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Corporate Information

 
Press Release (Mar 31,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 9:00 PM Mar 31st)
*Updates are underlined
All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.
Unit 1 (Shut down) 
- Explosive sound and white smoke were confirmed after the big quake 
  occurred at 3:36 pm Mar 12th. It was assumed to be hydrogen explosion.
- At approximately 2:30 am on March 23rd, seawater injection to the nuclear 
  reactor through the feed water system was initiated.
- At approximately 10:50 am on March 24th, white fog-like steam arising 
  from the roof part of the reactor building was observed.
- We had been injecting seawater into the reactor, but from 3:37 pm on 
  March 25th, we started injecting freshwater.
- We had been injecting fresh water to the reactor using fire engines; 
  however we switched over utilizing temporary electrical pump at 8:32 
  am on March 29th.
Unit 2 (Shut down) 
- At approximately 6:00 am on March 15th, an abnormal noise began emanating 
  from nearby Pressure Suppression Chamber and the pressure within the 
  chamber decreased. 
- At 6:20 pm on March 21st, white smoke was confirmed arising from the top 
  of the reactor building. As of 7:11 am on March 22nd, smoke decreased to 
  the level to nearly non-existent.
- We have been injecting seawater into the reactor, but from 10:10 am on 
  March 26th, we started injecting fresh water (with boric acid).
- We had been injecting fresh water in to the reactor utilizing fire pump, 
  however, we switched over to utilizing temporary electrical pump from 
  6:31 pm on March 27th.
Unit 3 (Shut down) 
- Explosive sound and white smoke were confirmed at 11:01am March 4th. It 
  was assumed to be hydrogen explosion.
- At 8:30am on March 16th, fog like steam was confirmed arising from the 
  reactor building.
- At approximately 6:15 am on March 17th the pressure of the Suppression 
  Chamber has temporarily increased. We were preparing to implement 
  measures to reduce the pressure of the reactor containment vessel 
  (partial discharge of air containing radioactive material to outside) 
  in order to fully secure safety. However, at present, it is not a 
  situation to immediately implement measures and discharge air containing 
  radioactive material to outside. We will continue to monitor the status 
  of the pressure of the reactor containment vessel.
- At approximately 4:00 pm, March 21st, light gray smoke was confirmed 
  arising from the floor roof of the Unit 3 building. On March 22nd, the 
  color of smoke changed to somewhat white and it is slowly dissipating.
- At around 4:20 pm on March 23rd, our staff confirmed light black smoke 
  belching from the Unit 3 building. At approximately 11:30 pm on March 
  23rd and 4:50 am on March 24th, our employee found no signs of smoke.
- We had been injecting sea water into the reactor pressure vessel, but 
  from 6:02 pm on March 25th, we started injecting freshwater.
- We had been injecting fresh water in to the reactor utilizing fire pump, 
  however, we switched over to utilizing temporary electrical pump from 
  8:30 pm on March 28th.
Unit 4 (outage due to regular inspection) 
- At approximately 6 am on March 15th, we confirmed the explosive sound 
  and the sustained damage around the 5th floor rooftop area of the 
  Nuclear Reactor Building.
- On March 15th and 16th, we respectively confirmed the outbreak of fire 
  at the 4th floor of the northwestern part of the Nuclear Reactor 
  Building. We immediately reported this matter to the fire department 
  and the related authorities. TEPCO employees confirmed that each fire 
  had already died down by itself. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened.
Unit 5 (outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 5 am, March 19th, we started the Residual Heat Removal System Pump 
  (C) in order to cool the spent fuel pool.
- At 2:30 pm, March 20th, the reactor achieved reactor cold shutdown. At 
  around 5:24 pm on March 23rd, when we switched the temporary Residual 
  Heat Removal System Seawater Pump, it has stopped automatically. At 
  around 4:14 pm, March 24th we replaced the pump, and restarted cooling 
  of reactor at around 4:35 pm.
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened.
Unit 6 (outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- We completed the repair work on the emergency diesel generator (A).
- At 10:14 pm, March 19th, we started the Residual Heat Removal System 
  Pump (B) of Unit 6 in order to cool the spent fuel pool.
- At 7:27 pm, March 20th, the reactor achieved reactor cold shutdown.
- In relation to the two seawater side pumps of the Residual Heat Removal 
  System, we switched the power source from temporary to permanent at 3:38 
  PM and 3:42PM, Mar 25 respectively.
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened.
Today's work for cooling the spent fuel pools 
- From 9:25 am 30th March, freshwater injection to Unit 2 was conducted by 
  a temporary motor driven pump. But, because of the malfunction of that 
  pump at 9:45 am, we decided to switch to the fire fighting pump. At 0:30 
  pm, we switched to use the fire pump. Though the injection of the flesh 
  water was stopped temporarily because we found the tear in a part of the 
  hose at 0:47 pm and 1:10 pm, we restarted injection of the flesh water 
  at 7:05 pm, and finished at 11:50 pm.
- Water spraying by the concrete pump truck to Unit 1 was conducted from 
  1:03 pm to 4:04 pm. 
- Water spraying by the concrete pump truck to Unit 3 was conducted from 
  4:30 pm to 7:33 pm. 
- We are considering further spraying subject to the conditions of spent 
  fuel pools.
Draining water from underground floor of turbine buildings 
- In regard with transferring water from a condensate storage tank to a 
  suppression pool water surge-tank in unit 3, work was implemented from 
  5:40 pm 28th March, and finished at 8:40 am today.
- In regard with transferring water from a condensate storage tank to a 
  suppression pool water surge-tank in unit 1, work began at 0:00 pm today. 
- In regard with transferring water from the vertical shaft of unit 1 to 
  the centralized environmental facility storage tank, work was implemented 
  from 9:20 am today and finished at 11:25 am today.
Casualties 
- Presence of 2 TEPCO employees at the site is not confirmed on March 11th.
- On March 24th, it was confirmed that 3 workers from cooperative companies 
  who were in charge of cable laying work in the 1st floor and the 
  underground floor of turbine building were exposed to the radiation dose 
  of more than 170 mSv. 2 of them were confirmed that their skins on legs 
  were contaminated. After they were decontaminated, since there was a 
  possibility of beta ray burn injury, they were transferred to Fukushima 
  Medical University Hospital. The third worker was also transferred to 
  Fukushima Medical University Hospital on March 25th. Later, the 3 workers 
  were transferred to National Institute of Radiological Sciences in Chiba 
  Prefecture. They all left the hospital on March 28th.
  Regarding this event, TEPCO has reported to the related government 
  ministries and agencies on measures to be taken to assure appropriate 
  radiation dose control and radiation exposure related operations.
  We will inform the related parties of countermeasures and continue to 
  take all possible measures to future management.
 Others 
- We measured radioactive materials (iodine etc.) inside of the nuclear 
  power station area (outdoor) by monitoring car and confirmed that 
  radioactive materials level is getting higher than ordinary level. As 
  listed below, we have determined that specific incidents stipulated in 
  article 15, clause 1 of Act on Special Measures Concerning Nuclear 
  Emergency Preparedness (Abnormal increase in radiation dose measured at 
  site boundary) have occurred.
  · Determined at 4:17 pm Mar 12th (Around Monitoring Post 4)
  · Determined at 8:56 am Mar 13th (Around Monitoring Post 4)
  · Determined at 2:15 pm Mar 13th (Around Monitoring Post 4)
  · Determined at 3:50 am Mar 14th (Around Monitoring Post 6)
  · Determined at 4:15 am Mar 14th (Around Monitoring Post 2) 
  · Determined at 9:27 am Mar 14th (Around Monitoring Post 3) 
  · Determined at 9:37 pm Mar 14th (Around main entrance) 
  · Determined at 6:51 am Mar 15th (Around main entrance) 
  · Determined at 8:11 am Mar 15th (Around main entrance) 
  · Determined at 4:17 pm Mar 15th (Around main entrance) 
  · Determined at 11:05 pm Mar 15th (Around main entrance)
  · Determined at 8:58 am Mar 19th (Around MP5)
  From now on, if the measured figure fluctuates and goes above and below 
  500 micro Sv/h, we deem that as the continuous same event and will not 
  regard that as a new specific incidents stipulated in article 15, clause 
  1 of the Act on Special Measures Concerning Nuclear Emergency 
  Preparedness (Abnormal increase in radiation dose measured at site 
  boundary) has occurred. In the interim, if we measure a manifestly 
  abnormal figure and it is evident that the event is not the continuous 
  same event, we will determine and notify.

- The national government has instructed evacuation for those local 
  residents within 20km radius of the periphery and evacuation to inside 
  for those residents from 20km to 30km radius of the periphery, because 
  it is possible that radioactive materials are discharged.
- At around 10:37 am March 21st, water spraying to common spent fuel pool 
  and finished at 3:30 pm (conducted by TEPCO).
- At around 3:37 pm, March 24th, electricity supply to common spent fuel 
  pool has started from external power source. At around 6:05 pm, fuel 
  pool cooling pump was started to cool the pool.
- We found no signs of abnormal situation for the casks by visual 
  observation during the patrol activity. A detailed inspection is under 
  preparation.
- At Units 5 and 6, in order to prevent hydrogen gas from accumulating 
  within the buildings, we have made three holes on the roof of the 
  reactor building for each unit.
- In total 12 fire engines are lent for the water spraying to the spent 
  fuel pools and water injection to the nuclear reactors by various 
  regional fire departments* as well as Tokyo Fire Department. Also, 
  instruction regarding the setting and operation of large scale 
  decontamination system was provided by Niigata City Fire Headquarter 
  and Hamamatsu City Fire Headquarter.
  *: Koriyama Fire Department, Iwaki Fire Brigade Headquarters, Fire 
  Headquarters of Sukagawa District Wide Area Fire-fighting Association, 
  Yonezawa City Fire Headquarters, Utsunomiya City Fire Headquarters, Fire 
  Headquarters of Aizu-Wakamatsu wide area municipal association, Saitama 
  City Fire Bureau, and Niigata City Fire Bureau.
- By March 22nd, Units 1 through 6 were started to be energized from the 
  external power source.
- At 3:30PM, March 27th, we found that there was water in the trenches of 
  Units 1 to 3. The radioactive emission at the surface of the water was 
  0.4mSv/h for Unit 1 and over 1,000mSv/h for Unit 2. As for Unit 3, we 
  couldn't have access to the surface because of debris. We will continue 
  to monitor water in the trenches.
- On March 28th, a puddle of water was found at a centralized environmental 
  facility process main building. As a result of a radioactivity analysis, 
  on March 29th, we detected approximately 1.2 x 10Bq/cm3 in a full dose at 
  a radiation controlled area and 2.2 x 10Bq/cm3 in a full dose at a 
  non-controlled area.
- At 12:03 pm, March 29th, when taking off the flange of the pipe of the 
  seawater piping of the Residual Heat Removal System, 3 workers from our 
  subcontractor were soaked with water in the pipe. After wiping the water 
  off, we confirmed that there was no radioactive contamination to their 
  bodies.
- At 12:21 31st March, campaigner's sound truck (1 driver) tried to enter 
  the site form the site's main gate, however it left after it was stopped 
  to enter. We reported this incident to Fukushima Prefecture Police 
  Department.
- A barge of the U.S. Forces with fresh water to be used to cool down 
  reactors etc. was towed by a ship of Maritime Self-Defense Force and at 
  3:42 pm on March 31st 2011, came alongside the pier. As soon as the 
  supply of water is ready, we will replenish the fresh water with filtrate 
  tanks. 
- We will continue to take all measures to ensure the safety and to 
  continue monitoring the surrounding environment around the Power Station. 
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