the Pressure Vessel to the pedestal of the Containment Vessel.
  • The corium on the pedestal caused corium-concrete interactions.
  • The corium remains in the Containment Vessel.

The figure on the left, released by TEPCO on November 30, shows its estimates of the debris and the corium in Unit No. 1 as of November. TEPCO started to inject water through the Feedwater Line to Pressure Vessel on March 23, and to inject nitrogen gas to Containment Vessel on April 6.

06:50 The Minister of Economy, Trade and Industry ordered TEPCO to vent the Containment Vessels.    
07:11 Prime Minister Kan Naoto arrived at the Power Station.
07:51 07:30 Working to connect pump(s) to batteries, to inject water from tanks to the Reactor Core, and to restore the power for the Electromaginetic Valve for venting.
As of 07:30, workers were setting up temporary cables to restore power for venting*.
* Corrected by the Nuclear and Industrial Safety Agency on July 1.
Working to secure AC power from power supply vehicles.    
08:04 Prime Minister left the Power Station.
08:30 The water level in the Reactor Core had dropped near the Top of Active Fuel. Workers were injecting water into the Reactor Core with a pump of a fire truck*.
* This information was added by the Nuclear and Industrial Safety Agency on July 1.
     
08:30 Decided to vent the Containment Vessel at 9:00.      
09:07 09:15 Opened the valves to vent the Containment Vessel.
A pair of operators, wearing fire resistant suits and self-contained breathing apparatus, entered the Reactor Building and opened the valve by 25 % to vent the Containment Vessel (Drywell) as planned*.
* Corrected by TEPCO on June 18.
     
09:24 Another pair of operators left the Control Room for the Torus Room, where they could manually open the smaller one of the two valves to vent the Suppression Chamber (Wetwell). But they were exposed to high radiation on the way, and went back to the Control Room without opening the valve*.
* This fact was made public on June 18 by TEPCO.
     
10:04 Part of the Fuel Rods began to be exposed above water.
   10:04  −50 cm
   11:20  −90 cm
   12:05  −150 cm
   15:28  −170 cm
   18:30  lower than scale
← The data on the left were denied by the analysis made public by TEPCO on May 16 that the Reactor Core of Unit No.1 had supposedly begun to melt down approximately at 19:30, March 11.
10:17 Began to vent the Containment Vessel*.
* This datum is not consistent with others. This information was made public on March 27 for the first time for unknown reasons.

Operators gave up opening manually the smaller valve, and tried to open it remotely with compressed air which had been used for instrumentation.
They made an attempt at 10:17, another at 10:23, and a third at 10:24, on none of which occasions they could confirm the valve was opened.
Operators confirmed at 10:40 that the readings of the monitoring posts had gone up, and considered that radioactive materials were lilely to have been released. But the readings dropped at 11:15, which suggested the vent had been a failure*.
* Corrected by TEPCO on June 18.
     
10:49 One of the two valves to vent the Containment Vessel would not open.      
11:13 Seemingly the vent had begun, as the pressure in the Containment Vessel decreased from 0.8 kPa to 0.74 kPa.      
11:36     The Reactor Core Isolation Cooling System failed. The cause is unknown*.
* This fact was made public by TEPCO on May 16.
 
12:00     The pressure in the Pressure Vessel had been more than 7 MPa, a reading in usual operation, till noon. The pressure began to drop sharply, and it was less than 1 MPa six hours later. The cause is unknown.  
12:06
- 03:05, March 13
    Sprayed water to the Suppression Chamber with the Diesel Driven Fire Protection Pump*.
* This fact was made public by TEPCO on December 22.
 
12:35     The High Pressure Core Flooder System started because the water level in the Pressure Vessel dropped.  
13:00 The water level in the Reactor Core was dropping.      
14:00 The pressure in the Drywell rose. Opened a valve.
After operators learned they could not manually open the smaller valve in the Suppression Chamber on site, they began to consider opening the larger one. They needed a gas compressor and an adaptor to open it. They asked contract manufacturers for ones, and borrowed approximately at 12:30. Because of high radiation inside, they set the compressor in front of the Large-Scale Door, and started it at 14:00*.
* Corrected by TEPCO on June 18.
     
14:30 The pressure in the Drywell dropped, from 0.75 MPa to 0.67 MPa.
* According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, the Wetwell of the Containment Vessel was vented.
** According to TEPCO's press release on June 18, operators confirmed the pressure in the Drywell had decreased, and concluded that the vent of the Suppression Chamber (Wetwell) had been a success. The pressure dropped from 0.75 MPa to 0.58 MPa at 14:50.
     
14:53 Stopped injecting freshwater into the Reactor Core. Had injected 80 m3 of water by then*.
* This fact was made public by TEPCO on May 16.
     
15:28 The pressure in the Drywell dropped to 0.54 MPa.      
Approx. 15:30   Approximately 40 workers had connected cables from a high-power supply vehicle to one of survived power center switchgears in the Turbine Building by 15:30. Operators intended to start up Standby Liquid Control pumps*.
* This information was made public on June 18 by TEPCO.
   
15:36 A hydrogen explosion in the Reactor Building. Because of the explosion at the Reactor Building of Unit No. 1, the power supply vehicle failed, the cables were damaged by debris, and the workers had to be evacuated.
* This information was made public on June 18 by TEPCO.
   
16:27 More than 500 μSv/h of radiation (1,015 μSv/h) was detected on the border of the Power Station.
18:25 The Prime Minister ordered local governments to advise people within 20 km of the Power Station to evacuate the area.
19:04 Began to inject seawater into the Reactor Core with a pump of fire truck*.
* This fact was made public by TEPCO on May 16.
← According to a press release of the government on May 22 and a news conference of TEPCO on May 26, TEPCO actually began the injection of seawater at 19:04, but it reported to the government that it had begun at 20:20:
The Government TEPCO
   Around
12:00
Shimizu, the president of TEPCO, permitted opertors of the Fukushima Daiichi Power Station to begin preparation for injecting seawater into the Reactor Core of Unit No. 1.
   Around
14:50
Shimizu permitted opertors of the Power Station to inject seawater into the Reactor Core.
14:53 Stopped injecting freshwater (because water had run out).
15:18 - 15:21 Operators of the Power Station notified by facsimile to the Cabinet Secretariat, the Nuclear and Industrial Safety Agency, as well as to local governments, police and fire stations, that they were planning to inject seawater through the Fire Extinguisher Line into the Reactor Core of Unit No. 1 as soon as they were ready*.
* This fact was confirmed by the Government in a committee of the House of Representatives on May 31.
15:36 Hydrogen explosion.
Around
18:00 - 18:20
Prime Minister Kan met staff including senior members of the Nuclear Safety Commission, the Nuclear and Industrial Safety Agency and TEPCO. They discussed possible problems of injecting seawater into the Reactor Core.
Kan asked Madarame, the chair of the Commission, about the probability that chain reaction might spontaneously restart. He said it was not zero.
  
18:05 Kaieda, the Minister of Economy, Trade and Industry, gave TEPCO an oral direction to prepare for injection of to inject seawater*.
* Corrected by the Government in a committee of the House of Representatives on May 31.
   19:04Operators of the Power Station began to inject seawater into the Reactor Core.
   19:06A senior fellow of TEPCO, who had met Prime Minister Kan at his official residence, told the staff of the Government that the operators of the Power Station had begun to inject seawater into the Reactor Core. The information was not delivered to Prime Minister Kan.
   19:25The senior fellow of TEPCO told its headqurters that Kan had been worried about the probability of chain reaction.
The headquaters decided that the utility should wait for Prime Minister's consent.
They held a meeting with operators of the Power Station in Fukushima with videoconferencing system, and told them to suspend the injection.
Although the plant manager of the Power Station did not oppose the direction at the conference, he ignored it and continued the injection. The manager has an authority to make the decision.
19:40Staff of the Nuclear and Industrial Safety Agency reported to Prime Minister that chain reaction would be unlikely to restart if seawater was injected into the Reactor Core.   
19:55Prime Minister directed to inject seawater into the Reactor Core.   
20:05 Kaieda, the Minister of the METI, ordered TEPCO to inject seawater.
   20:20Operators of the Power Station reported that they had begun to inject seawater following the Minister's order.
   20:45Operators began to add boric acid to the seawater*.
* This fact was made public on June 13 by TEPCO.
20:20 Began to pump seawater and boric acid through the Fire Extinguisher Line into the Reactor Core.
* This datum was not correct. The facts are shown on the right.
20:36     Power for the water level gauges of the Reactor Core was lost*.
* This fact was made public by TEPCO on December 22.
 
20:41 Confirmed that the Containment Vessel was intact. (Chief Cabinet Secretary)      
March 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
02:00     The pressure in the Pressure Vessel began to rise. It had been around 1 MPa since 19:00, March 12, and began to show a sharp rise around 02:00, May 13, to more than 7 MPa for two hours. The cause is unknown.  
02:44 02:42     The High Pressure Core Flooder System stopped because the pressure in the Pressure Vessel was low*. The HPCF System was unable to restart later because the battery was out.
* According to the governmental report to the International Atomic Energy Agency made public on June 7, there is a possibility that the system stopped because steam had leaked out of it.
** According to a report to the Nuclear and Industrial Safety Agency submitted by TEPCO on December 22, operators in the Control Room manually stopped the High Pressure Core Flooder System. As the turbine of the System had shown a vibration, the operators feared that the System might be damaged. They did not suppose that the System was able to inject water into the Reactor Core because the pressure in the Core and that in the System were almost equal. The operators intended to inject water with Diesel pumps.
 
03:00 Supposedly the Pressure Vessel was filled with water. ← The estimate on the left was denied by the analysis made public by TEPCO on May 16 that the Reactor Core of Unit No.1 had supposedly begun to melt down approximately at 19:30, March 11.
04:15     The water level in the Pressure Vessel dropped to the top of the Fuel Rods.  
04:50     Oparators in the Control Room tried to open the larger one of the two valves to vent the Suppression Chamber remotely with a small generator, approximately at 04:50. Later one of the operators went to see the Torus Room and confirmed the valve was shut*.
* This information was made public by TEPCO on June 18.
 
05:00 Continued pumping seawater into the Pressure Vessel, because the water level was not confirmed.      
05:08
- 07:43
    Sprayed water to the Suppression Chamber with the Diesel Driven Fire Protection Pump*.
* This fact was made public by TEPCO on December 22.
 
05:10     The Emergency Core Cooling Systems were disabled. The High Pressure Core Flooder System had failed earlier, and the Reactor Core Isolation Cooling was unable to work.
Preparing to vent the Containment Vessel.
 
05:58     Informed the government of the malfunctioned ECCS.  
07:30     Estimated that the Fuels were beginning to melt.  
07:39     Began to spray water to the Containment Vessel.
The spray was suspended between 08:40 and 09:10*.
* This fact was made public by TEPCO on December 22.
 
Approx. 07:40     * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuel Rods had begun to be exposed above water approximately at 07:40.  
08:10   Operators, carrying self-contained breathing apparatus and flashlights, entered the Reactor Building and opened the valve by 25 % to vent the Containment Vessel (Drywell) as planned*.
* This fact was made public on June 18 by TEPCO.
   
08:35     Operators entered the Reactor Building and opened the valve by 15 % to vent the Containment Vessel (Drywell) as planned*.
* This fact was made public on June 18 by TEPCO.
 
08:41     Began to vent the Containment Vessel.
Ready to vent the Suppression Chamber. Opened the larger one of the two valves to vent, but the vent did not begin because the pressure in the Suppression Chamber was not high enough for the rupture disc to break up*.
* Corrected by TEPCO on June 18.
 
08:55 Continued pumping seawater into the Pressure Vessel at the rate of 1 m3/min.
The water level: (A) lower than scale, (B) −1700 mm, although reliability of the level gauges was not confirmed.
     
08:56 More than 500 μSv/h of radiation (882 μSv/h) was detected on the border of the Power Station.
(Approx.) 09:00     The pressure in the Pressure Vessel showed a sharp drop. The cause is unknown.
* According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, the Main Steam Relief Safety Valves were opened at 09:08.
** According to TEPCO's press release on June 18, operators had to gather batteries from wokers' private cars to open the Main Steam Relief Safety Valves.
 
Approx. 09:10     * TEPCO released an analysis on March 12, 2012, that the Fuel Rods had begun to be exposed above water approximately at 09:10.  
09:20     The pressure in the Pressure Vessel was decreasing.  
09:24 → According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, most of the radiation leakage from Unit No. 3 were:
· Released radiation when the Containment Vessel was vented,
· Leakage from the Contaiment Vessel after the vent, as the pressure in the Vessel decreased.

The Agency estimates approximately 0.3 % - 0.8 % of iodine and 0.2 % - 0.6 % of caesium were released to the atmosphere.
The pressure in the Drywell dropped, from 0.637 MPa (absolute) at 09:10, to 0.540 MPa (absolute) at 09:24, which suggests the Containment Vessel was vented*.
* This information was made public by TEPCO on June 18.
 
09:25     Began to inject freshwater and boric acid (with a fire truck*) through the Fire Extinguisher Line into the Reactor Core.
* Added by TEPCO on June 18.
 
09:28     Operators noticed that the air pressure of the gas cylinder to operate the larger vent valve was decreasing, approximately at 09:28. Later some of them went to the Torus Room and confirmed air was leaking. They began repairing*.
* This information was made public by TEPCO on June 18.
 
Approx. 10:00     * The Nuclear and Industrial Safety Agency released an analysis on June 6 that hydrogen had begun to be produced approximately at 10:00.  
Approx. 10:20     * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuels had begun to be damaged approximately at 10:20.  
Approx. 10:40     * TEPCO released an analysis on March 12, 2012, that the Fuels had begun to be damaged approximately at 10:40. The utility's analysis showed that the Pressure Vessel was not impaired through the accident.  
11:00 The Prime Minister ordered local governments to advise people within 30 km of the Power Station to stay indoors. He had ordered them to advise people within 20 km to evacuate the area.
11:00   Began to vent the Containment Vessel.
Ready to vent the Suppression Chamber. Opened the larger one of the two valves to vent. But the vent did not begin because the pressure in the Drywell was not high enough for the rupture disc to break up*.
* Corrected by TEPCO on June 18.
   
12:18 11:17     The vent failed. Tha valve was shut by unknown cause.
* According to TEPCO's press release on June 18, operators confirmed on site at 11:17 that the larger vent valve was shut due to air leak.
 
11:55     The pressure in the Pressure Vessel dropped down to 0.12 MPa.  
Approx. 12:00     * The Nuclear and Industrial Safety Agency estimates, in the analysis released on June 6, that the Pressure Vessel was damaged approximately at 12:00, while one of its simulations suggests the Vessel was damaged approximately at 22:10, March 14.  
12:20     Stopped injecting freshwater into the Reactor Core*.
* This fact was made public by TEPCO on June 18.
 
12:30     Operators on site opened the larger vent valve at 12:30. They attempted to lock it opened, but could not*.
* This information was made public by TEPCO on June 18.
 
13:12     Began to pump seawater and boric acid (with a fire truck*) through the Fire Extinguisher Line into the Reactor Core.
* Added by TEPCO on June 18.
 
14:15 More than 500 μSv/h of radiation (905 μSv/h) was detected on the border of the Power Station.
14:31     More than 300 mSv/h of radiation was detected in front of the Double Door of the Reactor Building*.
* This datum was made public by TEPCO on June 18.
 
15:28     12 mSv/h of radiation was detected in the No. 3's side of the Control Room. Operators were evacuated to the No. 4's side*.
* This datum was made public by TEPCO on June 18.
 
Approx. 17:52     Workers set a compressor in front of the Large-Scale Door to open the vent valve on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
18:45 Continued pumping seawater into the Pressure Vessel at the rate of 1 m3/min.
The water level: (A) lower than scale, (B) −1700 mm, although reliability of the level gauges is unknown.
     
Approx. 19:00     * According to the analysis released by TEPCO on May 23, the Reactor Core began to melt around 19:00.  
Approx. 20:10     Operators concluded that the larger one of the two vent valves on the Suppression Chamber was open, as the pressure in the Drywell had dropped*.
* This information was made public by TEPCO on June 18.
 
March 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
01:10 Stopped pumping seawater into the Reactor Core, because there was little water in the resevoir.
* The temporary resevoir was a drain pit of the reversing valves in Unit No. 3. The pit had been flooded with seawater. This information was added by TEPCO on June 18.
  Stopped pumping seawater into the Reactor Core, because there was little water in the resevoir.
* The temporary resevoir was a drain pit of the reversing valves in Unit No. 3. The pit had been flooded with seawater. This information was added by TEPCO on June 18.
 
02:20 More than 500 μSv/h of radiation (751 μSv/h) was detected on the border of the Power Station.
02:40 More than 500 μSv/h of radiation (650 μSv/h) was detected on the border of the Power Station.
03:00 According to the report submitted to the Ministry of Economy, Trade and Industry by TEPCO on November 30, the utility estimates:
  • Parts of the Fuels of Unit No. 3 melted down from the proper place either to the bottom of the Pressure Vessel or to the pedestal of the Containment Vessel.
  • Other parts of the Fuels remain in the proper place.

The figure on the right, released by TEPCO on November 30, shows its estimates of the debris and the corium in Unit No. 3 as of November. TEPCO started to inject water through the Feedwater Line to Pressure Vessel on May 12, and through the Core Spray Line on September 1.

According to the analysis released by TEPCO on May 23, if the water gauges showed false data, as found at Unit No.1 on May 10, and actually the water in the Reactor Core had been lost, most of the Fuel had melted down on the bottom of the Pressure Vessel by 03:00, March 14. If the reading of the gauges were true, most of the Fuels melted above the Core Support Plate.
Unit No. 3 as of November
Click the figure for a larger one.
03:20     Resumed pumping seawater (with a fire truck*) into the Reactor Core.
* Added by TEPCO on June 18.
 
Approx. 03:40     Operators tried to open the smaller one of the two vent valves on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
04:00 More than 500 μSv/h of radiation (820 μSv/h) was detected on the border of the Power Station.
04:08       The temperature of the water in the Storage Pool of Spent Nuclear Fuels rose to 84 ºC.
05:20     Began to vent the Containment Vessel*.
* This datum is not consistent with others. This information was made public on March 27 for the first time for unknown reasons.
* The datum is affirmed in the governmental report to the International Atomic Energy Agency made public on June 7.
* According to TEPCO's press release on June 18, operators tried again to open the smaller one of the two vent valves on the Suppression Chamber.
 
06:10     The pressure in the Containment Vessel rose to approximately 460 kPa. (The Maximum Working Pressure is 427 kPa when designed.)  
06:10     * According to TEPCO's press release on June 18, operators confirmed that the smaller vent valve was open.
** This information is not consistent with the datum above that the pressure in the Containment Vessel had exceeded the Maximum Working Pressure.
 
07:44     Planning to vent the Containment Vessel.
The vent is likely to release 100 times as much radioation as so far.
* Part of the information is not consistent with others.
 
07:55 07:52     Informed the government of the high pressure.  
08:20     Suspended the planned vent, as the water level in the Pressure Vessel rose. Continued supplying the Vessel with water.  
09:27 09:12* More than 500 μSv/h of radiation (518.7 μSv/h) was detected on the border of the Power Station.
* The time was corrected based on TEPCO's press release on June 18.
11:01   Opened the Relief Panels on the Reactor Building.

* According to TEPCO's press release on June 18, the larger vent valve on the Suppression Chamber, which had been opened in preparation for venting, was shut after the explosion at the Reactor Building of Unit No. 3. Operators cofirmed they were unable to reopen it.
On the other hand, firetrucks and hoses, which workers had set to inject seawater into the Reactor Core, were damaged and disabled because of the explosion.
A hydrogen explosion in the Reactor Building.

* The fire truck and the hoses were damaged by the explosion, and the injection of seawater was suspended, according to TEPCO's press release on June 18.
 
11:15     TEPCO reported that the explosion was the same event as the one at Unit No. 1, and that both the Containment Vessel and the Pressure Vessel were intact.  
13:14   Estimated that the Fuel Rods were going to be partly exposed above water at 16:00.    
13:25   The Reactor Core Isolation Cooling System failed by 13:25, resulting that the all Cooling Functions were lost. Informed the government.    
13:30   Corrected the earlier estimate. The Fuel Rods were going to be partly exposed above water at 15:30.
Preparing to supply the Reactor Core with water.
   
15:30   A cooling system was still working, injecting water into the Reactor Core.
Impossible to inject seawater into the Pressure Vessel due to high pressure inside.
* Part of this information is not consistent with others.
   
16:16   Corrected the earlier estimates again. The Fuel Rods were going to be partly exposed above water at 17:30.
Preparing to supply the Reactor Core with water.
   
16:20   To vent the Containment Vessel, to cool the Suppression Pool, and to depressure the Pressure Vessel would be needed before seawater was injected. Preparing to vent.    
Approx. 16:30     Resumed to inject seawater with a fire truck into the Reactor Core*.
* This fact was made public by TEPCO on June 18.
 
16:34   Began to pump seawater through the Fire Extinguisher Line into the Reactor Core*.
* According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, a rise of water level was not confirmed then, which suggests that the water was not delivered to the Reactor Core.


Operators reported to the Government that they were going to pump seawater through the Fire Extinguisher Line into the Reactor Core*.
* Corrected by TEPCO on June 18.
   
Approx. 17:00   * TEPCO released an analysis on March 12, 2012, that the Fuel Rods had begun to be exposed above water approximately at 17:00.    
17:17   The water level dropped to the top of the Fuel Rods.    
Approx. 18:00   * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuel Rods had begun to be exposed above water approximately at 18:00.    
18:06   Opened the Main Steam Relief Safety Valve. The water level rose from −1,500 mm to −1,100 mm. The pressure in the Pressure Vessel was 5.4 MPa. Stopped injecting water.
(Operators began to depressure the Pressure Vessel.)
   
18:22   The water level in the Pressure Vessel dropped to −3,700 mm. The Fuel Rods were totally exposed.    
19:03   The pressure in the Pressure Vessel dropped to 0.63 MPa.    
19:20   The injection of seawater was suspended because fuel of the fire pump had run out*.
* This fact was made public on June 13 by TEPCO.

Fuel of a fire truck ran out. The truck had been used to inject seawater into the Reactor Core*.
* Corrected by TEPCO on June 18.
   
Approx. 19:20   * TEPCO released an analysis on March 12, 2012, that the Fuels had begun to be damaged approximately at 19:20. The utility's analysis showed that the Pressure Vessel was not impaired through the accident.    
Approx. 19:50   * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Fuel Rods had begun to be exposed above water at a certain time between 19:50 and 22:30.    
19:54   Resumed pumping Began to pump** seawater (with two fire trucks) through the Fire Extinguisher Line into the Reactor Core*.
* The Nuclear and Industrial Safety Agency supposes possibility, in the analysis released on June 6, that water was not delivered to the Reactor Core.
** Corrected by TEPCO on June 18.
   
Approx. 20:00   * According to the analysis released by TEPCO on May 23, the Reactor Core began to melt approximately at 20:00.
* The Nuclear and Industrial Safety Agency released an analysis on June 6 that hydrogen had begun to be produced approximately at 20:00.
   
21:20   Confirmed the water level in the Reactor Core had been rising*.
* This fact was made public on June 13 by TEPCO.
   
21:35 More than 500 μSv/h of radiation (760 μSv/h) was detected on the border of the Power Station.
Approx. 22:00     * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Reactor Core (Fuels) had melted down approximately at 22:00.  
22:50   Unusual high pressure in the Containment Vessel. (The pressure in the Drywell exceeded the maximum working pressure, or 427 kPa gauge.) ← According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, most of the radiation leakage from Unit No. 2 were:
· Leakage caused by high pressure in the Contaiment Vessel. The Agency estimates the meltdown began after 21:00, March 14.
· Released radiation when the Containment Vessel was vented.
· Leakage from the Suppression Chamber.

The Agency estimates approximately 0.4 % - 7 % of iodine and 0.3 % - 6 % of caesium were released to the atmosphere.
Approx. 22:50   * The Nuclear and Industrial Safety Agency estimates, in the analysis released on June 6, that the Pressure Vessel was damaged at 22:50 in the earliest case.
Approx. 23:00   * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the Reactor Core (Fuels) had melted down approximately at 23:00.    
23:39   Informed the government of the high pressure.    
March 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:00   * The Nuclear and Industrial Safety Agency released an analysis on June 6 that the high pressure in the Containment Vessel suggested the Pressure Vessel had been damaged.    
00:02   Began to vent the Containment Vessel*.
* According to the analysis released by the Nuclear and Industrial Safety Agency on June 6, the vent of Drywell of the Containment Vessel continued for several minutes.

Ready to vent the Containment Vessel (Drywell), but did not begin the vent because the pressure was not high enough for the rupture disc to break up. Several minutes later, operators recognized the vent valve had been shut*.
* Corrected by TEPCO on June 18.
   
01:11   The pressure in the Pressure Vessel dropped from 1.44 MPa to 0.92 MPa.    
03:00   The pressure in the Containment Vessel exceeded the design pressure. Attempted to reduce the pressure and pumped water into the Reactor Core, but could not.    
06:10   An unusual noise near the Suppression Pool. The pressure in the Suppression Pool reduced.
* The Nuclear and Industrial Safety Agency corrected some of its previous press releases on July 1, and omitted the reference to 'an unusual noise' for unknown reason.
← According to the governmental report to the International Atomic Energy Agency made public on June 7, there is a possibility that:
· Hydrogen was produced in a reaction between zirconium and water in the Reactor Vessel.
· The hydrogen entered the Suppression Chamber via the opened Main Steam Relief Safety Valve.
· The hydrogen leaked from the Suppression Chamber to the Torus Room and exploded there.
But the cause of the explosion is not specified in the report.
06:14 Between 06:10 and 06:20       A noise.** The walls were partly broken*.
* The Government admits, in its Report to the International Atomic Energy Agency made public on June 7, that the cause of the explosion in the Reactor Building is still unknown.
** The Nuclear and Industrial Safety Agency corrected some of its previous press releases on July 1, and omitted the reference to 'a noise' for unknown reason.
06:14     A somke was recognized.  
around 06:20   An emergency in the Suppression Pool was suspected.    
06:50 More than 500 μSv/h of radiation (583.7 μSv/h) was detected on the border of the Power Station.
06:56       The upper part of the Reactor Building was deformed.
07:00 The plant manager reported to the Government that he was going to make most of workers and operators to evacuate the Fukushima Daiichi Power Station to the Fukushima Daini. 650 people moved to the Fukushima Daini, and about 70 people kept working in the Fukushima Daiichi.
08:11 More than 500 μSv/h of radiation (807 μSv/h) was detected on the border of the Power Station.
08:25   A white smoke was recognized from the 5th floor of the Reactor Building.    
09:38       A fire was recognized on the 3rd floor of the Reactor Building.
10:01 The Ministry of Economy, Trade and Industry asked the U.S. Military for help to extinguish the fire on the Reactor Building of Unit No. 4.
10:22     400 mSv/h of radiation was detected outside the Reactor Building.  
10:59 The staff at the off-site center were ordered to evacuate to the office of Fukushima Prefecture.
12:25 Approx. 11:00       Confirmed that the fire went out.
* The time was corrected by TEPCO on June 18.
11:01 The Prime Minister advised people within from 20 km to 30 km of the Power Station to stay indoors.
11:26 The staff at the off-site center completed evacuation to the office of Fukushima Prefecture.
13:24 The debris from the explosions would prevent fire trucks and other vehicles from coming into the site.
16:00 More than 500 μSv/h of radiation (531.6 μSv/h) was detected on the border of the Power Station.
16:00     Operators confirmed that the both of the vent valves on the Suppression Chamber had been shut*.
* This information was made public by TEPCO on June 18.
 
16:05     Operators opened the larger vent valve on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
20:00
Unit No. 2 as of November
Click the figure for a larger one.
According to the analysis released by TEPCO on May 23, if the water gauges showed false data, as found at Unit No.1 on May 10, and actually the water in the Reactor Core had been lost, most of the Fuel had melted down on the bottom of the Pressure Vessel by 20:00, March 15. If the readings of the gauges were true, most of the Fuels melted above the Core Support Plate. According to the report submitted to the Ministry of Economy, Trade and Industry by TEPCO on November 30, the utility estimates:
  • Parts of the Fuels of Unit No. 2 melted down from the proper place either to the bottom of the Pressure Vessel or to the pedestal of the Containment Vessel.
  • Other parts of the Fuels remain in the proper place.

The figure on the left, released by TEPCO on November 30, shows its estimates of the debris and the corium in Unit No. 2 as of November. TEPCO started to inject water through the Feedwater Line to Pressure Vessel on May 29, and through the Core Spray Line on September 14.

23:05 More than 500 μSv/h of radiation (4548 μSv/h) was detected on the border of the Power Station.
March 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
01:55     Operators opened the smaller vent valve on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
05:45       A fire was recognized on the 3rd floor of the Reactor Building.
08:34     A white smoke steam gushed out of the Reactor Building.
* Corrected by the Nuclear and Industrial Safety Agency on July 1.
 
10:00     A white smoke was recognized.  
10:45     Workers in the Control Room were evacuated, fearful that the Containment Vessel might be damaged.  
11:14     Estimated that a large part of the white smoke had been steam from the Storage Pool.  
11:33     Estimated that the Containment Vessel had not been seriously damaged. The workers went back to the Control Room. Resumed pumping water.  
March 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:48
- 10:01
    Helicopters of the Ground Self-Defense Force sprayed approximately 30 tons of water to the Storage Pool of Spent Nuclear Fuels.  
19:05
- 19:13
    A water truck of the Police sprayed approximately 44 tons of water to the Storage Pool.  
19:35
- 20:09
    Five fire trucks of the Self-Defense Force sprayed approximately 30 tons of water to the Storage Pool. The radiation level slightly went down from 3,630 μSv/h to 3,586 μSv/h.  
21:00     Operators confirmed that the larger one of the two vent valves on the Suppression Chamber had been shut*.
* This information was made public by TEPCO on June 18.
 
21:30     Operators opened the larger vent valve on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
March 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:30     Operators confirmed that the larger one of the two vent valves on the Suppression Chamber had been shut, and soon opened it*.
* This information was made public by TEPCO on June 18.
 
around 14:00
- 14:38
    Six fire trucks of the Self-Defense Force sprayed approximately 40 tons of water to the Storage Pool.  
14:42
- 14:45
    TEPCO sprayed water to the Storage Pool with a fire truck of the US Military.  
17:48 Based on the International Nuclear Event Scale, the domestic Nuclear and Industrial Safety Agency gave a temporary rating to the accident of each unit.
Level 5: Accident with wider consequences Level 5: Accident with wider consequences Level 5: Accident with wider consequences Level 3: Serious incident
March 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:30
- 01:10
    Fire trucks of the Tokyo Fire Department sprayed water to the Storage Pool.  
08:58 More than 500 μSv/h of radiation was detected on the border of the Power Station.
11:30     Operators confirmed that the larger one of the two vent valves on the Suppression Chamber had been shut*.
* This information was made public by TEPCO on June 18.
 
13:30   The Electrical Substation was connected to external electricity.    
14:05
- 03:40, March 20
    Fire trucks of the Tokyo Fire Department sprayed approximately 2,430 tons of water to the Storage Pool. The radiation level slightly went down from 3,417 μSv/h to 2,758 μSv/h.  
March 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00     The temperature in the Pressure Vessel exceeded 300 ºC. (When the reactor is normally operated, it is 280-290 ºC.) The pressure in the Pressure Vessel rose.  
08:21
- 09:40
      Ten fire trucks of the Self-Defense Force sprayed approximately 80 tons of water to the Storage Pool.
11:25     Operators opened the larger vent valve on the Suppression Chamber*.
* This information was made public by TEPCO on June 18.
 
15:08
- 17:20
  TEPCO sprayed approximately 40 tons of seawater into the Storage Pool with a fire truck.    
18:30
- 19:45
      Ten fire trucks of the Self-Defense Force sprayed approximately 80 tons of water to the Storage Pool.
21:36
- 03:58, March 21
    Fire trucks of the Tokyo Fire Department sprayed approximately 1,137 tons of water to the Storage Pool.  
March 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:37
- 08:41
      13 fire trucks, 12 of the Self-Defense Force and one of the US Military, sprayed approximately 90 tons of water to the Storage Pool. The radiation level slightly went down from 2,319 μSv/h to 2,126 μSv/h.
14:30 Radioactive nuclides were detected in the seawater sampled near the water-discharging pipes of the Power Station.
Nuclide Detected level Allowed level
58Co 5.995 × 10−2 Bq/cm3 1 × 102 Bq/cm3
131I 5.066 × 100 Bq/cm3 4 × 10−2 Bq/cm3
132I 2.136 × 100 Bq/cm3 3 × 100 Bq/cm3
134Cs 1.486 × 100 Bq/cm3 6 × 10−2 Bq/cm3
135Cs 2.132 × 10−1 Bq/cm3 3 × 10−1 Bq/cm3
137Cs 1.484 × 100 Bq/cm3 9 × 10−2 Bq/cm3
15:55     A gray smoke was recognized.  
18:02     The smoke went out.  
18:22 18:20   Steam was recognized.
* The time was corrected by the Nuclear and Industrial Safety Agency on July 1.
   
March 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
11:20 The temperature of the Pressure Vessel exceeded 400 ºC      
15:10
- 15:59
    Fire trucks of the Tokyo Fire Department and of the Osaka Municipal Fire Department sprayed approximately 150 tons of water to the Storage Pool.  
16:19
- 17:01
  Fire trucks of the Tokyo Fire Department sprayed approximately 18 tons of water to the Storage Pool. The temperature of the water in the Storage Pool went down from 53 ºC to 51 ºC.    
17:17
- 20:32
      TEPCO sprayed 150 tons of water to the Storage Pool with a concrete pumping truck.
22:46     The lighting of the Control Room was restored.  
March 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
02:33 Began pumping through the Feedwater Line, as well as through the Fire Extinguisher Line, increasing water into the Reactor Core (from 2 m3/h to 18 m3/h).      
09:00 Stopped pumping water through the Fire Extinguisher Line, while continued pumping through the Feedwater Line at the rate of 11 m3/h.      
10:00
- 13:02
      TEPCO sprayed approximately 125 tons of water to the Storage Pool with a concrete pumping truck. The radiation Level changed from 211.49 μSv/h 224.1 μSv/h.
11:03
- 13:20
    TEPCO pumped approximately 35 tons of water through the Water Cleanup System into the Storage Pool.  
16:20     A black smoke was recognized.  
23:30     Confirmed the black smoke had gone out.  
March 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:35
- 16:05
      TEPCO pumped approximately 120 tons of water through the Water Cleanup System into the Storage Pool.
around 10:50 A misty steam was recognized from the top of the Reactor Building.      
11:30 The lighting of the Control Room was restored.      
14:25     200 mSv/h of radiation was detected in water (estimated 3-5 cm deep) near the High Pressure Condensate Pump in the basement of the Turbine Building.  
14:36
- 17:30
      TEPCO pumped approximately 150 tons of water with a concrete pumping truck.
17:00 17:10
- 07:30 17:30, March 29
Transferred pooled water in the basement of the Turbine Building to the Condenser*.
* Corrected by the Nuclear and Industrial Safety Agency on July 1.
     
March 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:05
- 10:20
      TEPCO pumped water through the Water Cleanup System into the Storage Pool.
08:30 Approximately 1,250 times as much iodine-131 (131I) as legally allowed level was detected in the seawater sampled near the discharging pipes into the sea at 08:30.
09:00   A trace was found that suggested water in the Reactor Building had flowed through the Large-Scale Door into the usual drain.    
10:30
- 12:19
  TEPCO pumped (30 tons of) seawater through the Water Cleanup System into the Storage Pool.    
13:28
- 16:00
    Fire trucks of the Kawasaki Municipal Fire Department sprayed approximately 450 tons of water to the Storage Pool.  
15:37 Began pumping freshwater into the Reactor Vessel.      
18:02     Began pumping freshwater into the Reactor Vessel.  
19:05
- 22:07
      TEPCO sprayed approximately 150 tons of water to the Storage Pool with a concrete pumping truck.
23:10 3.8 million Bq/cm3 of radiation was detected in water sampled from a pooled water on the 1st floor of the Turbine Building.
91Y5.2 × 104 Bq/cm3
131I2.1 × 105 Bq/cm3
134Cs1.6 × 105 Bq/cm3
136Cs1.7 × 104 Bq/cm3
137Cs1.8 × 105 Bq/cm3
140La3.0 × 102 Bq/cm3
     
March 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
10:10   Began pumping freshwater into the Reactor Vessel.    
14:30 Approximately 1,850 times as much iodine-131 (131I) as legally allowed level was detected in the seawater sampled near the discharging pipes into the sea at 14:30.
16:46   The lighting of the Control Room was restored.    
March 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
    TEPCO anounced that it detected more than 1,000 mSv/h of radiation on the surface of water which had been sampled from pooled water in the Turbine Building on March 26. Approximately 10 million times (2.9 × 109 Bq/cm3) as much iodine-134 (134I) as in water in the Reactor Core was detected in the sample. (Corrected on March 28.)    
07:30 Transferring pooled water in the Turbine Building into the Condenser. Preparing to transfer pooled water in the Turbine Building into the Condenser. Considering to transfer pooled water in the Turbine Buildings into the Condensers.
12:34
- 14:36
    TEPCO sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck.  
15:10 Pumping the pooled water in the Turbine Building into the Condenser with three pumps.      
15:30 Found contaminated water in the Trenches outside the Turbine Buildings.  
0.4 mSv/h on the surface. More than 1,000 mSv/h on the surface. Not measurable, blocked by the debris.  
16:55
- 19:25
      TEPCO sprayed 125 tons of water to the Storage Pool with a concrete pumping truck.
18:31   Began to use an electric temporary pump, instead of the pump of a fire car, to feed the Reactor Vessel with water at the rate of 9 tons per hour. Began to use water from one of the Freshwater Tanks, instead of a temporary tank.    
March 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  238Pu, 239Pu and 240Pu were detected in five samples of soil, taken on March 21 and 22 in the Power Station. While the quantities were not significantly larger than ones from the fallout of the past nuclear tests, two samples of the five suggested possibility that the plutonium had derived from this accident.
00:07   TEPCO corrected the datum of iodine-134 (134I) that it had anounced on March 27: 134I had not been detected. It did not correct the datum of the pooled water in the Turbine Building.    
08:32 08:30     Began to use an electric temporary pump, instead of the pump of a fire car, to feed the Reactor Vessel with water at the rate of 7 tons per hour.  
11:15   Approximately 100,000 times as radioactive water as usual Core water was found in the basement of the Turbine Building. The water was assumed to have leaked from the Containment Vessel and flowed there through unknown paths.    
17:40
- 08:37, March 31
    Transferred water in the Condensate Storage Tank to the Surge Tank.  
March 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:32 Began to use an electric temporary pump, instead of the pump of a fire car, to feed the Reactor Vessel with water at the rate of 8.5 tons per hour.      
11:50       The lighting of the Control Room was restored.
14:17
- 18:18
    TEPCO sprayed 100 tons of water to the Storage Pool with a concrete pumping truck.  
16:30 15:30   Began to use an electric temporary pump to feed the Storage Pool with freshwater.
* The time was corrected by the Nuclear and Industrial Safety Agency on July 1.
   
16:36 Pooled water was found in the basement of the Central Eenvironmental Facility Main Building. Radiation was detected in the water.
   12 Bq/cm3 in the radiation controlled area.
   22 Bq/cm3 in the neighboring boiler room (not in radiation controlled area).
16:45
- 11:50, April 1
  Transferred water in the Condensate Storage Tank to the Surge Tank.    
March 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Approximately 3,355 times as much iodine-131 (131I) as legally allowed level was detected in the seawater sampled near the discharging pipes into the sea at 13:55, March 29.
09:45   The hose of the fire water to feed the Storage Pool with water ruptured. The electric temporary pump had malfunctioned.
The electric temporary pump to inject water to the Storage Pool malfunctioned at 09:45. Resume to inject water with a fire pump at 12:30, but suspended the injection at 12:47 due to rupture of a hose*.
* Corrected by the Nuclear and Industrial Safety Agency on July 1.
   
14:04
- 18:33
      TEPCO sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck.
19:05
- 23:50
  Supplied the Storage Pool with water, using a pump of fire truck.    
March 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Approximately 10,000 times as much iodine-131 (131I) as legally allowed level was detected in groundwater. 4.3 × 102 Bq/cm3.      
08:51 Approximately 4,385 times as much iodine-131 (131I) as legally allowed level was detected in the seawater sampled near the discharging pipes into the sea at 08:40, March 30.
09:20
- 11:25
Part of contaminated water in the Trench was transferred to the Central Radioactive Waste Building. The water level in the Trench went down, from 0.14 m below the top, to 1.14 m.      
12:00
- 15:26, April 2
Transferred water in the Condensate Storage Tank to the Surge Tank.      
13:03
- 16:04
Sprayed approximately 90 tons of water to the Storage Pool with a concrete pumping truck.      
15:42 A US military barge, carrying freshwater to cool the Reactor Cores, was tugged by a Japan Maritime Self-Defense Force ship to the pier of the Power Station.
16:30
- 19:33
    Sprayed approximately 105 tons of water to the Storage Pool with a concrete pumping truck.  
April 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:28
- 14:14
      TEPCO sprayed approximately 180 tons of water to the Storage Pool with a concrete pumping truck.
14:56
- 17:05
  Supplied the Storage Pool with approximately 70 tons of water through the usual line.    
15:00
- 16:04
Sprayed 2,000 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 500 m2 of the ground near the Shared Pool.
15:58 Began transferring water in the U.S. barge to a tank. Stopped the transfer at 16:25 due to the leak from the hose.
April 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:10 Another US military barge, carrying freshwater, was tugged to the pier of the Power Station.
09:30   Found contaminated water, more than 1,000 mSv/h, in a Pit near the Water Intake from the sea. Found a crack, approximately 20 cm long, in the concrete near the Pit. Water in the Pit leaked through the crack into the sea.    
09:52
- 12:54
    TEPCO sprayed approximately 75 tons of water to the Storage Pool with a concrete pumping truck.  
10:20
- 16:40
Transferred water in the first U.S. barge to a tank.
16:25
- 19:15
      Began to transfer the contaminated water in the Central Environmental Facility Main Building to the Turbine Building of Unit No. 4*.
* This information was added by the Nuclear and Industrial Safety Agency on July 1.
16:25
- 19:15
  Concreted the Pit to prevent the contaminated water from leaking into the sea.    
17:10
- 13:10, April 9
  Transferred water in the Condenser to the Condensate Storage Tank.    
April 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
12:18 11:50 Began to use electricity from the external grid, insteand of one from power supply vehicles, for the electric temporary pumps to feed the Pressure Vessels with water.  
13:47
- 14:30
  Attempted to stop the leaking water with superabsorbent polymer and sawdust.    
13:55
- 09:30, April 10
Transferred water in the hot well tank of the Condenser to the Condensate Storage Tank.      
17:14
- 22:16
      TEPCO sprayed approximately 180 tons of water to the Storage Pool with a concrete pumping truck.
17:42   Poured water with a truck into the Pit and stirred it to prevent sawdust from being dried.    
April 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:08   Poured tracer (white powder) into the Pit in order to detect the leakage path of the contaminated water. (The tracer was not recognized at the Water Intake as of 09:30, April 5.)    
09:22     Stopped transferring the water in the Central Environmental Facility Main Building to the Turbine Building of Unit No. 4, because the water level of the Pit of Unit No. 3 had been rising since the previous day.
11:05
- 13:37
  TEPCO supplied the Storage Pool with approximately 70 tons of water.    
11:54 The second US military barge, reloaded with freshwater, reentered the pier of the Power Station.
17:03
- 19:19
    TEPCO sprayed approximately 70 tons of water to the Storage Pool with a concrete pumping truck.  
19:03
- 06:30,
April 6
and
14:30,
April 8
- 17:40,
April 10
Dumped approximately 9,070 10,393* tons of low-level contaminated water in the Radioactive Waste Treatment Facility into the sea.
* Corrected by TEPCO on May 20.
21:00 Began dumping low-level groundwater pooled in the Subdrain Pit of Unit Nos. 5 and 6 into the sea.
April 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Approximately 7.5 million times as much radioactive iodine-131 as allowed level was detected in seawater sampled near the Bar Screen of Unit No. 2 at 11:50, April 2.
13:00
- 16:30, April 5
Sprayed 2,400 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 6,000 m2 of the ground near Unit No. 4 and the Shared Pool.
14:15   Injected tracer (white powder) into the Rubble under the Pit, and confirmed the tracer was contained in the leaking water.    
15:00
- 16:30
Piled 22 large sandbags around the breakwater in order to stop contaminated water from flowing into the external sea.
15:07   Dug hole(s) around the Pit, and injected approximately 6,000 liters of coagulator. Leakage continued, although it showed a temporary decreasing for a while. Continued injecting coagulator.    
17:35
- 18:22
      TEPCO sprayed approximately 20 tons of water to the Storage Pool with a concrete pumping truck.
April 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  238Pu, 239Pu and 240Pu were detected in samples of soil, taken on March 25 and 28 in the Power Station. While the quantities were not significantly larger than ones from the fallout of the past nuclear tests, the ratio of the three nuclides suggests the possibility that part of the plutonium had derived from this accident.
05:38   Confirmed the contaminated water had stopped leaking from the Pit.    
12:30
- 14:30
Sprayed 2,400 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 6,000 m2 of the ground near the Shared Pool.
22:30 Began to inject nitrogen gas into the Containment Vessel in order to prevent a hydrogen explosion. But the injection was soon suspended due to a crack in one of the pipes.      
April 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
01:31 Resumed injecting nitrogen gas into the Containment Vessel in order to prevent a hydrogen explosion.      
06:53
- 08:53
    Supplied the Storage Pool with approximately 70 tons of water.  
13:29
- 14:34
  Supplied the Storage Pool with approximately 36 tons of water.    
18:23
- 19:40
      Supplied the Storage Pool with approximately 38 tons of water.
23:32 Another earthquake hit. Siginificant disorders caused by the quake were not seen as of 23:52.
April 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
11:00
- 14:00
Sprayed 1,300 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 680 m2 of the ground near the Shared Pool.
17:08
- 20:00
    TEPCO sprayed approximately 20 tons of water to the Storage Pool with a concrete pumping truck.  
18:30     Operators confirmed that the both of the vent valves on the Suppression Chamber had been shut*.
* This information was made public by TEPCO on June 18.
 
April 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  03:29 Closed all the valves of the Containment Vessel
03:59 Opened the injecting valve to supply the Containment Vessel with nitrogen gas of higher purity
04:10 Opened all the valves
     
17:07
- 19:24
    TEPCO sprayed approximately 90 tons of water to the Storage Pool with a concrete pumping truck.  
April 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 17:00
Began removing debris in the site with a remote-contolled heavy construction equipment.
10:37
- 12:38
  Supplied the Storage Pool with approximately 60 tons of water.    
13:00
- 14:00
Sprayed 2,000 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 550 m2 of the ground near the Shared Pool.
15:59
- 16:28
Flied an unmanned helicopter to take movies of the Reactor Buildings of Nos. 1, 2, 3 and 4.
17:15
- 19:15
    Supplied the Storage Pool with approximately 80 tons of water.  
April 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment.
10:45 Completed the setting of silt fence at the water break.
12:00
- 13:00
Sprayed 2,400 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,200 m2 of the ground near the Shared Pool.
17:16 Another earthquake hit. Electricity from the external grid stopped.
The water-supplying pump to the Reactor Core stopped due to the blackout.
The nitrogen-supplying pump to the Containment Vessel stopped due to the blackout.
17:56 The external grid was restored.
18:04 The water-supplying pump resumed.
23:34 The nitrogen-supplying pump resumed.
The water-supplying pump to the Reactor Core stopped due to the blackout.
17:56 The external grid was restored.
18:04 The water-supplying pump resumed.
The water-supplying pump to the Reactor Core stopped due to the blackout.
18:04 The water-supplying pump resumed.
 
April 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:38 A fire was recognized at the Sampling Equipment at the discharging pipes into the sea. Extinguished the fire by 09:12.
10:00       Sampled water in the Storage Pool of Spent Nuclear Fuels.
Temperature: approximately 90 ºC; Radiation level: approximately 84 mSv/h at approximately 6 meters above the floorboard of the 5th floor of the Reactor Building.
11:20 Based on the International Nuclear Event Scale, the domestic Nuclear and Industrial Safety Agency reviewed the previous ratings and gave a temporary rating of Level 7 (Major accident) to the accident of Unit Nos. 1, 2 and 3.
The Nuclear Safety Comission of Japan used the actually monitored data around the Fukushima Daiichi Nuclear Power Station and estimated the radiation of two nuclides that had been released from the station into atmosphere during the period from March 11 to April 5: 1.5 × 1017 Bq of iodine-131, and 1.2 × 1016 Bq of caesium-137 (or 4.8 × 1017 Bq in converted value to iodine-131); The total radiation of the two nuclides was 6.3 × 1017 Bq in converted value to iodine-131, which does not include radiation of rare gases released into atmosphere, of materials released into the sea, and of materials in soil.
The Nuclear and Industrial Safety Agency calculated the released radiation as well: 1.3 × 1017 Bq of iodine-131, and 6.1 × 1015 Bq of caesium-137 (or 2.4 × 1017 Bq in converted value to iodine-131); The total radiation of the two nuclides was 3.7 × 1017 Bq in converted value to iodine-131, which includes the ones released into atmosphere, into sea and in soil. The calculation depended on the analysis of the reactors by Japan Nuclear Energy Safety Organization.
The both estimates suggested the accident was assessed as Level 7 (more than several tens of thousands of tera-becquerel, or more than 1016 Bq) on the International Nuclear Event Scale.
 
12:00
- 13:00
Sprayed 1,400 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 700 m2 of the ground near the Shared Pool.
13:00   Set a metal panel outside the Bar Screen.    
14:07 Another earthquake hit. Siginificant disorders caused by the quake were not seen as of 14:30.
16:26
- 17:16
    TEPCO sprayed approximately 35 tons of water to the Storage Pool with a concrete pumping truck.  
19:35
- 17:04, April 13
  Transferred pooled water in the Trench of the Turbine Building to the hot well tank of the Condenser.    
April 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
        Radioactive nuclides found in the water of the Storage Pool, sampled on April 12, were:
   Iodine-131 approximately 220 Bq/cm3 (not detectable on March 4)
   Caesium-134 approximately 88 Bq/cm3 (not detectable on March 4)
   Caesium-137 approximately 93 Bq/cm3 (0.13 Bq/cm3 on March 4)
00:30
- 06:57
      TEPCO sprayed approximately 195 tons of water to the Storage Pool with a concrete pumping truck.
around 10:00   Set two metal panels outside the Bar Screen.    
11:00
- 11:30
Sprayed 1,000 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 400 m2 of the ground near the Shared Pool.
11:00
- 16:10
Continued removing debris with a remote-contolled heavy equipment. Three intermodal containers of debris near Unit Nos. 3 and 4. Three intermodal containers of debris near the old walfare building.
13:15
- 14:55
  Supplied the Storage Pool with approximately 60 tons of water.    
13:50     Completed setting silt fences outside the Bar Screens of Unit Nos. 3 and 4.
April 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
10:17
- 12:25
    Flied an unmanned helicopter to take movies of the Reactor Buildings of Nos. 3 and 4.
12:00
- 13:30
Sprayed 3,500 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,600 m2 of the ground near the Shared Pool.
12:20 Completed setting silt fences outside the Bar Screens and Water Intakes of Unit Nos. 1 and 2.    
15:56
- 16:32
    TEPCO sprayed approximately 25 tons of water to the Storage Pool with a concrete pumping truck.  
April 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Moved water supply equipments, such as temporary diesel generators and pump controllers, to higher places, fearful of another tsunami.
08:02
- 09:55
Flied an unmanned helicopter to take movies of the Reactor Buildings of Nos. 1, 2, 3 and 4.
09:00
- 15:45
Continued removing debris with a remote-contolled heavy equipment. An intermodal container of debris near Unit Nos. 3 and 4.
11:30
- 13:00
Sprayed 3,800 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,900 m2 of the ground near the Shared Pool.
14:15   Set four metal panels outside the Bar Screen. Three panels left to set.    
14:30
- 18:29
      TEPCO sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck.
15:45     Sank sandbags of zeolite at three points near the Bar Screens of Unit Nos. 3 and 4. Each bag has 100 kg of zeolite in it.
April 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris in the site.
10:13
- 11:54
  Supplied the Storage Pool with approximately 45 tons of water.    
11:19 Another earthquake hit. Siginificant disorders caused by the quake were not seen as of 11:38. Stopped the temporary pump to the Storage Pool of the Reactor No. 2 for safety purposes, at 11:40. Confirmed the pump was intact.
11:30
- 13:00
Sprayed 3,800 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,800 m2 of the ground near the Shared Pool.
April 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  TEPCO released Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station.
http://www.tepco.co.jp/en/press/corp-com/release/11041707-e.html
According to the document, TEPCO set two steps as their targets:
   Step 1 (around 3 months): Radiation dose is in steady decline.
   Step 2 (around 3-6 months after Step 1 is completed): Release of radioactive materials is under control and radiation dose is being significantly held down.
09:00
- 11:15
Sank two sandbags of zeolite between the Screen Pump Rooms of Unit Nos. 1 and 2, and five between the Rooms of the Nos. 2 and 3.  
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris in the site.
10:00
- 13:30
Sprayed 3,800 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,900 m2 of the ground near the Central Radioactive Waste Building.
11:30
- 17:30
Remote controlled robots surveyed the inside of the Reactor Buildings of Unit Nos. 1 and 3.   Remote controlled robots surveyed the inside of the Reactor Buildings of Unit Nos. 1 and 3.  
14:34 Power to the Shared Storage Pool of Spent Nuclear Fuels downed due to short circuit. Restored at 17:30.
17:39
- 21:22
      TEPCO sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck.
    Radioactive nuclides found in the water that had been sampled from the Skimmer Surge Tank on April 16 were:
   Cs-134  160,000 Bq/cm3
   Cs-137  150,000 Bq/cm3
   I-131  4,100 Bq/cm3
   
April 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Stopped injecting water to the Reactor Cores in order to change hoses.  
Stopped from 11:50 to 12:12. Stopped from 12:13 to 12:37. Stopped from 12:38 to 13:05.
09:00
- 14:30
Sprayed 3,300 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,200 m2 of the ground near the Central Radioactive Waste Building.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris in the site.
09:30
- 17:40
  Injected approximately 17,000 liters of water glass into the Power Trench.    
13:42
- 14:33
  Remote controlled robots surveyed the inside of the Reactor Building of Unit No. 2.    
14:17
- 15:02
    Supplied the Storage Pool with approximately 30 tons of water.  
17:40   Completed leak test of the pipe to transefer contaminated water from Unit No. 2 to the Central Radioactive Waste Building. The other tasks for the purpose were completed by 19:00.    
April 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00
- 15:30
  Injected approximately 7,000 liters of water glass into the Power Trench.    
09:00
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris in the site.
10:08   Began transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
10:17
- 11:35
      TEPCO sprayed approximately 40 tons of water to the Storage Pool with a concrete pumping truck.
10:23 Liaised power cables of the four reactors from external grid, fearful of partial blackout.
16:08
- 17:28
  Supplied the Storage Pool with approximately 47 50 tons of water.    
April 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
17:08
- 20:31
      TEPCO sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck.
April 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
    Completed the work with water glass to stop the leak of highly contaminated water, first found on April 2, from a crack in concrete near the Water Intake Screen of Unit No. 2.
The total volume of leaked water was estimated approximately 520 m3, and the water is supposed to have contained approximately 4.7 × 1015 Bq of radiation.
   
09:00
- 16:00
Removed highly radioactive debris near the former Main Office Building (09:00-16:00), and Unit Nos. 3 and 4(14:45-16:00).
11:43
- 12:50
Flied an unmanned helicopter to take movies of the Reactor Buildings of Nos. 1, 2, 3 and 4.
12:00
- 15:00
Sprayed 12,800 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 1,300 m2 of the ground near the Shared Pool and to approximately 5,100 m2 near the Reactor Buildings Nos. 5 and 6.
17:14
- 21:20
      TEPCO sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck.
April 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Plutonium-238, plutonium-239 and plutonium-240 were detected in soil at the three points, which are designated for regular sampling in the Power Station. The samples were taken on April 7 and 11. While the detected levels of the plutonium doses are as high as the ones from the fallout of the past nuclear tests, the possibility can not be denied that part of the plutonium derived from this accident.
Uranium-234, uranium-235 and uranium-238 were detected in soil at the three points, which are designated for regular sampling in the Power Station. The sample was taken on April 11. The detected levels of the uranium doses are evaluated as high as the ones of background radiation of uranium.
00:00 The government designated that the area within 20 km of the Fukushima Daiichi Nuclear Power Station should be no-entry zone. While the government had advised local governments concerned to evacuate people out of the area on March 12, people can be penalized for entering the area after the establishment of the no-entry zone.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris in the site.
09:44 The government advised local governments concerned to evacuate people in a month from the newly designated areas, including parts of the towns of Iitate and Kawamata. The government opened on-the-site offices in the two towns.
13:40
- 14:00
    Supplied the Storage Pool with approximately 10 tons of water.  
14:19
- 15:40
    TEPCO sprayed approximately 50 tons of water to the Storage Pool with a concrete pumping truck.  
15:55
- 17:40
  Supplied the Storage Pool with approximately 50 tons of water.    
17:52
- 23:53
      TEPCO measured the temperature of the water in the Storage Pool (approximately 91 ºC before spraying) and sprayed approximately 200 tons of water to the Pool with a concrete pumping truck.
April 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
12:30
- 16:44
      TEPCO sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck. The temperature of the water dropped from 83 ºC to 66 ºC.
April 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
11:30
- 13:00
Sprayed 3,500 liters of resin, which is expected to prevent radioactive dusts from being blown by wind, to approximately 860 m2 of the ground near Unit No. 5.
12:25
- 17:07
      TEPCO sprayed approximately 165 tons of water to the Storage Pool with a concrete pumping truck. The temperature of the water dropped from 86 ºC to 81 ºC.
April 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
18:15
- 00:26 April 26
      Sprayed approximately 210 tons of water to the Storage Pool with a concrete pumping truck.
April 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
      Measured 1,120 mSv/h of radiation dose near the entrance of the Shutdown Cooling Pump Room.  
11:35
- 13:24
Remote controlled robots surveyed the inside of the Reactor Buildings.      
12:25
- 14:03
    Supplied the Storage Pool with approximately 47.5 tons of freshwater.  
13:30
- 17:00
Sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 5,000 m2 of the ground near Unit No. 3.
16:50
- 20:35
      Sprayed approximately 130 tons of water to the Storage Pool with a concrete pumping truck.
April 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
09:00
- 17:00
Sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 7,500 m2 of the ground near Unit Nos. 1, 2, 3 and 4.
10:02 Began to increase the water into the Reactor Core, from 5.9 m3/h to 14 m3/h. At 16:00, found the pressures both in the Reactor Vessel and in the Containment Vessel were dropping. Decided to keep injecting water at the rate of 10 m3/h until the pressures were stable.      
12:18
- 14:01,
14:32
- 15:15
      Sprayed approximately 85 tons of water to the Storage Pool with a concrete pumping truck.
April 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 3 with a remote-contolled heavy equipment.
10:15
- 11:28
  Supplied the Storage Pool with approximately 43 tons of freshwater.    
10:30
- 12:00
Workers sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 450 m2 of the ground near Unit No. 5.
11:55       Sampled water in the Storage Pool.
April 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 3 with a remote-contolled heavy equipment.
09:16   Temporarily stopped transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building, due to checkup of the Waste Building and installation of additional monitoring devices.    
10:14 Decreased the water into the Reactor Core from 10 m3/h to 6 m3/h.      
10:30
- 14:00
Sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 5,800 m2 of the ground near Unit the No. 5 and to 7,000 m2 near Unit No. 4.
11:36
- 14:05
Remote controlled robots surveyed the 1st floor of the Reactor Building, confirming that there was not significant water leakage from the Containment Vessel.      
April 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:15
- 16:15
Continued removing debris in the site with a remote-contolled heavy equipment.
10:30
- 14:00
Workers sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 5,400 m2 of the ground near the Main Office Building, while a remote-contolled equipment did to 2,000 m2 near Unit No. 4.
11:00 TEPCO released the data of the amounts of external radiation doses that workers had exposed to as of March 31. Two workers were found exposed to more than 200 mSv of radiation.
12:08     External power from another electricity grid was connected to Unit Nos. 3 and 4.
around 14:05   Resumed transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
May 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
10:30
- 14:00
Workers sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 4,400 m2 of the ground near the Main Office Building, while a remote-contolled equipment did to 1,000 m2 near Unit No. 4.
13:35   Began to seal the Pit of the Trench.    
May 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Began to work to install local ventilators so that workers could enter the reactor building.      
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment.
10:05
- 11:40
  Supplied the Storage Pool with approximately 55 tons of freshwater.    
10:30
- 14:00
Workers sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 5,500 m2 of the ground near the Main Office Building, while a remote-contolled equipment did to 4,000 m2 near Unit No. 4.
11:00   Checked the situation of transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building. Remarkable symptoms were not recognized.    
12:58
- 14:53
Installed alarm systems to the pumps for injecting water into the Reactor Cores of Unit Nos. 1, 2 and 3.  
May 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Sprayed resin, which is expected to prevent radioactive dusts from being blown by wind, to 4,000 m2 of the ground near Unit No. 3 and to 5,300 m2 near the Old Main Office Building.
May 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris around Unit Nos. 2 and 3 with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
9:40
- 15:45
  Poured 80 m3 of concrete to seal the Pit.    
10:09     Increased the rate to inject water into the Reactor Core, from 7 m3/h to 9 m3/h, due to the rising temperature in the Reactor Vessel.  
10:25
- 10:35
      Measured the level and the temperature of the water in the Storage Pool.
10:30
- 14:00
Workers sprayed 10,500 liters of resin to approximately 5,200 m2 of the ground around the Old Main Office Building
14:00
- 16:00
Sprayed 10,000 liters of resin to approximately 4,000 m2 of the ground near Unit No. 3 with an unmanned crawler dump.
May 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Built a duct to prevent the polluted air from escaping the door of the Reactor Building. Started a local ventilator. Began to sample dusts.
(Stopped the ventilator at 20:02, May 8.)
     
09:00
- 16:00
Continued removing debris around Unit Nos. 2 and 3 with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
10:30
- 14:00
Workers sprayed 10,500 liters of resin to approximately 5,350 m2 of the ground around the Old Main Office Building.
11:55
- 12:05
      Measured the level and the temperature of the water in the Storage Pool.
12:19
- 20:46
      Sprayed water to the Storage Pool with a concrete pumping truck.
13:00
- 16:00
Sprayed 10,000 liters of resin to approximately 4,000 m2 of the ground near Unit No. 2 with an unmanned crawler dump.
16:36 Started the all local ventilators, six in all, so as to prevent the polluted air from escaping the Reactor Building.      
May 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
09:36
- 11:16
  Supplied the Storage Pool with water.    
10:01 Increased the water into the Containment Vessl from 6 m3/h to 8 m3/h.      
10:30
- 14:00
Sprayed resin to approximately 5,200 m2 of the ground.
11:00
- 14:00
Sprayed resin to approximately 4,000 m2 of the ground around Unit No. 1 with an unmanned crawler dump.
12:38
- 17:51
      Sprayed 180 tons of water to the Storage Pool with a concrete pumping truck.
May 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Sprayed resin to approximately 5,150 m2 of the ground.
09:22   Temporarily stopped transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building, due to construction of pipes to inject water to the Reactor Core. Resumed transferring at 16:02.    
14:05
- 17:30
      Sprayed approximately 120 tons of water to the Storage Pool with a concrete pumping truck.
May 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00
- 17:00
  Continued the work to seal the Pit of the Trench.    
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment. Removed nine intermodal containers of debris.
10:30
- 14:00
Sprayed resin to approximately 5,100 m2 of the ground.
12:10
- 14:10
    Supplied the Storage Pool with approximately 60 tons of water.  
16:18     Began to transfer the water in the Condenser to the basement of the Turbine Building.  
20:08 Cut off part of the duct penetrating the double door of the Reactor Building.      
May 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Strontium-89 and strontium-90 were detected in soil at the three points, which are designated for regular sampling in the Power Station. The samples were taken on April 18.
      Radioactive nuclides found in the water of the Storage Pool, sampled on May 8, were:
   I-131  approximately 11,000 Bq/cm3 (not detectable on March 2)
   Cs-134   approximately 140,000 Bq/cm3 (not detectable on March 2)
   Cs-136  approximately 1,600 Bq/cm3 (not detectable on March 2)
   Cs-137  150,000 Bq/cm3 (not detectable on March 2)
 
04:01
- 04:17
Sampled dusts in the air out of the Reactor Building.      
04:17 Opened the double door of the Reactor Building.      
04:18
- 04:47
Workers entered the Reactor Building to survey the inside. The maximum radiation dose to the workers was 10.5 mSv.      
05:00 Confirmed that radiation dose did not increase significantly after the double door of the Reactor Building had been opened.      
05:10 Completed uninstallation of the Positive Pressure House.      
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
10:30
- 14:00
Sprayed resin to approximately 5,250 m2 of the ground.
12:14
- 15:00
    Supplied the Storage Pool with freshwater. Added corrosion inhibitor, approximately 0.5 m3 of hydrazine, to the water from 12:39 to 14:36.  
16:05
- 19:05
      Sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, approximately 0.23 m3 of hydrazine, to the water from 16:11 to 18:38.
May 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
      Began to install pipes to transfer contaminated water in the Turbine Building to the Central Radioactive Waste Building.  
  Sprayed resin to approximately 6,000 m2 of the ground around Unit Nos. 1 and 2 with an unmanned crawler dump.
  Sprayed resin to approximately 5,050 m2 of the ground.
  Measured radiation of several debris near the Large-Scale Door of the Reactor Building of Unit No. 3 with a TALON robot. Collected the debris with a Bobcat robot.
09:00
- 16:00
Continued removing debris in the site with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:01   Temporarily stopped transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building, due to construction of pipes to inject water to the Reactor Core of Unit No. 3.    
09:30
- 15:30
      Removed debris near the Large-Scale Door in preparation for construction of support structure of the Storage Pool.
09:31     Flushed pipes (- 11:51). Began to install pipes on the Turbine Building side.  
09:40
- 10:55
Corrected the water level gauges of the Pressure Vessel.      
13:09
- 14:45
  Supplied the Storage Pool with approximately 56 tons of freshwater. Added corrosion inhibitor, approximately 1.2 m3 of hydrazine, to the water from 13:19 to 14:35.    
May 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
      Welded an expansion plug to the Feedwater Line.  
08:47 Started temporary diesel generators to operate feedwater pumps of Unit Nos. 1, 2 and 3, due to construction of the external power grid.  
08:50 Temporarily stopped injecting nitrogen gas to the Containment Vessel, due to construction of the external power grid.      
09:00
- 16:00
Continued removing debris near the Turbine Building of Unit No. 3.
09:50
- 11:14
Corrected the pressure gauges of the Containment Vessel.      
10:30
- 16:00
Sprayed resin to approximately 5,250 m2 of the ground.
11:00
- 16:00
Sprayed resin to approximately 6,000 m2 of the ground near the Turbine Building of Unit No. 1.
12:30     Found water was flowing into the Cable Pit near the Screens of the discharging pipe into the sea. The level of the water in the Pit was not high. Sampled water for nuclide analysis. Attempting to find out where the water was going from the Pit.  
15:55 Resume to operate the feedwater pumps of Unit Nos. 1, 2 and 3 with power from the external grid.  
15:58 Resume to inject nitrogen gas to the Containment Vessel.      
16:07
- 19:38
      Sprayed approximately 120 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, hydrazine, to the water from 16:14 to 19:36.
18:45     Stopped the water into the Cable Pit by pouring concrete.  
May 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:00 Recognized that the water level in the Pressure Vessel was lower than the scale.      
10:30
- 14:00
Sprayed resin to approximately 5,250 m2 of the ground.
15:20   Resumed transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
16:53     Began to inject water through the Feedwater Line into the Pressure Vessel at the rate of 3 m3/h, while keeping supplying water through the Fire Extinguisher Line.  
May 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 1.
09:00
- 14:30
Sprayed resin to approximately 5,250 m2 of the ground.
11:00
- 15:00
Sprayed resin to approximately 6,000 m2 of the ground around Unit No. 1 with an unmanned crawler dump.
16:01     Decreased water into the Reactor Core through the Fire Extinguisher Line from 9 m3/h to 6 m3/h, while increased water through the Feedwater Line from 3 m3/h to 6 m3/h*.
* This fact was made public by TEPCO.
 
16:01
- 18:04
Remote controlled robots surveyed the inside of the Reactor Building.      
16:04
- 19:04
      Sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.12 m3 of hydrazine, to the water from 16:20 to 18:41.
May 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 3.
10:01     Increased water into the Reactor Core through the Fire Extinguisher Line from 6 m3/h to 9 m3/h, while keeping water through the Feedwater Line at the rate of 6 m3/h*.
* This fact was made public by TEPCO.
 
10:30
- 14:00
Sprayed resin to approximately 5,250 m2 of the ground.
10:50
- 11:13
Surveyed the inside of the Reactor Building of Unit No. 1, so as to install cooling systems.      
11:00
- 15:00
Sprayed resin to approximately 7,000 m2 of the ground around the Turbine Building of Unit No. 2 with an unmanned crawler dump.
13:00
- 14:37
  Supplied the Storage Pool with approximately 56 tons of water.    
15:07
- 15:18
Began to supply the Storage Pool with water. Suspended due to strong winds.      
May 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 3. Removed five intermodal containers of debris.
10:30
- 14:00
Sprayed resin to approximately 7,000 m2 of the ground.
13:28 Increased the water into the Reactor Core, from 8 m3/h to 10 m3/h, in order to watch the sensitivity of data of the Reactor Vessel and the Container Vessel.      
14:33
- 17:00
    Added 180 kg of sodium pentaborate to the water into the Reactor Core through the Fire Extinguisher Line.  
16:25
- 20:25
      Sprayed approximately 140 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.30 m3 of hydrazine, to the water from 16:26 to 18:30.
May 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near Unit No. 3 with a remote-contolled robot.
10:30
- 14:00
Workers sprayed resin to approximately 7,000 m2 of the ground.
11:00
- 15:45
Sprayed resin to approximately 6,550 m2 of the ground around the Turbine Building of Unit No. 1 with an unmanned crawler dump.
15:00
- 18:32
    Supplied the Storage Pool with approximately 106 tons of water through the line of the Fuel Pool Cooling Cleanup System. Added corrosion inhibitor, hydrazine, to the water.  
May 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris near the Turbine Building of Unit No. 3 with a remote-contolled robot.      
10:11     Increased water into the Reactor Core through the Feedwater Line from 6 m3/h to 9 m3/h, while keeping water through the Fire Extinguisher Line at the rate of 9 m3/h.  
10:30
- 14:00
Workers sprayed resin to approximately 6,550 m2 of the ground.
11:50 Decreased the water into the Reactor Core, from 10 m3/h to 6 m3/h.      
16:14
- 20:06
      Sprayed approximately 120 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, hydrazine, to the water from 16:40 to 18:35.
18:04     Began transferring the highly contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
May 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:00
- 14:30
Workers sprayed resin to approximately 6,750 m2 of the ground.
09:24
- 09:38
  Workers entered the Reactor Building to survey the inside.    
10:40 Had two barges leave the pier of the Power Station for preparation of arrival of a Mega-Float (a very large floating structure).
13:10
- 14:40
  Supplied the Storage Pool with approximately 53 tons of freshwater. Added corrosion inhibitor, hydrazine, to the water from 13:15 to 14:30.    
16:30
- 16:40
    Workers entered the Reactor Building to survey the inside.  
May 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
10:00
- 11:00
Sank seven sandbags of zeolite near the Bar Screen of Unit Nos. 1 and 2, and three near that of Nos. 3 and 4.
10:30
- 14:30
Workers sprayed resin to approximately 8,750 m2 of the ground.
16:30
- 19:30
      Sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck.
May 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Decontaminated one of the eight monitoring posts in the site, and laid a shield under the detector.
09:00
- 16:00
The government ordered TEPCO to submit a report on the installation of a substitute system for the Fuel Pool Cooling Cleanup Systemn in Unit No. 2.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed nine intermodal containers of debris.
09:30
- 12:15
Workers entered the Reactor Building. They checked the level of pooled water and measured radiation with a γ-camera.      
10:30
- 14:30
Workers sprayed resin to approximately 8,250 m2 of the ground.
14:15     Increased water into the Reactor Core through the Feedwater Line from 9 m3/h to 12 m3/h, while keeping water through the Fire Extinguisher Line at the rate of 9 m3/h.  
15:06
- 16:15
Sprayed approximately 60 tons of water to the Storage Pool with a concrete pumping truck, before suspended spraying due to strong winds.      
17:39
- 23:54
    Decreased water into the Reactor Core through the Fire Extinguisher Line from 9 m3/h to 8 m3/h at 17:39, to 7 m3/h at 20:43, and to 6 m3/h at 23:54.  
  TEPCO submitted a report to the Nuclear and Industrial Safety Agency on the quantities of radiation that leaked into the sea.
1.From April 1 to April 6500 m3 of highly contaminated water in the Turbine Building of Unit No. 2 leaked into the port of the Power Station. The radiation in the leaked water was 4.7 × 1015 Bq in total of representative three nuclides, I-131, Cs-134 and Cs-137.
2.From April 4 to April 1010,393 m3 of contaminated water in the Radioactive Waste Treatment Facility was released into the sea on emergent necessity. The radiation in the released water was 1.5 × 1011 Bq.
3.From May 10 to May 11250 m3 of highly contaminated water in the Turbine Building of Unit No. 3 leaked into the port of the Power Station. The radiation in the leaked water was 2.0 × 1013 Bq in total of representative three nuclides, I-131, Cs-134 and Cs-137.
May 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed eleven intermodal containers of debris.
09:35 A Mega-Float (a very large floating structure), which will be used to store contaminated water with low-level radiation, arrived at the pier of the Power Station.
Approx. 14:00 Injection of nitrogen was suspended due to high temperature of the compressor.      
15:12
- 15:15
    Replaced the fire pump to supply water through the Feedwater Line with an electric pump that was set up on high ground.  
16:00
- 19:56
      Sprayed approximately 130 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, hydrazine, to the water from 16:23 to 19:00.
17:11 Resumed injection of nitrogen gas with a back-up device at the rate of approximately 20 m3/h. Increased nitrogen, to the rate of approximately 26 m3/h, at 20:31.      
May 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed sixteen trees.
      Based on the actual quantity of water that had been pumped out, TEPCO revalued that the rate of transferred water from the basement of the Turbine Building to the Central Radioactive Waste Building had been 20 m3/h, instead of 12 m3/h.  
10:56 The back-up device to inject nitrogen gas stopped.      
11:23 Started pumps that were there to be installed in Unit Nos. 2 and 3 to inject nitrogen gas to the No. 1.      
12:30
- 13:50
Sampled air at the opened door of the Reactor Building with a portable dust sampler put on the nozzle of a concrete pumping truck.      
13:02
- 14:40
  Supplied the Storage Pool with approximately 56 tons of water with a temporary pump. Added corrosion inhibitor, 1.0 m3 of hydrazine, to the water from 13:04 to 14:03.    
15:33
- 17:09
Sprayed approximately 90 tons of freshwater to the Storage Pool with a concrete pumping truck. Sampled dusts in the air.      
May 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
  Decontaminated one of the eight monitoring posts in the site, and laid a shield under the detector.
11:00
- 15:30
Sprayed resin to approximately 6,000 m2 of the ground around the Turbine Building of Unit No. 3 with an unmanned crawler dump.
11:31
- 17:19
    Decreased water into the Reactor Core through the Fire Extinguisher Line from 6 m3/h to 5 m3/h at 11:31, to 4 m3/h at 14:08, and to 3 m3/h at 17:19, while keeping water through the Feedwater Line at the rate of 12 m3/h.  
16:00
- 19:09
      Sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.3 m3 of hydrazine, to the water from 16:08 to 18:30. Sampled dust in the air at the opened door from 14:17 to 14:37.
May 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
09:30
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
10:15
- 13:35
    Supplied the Storage Pool with approximately 100 tons of freshwater with a temporary pump. Added corrosion inhibitor, 0.8 m3 of hydrazine, to the water from 10:20 to 12:58.  
11:00
- 14:00
Sprayed resin to approximately 6,000 m2 of the ground around the Turbine Buildings of Unit Nos. 2 and 3 with an unmanned crawler dump.
May 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
      Corrected the reading of water into the Reactor Core through the Feedwater Line from 12 m3/h to 13.5 m3/h.  
09:05
- 15:30
  Temporarily stopped transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building, due to preparation for change of power supplies. Resumed the transfer at 15:30.    
09:10     Temporarily stopped transferring the highly contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building, due to checkup.  
09:14
- 09:18
15:16
- 15:18
Temporarily stopped the injection of nitrogen into the Containment Vessel for change of powers.      
09:30
- 13:30
Workers sprayed resin to approximately 8,750 m2 of the ground.
15:45 Confirmed the compressor to inject nitrogen had failed. Resumed the injection at the rate of 28 m3/h with another compressor at 19:44.      
16:36
- 20:04
      Sprayed approximately 121 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.3 m3 of hydrazine, to the water from 16:42 to 18:49.
May 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 7,875 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
10:06
- 11:36
  Supplied the Storage Pool with approximately 53 tons of water with a temporary pump. Added corrosion inhibitor, hydrazine, to the water from 10:10 to 11:10.    
13:30
- 16:00
Sprayed resin to approximately 6,000 m2 of the ground around the Reactor Building of Unit No. 1 with an unmanned crawler dump.
14:45
- 14:30, May 27
  Pumped water out of the Condenser to the basement of Turbine Building, in preparation for construction of pipe to the Pressure Vessel.    
15:19
- 15:32
  Workers entered the Reactor Building to sample dusts inside.    
16:01   Suspended transferring the highly contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
20:52     Decreased water into the Reactor Core through the Fire Extinguisher Line from 3 m3/h to 2 m3/h, while keeping water through the Feedwater Line at the rate of 13.5 m3/h.  
May 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 12:00
Removed a piece of debris emitting high radiation of 1,000 mSv/h near the Reactor Building of Unit No. 3.
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
10:30
- 12:00,
and around 15:00
Workers entered the Reactor Building to sample flooded water in the basement floor and to set up level gauges and hoses.      
11:25
- 16:00
Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 6,600 m2 of the walls of the Turbine Building.      
17:05
- 20:00
      Sprayed approximately 100 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.2 m3 of hydrazine, to the water from 17:24 to 18:53.
20:42     Decreased water into the Reactor Core through the Fire Extinguisher Line from 2 m3/h to 1 m3/h, while keeping water through the Feedwater Line at the rate of 13.5 m3/h.  
May 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
13:00
- 14:00
Workers sprayed resin to approximately 4,375 m2 of the ground.
13:28
- 15:08
    Supplied the Storage Pool with approximately 50 tons of water with a temporary pump. Added corrosion inhibitor, 0.38 m3 of hydrazine, to the water from 13:42 to 14:40.  
16:47
- 17:00
Carried out a leak test of the Fuel Pool Cooling Cleanup System.      
17:56
- 19:45
      Sprayed approximately 60 tons of freshwater to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.5 m3 of hydrazine, to the water from 18:02 to 19:45.
20:54     Stopped pumping water into the Reactor Core through the Fire Extinguisher Line, while keeping injection of water through the Feedwater Line at the rate of 13.5 m3/h.  
May 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
11:10
- 15:35
Supplied the Storage Pool with approximately 168 tons of freshwater with a temporary pump.      
11:33   Began to inject water through the Feedwater Line into the Reactor Core, while keeping injection through the Fire Extinguisher Line. The rates of injection were 7 m3/h through the Fire Extinguisher Line and 5 m3/h through the Feedwater Line.    
May 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:01
- 18:05
  Decreased water into the Reactor Core through the Fire Extinguisher Line from 7 m3/h to 2 m3/h at 00:01, to 1 m3/h at 10:38 and to 0 m3/h at 18:05, while keeping water through the Feedwater Line at the rate of 5 m3/h.    
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
12:06
- 13:52
  Supplied the Storage Pool with approximately 53 tons of water with a temporary pump.    
May 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
09:00
- 16:00
    Robots entered the Reactor Building for survey.  
10:19     Decreased water into the Reactor Core through the Feedwater Line from 13.5 m3/h to 12.5 m3/h.  
14:30 An explosive noise was heard near the Reactor Building of Unit No. 4 where a remote-contolled heavy equipment was removing debris. The noise was caused by a gas cylinder that was picked up by the equipment and blew up.
17:21   Began to circulate water in the Storage Pool through a substitute chiller. Set the circulation rate at 100 m3/h at 18:11, and decreased it to 80 m3/h at 01:47, June 1.    
20:30 Decreased water into the Reactor Core through the Feedwater Line from 6 m3/h to 5 m3/h.      
  * According to the governmental report to the International Atomic Energy Agency made public on June 7, the total amount of water injected into the Pressure Vessel was approximately 13,700 tons as of May 31. Approximately 5,100 tons of the water is estimated to have vapored in steam. The rest of the water is supposed to have leaked from the bottom of the Pressure Vessel. * According to the governmental report to the IAEA made public on June 7, the total amount of water injected into the Pressure Vessel was approximately 21,000 tons as of May 31. Approximately 7,900 tons of the water is estimated to have vapored in steam. The rest of the water is supposed to have leaked from the bottom of the Pressure Vessel. * According to the governmental report to the IAEA made public on June 7, the total amount of water injected into the Pressure Vessel was approximately 20,700 tons as of May 31. Approximately 8,300 tons of the water is estimated to have vapored in steam. The rest of the water is supposed to have leaked from the bottom of the Pressure Vessel.  
June 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:06
- 06:53
  Injected approximately 25 tons of freshwater into the Storage Pool through the Fuel Pool Cooling Cleanup System with a temporary pump.    
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed twelve intermodal containers of debris.
10:10     Decreased water into the Reactor Core through the Feedwater Line from 12.5 m3/h to 11.5 m3/h.  
11:00
- 13:30
  Began to spray silicate, encapsulant of radioactive material, with a water tower truck to 2,200 m2 of the walls of the Reactor Building.    
14:34
- 15:54
    Supplied the Storage Pool with approximately 40 tons of freshwater with a temporary pump. Added corrosion inhibitor, 0.14 m3 of hydrazine, to the water from 14:41 to 15:26.  
June 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,525 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed eleven intermodal containers of debris.
11:00
- 14:00
  Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 7,200 m2 of the walls of the Turbine Building.    
12:50
- 21:56, June 4
    Transferred water in the Condenser to the Condensate Storage Tank.  
June 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
10:30
- 15:00
    Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 4,800 m2 of the walls of the Turbine Building.  
12:21 Installed temporary pressure gauges to the primary cooling system to gauge the pressure in the Reactor Core.      
13:16
- 13:32
    Suspended the injection of water into the Reactor Core due to construction of a new injection line.  
13:49
- 14:09
  Suspended the injection of water into the Reactor Core due to construction of a new injection line.    
14:35
- 21:15
      Sprayed approximately 210 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 1 m3 of hydrazine, to the water from 14:44 to 18:58.
Around 15:00
- 17:00
Robots entered the Reactor Building for survey.      
18:39
- 12:28, June 4
  Transferred part of pooled water in the Trench of the Turbine Building to the Condenser.    
June 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 10,500 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
    Workers entered the Reactor Building for survey.    
09:57
- 10:02
13:43
- 13:56
Suspended the injection of water into the Reactor Core due to construction of a new injection line.      
10:00
- 12:00
      Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 7,200 m2 of the walls of the Turbine Building.
14:23
- 19:45
      Sprayed approximately 180 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.4 m3 of hydrazine, to the water from 14:51 to 18:41.
18:39
- 08:40, June 16
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
June 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
10:16
- 10:48
Supplied the Storage Pool with approximately 15 tons of freshwater with a temporary pump.      
13:08
- 15:14
Supplied the Storage Pool with approximately 60 tons of freshwater with a temporary pump. Added corrosion inhibitor, 0.12 m3 of hydrazine, to the water from 13:14 to 14:16.      
18:26
- 10:44, June 9
    Transferred pooled water in the Turbine Building to the Hotwell of the Condenser.  
June 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The Nuclear and Industrial Safety Agency reviewed its estimate of released radiation from the Fukushima Daiichi Nuclear Power Station into the atmosphere. The total radiation of the released nuclides in the first 120 hours after the earthquake was 7.7 × 1017 Bq in converted value to iodine-131. The estimate is based on the data submitted by TEPCO and certain probable suppositions, as contrasted with previous versions, made public on April 12, that did not deploy TEPCO's detailed data.
* The data that are marked with '*' were corrected by the Nuclear and Industrial Safety Agency on October 20.
Estimates of radioactive materials released into the atmosphere in the first 120 hours after the earthquake (Bq)
NuclidesHalf-livesUnit No. 1Unit No. 2Unit No. 3Total
Xe-1335.2 d3.4 × 10183.5 × 10184.4 × 10181.1 × 1019
Cs-1342.1 y7.1 × 10141.6 × 10168.2 × 10141.8 × 1016
Cs-13730.0 y5.9 × 10141.4 × 10167.1 × 10141.5 × 1016
Sr-8950.5 d8.2 × 10136.8 × 10141.2 × 10152.0 × 1015
Sr-9029.1 y6.1 × 10124.8 × 10138.5 × 10131.4 × 1014
Ba-14012.7 d1.3 × 10141.1 × 10151.9 × 10153.2 × 1015
Te-127m109.0 d2.5 × 10147.7 × 10146.9 × 10131.1 × 1015
Te-129m33.6 d7.2 × 10142.4 × 10152.1 × 10143.3 × 1015
Te-131m30.0 h 9.5 × 1013
*2.2 × 1015
5.4 × 1010
*2.3 × 1015
1.8 × 1012
*4.5 × 1014
9.7 × 1013
*5.0 × 1015
Te-132 78.2 h7.4 × 1014
*2.5 × 1016
4.2 × 1011
*5.7 × 1016
1.4 × 1013
*6.4 × 1015
7.6 × 1014
*8.8 × 1016
Ru-10339.3 d2.5 × 1091.8 × 1093.2 × 1097.5 × 109
Ru-106368.2 d7.4 × 1085.1 × 1088.9 × 1082.1 × 109
Zr-9564.0 d4.6 × 10111.6 × 10132.2 × 10111.7 × 1013
Ce-14132.5 d4.6 × 10111.7 × 10132.2 × 10111.8 × 1013
Ce-144284.3 d3.1 × 10111.1 × 10131.4 × 10111.1 × 1013
Np-2392.4 d3.7 × 10127.1 × 10131.4 × 10127.6 × 1013
Pu-23887.7 y5.8 × 1081.8 × 10102.5 × 1081.9 × 1010
Pu-23924065 y8.6 × 1073.1 × 1094.0 × 1073.2 × 109
Pu-2406537 y8.8 × 1073.0 × 1094.0 × 1073.2 × 109
Pu-24114.4 y3.5 × 10101.2 × 10121.6 × 10101.2 × 1012
Y-9158.5 d3.1 × 10112.7 × 10124.4 × 10113.4 × 1012
Pr-14313.6 d3.6 × 10113.2 × 10125.2 × 10114.1 × 1012
Nd-14711.0 d1.5 × 10111.3 × 10122.2 × 10111.6 × 1012
Cm-242162.8 d1.1 × 10107.7 × 10101.4 × 10101.0 × 1011
I-1318.0 d1.2 × 10161.4 × 10177.0 × 10151.6 × 1017
I-1322.3 h4.5 × 1014
*1.3 × 1013
9.6 × 1011
*6.7 × 106
1.8 × 1013
*3.7 × 1010
4.7 × 1014
*1.3 × 1013
I-13320.8 h6.5 × 1014
*1.2 × 1016
1.4 × 1012
*2.6 × 1016
2.6 × 1013
*4.2 × 1015
6.8 × 1014
*4.2 × 1016
I-1356.6 h6.1 × 1014
*2.0 × 1015
1.3 × 1012
*7.4 × 1013
2.4 × 1013
*1.9 × 1014
6.3 × 1014
*2.3 × 1015
Sb-1273.9 d1.7 × 10154.2 × 10154.5 × 10146.4 × 1015
Sb-1294.3 h1.6 × 1014
*1.4 × 1014
8.9 × 1010
*5.6 × 1010
3.0 × 1012
*2.3 × 1012
1.6 × 1014
*1.4 × 1014
Mo-9966.0 h 8.1 × 107
*2.6 × 109
1.0 × 104
*1.2 × 109
6.7 × 106
*2.9 × 109
8.8 × 107
*6.7 × 109
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
10:20 Removed a piece of debris emitting high radiation of 950 mSv/h near the Reactor Building of Unit No. 3.
15:56
- 18:35
      Sprayed approximately 90 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.2 m3 of hydrazine, to the water from 16:15 to 17:45.
June 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed ten intermodal containers of debris.
  The Government issued the Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety - The Accident at TEPCO's Fukushima Nuclear Power Stations -.
http://www.kantei.go.jp/foreign/kan/topics/201106/iaea_houkokusho_e.html
June 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
14:20
- 17:32
Power failed in Unit Nos. 1 and 2.
· Blackouts in the Control Rooms of Unit Nos. 1 and 2.
· The transfer of pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building was stopped.
· Two Monitoring Posts, Nos. 7 and 8, failed.
· Suspended the injection of nitrogen into the Containment Vessel of Unit No. 1 at 14:57.
The power was recovered at 17:32.
· The Monitoring Posts were recovered at 17:50.
· Resumed the injection of nitrogen at 17:54.
· Resumed the transfer of the water at 18:03.
   
15:00
- 15:40
Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 1,000 m2 of the walls of the Reactor Building.      
16:12
- 19:41
      Sprayed approximately 120 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.4 m3 of hydrazine, to the water from 16:16 to 18:05.
June 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 14:00
Sprayed silicate, encapsulant of radioactive material, with a water tower truck to the walls of the Reactor Building.   Sprayed silicate, encapsulant of radioactive material, with a water tower truck to the walls of the Reactor Building.  
11:47
- 12:14
    Workers entered the Reactor Building for survey.  
13:42
- 15:31
    Supplied the Storage Pool with approximately 55 tons of water with a temporary pump. Added corrosion inhibitor, 0.19 m3 of hydrazine, to the water from 13:45 to 14:40.  
June 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 4,375 m2 of the ground.
11:00
- 16:00
Sprayed silicate, encapsulant of radioactive material, with a water tower truck to the walls of the Turbine Building. Sprayed silicate, encapsulant of radioactive material, with a water tower truck to the walls of the Turbine Building and the Reactor Building.    
14:00
- 14:30
      Workers entered the Reacor Building for survey of the Srorage Pool.
June 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
12:42   Carried out an active test of a local ventilator in the Reactor Building from 11:45 to 12:19. Opened the double door of the Reactor Building at 12:39. Started the ventilator at 12:42    
15:30
- 17:01, June 12
    Transferred highly contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
June 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment.
June 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
10:00 Started a seawater circulation cleaning unit.
10:09
- 11:48
    Supplied the Storage Pool with freshwater with a temporary pump. Added corrosion inhibitor, 0.26 m3 hydrazine, to the water from 10:13 to 11:36.  
14:58
- 17:43
Transferred approximately 75 tons of water in the Condenser to the Turbine Building, in order to transfer the pooled water in the Turbine Building of Unit No. 2 to the Condenser of Unit No 1.      
16:36
- 21:00
      Sprayed approximately 150 tons of water to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.5 m3 hydrazine, to the water from 16:38 to 19:15.
June 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 8,750 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
03:45
- 14:00
Carried out an active test of caecium adsorption system for contaminated water.
10:05
- 08:46, June 16
    Resumed transferring the highly contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
12:14
- 13:31
  Suspended the injection of water into the Reactor Core of Unit No. 2, due to change of hoses, from 12:14 to 12:37.
Suspended the injection of water into the Reactor Core of Unit No. 3, due to change of hoses, from 13:02 to 13:31.
 
14:09
- 15:35
Injected water into the Reactor Core with a fire pump, due to change of hoses, Restarted an electric temporary pump at 15:50.      
16:10
- 20:52
      Sprayed approximately 150 tons of freshwater to the Storage Pool with a concrete pumping truck. Added corrosion inhibitor, 0.6 m3 hydrazine, to the water from 16:11 to 19:15.
June 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 7,000 m2 of the ground.
10:06 Decreased water into the Reactor Core through the Feedwater Line from 5 m3/h to 4.5 m3/h.      
10:33
- 09:52, June 16
Transferred the contaminated water in the Condenser to the Condensate Storage Tank.      
13:10
- 20:35
Carried out an active test of water decontamination system.
22:40
- 19:20, June 16
Carried out an active test of caecium adsorption system and decontamination system in series.
June 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 6,660 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
13:14
- 15:44
      Supplied approximately 75 tons of freshwater to the Storage Pool with a temporary spray line. Added corrosion inhibitor, 0.2 m3 of hydrazine, to the water from 13:48 to 15:18.
19:20 The active test of the water decontamination systems was suspended due to a water leak in the caecium adsorption system.
June 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 7,000 m2 of the ground.
10:19
- 11:57
    Supplied the Storage Pool with approximately 49 tons of freshwater with a temporary pump. Added corrosion inhibitor, 0.19 m3 hydrazine, to the water from 10:23 to 11:31.  
14:20   Began to transfer pooled water in the Trench of the Turbine Building of Unit No. 2 to the Condenser in the Turbine Building of Unit No. 1 at 14:20. Recognized the water did not flow, and stopped the pumps at 14:59. The cause is unknown. The cause was malfunction of a pump.    
20:00
- 00:54, June 18
Began the operation of the water decontamination systems. It was suspended at 00:54, June 18, because the level of radiation in the caecium adsorption system had reached where to change filters.
June 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 7,000 m2 of the ground.
10:00
- 10:00, June 20
Stopped the seawater circulation cleaning unit, due to maintenance.
13:00
- 15:00
      Sprayed silicate, encapsulant of radioactive material, with a water tower truck to 3,200 m2 of the walls of the Reactor Building. Achieved the task of spraying silicate to the walls and roofs of the Reactor Buildings and the Turbine Buildings.
13:31
- 00:02, June 20
    Resumed transferring the highly contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
16:05
- 19:23
      Supplied approximately 99 tons of freshwater to the Storage Pool with a temporary spray line. Added corrosion inhibitor, 0.8 m3 of hydrazine, to the water from 16:29 to 18:33.
Approx. 21:00 Confirmed water leak in the water decontamination systems while preparing to change filters.
June 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 6,610 m2 of the ground.
09:14
- 11:57
      Supplied approximately 80 tons of freshwater to the Reactor Well and the Dryer-Separator Pool.
  Due to construction of the Switching Station to Unit Nos. 1 and 2,  
Switched power supplies to inject water into the Reactor Core from the external electricity to diesel generators from 10:35 to 15:47, and suspended injection of nitrogen from 11:48 to 16:05. Switched power supplies to inject water into the Reactor Core from the external electricity to diesel generators from 10:49 to 15:35, suspended water circulation to the Storage Pool from 11:03 to 16:00, and stopped the local ventilator from 12:12 to 16:22. Switched power supplies to inject water into the Reactor Core from the external electricity to diesel generators, from 11:03 to 15:09.
19:30
- 23:45
Carried out an active test of caecium adsorption system with highly contaminated water.
20:46
- 05:00, June 20
  Workers entered the Reactor Building at 20:45. Slightly opened the double door of the Reactor Building at 20:51, and made it full open at 05:00, June 20.    
June 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
09:00
- 13:00
Workers sprayed resin to approximately 5,250 m2 of the ground.
09:49
- 09:52
10:06
- 11:29, June 21
      Resumed to supply freshwater to the Reactor Well and the Dryer-Separator Pool.
10:00
- 13:30
Sprayed resin to approximately 5,900 m2 of the ground with an unmanned crawler dump.
10:25
- 14:50
Carried out an active test of caecium adsorption system with highly contaminated water.
13:37
- 17:09, June 21
  Resumed to transfer pooled water in the Trench of the Turbine Building of Unit No. 2 to the Condenser of Unit No. 1.    
14:30   Opened the Large-Scale Door.    
June 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:45
- 07:20
Carried out an active test of water decontamination system. The system failed due to malfunction at 07:20
09:00
- 13:00
Workers sprayed resin to approximately 5,250 m2 of the ground.
10:00
- 13:30
Sprayed resin to approximately 5,900 m2 of the ground with an unmanned crawler dump.
10:02 Decreased water into the Reactor Core through the Feedwater Line from 4.5 m3/h to 4.0 m3/h.      
10:04   Decreased water into the Reactor Core through the Feedwater Line from 5 m3/h to 4.5 m3/h.    
10:06     Decreased water into the Reactor Core through the Feedwater Line from 11 m3/h to 10 m3/h.  
11:45
- 12:52
      Resumed to supply freshwater to the Reactor Well and the Dryer-Separator Pool.
11:55
- 18:03
Suspended the injection of nitrogen due to construction.      
12:16
-10:00, June 22
Resumed an active test of water decontamination system.
13:15
- 13:25
  Workers entered the Reactor Building for survey.    
15:32
- 09:58, June 28
    Transferred pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
June 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 13:00
Workers sprayed resin to approximately 5,250 m2 of the ground.
10:00
- 13:30
Sprayed resin to approximately 8,300 m2 of the ground with an unmanned crawler dump.
08:23
- 14:31
      Resumed to supply freshwater to the Reactor Well and the Dryer-Separator Pool.
09:56
- 15:10, July 7
(Temporarily suspended on June 27.)
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
10:00 Stopped the active test of water decontamination system due to flushing.
10:02 Decreased water into the Reactor Core through the Feedwater Line from 4.0 m3/h to 3.5 m3/h.      
10:04   Decreased water into the Reactor Core through the Feedwater Line from 4.5 m3/h to 4.0 m3/h.    
14:31
- 16:38
      Supplied freshwater to the Storage Pool with a temporary spray line.
June 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:43
- 13:00
Resumed the active test of water decontamination system. Stopped the test due to flushing at 13:00.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 5,160 m2 of the ground.
09:32
- 15:29
      Resumed to supply freshwater to the Reactor Well and the Dryer-Separator Pool.
10:13     Decreased water into the Reactor Core through the Feedwater Line from 10.0 m3/h to 9.5 m3/h.  
10:36
- 12:26
  Installed temporary pressure gauges to the Reactor Core.    
14:44
- 10:00, June 24
Resumed the active test of water decontamination system.
18:27 Began to inject water into the Reactor Cores of Unit Nos. 1 and 2 with the pump of Unit No. 1. Stopped the pump of Unit No. 2.    
June 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:58   A remote-contolled helicopter went down on the roof of the Reactor Building and failed. It had been sampling dust in the air.    
09:00
- 13:00
Workers sprayed resin to approximately 4,659 m2 of the ground.
09:00
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
10:00
- 13:30
Sprayed resin to approximately 5,400 m2 of the ground with an unmanned crawler dump.
10:07     Decreased water into the Reactor Core through the Feedwater Line from 9.5 m3/h to 9.0 m3/h.  
10:31
- 12:42
    Remote controlled robots surveyed radiation in the Reactor Building.  
12:50
- 10:00, June 25
Resumed the active test of water decontamination system.
12:50 Started a desalination unit.
June 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
10:00
- 13:30
Sprayed resin to approximately 2,400 m2 of the ground with an unmanned crawler dump.
10:00
- 10:00, June 28
Stopped the seawater circulation cleaning unit, due to maintenance.
15:00 Resumed the active test of water decontamination system.
15:24 The water decontamination system stopped due to an alarm by one of the two water level gauges in the oil separator. After the system was restarted, it stopped again due to the same alarm at 16:10. TEPCO concluded the alarms had been false, and re-restarted the system at 16:35.
June 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 4,490 m2 of the ground.
09:56
- 11:23
    Supplied approximately 45 tons of water and boric acid to the Water Cleanup System of the Storage Pool.  
10:00
- 18:10
Temporarily stopped the active test of the water decontamination system due change of adsorption tower vessels.  
June 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Temporarily switched power supplies to inject water into the Reactor Cores from the external electricity to diesel generators from 08:08 to 14:38, due to construction of external power.  
Suspended injection of nitrogen from 08:51 to 15:07. Suspended the substitute chiller of the Storage Pool through from 08:23 to 16:53, and the pump to transfer the contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building from 09:02 to 17:07.  
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
10:00
- 12:30
Sprayed resin to approximately 5,300 m2 of the ground with an unmanned crawler dump.
15:00
- 17:18
    Supplied approximately 60 tons of water and boric acid to the Water Cleanup System of the Storage Pool.  
16:20 Began to use water that had been processed with the decontamination system, as well as water from the filtration tank, to inject into the Reactor Cores of Unit Nos. 1, 2 and 3.  
17:55 Water leak was found in the decontamination system. The injection of the processed water into the Reactor Cores was suspended.  
June 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
09:00
- 13:00
Workers sprayed resin to approximately 5,410 m2 of the ground.
09:40
- 15:29
      Supplied water to the Reactor Well and the Dryer-Separator Pool.
14:36 Resumed to inject water that had been processed with the decontamination system into the Reactor Cores.  
15:00 A small amount of water was found to seep out of one of the pumps of the decontamination system. A worker put a saucer under the seeping point at 15:45. Additional seeping was not recognized.  
20:06   Began to inject nitrogen gas into the Containment Vessel.    
June 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:10 Two pinholes were found in hoses of the water decontamination system.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:30 Water leak was found in the desalination unit. Repaired at 10:30  
10:59 Stopped injecting water that had been processed with the decontamination system into the Reactor Cores. Changed the hoses that had pinholes.  
13:28
- 14:21
      Workers entered the 5th floor of the Reactor Building for survey.
13:33 Resumed to inject water that had been processed with the decontamination system into the Reactor Cores.  
13:49 Recognized that water into the Reactor Core was less than 3.5 m3/h, and increased it to 3.5 m3/h.      
14:45
- 15:53
    Supplied the Storage Pool with approximately 30 tons of freshwater with a temporary pump.  
14:53 Suspended the operation of the water decontamination system, due to an alarm that suggested water leank in the on-site bunker building.  
  Constructed stoplogs at the Intakes of Unit Nos. 1, 2, 3 and 4.
17:40 Water leak was found in the desalination unit. Repaired at 23:17.  
18:45 Restarted the water decontamination system.  
18:54 Suspended the water decontamination system.  
21:15 Restarted the water decontamination system.  
June 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
08:56
- 14:49, July 9
    Transferred pooled water in the Turbine Building to the Central Radioactive Waste Building.  
09:00
- 15:52, July 1
Suspended the operation of the desalination unit at 09:00, because a tank was full. Set another tank, and restarted the unit at 15:52, July 1.  
10:46
- 13:35
Suspended the water decontamination system for flushing.  
11:30
- 11:55
      Supplied freshwater to the Storage Pool with a temporary spray line.
13:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
17:00 Completed the construction of temporary seawall.
18:50 Restarted the water decontamination system.  
19:47     Started the Water Cleanup System of the Storage Pool.  
July 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
07:27
- 14:22, July 2
Suspended injecting water that had been processed with the decontamination system into the Reactor Cores, due to construction of buffer tanks.  
10:00
- 16:00, July 3
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:00     Began to circulate water in the Storage Pool through a substitute chiller.  
11:43
- 16:36
    Began to clean the 1st floor of the Reactor Building with remote-controlled robots. Other robots surveyed radiation from 10:59 to 12:14.  
July 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
10:00
- ?
Stopped the seawater circulation cleaning unit, due to maintenance.
10:30
- 13:45
Suspended the water decontamination system for flushing.  
10:59
- 12:14
    Surveyed radiation on the 1st floor of the Reactor Building with remote-controlled robots.  
July 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:30
- 16:00
    Laid steel plates near the Large-Scale Door to decrease radiation in the Reactor Building.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
10:39
- 12:50
Suspended the water decontamination system for flushing.  
July 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:40 Increased water into the Reactor Core, at 08:40, to the rate of 7.5 m3/h for flushing, as the rate had decreased to 3.0 m3/h. Reset the rate to 3.8 m3/h at 08:50.      
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
09:13
- 18:18
      Supplied water to the Reactor Well and the Dryer-Separator Pool.
13:30
- 17:00
Resumed to transfer contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
17:18
- 06:53, July 6
Transferred processed water to the buffer tanks.  
July 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
10:00
- 17:00
Resumed to transfer contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:30
- 13:20
Suspended the water decontamination system to change adsorption vessels.  
15:10
- 17:30
Supplied approximately 75 tons of water to the Water Cleanup System of the Storage Pool.      
July 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00
- 11:09, July 7
Suspended the desalination unit.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
15:24
- 17:10
    Surveyed radiation on the 1st floor of the Reactor Building with remote-controlled robots.  
July 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
04:52
- 23:30
Transferred processed water to the buffer tanks.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed nine intermodal containers of debris.
10:09
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:00
- 12:50
Suspended the water decontamination system to change adsorption vessels.  
July 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
02:45
- 04:44
Transferred processed water to the buffer tanks.  
08:20
- 14:24
    Suspended the substitute chiller of the Storage Pool of Unit No. 3, due to construction of a chiller in Unit No. 4.
08:22
- 13:52
      Supplied water to the Reactor Well and the Dryer-Separator Pool.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
10:00
- 12:04
Suspended the water decontamination system to change adsorption vessels.  
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:34
- 13:49
  Sampled dusts in the air on the 2nd and 3rd floors of the Reactor Building with robots.    
10:44
- 12:30
  Flushed the line from the Trench of the Turbine Building to the Central Radioactive Waste Building.    
13:35
- 13:44
    Workers on an aerial work platform surveyed the Reactor Building.  
13:51
- 07:35, July 9
Transferred processed water to the buffer tanks.  
15:22     Flushed the line from the Turbine Building to the Central Radioactive Waste Building.  
July 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 3.4 m3/h.    
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:00
- 10:30, July 13
Stopped the seawater circulation cleaning unit, due to maintenance.
15:59
- 12:11, July 10
Transferred processed water to the buffer tanks.  
July 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
04:53
- 17:06
Suspended the water decontamination system, due to water leakage.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
15:15
- 11:11, July 15
    Transferred pooled water in the Turbine Building to the Central Radioactive Waste Building.  
21:20
-
Transferred processed water to the buffer tanks. Decreased water to the tank from 23 m3/h to 18 m3/h at 16:22, July 13.  
July 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
July 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h.    
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
08:51
- 16:58
Suspended the water decontamination system, due to water leakage.  
11:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:22
- 12:03
      Supplied water to the Reactor Well and the Dryer-Separator Pool. Suspended due to water leak.
July 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.4 m3/h.      
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:09
- 11:02, July 15
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
11:00 Suspended the water decontamination system to change adsorption vessels. Water leakeage was found at 13:07.  
11:50
- 12:45
      Supplied water to the Reactor Well and the Dryer-Separator Pool. Suspended due to water leak.
July 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:30 The rate of the water into the Reactor Core was 3.5 m3/h.      
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
18:30 Restarted the water decontamination system.  
20:01     Began to inject nitrogen gas into the Containment Vessel.  
July 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:14
- 14:21
Suspended the water decontamination system, as the water flow had decreased for unknown causes.  
08:22
- 11:47
    Suspended the substitute chiller of the Storage Pool.  
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
08:55 Increased the rate of the water into the Reactor Core to 3.8 m3/h, after it had dropped to 3.3 m3/h.      
09:34
- 11:20
Open the silt fence at the water break, as ships entered and left the pier.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
13:05
- 19:15
      Supplied water to the Reactor Well and the Dryer-Separator Pool.
14:21 Restarted the water decontamination system.  
18:32
- 03:20, July 17
Transferred processed water in temporary tanks to buffer tanks.  
July 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.3 m3/h.    
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
10:00
- 15:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:50
- 13:41
Suspended the water decontamination system to change adsorption vessels.  
10:50
- 15:59, July 21
    Resumed to transfer pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
10:56
- 16:04, July 21
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
11:22
- 15:52
      Supplied water to the Reactor Well and the Dryer-Separator Pool.
July 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
10:06 Increased the rate of the water into the Reactor Core to 3.8 m3/h, after it had dropped to 3.0 m3/h.      
14:25 Began to inject water into the Reactor Cores of Unit Nos. 1 and 2 with the pump of Unit No. 2. Stopped the pump of Unit No. 1. Set the rate of the water into the Reactor Core of each Unit to 4.0 m3/h.    
July 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:55
- 16:05
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
08:30
- 14:40
    Began to cover holes of the Turbine Building with a temporary roof.  
  The rate of the water into the Reactor Core was 4.0 m3/h. The rate of the water into the Reactor Core was 4.1 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
11:00
- 14:59
Changed adsorption vessels of the water decontamination system.  
July 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  TEPCO released Progress status of "Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station."
http://www.tepco.co.jp/en/press/corp-com/release/11071905-e.html
TEPCO stated in the document that it had achieved the target of Step 1 of the Roadmap, 'radiation dose is in steady decline.'
08:30
- 15:00
    Continued the construction of a temporary roof to cover holes of the Turbine Building.  
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
10:10 The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h.    
11:00
- 15:03
Suspended the water decontamination system to change adsorption vessels.  
11:00
- 15:03
Suspended the water decontamination system to change adsorption vessels.  
July 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.7 m3/h.   The rate of the water into the Reactor Core was 9.0 m3/h.  
11:15
- 15:39
      Supplied water to the Dryer-Separator Pool.
July 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:38
-14:52
    Suspended the substitute chiller of the Storage Pool, due to construction of external grid.  
08:38
- 00:23, July 22
Suspended the water decontamination system, due to construction of external grid. Changed adsorption vessels.  
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.8 m3/h.   The rate of the water into the Reactor Core was 9.1 m3/h.  
July 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:06
- 06:02
  Flied an unmanned helicopter over the Reactor Building to sample dust in the air.    
07:10
- 11:50
    The substitute chiller of the Storage Pool was suspended, due to failure of a circuit breaker.  
07:10
- 15:37
The water decontamination system was suspended, due to failure of a circuit breaker.  
08:30
- 15:30
    Completed the construction of a temporary roof to cover holes of the Turbine Building.  
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
16:53
- 09:48, July 29
    Transferred pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
16:56
- 09:43, July 29
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
17:00
- 11:04, July 23
Supplied buffer tanks with water from the filtrate tank.  
July 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
03:24
- 11:45
    Suspended the substitute chiller of the Storage Pool, due to construction of external grid.  
04:37
- 06:08
    Flied an unmanned helicopter over the Reactor Building to sample dust in the air.  
08:45
- 15:26
The water decontamination system was suspended, due to construction of external grid.  
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
09:35 The rate of the water into the Reactor Core was 3.6 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.2 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
14:15
- 19:00
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
18:10
- 19:27
Transferred processed water in temporary tanks to buffer tanks.
July 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
04:28
- 05:57
Flied an unmanned helicopter over the Reactor Building to sample dust in the air.      
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
10:37
- 15:20
      Supplied water to the Dryer-Separator Pool.
11:10 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.3 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
11:27
- 15:11
Transferred processed water in temporary tanks to buffer tanks.
11:57
- 19:19
The desalination unit failed.  
12:30
- 16:35
Changed adsorption vessels of the water decontamination system.  
17:44
-
Supplied buffer tanks with water from the filtrate tank.  
20:00 Changed conpressors for injecting nitrogen gas into the Containment Vessel to the one that supplied the gas to the vessels of Unit Nos. 2 and 3.      
July 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
11:10 The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
10:29
- 10:48
Changed adsorption vessels of the water decontamination system.  
12:29
- 13:27
  Supplied the Storage Pool with 1 m3 of hydrazine through the substitute chiller.    
21:35
- 21:56
A pump failed in a line of the caecium adsorption system.  
July 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:59
- 16:01
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
11:10 The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
11:15
- 12:52
  Supplied the Storage Pool with 1.2 m3 of hydrazine through the substitute chiller.    
11:15
- 13:00
    Robots entered the Reactor Building for survey.  
11:37
- 14:06
Changed adsorption vessels of the water decontamination system.  
13:05
- 14:15
15:05
- 15:43
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
July 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
10:00
- 10:45
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure). The transfer was suspended due to water leak.
10:20
- 13:00
      Leak test of the primary line of the substitute chiller for the Storage Pool.
10:50
- 11:37
      Active test of the secondary line of the substitute chiller for the Storage Pool.
11:06
- 11:28
Changed adsorption vessels of the water decontamination system.  
12:00
- 12:40
    Workers entered the Reactor Building for survey.  
18:10 The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
July 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
09:30
- 11:10
11:30
- 11:50
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:08
- 10:08
      Pressure test of the primary line of the substitute chiller for the Storage Pool.
10:55
- 11:53
      Active test of the secondary line of the substitute chiller for the Storage Pool.
11:11
- 12:15
Changed adsorption vessels of the water decontamination system.  
14:33
- 18:50
      Supplied water to the Dryer-Separator Pool.
17:30   Set the rate of the water into the Reactor Core at 3.6 m3/h, after it had dropped to 3.2 m3/h.    
16:08
- 16:00, July 30
Transferred processed water in temporary tanks to the buffer tank.  
July 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:08
-
A pump failed in a line of the caesium adsorption system.  
08:45
- 16:10
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
10:03
- 16:09
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
10:20
- 10:35
12:25
- 12:45
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
10:37
- 12:50
Sampled gas in the Containment Vessel.      
11:00
- 11:34
Changed adsorption vessels of the water decontamination system.  
11:55
- 13:29
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
July 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed nine intermodal containers of debris.
09:15
- 09:30
12:05
- 12:20
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:12
- 12:57
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
11:30
- 13:35
Changed adsorption vessels of the water decontamination system.  
11:57 Set the rate of the water into the Reactor Core at 3.6 m3/h, after it had dropped to 3.4 m3/h. Set the rate of the water into the Reactor Core at 3.6 m3/h, after it had dropped to 3.3 m3/h. The rate of the water into the Reactor Core was 8.9 m3/h.  
13:16
- 14:47
      Supplied water to the Dryer-Separator Pool.
16:10
- 18:49, August 2
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
16:13
- 07:17, August 4
    Transferred pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
July 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:01 Set the rate of the water into the Reactor Core at 3.7 m3/h, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 3.7 m3/h, after it had dropped to 3.2 m3/h. The rate of the water into the Reactor Core was 8.9 m3/h.  
08:00
- 16:10
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
08:35
- 08:45
11:10
- 11:20
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
08:47
- 09:38
      Supplied approximately 25 tons of freshwater to the Storage Pool with a temporary spray line.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
  Water leakage was found on a hose of the desalination unit at 10:50. Suspended the pump at 11:15, and the unit at 11:20. After changing hoses, resumed the unit at 15:02.
12:44       Began to circulate water in the Storage Pool through a substitute chiller.
13:58
- 10:21, August 1
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
August 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:06
- 08:48
      Supplied approximately 20 tons of freshwater to the Storage Pool with a temporary spray line.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 8.9 m3/h.  
11:35
- 13:55
Changed adsorption vessels of the water decontamination system.  
11:50
- 12:15
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
14:30 Workers detected more than 10 Sv/h of radiation at the bottom of the Main Exhaust Stack of Unit Nos. 1 and 2.    
17:55
- 17:56
The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
August 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:19 More than 5 Sv/h of radiation was detected on the second floor of the Turbine Building.      
17:05
- 17:37
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
August 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:52 Suspended the injection of nitrogen into the Pressure Vessel till 08:33 to change pumps. Suspended the injection of nitrogen into the Pressure Vessel till 05:58 and between 08:27 and 08:29 to change pumps. Suspended the injection of nitrogen into the Pressure Vessel till 08:29 to change pumps.  
08:00
- 16:10
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:10
- 11:32
Changed adsorption vessels of the water decontamination system.  
August 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:32
- 15:30
Suspended the water decontamination system due to construction.  
07:09
- 16:56, August 9
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
08:00
- 16:10
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.4 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
15:42
- 16:02
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
17:50   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.2 m3/h.    
18:55
- 20:30
The water decontamination system was suspended due to malfunction of a pump.  
19:00 Water leak was found on a hose of the water decontamination system. Shut a valve and stopped the leakage.  
August 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
02:12
- 04:03
The water decontamination system was suspended due an alarm.  
08:42
- 16:46, August 15
    Transferred pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
08:45
- 16:45
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
09:02 Set the rate of the water into the Reactor Core at 3.9 m3/h, after it had dropped to 3.4 m3/h.      
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
15:20
- 17:51
Supplied approximately 75 tons of freshwater to the Storage Pool through the Fuel Pool Cooling Cleanup System.      
16:44
- 17:35
    Supplied the Storage Pool with freshwater.  
August 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:20
- 14:30
Suspended the desalination unit due to checkup.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
09:40
- 11:00
12:55
- 13:10
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:08
- 17:30
Changed adsorption vessels of the water decontamination system.  
August 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:05
-
A pump failed in a line of the water decontamination system.  
07:19 The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. Set the rate of the water into the Reactor Core at 9.0 m3/h, after it had increased to 9.5 m3/h.  
08:07
- 15:31
The water decontamination system was suspended due to failure of a pump.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
15:56
- 16:27
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
August 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:49
- 18:32
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 8.9 m3/h.  
10:00
- 17:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:07
- 14:01
Changed adsorption vessels of the water decontamination system.  
20:20
- 22:32
The water decontamination system was suspended, struck by lightning.  
August 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
01:50
- 09:35
The desalination unit was suspended by an alarm.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 8.9 m3/h.  
10:00
- 17:00, August 12
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure). The transfer was suspended from 10:12 to 13:35 on August 9, due to water leak.
10:39
- 11:13
  Sampled gas in the Containment Vessel.    
11:27
- 12:47
Changed adsorption vessels of the water decontamination system.  
August 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:32 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
08:59
- 09:19
Supplied approximately 100 tons of freshwater to the Storage Pool through the Fuel Pool Cooling Cleanup System.      
09:00 Began to construct the covering of the Reactor Building.      
10:06
- 14:19
Transferred contaminated water in the on-site bunker building to the Process Main Building.
11:21
- 15:00
Changed adsorption vessels of the water decontamination system.  
11:22 Began to circulate water in the Storage Pool through a substitute chiller.      
12:20 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had increased to 4.0 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had increased to 4.0 m3/h.    
12:45
- 13:20
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
13:08
- 13:47
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
16:22     Set the rate of the water into the Reactor Core at 9.1 m3/h, after it had dropped to 8.8-8.9 m3/h.  
16:47
- 11:43, August 16
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
August 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
11:00
- 12:21
Changed adsorption vessels of the water decontamination system.  
11:20       A small amount of water leak was found on a hose to the substitute chiller of the Storage Pool.
12:25
- 12:40
The water decontamination system was suspended, due to failure of a water level gauge.  
August 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
03:22       A small amount of water leak was found on another hose to the substitute chiller of the Storage Pool.
03:52 Set the rate of the water into the Reactor Core at 3.9 m3/h, after it had dropped to 3.2 m3/h.      
08:00
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
12:12
- 14:07
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
15:20
- 15:55
Supplied approximately 15 tons of freshwater to the Storage Pool through the Fuel Pool Cooling Cleanup System.      
18:17
- 22:59
The water decontamination system was suspended, due to an alarm.  
19:30   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 9.0 m3/h, after it had increased to 9.5 m3/h.  
August 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:11
- 12:01, Aug 15
The desalination unit was suspended due to a hose trouble.
09:30
- 09:30, August 15
Stopped the seawater circulation cleaning unit, due to maintenance.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
10:56
- 11:44
      Supplied approximately 24 tons of freshwater to the Storage Pool with a temporary spray line.
11:01
- 15:25
Changed adsorption vessels of the water decontamination system.  
16:41
-17:14
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
17:00
- 10:00, August 14
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
19:36 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h.      
August 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
11:00
- 15:16
Changed adsorption vessels of the water decontamination system.  
16:14
- 16:41
      Supplied approximately 13.5 tons of freshwater to the Storage Pool with a temporary spray line.
August 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
21:48   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
August 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
12:04
- 14:43, August 18
Suspended the water decontamination system, due to an active test of the second caesium adsorption system.  
13:28
- 13:40
Changed adsorption vessels of the water decontamination system.  
16:15
- 17:03
      Supplied approximately 25 tons of freshwater to the Storage Pool with a temporary spray line.
August 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:58
- 15:00
      Stopped the substitute chiller of the Storage Pool to change hoses.
08:50
- 17:25
Transferred contaminated water in the Miscellaneous Solid Waste Volume Reduction Treatment Building to the Process Main Building.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 9.0 m3/h.  
10:40
- 09:43, August 19
Stopped one of pumps in the water decontamination system, due to water leakage.  
15:38
- 16:00
      Supplied approximately 10 tons of freshwater to the Storage Pool with a temporary spray line.
15:46   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h.    
August 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:15
- 12:20
    Installed new valves to regulate water into the Reactor Core.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 9.1 m3/h.  
11:08
- 13:00
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
11:28
- 17:11
Supplied buffer tanks with water from the filtrate tank.  
12:27     Set the rate of the water into the Reactor Core at 8.0 m3/h.  
14:10
- 15:18
  Injected 10 tons of freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.    
16:19
- 10:03, August 25
  Transferred pooled water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
17:19
- 17:50
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
August 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
08:51
- 09:28, August 21
    Transferred pooled water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 8.0 m3/h.  
14:00
- 15:44
Resumed the water decontamination sysytem.  
15:30   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
August 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:00
Continued removing debris with a remote-contolled heavy equipment.
10:24       Started up a desalination unit for the Storage Pool at 10:24. The unit was suspended at 10:42 due to an alarm. Restarted the unit at 11:34.
11:00
- 14:54
Changed vessels of the water decontamination system.  
11:00
- 12:00, August 23
Stopped the seawater circulation cleaning unit for maintenance.
13:00     Set the rate of the water into the Reactor Core at 7.0 m3/h.  
August 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
09:39
- 09:30, August 24
    Transferred contaminated water in the basement of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.  
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
11:00
- 14:54
Changed vessels of the water decontamination system.  
11:02
- 11:30
Transferred contaminated water in the on-site bunker building to the Process Main Building.
August 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:07
- 20:15
Stopped the second caesium adsorption system to change vessels. 3 Sv/h of radiation was detected in one of the pipes of the system.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
10:34
- 18:26
      The desalination unit was suspended due to an alarm.
11:30
- 14:34
Changed vessels of the water decontamination system.  
August 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:10
- 15:07
Stopped the second caesium adsorption system to change vessels.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
10:35
- 12:29
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
16:00
- 20:35
Changed vessels of the water decontamination system.  
16:15
- 09:46, August 30
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
17:32     An alarm on the substitute chiller of the Storage Pool, warning low pressure in a pump. Supplied the Storage Pool with freshwater from 18:04 to 18:44.  
August 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
09:00
- 12:35
    Sampled dusts at the door of the Reactor Building.  
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
11:05
- 11:35
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
11:58
- 12:37
      Supplied approximately 20 tons of freshwater to the Storage Pool with a temporary spray line.
12:30       A small amount of water leakage was found on a hose of the substitute chiller of the Storage Pool.
August 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris. The heavy equipment gave damage to the pipe of the voltage converter of Unit No. 3, causing leakage of the transformer oil.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
10:03
- 09:31, August 30
  Transferred pooled water in the Trench of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.    
11:04
- 15:15
Changed vessels of the water decontamination system.  
August 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:32
- 18:04
Stopped the second caesium adsorption system to change vessels.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed nine intermodal containers of debris.
10:20
- 10:50
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
11:01
- 13:58
Changed vessels of the water decontamination system.  
14:21
- 16:54
The water decontamination system was suspended because one of the pumps in the system had failed.  
16:52
- 17:28
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
August 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed ten intermodal containers of debris.
09:25
- 09:30, August 29
Stopped the seawater circulation cleaning unit for maintenance.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 7.1 m3/h.  
23:45
- 10:54, August 28
The desalination unit of the decontamination system was suspended due to an alarm.  
August 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:10
- 14:25
Sampled dusts at the door of the Reactor Building.      
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 7.1 m3/h.  
11:01
- 11:12
Changed vessels of the water decontamination system.  
11:05
- 12:12
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
16:04
- 16:37
      Supplied approximately 16.5 tons of freshwater to the Storage Pool with a temporary spray line.
August 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:00
-
The desalination unit of the decontamination system was suspended due to an alarm.  
07:08
- 14:25
Stopped the second caesium adsorption system to change vessels.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
09:45
- 09:30, September 6
The seawater circulation cleaning unit was suspended because a pinhole was found.
10:35
- 13:20
  Sampled dusts at the blowout panels of the Reactor Building.    
August 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
09:39
- 09:35, September 13
  Transferred contaminated water in the Trench of the Turbine Building to the Central Radioactive Waste Building.    
09:54
- 09:11, September 8
    Transferred contaminated water in the basement of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.  
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
11:04
- 14:25
Changed vessels of the water decontamination system.  
11:05
- 13:00
    Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.  
16:05
- 16:37
      Supplied approximately 15 tons of freshwater to the Storage Pool with a temporary spray line.
18:56   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
August 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
11:07
- 11:31
Changed vessels of the water decontamination system.  
11:30
- 13:00
    Installed flexible hoses to inject water to the Reactor Core through the Core Spray Line.  
        Pooled water was found in the liner drain of the Storage Pool. The cause was unknown. The water was supposed to flow in the basement of the Reactor Building.
15:00 Water leak was found in one of the coagulation and settling units of the water decontamination system.  
September 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
09:16
- 16:04
Changed vessels of the second caesium adsorption system.  
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 7.0 m3/h.  
11:00
- 13:00
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
14:09
- 14:58
    Began to inject water to the Reactor Core through the Core Spray Line at 14:09, as well as through the Feedwater Line. The rate of the water through the Feedwater Line was 7 m3/h, while one through the Core Spray Line was 1 m3/h at 14:58.  
15:20 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h.      
September 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
07:17   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 6.8 m3/h, while one through the Core Spray Line was 1.2 m3/h.  
11:06
- 11:22
Changed vessels of the water decontamination system.  
14:50     Set the rate of the water into the Reactor Core through the Core Spray Line at 2 m3/h, while keeping one through the Feedwater Line at 7 m3/h.  
September 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:40 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 7 m3/h, while one through the Core Spray Line was 2 m3/h.  
14:37     Set the rate of the water into the Reactor Core through the Core Spray Line at 3 m3/h, while keeping one through the Feedwater Line at 7 m3/h.  
16:20
- 17:08
      Supplied approximately 16.6 tons of freshwater to the Storage Pool with a temporary spray line.
September 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:24
- 17:01
Changed vessels of the second caesium adsorption system.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 7 m3/h, while one through the Core Spray Line was 3 m3/h.  
11:31
- 14:32
Changed vessels of the water decontamination system.  
September 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 7 m3/h, while one through the Core Spray Line was 3 m3/h.  
10:59
- 12:47
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
11:30
- 14:25
Changed vessels of the water decontamination system.  
14:35
- 15:05
Supplied approximately 15 tons of freshwater to the Storage Pool through the Fuel Pool Cooling Cleanup System.      
14:43     Set the rate of the water into the Reactor Core through the Feedwater Line at 6 m3/h, while keeping one through the Core Spray Line at 3 m3/h.  
September 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:51
-
One of the three water decontamination systems was suspended at 05:51, as a motor of a coagulation and settling unit had failed. After restarting the motor, two of the decontamination systems were suspended at 06:21, due to an alarm. Successfully restarted the motor at 15:13.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 6 m3/h, while one through the Core Spray Line was 3 m3/h.  
10:03
- 10:42
  Stopped the substitute chiller to clean tanks.    
10:11
- 14:54
  Transferred contaminated water in the Condenser to the Turbine Building.    
16:09
- 16:52
      Supplied approximately 22 tons of freshwater to the Storage Pool with a temporary spray line.
16:27   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
September 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:05
- 14:17
Stopped the second caesium adsorption system to change vessels.  
  The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 6 m3/h, while one through the Core Spray Line was 3 m3/h.  
10:00
- 16:07
  Transferred contaminated water in the Condenser to the Turbine Building.    
10:19
- 16:01
Transferred contaminated water in the on-site bunker building to the Process Main Building.
10:20
- 10:45
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
11:28
- 14:53
Changed vessels of the water decontamination system.  
11:30       A small amount of water leak was found from a hose of the primary line of the substitute chiller.
14:46
- 14:55
Set the rate of the water into the Reactor Core at 3.8 m3/h at 14:53, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h at 14:55, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line at 5.0 m3/h at 14:46, while keeping one through the Core Spray Line at 3.0 m3/h.  
September 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:00
- 12:08
The second caesium adsorption system was suspended due to operator error.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
09:30
- 09:35, September 11
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 5 m3/h, while one through the Core Spray Line was 2.9 m3/h.  
22:33   Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
September 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eleven intermodal containers of debris.
09:58
- 10:17
Changed vessels of the water decontamination system.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 5 m3/h, while one through the Core Spray Line was 2.9 m3/h.  
10:40
- 11:20
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
14:34
- 15:14
      Supplied approximately 19 tons of freshwater to the Storage Pool with a temporary spray line.
September 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed eight intermodal containers of debris.
09:57
-
Stopped the seawater circulation cleaning unit, due to maintenance.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 5 m3/h, while one through the Core Spray Line was 2.9 m3/h.  
10:04
- 10:25
Changed vessels of the water decontamination system.  
September 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 12:50
Changed vessels of the second caesium adsorption system.  
09:45
- 13:30
Sampled dusts at the door of the Reactor Building.      
10:00
- 09:44, September 15
    Transferred contaminated water in the basement of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.  
17:40 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h.    
September 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:05
- 09:35
    Sampled dusts at the door of the Reactor Building.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 5 m3/h, while one through the Core Spray Line was 3 m3/h.  
10:03
- 10:19
Changed vessels of the water decontamination system.  
14:01     Set the rate of the water into the Reactor Core through the Feedwater Line at 4 m3/h, while keeping one through the Core Spray Line at 3 m3/h.  
16:06
- 16:48
      Supplied approximately 19 tons of freshwater to the Storage Pool with a temporary spray line.
September 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
03:58
- 19:20, September 14
Stopped the (first) caesium adsorption system for maintenance.  
08:45
- 16:45
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:51
- 13:16, October 4
  Transferred contaminated water in the Trench of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
16:45
- 17:24
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
18:07 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.6 m3/h. Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.    
September 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:15
- 12:10
Sampled gas inside the Containtment Vessel.      
09:47
- 12:25
      Stopped the desalination unit due to construction to install an electrodialyser.
09:53
- 14:35, September 16
Transferred pooled water in the Condenser to the Turbine Building.      
14:59   Started to inject water to the Reactor Core through the Core Spray Line at 14:59, as well as through the Feedwater Line. The rate of the water through the Core Spray Line was 1.0 m3/h at 15:25.    
September 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
08:55
- 14:10
Changed vessels of the second caesium adsorption system.  
09:54
- 09:46, September 30
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
15:45   Set the rate of the water into the Reactor Core through the Core Spray at 2.0 m3/h, while keeping one through the Line Feedwater Line at 3.9 m3/h.    
18:22 The (first) caesium adsorption system and the decontamination system were found malfunctioning. Stopped them to probe the cause at 18:22. Restarted the adsorption system at 18:42.  
September 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
09:11   Set the rate of the water into the Reactor Core through the Core Spray at 2.0 m3/h, after it had dropped to 1.8 m3/h.    
  The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 4 m3/h, while one through the Core Spray Line was 3 m3/h.  
10:16
- 14:15
    Injected boric acid to the Reactor Core.  
10:35
- 11:19
      Supplied approximately 23 tons of freshwater to the Storage Pool with a temporary spray line.
10:54
- 14:50
Suspended the second caesium adsorption system at 10:54, as the water flow had decreased. After changing control boards, restarted the system at 14:50.  
15:05
- 15:41
Set the rate of the water into the Reactor Core at 3.8 m3/h at 15:41, after it had dropped to 3.5 m3/h. Set the rate of the water into the Reactor Core through the Core Spray at 3.0 m3/h at 15:35, while keeping one through the Line Feedwater Line at 3.9 m3/h. Set the rate of the water into the Reactor Core through the Core Spray at 8 m3/h at 15:05, while keeping one through the Line Feedwater Line at 4 m3/h.  
September 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
  The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 2.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 12:00, September 26
Stopped the seawater circulation cleaning unit, due to maintenance.
10:05
- 11:05
  Sampled dust in the air at the opened door of the Reactor Building.    
13:55
- 14:34
  Injected approximately 8 tons of freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.    
14:43
- 15:43
  Sampled dust in the air at the opened door of the Reactor Building.    
September 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment.
09:25
- 09:55
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 2.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:54
- 11:31
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
11:26       Began to operate the electrodialyser in the desalination unit.
16:18
- 17:02
      Supplied approximately 22 tons of freshwater to the Storage Pool with a temporary spray line.
September 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:08
- 12:57
Stopped the second caesium adsorption system to change vessels.  
15:16   Set the rate of the water into the Reactor Core through the Core Spray at 4.0 m3/h, while keeping one through the Line Feedwater Line at 3.9 m3/h.    
September 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.6 m3/h, while one through the Core Spray Line was 4.0 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
September 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 15:30
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.6 m3/h, while one through the Core Spray Line was 4.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
11:40 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had been 3.7 m3/h. Set the rate of the water into the Reactor Core through the Core Spray from 4.1 m3/h to 4.0 m3/h, while setting one through the Line Feedwater Line from 3.5 m3/h to 4.0 m3/h.    
13:00       A small amount of water leak was found on a hose to the substitute chiller of the Storage Pool.
  There was a leak of rain in the roof over the vistors' area of the Control Room of Unit Nos. 1 and 2. There was a leak of rain in the roof of Turbine Building.  
21:47
- 22:02
Suspended the second caesium adsorption system, because it was confirmed that workers had installed wrong vessels.  
September 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:00
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 4 m3/h, while one through the Core Spray Line was 4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
15:17
- 15:36
  Set the rate of the water into the Reactor Core through the Core Spray Line at 5.0 m3/h at 15:36. Set the rate of the water into the Reactor Core through the Feedwater Line at 3 m3/h, and the one the Core Spray Line at 8.0 m3/h at 15:17.  
17:12
- 09:46, September 25
  Installed an additional pump to transfer contaminated water in the Trench of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.    
September 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:42
- 16:53
Stopped the second caesium adsorption system to change vessels.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 4 m3/h, while one through the Core Spray Line was 5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.9 m3/h.  
September 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed ten intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 8 m3/h.  
11:35
- 12:05
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
20:30
- 17:02, September 25
The second caesium adsorption system was automatically suspended, because an air compressor had failed.  
September 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 5.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 8 m3/h.  
18:00 The Nuclear and Industrial Safety Agency gave oral directions to the TEPCO that:
  1. the utility should find out the concentration of hydrogen in the Containment Cooling System (of Unit No. 1), and take proper measures such as exhausting or replacing the gas, before continuing tasks;
  2. because there are possibilities that hydrogen is also encased in the other systems, the utility should take careful actions such as measuring concentration of hydrogen before starting a work on the systems;
  3. the utility should endeavor to find out the concentration of hydrogen in the Containment Vessel;
  4. the utility should also take the same actions on Unit Nos. 2 and 3.
 
September 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 5.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 7.9 m3/h.  
15:05   Set the rate of the water into the Reactor Core through the Core Spray Line at 6.0 m3/h.    
18:17 A pump failed in one of the lines of the (first) caesium adsorption system.  
September 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:27
- 11:30
Stopped the (first) caesium adsorption system, due to construction of a monitoring system.  
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8 m3/h.  
13:57
- 15:48
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
September 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8 m3/h.  
10:39
- 12:22
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
September 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed seven intermodal containers of debris.
08:52
- 16:47
Stopped the second caesium adsorption system to change vessels.  
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 8 m3/h.  
10:45
- 11:15
Opened the silt fence near the Water Intakes due to construction of sheet piles to prevent contaminated water from spreading into the sea.
13:20
- 15:10
    Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.  
September 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
09:50
- 09:50, October 3
Stopped the seawater circulation cleaning unit due to maintenance.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 13:16, October 12
    Transferred contaminated water in the basement of the Turbine Building to the Incineration of the Central Radioactive Waste Building.  
14:19
- 17:38
The (first) caesium adsorption system was suspended because a pump in the system had failed.  
15:00
- 19:26
    Stopped the substitute chiller because of installation of a transformer.  
October 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8 m3/h.  
October 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
October 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:54
- 15:03
      Stopped the secondary line of the substitute chiller of the Storage Pool due to construction.
08:55
- 12:05
Sampled dusts at the door of the Reactor Building.      
10:37
- 15:37
Transferred contaminated water in the on-site bunker building to the Process Main Building.
10:59
- 10:22, October 9
    Transferred pooled water in the Condenser to the Turbine Building.  
13:34
- 14:41
      Supplied approximately 15.4 tons of freshwater to the Storage Pool with a temporary spray line.
October 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:30
- 19:05
Stopped the second caesium adsorption system to change vessels.  
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 6.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.4 m3/h, while one through the Core Spray Line was 8 m3/h.  
15:00   Set the rate of the water into the Reactor Core through the Core Spray Line at 7.0 m3/h.    
October 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:26
- 10:26
  Sampled dusts at the blowout panels of the Reactor Building.    
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.8 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:31
- 11:27
  Injected approximately 8.6 tons of freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.    
October 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:28 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.5 m3/h.      
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.7 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
13:48
- 09:07, October 12
  Transferred contaminated water in the basement of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
14:13
- 15:47
    Sampled dusts over the roof of the Reactor Building.  
17:38   Set the rate of the water into the Reactor Core at 3.8 m3/h.    
October 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
11:30
- 14:03
Sampled dusts at the Equipment Hatch and at the the Large-Scale Door.      
  The rate of the water into the Reactor Core was 4.0 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.7 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:32
- 12:32
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
14:06
- 15:50
Began to spray water to logged trees and the ground on the site of the Power Station, in order to prevent the logs from combusting spontaneously and radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
October 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:30
- 15:25
Sprayed water to logged trees and the ground on the site of the Power Station, in order to prevent the logs from combusting spontaneously and radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.7 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:03
- 09:55, October 10
Stopped the seawater circulation cleaning unit, due to maintenance.
October 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
17:07
- 22:30
Began to cut a pipe of the Containment Spray Line, after having purged hydrogen out of the line and confirmed that the concentration of hydrogen inside was low enough, in order to install a system for controlling gases in the Containment Vessel. Finished cutting the pipe at 22:30. Sealed the pipe at 00:37, October 10.      
October 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
October 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:40
- 13:50
Sprayed water to logged trees and the ground on the site of the Power Station, in order to prevent the logs from combusting spontaneously and radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.6 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8 m3/h.  
13:45
- 15:17
    Sampled dusts over the roof of the Reactor Building.  
October 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:41
- 10:08
    Sampled dusts over the roof of the Reactor Building.  
09:10
- 12:30
Sprayed water to logged trees and the ground on the site of the Power Station, in order to prevent the logs from combusting spontaneously and radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.6 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8 m3/h.  
14:17
- 15:17
Sampled dusts over the roof of the Reactor Building.      
October 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:40
Sprayed water to logged trees and the ground on the site of the Power Station, in order to prevent the logs from combusting spontaneously and radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 12:00
  Sampled dusts in the Reactor Building.    
13:05
- 14:50
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
14:02
- 09:16, October 18
    Transferred contaminated water in the basement of the Turbine Building to the Incineration of the Central Radioactive Waste Building.  
14:17
- 09:10, October 18
  Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.    
October 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
October 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 12:38
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:20
- 09:35, October 17
Stopped the seawater circulation cleaning unit, due to maintenance.
October 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:06
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
October 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
09:10
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8 m3/h.  
10:28
- 12:06
  Supplied the Storage Pool with hydrazine through the substitute chiller.    
October 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed two intermodal containers of debris.
09:00
- 10:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.0 m3/h.  
06:09
- 17:55, October 19
Stopped the (first) caesium adsorption system due to construction.  
09:04
- 13:29, October 19
Stopped the second caesium adsorption system due to construction.  
17:55   Set the rate of the nitrogen gas into the Containment Vessel at 14 m3/h.    
October 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed six intermodal containers of debris.
09:00
- 10:20
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:44
- 14:05
Transferred contaminated water in the on-site bunker building to the Process Main Building.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
Workers looked around the Isolation Condenser and reported that they could not find any cracks which might have caused Loss of Coolant, and that the valves (2A, 2B) of the Condenser had been opened.      
16:43
- 17:29
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
21:06 A pump failed on one of the lines of the caesium adsorption system.  
October 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
09:17
- 12:00
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.5 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 09:16, October 28
    Transferred pooled water in the basement of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.  
10:12
- 09:32, October 28
  Transferred pooled water in the Trench of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building. One of the two pumps failed at 09:34, October 24.    
13:01
- 14:41
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
14:00
- 15:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
October 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:10
- 11:07
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.4 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:20
- 11:52
  Injected water into the temporary water-level gauge in an attempt to restore the original gauge.    
October 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:05
- 09:58
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:20
- 09:45, October 24
Stopped the seawater circulation cleaning unit, due to maintenance.
10:35
- 09:07, October 24
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
October 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
October 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment.
09:00
- 10:45
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 3.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 11:30
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
October 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed an intermodal container of debris.
09:00
- 10:15
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:50
- 15:51
Some of the Reactor supervisory instruments were blacked out due to construction.    
  The rate of the water into the Reactor Core was 3.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 11:30
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:31
- 11:31
  Sampled dusts at the blowout panels of the Reactor Building.    
11:31
- 12:31
Sampled dusts at the Equipment Hatch and at the Large-Scale Door.      
14:22 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.4 m3/h.      
17:31
- 14:01, October 26
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
18:10 Set the rate of the water into the Reactor Core at 3.8 m3/h, after it had dropped to 3.0 m3/h at 17:48.      
18:52   Set the rate of the water into the Reactor Core at 3.0 m3/h through the Feedwater Line, after it had dropped to 2.7 m3/h.    
October 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed four intermodal containers of debris.
08:48
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:47 Set the rate of the water into the Reactor Core at 3.8 m3/h, in preparation for changing pumps due to construction. Changed pumps at 16:10. Set the rate of the water into the Reactor Core at 3.0 m3/h through the Feedwater Line, and at 7.0 m3/h through the Core Spray Line, in preparation for changing pumps due to construction. Changed pumps at 15:20. Set the rate of the water into the Reactor Core at 3.0 m3/h through the Feedwater Line, and at 8.0 m3/h through the Core Spray Line.  
10:06
- 11:28
    Changed regulating valves of the water into the Reactor Core.  
10:10
- 12:06
The water level gauges of the buffer tank and other instruments were blacked out due to construction to multiply power supplies.
13:05
- 13:42
  Replaced hydrogen gas with nitrogen in the Flammability Control System, due to construction of a gas control system to the Containment Vessel. The concentration of hydrogen in the system had been found 6.5 % on October 20. Confirmed the concentration was 0 % at 13:42.    
13:17
- 15:15
Cut a pipe of the Shutdown Cooling System after having confirmed that the concentration of hydrogen gas was less than 0.1 % in the system, due to construction of a gas control system to the Containment Vessel.      
October 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed three intermodal containers of debris.
08:57
- 10:53
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:55
- 14:35
  Used a reserve pump due to construction to add a regulating valve of the water into the Reactor Core.    
  The rate of the water into the Reactor Core was 3.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.0 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 8.0 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
13:30
- 15:08
    Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.  
October 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Began the construction of the underground wall to prevent contaminated groundwater from going out into the sea.
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:30
- 10:20
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:30
- 13:30
Used a reserve pump due to construction to change regulating valves of the water into the Reactor Core. Used a reserve pump due to construction to change regulating valves of the water into the Reactor Core.    
09:54
- 10:02, October 31
  Transferred contaminated water in the Trench of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
  The rate of the water into the Reactor Core was 3.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8.0 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
13:30 Set the rate of the water into the Reactor Core at 3.9 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line at 3 m3/h, and one through the Core Spray Line at 7.0 m3/h.    
13:30 Set the rate of the water into the Reactor Core at 4.5 m3/h.      
16:10 Set the rate of the water into the Reactor Core at 4.5 m3/h.      
18:00   Started up a gas control system.    
  Completed the construction of the cover of the Reactor Building to prevent radioactive materials from speading out.      
October 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:45
- 16:15
Continued removing debris with a remote-contolled heavy equipment. Removed five intermodal containers of debris.
09:03
- 12:54, October 31
  Stopped the seawater circulation cleaning unit, due to maintenance.    
09:05
- 10:53
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:47
- 10:19
Supplied approximately 12 tons of freshwater to the Storage Pool through the Fuel Pool Cooling Cleanup System.      
  The rate of the water into the Reactor Core was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
15:30 Set the rate of the water into the Reactor Core at 5.5 m3/h.      
18:10   Set the rate of the nitrogen gas into the Containment Vessel from 14 m3/h to 16.5 m3/h. The concentration of hydrogen gas in the gas control system had been 1 % at 18:00, October 28, and 2.3 % at 17:00, October 29.    
October 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
15:05 Set the rate of the water into the Reactor Core at 6.5 m3/h.      
18:10   Set the rate of the nitrogen gas into the Containment Vessel at 21 m3/h. The concentration of hydrogen gas in the gas control system had been 2.7 % at 17:00, October 30.    
October 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:37
- 17:03
Stopped the second caesium adsorption system to change vessels.  
09:35
- 11:45
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 6.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 6.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:12
- 11:50
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
14:59 Set the rate of the water into the Reactor Core at 7.5 m3/h.      
15:32
- 16:12
      Supplied approximately 10 tons of freshwater to the Storage Pool with a temporary spray line.
November 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:10
- 09:53
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 7.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.4 m3/h, while one through the Core Spray Line was 6.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 16:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
11:23
- 13:23
  Sampled dusts at the blowout panels of the Reactor Building.    
15:50   Set the rate of the water through the Feedwater Line into the Reactor Core from 2.4 m3/h to 3.0 m3/h, and one through the Core Spray Line from 6.9 m3/h to 7.0 m3/h.    
November 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  Some rodioactive nuclides with short half-lives, such as Xenon-133m, Xenon-133 and Xenon-135, were possibly detected in the gas that had been sampled on November 1 at the gas control system of the Containment Vessel. That suggests a nuclear fissile reaction might have occurred recently. TEPCO injected boric acid into the Reactor Core from 02:48 to 03:47 to prevent another fission.
NuclidesConcentrations (Bq/cm3)Half-lives
Krypton-854.4 × 10−111 years
Xenon-131m6.9 × 10−412 days
Xenon-1331.4 × 10−55 days
Xenon-1351.2 × 10−59 hours
The sample was taken from 13:51 to 14:20 on November 1 at the gas control system. The figures of concentration are shown on the supposition that the capture rate of rare gases by charcoal filter is 90 % as that of iodine is.
   
04:14 Set the rate of the water into the Reactor Core at 7.5 m3/h. Set the rate of the water through the Feedwater Line into the Reactor Core at 3.0 m3/h, and one through the Core Spray Line at 7.0 m3/h.    
  The rate of the water into the Reactor Core was 7.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
- 15:00
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
10:11
- 15:05, November 8
    Transferred pooled water in the basement of the Turbine Building to the Miscellaneous Solid Waste Volume Reduction Treatment Building.  
10:16
- 12:10
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
   
NuclidesConcentrations (Bq/cm3)Half-lives
Krypton-855.3 × 10−111 years
Xenon-131m6.1 × 10−412 days
Xenon-133Less than minimum detectable (1.5 × 10−5)5 days
Xenon-1351.7 × 10−59 hours
The sample was taken from 11:59 to 12:29 on November 2 at the gas control system. The figures of concentration are shown on the supposition that the capture rate of rare gases by charcoal filter is 90 % as that of iodine is.
   
November 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:53
- 06:12
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
  The rate of the water into the Reactor Core was 7.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:00
-
Transferred contaminated water in the temporary external tanks to the Mega-Float (a very large floating structure).
16:50   Set the rate of the nitrogen gas into the Containment Vessel from 21.0 m3/h to 26.0 m3/h. The concentration of hydrogen gas had been increasing from 2.7 % at 18:10 on October 30 to 2.9 % at 16:30 on November 3.    
November 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:35
- 06:51
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
  TEPCO submitted a report to the Nuclear and Industrial Safety Agency on the cause of radioactive xenon-135 gas that had been detected in Containment Vessel of Unit No.2. TEPCO concluded in the report that the gas had been caused by spontaneous fissions of curium-242, curium-244 and other nuclides, not by chain reactions of nuclear fuels, because:
  1. The concentration of the gas was low.
  2. The gas was detected on November 2 after boric acid had been injected into the Reactor Core.
  3. The data of the Reactor did not show a significant change.
  The rate of the water into the Reactor Core was 7.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
09:38
- 15:00, November 8
  Transferred contaminated water in the Trench of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
10:00
- 15:29
Transferred contaminated water in the on-site bunker building to the Process Main Building.
13:35
- 14:35
Sampled dusts over the roof of the Reactor Building.      
15:13 Set the rate of the water into the Reactor Core at 7.6 m3/h. Set the rate of the water through the Feedwater Line into the Reactor Core at 3 m3/h, and one through the Core Spray Line at 7.2 m3/h. Set the rate of the water through the Feedwater Line into the Reactor Core at 2.5 m3/h, and one through the Core Spray Line at 8.1 m3/h.  
15:48
- 09:41, November 6
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
November 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:22
- 11:00, November 7
Stopped the seawater circulation cleaning unit for maintenance.
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.4 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
11:25
- 14:00
    Sampled dusts over the roof of the Reactor Building.  
November 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8 m3/h.  
11:04   Started up a Radioactive Substance Removal System of the Storage Pool.    
November 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8 m3/h.  
14:30
- 19:17
    Stopped the substitute chiller to flush the pipes.  
  The Nuclear and Industrial Safety Agency affirmed the report by TEPCO on November 4 that the radioactive xenon-135 gas in the Containment Vessel had been caused by spontaneous fissions.
November 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
00:25
-
      The desalination unit of the Storage Pool was suspended.
15:29
- 20:25, November 9
Switched the pumps of the nitrogen gas suppliers into the Containment Vessels of Unit Nos. 1, 2 and 3 to temporary Diesel generator due to construction.  
16:05     Set the rate of the water through the Feedwater Line into the Reactor Core from 2.3 m3/h to 3.0 m3/h.  
16:23
- 16:54
The (first) caesium adsorption system was suspended after one of the pumps had failed.  
16:24
- 20:47, November 9
  Stopped the Radioactive Substance Removal System of the Storage Pool due to construction.    
November 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:41
- 22:29
Stopped the substitute chiller of the Storage Pool from 05:43 to 22:29, due to construction. Stopped the substitute chiller of the Storage Pool from 05:41 to 20:20, due to construction.    
09:08
- 10:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:22
- 12:55
    Sampled dusts over the roof of the Reactor Building.  
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.9 m3/h.  
11:14
- 11:24
  Stopped the gas control system of the Containment Vessel due to construction.    
November 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:20
- 15:24
Stopped the desalination unit to change softwares.
09:00
- 10:00
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:05
- 13:30
    Sampled dusts over the roof of the Reactor Building.  
09:10
- 08:59, November 30
  Transferred contaminated water in the basement of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 8.0 m3/h.  
13:10
- 14:49
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
November 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:10
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 8.0 m3/h.  
15:42
- 10:45, November 13
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
November 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:44
- 10:13, November 14
Stopped the seawater circulation cleaning unit for maintenance.
09:04
- 11:27
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:30
- 12:05
  Stopped the Radioactive Substance Removal System of the Storage Pool to change absorption towers.    
14:15
- 15:06
  Injected 9 tons of freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.    
14:15
- 15:06
      Supplied 10 tons of freshwater to the Storage Pool with a temporary spray line.
November 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 7.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
November 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:30
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 7.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 7.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
13:29
- 15:14
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
November 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:57
- 11:00
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:25
- 10:31, December 5
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
November 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:20
- 11:20
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:33
- 11:41
    Installed new valves to regulate water into the Reactor Core.  
16:03
- 16:47
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
November 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:03
- 10:38
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:15
- 13:09
Installed new valves to regulate water into the Reactor Core.    
  The rate of the water into the Reactor Core was 7.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 7.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
13:15
- 14:50
      Supplied the Storage Pool with 2 m3 ofhydrazine through the substitute chiller.
13:32
- 14:55
    Stopped the substitute chiller to flush the pipes.  
14:58
- 16:12
      The substitute chiller was suspended.
November 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 7.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 7.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.4 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
15:33 Set the rate of the water into the Reactor Core at 5.5 m3/h. Set the rate of the water into the Reactor Core at 3.1 m3/h through the Feedwater Line, and at 7.1 m3/h through the Core Spray Line. Set the rate of the water into the Reactor Core at 2.5 m3/h through the Feedwater Line, and at 8.1 m3/h through the Core Spray Line.  
22:47
- 14:00, November 22
One of the lines of the Desalination System (the Reverse Osmosis Membrane type) was suspended due to high pressure.
November 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:28
- 10:42
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:01
- 09:48, November 21
Stopped the seawater circulation cleaning unit, due to maintenance.
November 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 5.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.4 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
13:58 Set the rate of the water into the Reactor Core at 5.5 m3/h, after it had dropped to 5.3 m3/h.      
November 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:00
- 23:50
Due to change of transformers,
Stopped the Evaporation and Concentration Equipment from 05:00 to 23:50,
Stopped the Desalination System (the Reverse Osmosis Membrane type) from 05:07 to 17:18,
Stopped the (first) caesium adsorption system from 08:25 to 16:56,
Stopped the second caesium adsorption system from 08:26 to 17:40.
09:15
- 10:30
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8.1 m3/h.  
10:22
- 09:45, November 24
    Transferred pooled water in the Condensate Storage Tank to the Turbine Building.  
November 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:04
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 5.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
November 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:56
-
One of the lines of the Desalination System (the Reverse Osmosis Membrane type) was suspended due to high pressure.
  The rate of the water into the Reactor Core was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.3 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
12:15
- 11:20, December 1
One of the lines of the Desalination System (the Reverse Osmosis Membrane type) was suspended due to water leak.
November 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:31
- 17:05
Transferred contaminated water in the on-site bunker building to the Process Main Building.
  The rate of the water into the Reactor Core was 5.6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 7.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.2 m3/h, while one through the Core Spray Line was 8.2 m3/h.  
13:31
- 15:05
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
19:03
- 19:19
Set the rate of the water into the Reactor Core from 5.5 m3/h to 5.0 m3/h at 19:03. Set the rate of the water into the Reactor Core through the Core Spray Line from 7.2 m3/h to 5.6 m3/h at 19:11, while keeping one through the Feedwater Line at 2.9 m3/h. Set the rate of the water into the Reactor Core through the Core Spray Line from 8.5 m3/h to 6.7 m3/h at 19:19, while keeping one through the Feedwater Line at 2.3 m3/h.  
19:09     Set the rate of the nitrogen gas into the Containment Vessel from 14 m3/h to 28.5 m3/h.  
November 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:30
- 17:00
Due to change of power supplies,
Stopped the (first) caesium adsorption system from 06:30 to 15:00,
Stopped the second caesium adsorption system from 08:30 to 17:00.
  The rate of the water into the Reactor Core was 5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6.8 m3/h.  
10:20
- 10:30
10:57
- 11:02
Opened the silt fence near the Water Intakes to sample silt on the seabed of the port.
10:57
- 11:43
The Desalination System (the Reverse Osmosis Membrane type) was suspended due to water leak.
14:54
- 09:38, November 27
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
23:04
- 23:39
      The substitute chiller of the Storage Pool was suspended due to an alarm.
November 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:44
- 09:52, November 28
Stopped the seawater circulation cleaning unit for maintenance.
  The rate of the water into the Reactor Core was 5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 6.9 m3/h.  
10:18
- 11:02
Set the rate of the water into the Reactor Core from 5 m3/h to 4.5 m3/h at 11:02. Set the rate of the water into the Reactor Core through the Core Spray Line from 5.5 m3/h to 4.5 m3/h at 11:02, while keeping one through the Feedwater Line at 3 m3/h. Set the rate of the water into the Reactor Core through the Core Spray Line from 7 m3/h to 6 m3/h at 11:02, while keeping one through the Feedwater Line at 2 m3/h.  
November 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
06:33     Recognized that the valve of the substitute chiller of the Storage Pool had been shut for unknown cause, and that coolant water had not been delivered to the Pool.  
  The rate of the water into the Reactor Core was 4.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 1.9 m3/h, while one through the Core Spray Line was 6 m3/h.  
November 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:12
- 11:50, November 29
  The substitute chiller of the Storage Pool was suspended due to an alarm. Flushed the pipes and restarted the system.    
  The rate of the water into the Reactor Core was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 1.9 m3/h, while one through the Core Spray Line was 6 m3/h.  
November 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:24
- 13:00
    Sampled dusts over the roof of the Reactor Building.  
09:55
- 11:05
Stopped the nitrogen gas into the Containment Vessel due to construction of a line to the Pressure Vessel.      
  The rate of the water into the Reactor Core was 4.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 1.9 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:13
- 10:28
Set the rate of the water into the Reactor Core at 4.5 m3/h, after it had dropped to 4.2 m3/h.   Set the rate of the water into the Reactor Core through the Feedwater Line at 2.1 m3/h, after it had dropped to 1.9 m3/h.  
10:58       Started desalination of the Storage Pool with ion exchanger.
12:30
- 13:00
    A robot sampled dusts near the Large-Scale Door.  
13:47
- 14:37
  Stopped the nitrogen gas into the Containment Vessel due to construction of a line to the Pressure Vessel.    
November 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 12:30
    Sampled dusts over the roof of the Reactor Building.  
  The rate of the water into the Reactor Core was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:00
- 10:30
    A robot sampled dusts near the Large-Scale Door.  
11:33
- 13:07
Stopped the nitrogen gas into the Containment Vessel due to construction of a line to the Pressure Vessel.      
11:40
- 12:20
Stopped the nitrogen gas into the Containment Vessel due to construction of a line to the Pressure Vessel.      
13:26
- 15:04
  Supplied the Storage Pool with hydrazine through the substitute chiller.    
13:45   Began to inject nitrogen gas into the Pressure Vessel at 13:45, only unsuccessfully. The injection was suspended at 14:47. Recognized that one of the valves had been shut, and opened it. Resume to inject nitrogen into the Pressure Vessel at 10:46, December 1, and set the rate of the gas into the Pressure Vessel at 5 m3/h.    
16:04 Began to inject nitrogen gas into the Pressure Vessel. Set the rate of the gas into the Pressure Vessel 5 m3/h.      
16:26     Began to inject nitrogen gas into the Pressure Vessel. Set the rate of the gas into the Pressure Vessel 5 m3/h.  
18:03
- 07:51, December 13
  Transferred contaminated water in the Trench of the Turbine Building to the Incineration of the Central Radioactive Waste Building.    
23:13
- 13:50, December 2
  The substitute chiller of the Storage Pool was suspended due to an alarm. Flushed the pipes and restarted the system.    
December 1 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 4.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
10:05
- 12:03, December 4
      Stopped the ion exchanger to change resins.
13:21
- 14:56
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
December 2 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:01
- 15:36
    Stopped the substitute chiller due to construction.  
09:39   Set the rate of the nitrogen gas into the Pressure Vessel from 5 m3/h to 10 m3/h, while keeping that into the Containment Vessel at 26 m3/h.    
10:10
- 12:00
Sampled dusts at the ventilation of the Cover of the Reactor Building.      
10:35 Set the rate of the water into the Reactor Core at 4.5 m3/h, after it had dropped to 4.5 m3/h.      
12:00
- 14:00
  Sampled dusts at the blowout panels of the Reactor Building.    
13:00
- 14:00
Sampled dusts at the Equipment Hatch and at the Large-Scale Door.      
18:00
- 14:34, December 3
Due to change of power supplies,
Stopped the Evaporation and Concentration Equipment from 18:00, December 2, to 14:34, December 3,
Stopped the Desalination System (the Reverse Osmosis Membrane type) from 08:04, December 3, to 17:18, December 3,
Stopped the (first) caesium adsorption system from 08:30, December 3, to 14:22, December 3.
December 3 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 4.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
09:47
- 09:54, December 5
Stopped the seawater circulation cleaning unit for maintenance.
December 4 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
11:33 Realized that water, estimated 45 m3 approximately 15 m3, had been pooled on the floor around the Evaporation and Concentration Equipments at 11:33. Halted the Equipment 3A at 11:52 to stop the leakage.
Recognized that part of the water had leaked out of the equipment house at 14:30. 110 mSv/h of β ray and 1.8 mSv/h of γ ray were detected around the water.
Laid sandbags to stop the leakage out of the house. Pumped the pooled water in the house into the waste water tank from 18:10 to 22:20.
Approximately 150 liters of the leaked water supposedly flowed into the sea. Its total radiation is estimated 2.6 × 1010 Bq.
December 5 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:10
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 4.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
10:25
- 10:44
Set the rate of the nitrogen gas into the Pressure Vessel from 5 m3/h to 10 m3/h at 10:44.   Set the rate of the nitrogen gas into the Pressure Vessel from 5 m3/h to 10 m3/h at 10:25.  
10:35
- 12:05
    Sampled dusts over the roof of the Reactor Building.  
11:00   Stopped the operation of the Radioactive Substance Removal System of the Storage Pool, which had been working since November 6.    
17:47 Set the rate of the water into the Reactor Core at 4.5 m3/h, after it had dropped to 4 m3/h.   Set the rate of the water into the Reactor Core through the Feedwater Line at 2.2 m3/h.  
December 6 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:25
- 10:25
  Sampled dusts at the blowout panels of the Reactor Building.    
09:10
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 4.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 4.2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:00
- 08:54, December 7
    Transferred pooled water in the Condensate Storage Tank to the Turbine Building.  
December 7 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
04:17
- 11:37, December 10
  The substitute chiller of the Storage Pool was suspended due to an alarm.    
09:00
- 10:05
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 4.4 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 4.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:07
- 11:19, December 10
      Stopped the ion exchanger to change resins.
  Set the rate of the nitrogen gas into the Pressure Vessel from 10 m3/h to 15 m3/h at 13:15. Set the rate of the nitrogen gas into the Pressure Vessel from 10 m3/h to 13 m3/h. Set the rate of the nitrogen gas into the Pressure Vessel from 10 m3/h to 15 m3/h at 10:52.  
14:16   Set the rate of the nitrogen gas into the Containment Vessel from 26 m3/h to 20 m3/h.    
December 8 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:45
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 4.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
10:29 Started up a gas control system of the Containment Vessel.      
16:15   Set the rate of the nitrogen gas into the Pressure Vessel from 13 m3/h to 14.5 m3/h, and that into the Containment Vessel from 20 m3/h to 16.5 m3/h.    
December 9 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:05
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:05
- 19:00
    Filled the Condensate Storage Tank with water.  
10:13 Set the rate of the water into the Reactor Core from 4.2 m3/h to 4.5 m3/h. Set the rate of the water into the Reactor Core through the Core Spray Line at from 4.2 m3/h to 4.5 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line from 2.0 m3/h to 2.2 m3/h, while setting one through the Core Spray Line from 6.2 m3/h to 6.1 m3/h.  
December 10 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:40
- 09:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:00
- 10:30
    Sampled dusts over the roof of the Reactor Building.  
  The rate of the water into the Reactor Core was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 4.3 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:06
- 11:53, December 14
Stopped the seawater circulation cleaning unit for maintenance.
10:11 Began to inject water to the Reactor Core through the Core Spray Line, as well as through the Feedwater Line. The rate of the water through the Feedwater Line was 4.2 m3/h, while one through the Core Spray Line was 1 m3/h.      
11:25   Set the rate of the water into the Reactor Core through the Core Spray Line from 4.5 m3/h to 5.5 m3/h. Set the rate of the water into the Reactor Core through the Core Spray Line from 2.2 m3/h to 3.2 m3/h.  
14:00
- 09:22, December 12
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
December 11 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.1 m3/h, while one through the Core Spray Line was 1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 5.5 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:30
- 10:44
Set the rate of the water into the Reactor Core through the Core Spray Line from 1.0 m3/h to 2.0 m3/h at 10:30. Set the rate of the water into the Reactor Core through the Core Spray Line from 5.6 m3/h to 6.0 m3/h, while setting one through the Feedwater Line from 2.5 m3/h to 3.0 m3/h, at 10:44.    
11:10     Recognized that one of the valves of the Core Spray Line was trembling. Set the rate of the water into the Reactor Core through the Feedwater Line from 3.1 m3/h to 2.5 m3/h, while setting one through the Core Spray Line from 6.1 m3/h to 6.5 m3/h. The tremble did not stop. Reset the rate of the water into the Reactor Core through the Feedwater Line to 3.0 m3/h, while resetting one through the Core Spray Line to 6.0 m3/h.  
22:20
- 17:07, December 12
Stopped the substitute chiller of the Storage Pool due to construction.      
December 12 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:04
- 10:37, December 27
Stopped the second caesium adsorption system due to construction.  
09:20
- 11:00
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:30
- 12:00, December 14
    Transferred pooled water in the Condensate Storage Tank to the Turbine Building.  
  The rate of the water into the Reactor Core through the Feedwater Line was 4.4 m3/h, while one through the Core Spray Line was 1.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 5.9 m3/h.  
December 13 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:40
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:30
-
      Stopped the ion exchanger to change resins.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.4 m3/h, while one through the Core Spray Line was 1.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 6.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 6.1 m3/h.  
10:07
- 11:30
      Stopped the substitute chiller of the Storage Pool due to checkup.
13:18
- 14:53
  Supplied the Storage Pool with hydrazine through the substitute chiller.    
December 14 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:30
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.4 m3/h, while one through the Core Spray Line was 1.8 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.5 m3/h, while one through the Core Spray Line was 6.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6.0 m3/h.  
10:40   Set the rate of the water into the Reactor Core through the Core Spray Line from 6.2 m3/h to 6.0 m3/h, while setting one through the Feedwater Line from 2.5 m3/h to 3.0 m3/h.    
December 15 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:05
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.5 m3/h, while one through the Core Spray Line was 1.7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:45
- 11:04
Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.      
12:30
- 16:00, December 16
    Resumed to transfer pooled water in the Condensate Storage Tank to the Turbine Building.  
14:22
- 10:04, December 17
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Building.  
December 16 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:30
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:40 Set the rate of the water into the Reactor Core through the Core Spray Line from 1.6 m3/h to 2.0 m3/h.      
  The rate of the water into the Reactor Core through the Feedwater Line was 4.5 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.8 m3/h.  
  Prime Minister Noda Yoshihiko declared:
  • The reactors of the Fukushima Daiichi Power Station had been brought to a condition equivalent to cold shutdown,
  • The target of the Step 2 in the Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station, or the condition that radioactive materials are under control and radiation dose is significantly held down, had been completed.
December 17 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:58
- 10:22
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.8 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.8 m3/h.  
10:12
- 09:58, December 18
  Began to transfer contaminated water in the basement of the Turbine Building to the Incineration of the Central Radioactive Waste Building at 10:12. Recognized that one of the valves had been shut. Opened the valve at 13:22 and transferred the water at till 09:58, December 18.    
10:12
- 10:16, December 19
Stopped the seawater circulation cleaning unit for maintenance.
10:23
- 13:39
The substitute chiller of the Storage Pool was suspended after one of the pumps had been automatically halted due to water leak.      
15:02
- 15:52
      Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.
December 18 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.7 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.8 m3/h.  
10:00 Workers found approximately 125 230 220 m3 of contaminated water in the Trench between the Process Main Building and the Incineration of the Central Radioactive Waste Building. 3 mSv/h of radiation was detected on the surface of the water.
NuclidesConcentrations (Bq/cm3)
Caesium-1344.2 × 103
Caesium-1375.4 × 103
Iodine-131Less than minimum detectable
December 19 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:20
- 10:50
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.8 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.8 m3/h.  
11:14 Set the rate of the water into the Reactor Core through the Feedwater Line from 1.0 m3/h to 3.0 m3/h.      
18:00 Started up a gas control system.      
December 20 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
08:58
- 15:22, January 11
Suspended the (first) caesium adsorption system.
09:00
- 10:45
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.7 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 5.9 m3/h.  
10:47     Set the rate of the water through the Feedwater Line into the Reactor Core from 3.9 m3/h to 3.0 m3/h, and one through the Core Spray Line from 5.0 m3/h to 6.0 m3/h.  
11:00 Set the rate of the nitrogen gas into the Containment Vessel from 28 m3/h to 18 m3/h.      
15:03
- 14:18, December 23
  Suspended the substitute chiller due to checkeup. Flushed the pipe, and restarted the chiller.    
December 21 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
05:05 Set the rate of the water through the Feedwater Line into the Reactor Core from 4.3 m3/h to 4.5 m3/h, and one through the Core Spray Line from 1.8 m3/h to 2 m3/h.      
09:00
- 10:30
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.5 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h.  
13:57
- 09:42, December 23
  Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).    
14:52
- 15:15
  Set the rate of the nitrogen gas into the Containment Vessel from 16 m3/h to 10 m3/h at 14:52. Set the rate of the nitrogen gas expelled out of the Vessel with the gas control system from 40 m3/h to 32 m3/h at 15:15.    
December 22 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:00
- 10:45
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
09:43
- 11:06
    Suspended the substitute chiller due to cleaning.  
09:57
-
Stopped the seawater circulation cleaning unit for maintenance.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.6 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6.1 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:35 Set the rate of the nitrogen gas into the Containment Vessel from 18 m3/h to 13 m3/h, while setting the rate of the nitrogen gas expelled out of the Vessel with the gas control system from 30 m3/h to 26.9 m3/h at 15:15.      
13:30
- 15:15
    Supplied the Storage Pool with hydrazine through the substitute chiller.  
December 23 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:22
- 10:56
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.5 m3/h, while one through the Core Spray Line was 1.9 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.6 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6.5 m3/h.  
10:19
- 20:13
Transferred 120 m3 of the contaminated water in the Trench, between the Process Main Building and the Incineration of the Central Radioactive Waste Building, to the Incineration. 100 m3 of the water remained in the Trench.
10:30 Set the rate of the water into the Reactor Core through the Feedwater Line from 1.9 m3/h to 2 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line from 2.5 m3/h to 3 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line from 6.5 m3/h to 6 m3/h.  
16:07
- 09:38, December 25
Transferred pooled water in the basement of the Turbine Building of Unit No.1 to the basement of the Turbine Building of Unit No.2.    
December 24 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:10
- 11:08
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.3 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.9 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:37
- 11:05
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
14:35
- 09:50, December 26
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).  
December 25 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
16:28
- 16:40
    Injected freshwater to the Storage Pool to fill the Skimmer Surge Tank with water.  
December 26 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:20
- 10:55
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
  The rate of the water into the Reactor Core through the Feedwater Line was 4.3 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.8 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:10
- 09:54, December 27
  Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).    
13:22
- 13:43
Set the rate of the nitrogen gas into the Containment Vessel from 13 m3/h to 8 m3/h at 13:22. Set the rate of the nitrogen gas expelled out of the Vessel with the gas control system from 28 m3/h to 23 m3/h at 13:43.      
13:36
- 15:12
  Supplied the Storage Pool with 2 m3 of hydrazine through the substitute chiller.    
14:00
- 16:32
    Stopped the substitute chiller to flush the pipes.  
December 27 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.4 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2.7 m3/h, while one through the Core Spray Line was 6 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:14
- 15:18
Transferred contaminated water in the on-site bunker building to the Process Main Building.
10:50
- 12:30
Sprayed water to the ground on the site of the Power Station, in order to prevent radioactive dusts from spreading out. The water was decontaminated one which had been pooled in Unit Nos. 5 and 6.
11:00   Set the rate of the water into the Reactor Core through the Feedwater Line from 2.8 m3/h to 2 m3/h, and the one through the Core Spray Line from 6.0 m3/h to 7.0 m3/h.    
13:58
- 15:57
  Stopped the substitute chiller to flush the pipes.    
December 28 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.3 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 1.9 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
11:10
- 12:15
Set the rate of the nitrogen gas into the Containment Vessel from 8 m3/h to 18 m3/h at 11:10. Set the rate of the nitrogen gas expelled out of the Vessel with the gas control system from 23 m3/h to 30 m3/h at 12:15.      
13:28
- 15:07
      Supplied the Storage Pool with hydrazine through the substitute chiller.
15:22
- 09:44, January 3
  Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).    
15:32
- 09:03, December 29
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).  
December 29 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.3 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 1.8 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3.1 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:23
- 12:09
    Stopped the substitute chiller to flush the pipes.  
December 30 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
09:44 Set the rate of the water into the Reactor Core through the Feedwater Line from 4.4 m3/h to 4.5 m3/h, and the one through the Core Spray Line from 1.8 m3/h to 2 m3/h. Set the rate of the water into the Reactor Core through the Feedwater Line from 1.8 m3/h to 2 m3/h, while keeping the one through the Core Spray Line at 7 m3/h.    
  The rate of the water into the Reactor Core through the Feedwater Line was 4.5 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
10:27
- 13:42
    Stopped the substitute chiller to flush the pipes.  
14:37
- 09:58, December 31
    Transferred contaminated water in the basement of the Turbine Building to the Central Radioactive Waste Plant (the Incineration and the Process Main Building).  
16:54
- 09:56, January 4
    Stopped the substitute chiller.  
December 31 Unit No. 1 Unit No. 2 Unit No. 3 Unit No. 4
  The rate of the water into the Reactor Core through the Feedwater Line was 4.4 m3/h, while one through the Core Spray Line was 2 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 2 m3/h, while one through the Core Spray Line was 7 m3/h. The rate of the water into the Reactor Core through the Feedwater Line was 3 m3/h, while one through the Core Spray Line was 6 m3/h.  
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