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Press Release (Mar 05,2012)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, March 5)
  
* Updates from previous press release 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 on March 12, 2011. It was assumed to be hydrogen 
  explosion. 
- At 3:37 pm on March 25, 2011, we started injecting freshwater to the 
  reactor and are now injecting fresh water by a motor driven pump 
  powered by the off-site transmission line. 
- At 10:11 am on December 10, 2011, in addition to water injection from 
  water feeding system, we started water injection from piping of core 
  spray system to the reactor. 
  The current water injection amount from the reactor feed water system 
  is approx. 4.7 m3/h and that from the core spray system is approx. 
  1.9 m3/h. 
- At 1:31 am on April 7, 2011, we commenced injection of nitrogen gas 
  into Primary Containment Vessel. 
- At 11:22 am on August 10, 2011, we started cyclic cooling for the water 
  in the spent fuel pool by an alternative cooling equipment of the Fuel 
  Pool Cooling and Filtering System. 
- On October 28, 2011, we completed installation of the cover for the 
  Reactor Building in order to contain dispersion of radioactive 
  substances. 
- At 4:04 pm on November 30, 2011, we started operation to inject 
  nitrogen into the reactor pressure vessel. 
- At 6:00 pm on December 19, 2011, a full-scale operation of the PCV gas 
  management system started.
Unit 2 (Shut down) 
- At approximately 6:00 am on March 15, 2011, an abnormal noise began 
  emanating from nearby Pressure Suppression Chamber and the pressure 
  within the chamber decreased. 
- At 10:10 am on March 26, 2011, we started injecting freshwater to the 
  reactor and are now injecting fresh water by a motor driven pump 
  powered by the off-site transmission line. 
- At 2:59 pm on September 14, 2011, in addition to water injection from 
  feed water system, we started water injection from piping of core spray 
  system to the reactor. 
  The current water injection amount from the reactor feed water system 
  is approx. 2.9 m3/h and that from the core spray system is approx. 
  6 m3/h. 
- With regard to the water injection volume for Unit 2 reactor, which was 
  increased with temperature figure raising, we have gradually adjusted 
  it to the original volume before temperature increasing (Feed water 
  system: approx. 3.0m3/h, core spray system: approx. 6.0m3/h). During 
  our observing the plant parameter after decreasing the flow rate of 
  feed water system on February 22, we found that one thermometer in the 
  lower part of the RPV (top of the lower head 135°) indicated the 
  different movement from others. From 12:21 pm to 2:48 pm on February 23, 
  we investigated the concerned device. As the result of the measurement 
  of DC resistance, we found no breaking wire and availability of the 
  thermometer. But we confirmed that the DC resistance of it became 
  higher than the previous measurement test data. We will evaluate the 
  soundness of the concerned device and examine correspondence in future. 
  We make sure no re-criticality state because there were no significant 
  changes at the monitoring post and as the result of the sampling for 
  the Gas Control System of the Unit 2; we confirmed that the 
  concentration of Xe-135 was below the detectible limit. Through the 
  investigation, we confirmed the concerned device is soundness. We 
  submitted the report on the soundness of concerned device and the 
  alternative method for monitoring temperature inside the Reactor of 
  Unit 2 at Fukushima Daiichi Nuclear Power Station to NISA on March 1. 
  We continue the observation of the concerned device. 
   · At 11:00 am on March 5, the temperature of the lower part of the RPV 
     (top of the lower head 135°) : approx. 43.2 °C 
   · At 11:00 am on March 5, the temperature of the lower part of the RPV 
     (top of the lower head 270°) : approx. 40.7 °C (Reference) 
- At 5:21 pm on May 31, 2011, we started cyclic cooling for the water in 
  the spent fuel pool by an alternative cooling equipment of the Fuel 
  Pool Cooling and Filtering System. 
- At 8:06 pm on June 28, 2011, we started injecting nitrogen gas into the 
  Primary Containment Vessel. 
- At 6:00 pm on October 28, 2011, a full operation of the PCV gas control 
  system started. 
- At 10:46 am on December 1, 2011, we started the nitrogen injection to 
  the Reactor Pressure Vessel. 
- At 11:50 am on January 19, 2012, we started the operation of the spent 
  fuel pool desalting facility.
Unit 3 (Shut down) 
- Explosive sound and white smoke were confirmed at approximately 11:01 
  am on March 14, 2011. It was assumed to be hydrogen explosion. 
- At 6:02 pm on March 25, 2011, we started injecting fresh water to the 
  reactor and are now injecting fresh water by a motor driven pump 
  powered by the off-site transmission line. 
- At 2:58 pm on September 1, 2011, we started water injection by core 
  spray system in addition to water injection by the reactor feed water 
  system piping arrangement. 
  The current water injection amount from the reactor feed water system 
  is approx. 1.9 m3/h and that from the core spray system is approx. 
  5 m3/h. 
- At 7:47 pm on June 30, 2011, we started cyclic cooling for the water in 
  the spent fuel pool by an alternative cooling equipment of the Fuel 
  Pool Cooling and Filtering System. 
- At 8:01 pm on July 14, 2011, injection of nitrogen gas into the Primary 
  Containment Vessel started. 
- As installation works of the PCV gas control system was completed, we 
  started a test operation at 11:38 am on February 23, 2012. We confirmed 
  that an exhaust flow amount was stable at 33Nm3/h at 2:10 pm and 
  started an adjustment operation. 
- At 4:26 pm on November 30, 2011, we started operation to inject 
  nitrogen into the reactor pressure vessel.
Unit 4 (Outage due to regular inspection) 
- At around 6 am on March 15, 2011, we confirmed the explosive sound and 
  the sustained damage around the 5th floor rooftop area of Reactor 
  Building. 
- At 12:44 pm on July 31, 2011, we started cyclic cooling for the water 
  in the spent fuel pool by an alternative cooling equipment of the Fuel 
  Pool Cooling and Filtering System. 
- At 10:58 am on November 29, 2011, in order to decrease more salinity, 
  we installed Ion exchange equipment and started the operation of such 
  equipment. 
- At this moment, we don't think there is any reactor coolant leakage 
  inside the primary containment vessel.
Unit 5 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained. 
- At 5:00 am on March 19, 2011, we started the Residual Heat Removal 
  System Pump in order to cool the spent fuel pool. 
- At 2:45 pm on July 15, 2011, we started the operation of the original 
  Residual Heat Removal System (System B) by its original seawater pump. 
- At 10:11 am on December 22, 2011, since we finished the recovery work 
  of seawater pump (System B) of equipment water cooling system, we made 
  a trial run. At 11:25 am on the same day, we confirmed no abnormalities 
  and restarted the operation.
Unit 6 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained. 
- At 10:14 pm on March 19, 2011, we started the Residual Heat Removal 
  System Pump of Unit 6 to cool down Spent Fuel Pool. 
- At 2:33 pm on September 15, 2011, we started separately cooling the 
  reactor through the Residual Heat Removal System and the spent fuel 
  pool through Equipment Cooling Water System and Fuel Pool Cooling 
  System.
Others 
- At around 10:00 am on June 13, 2011, we started the operation of the 
  circulating seawater purification facility installed at the screen area 
  of Unit 2 and 3. 
- At 8:00 pm on June 17, 2011, we started operation of Water Treatment 
  Facility against the accumulated water. At 6:00 pm on July 2, we 
  started the circulating injection cooling to inject the water, which 
  was treated by the accumulated water treatment system, to the reactors 
  through the buffer tank. 
- At 7:41 pm on August 19, 2011, we started treatment of accumulated 
  water by parallel operation of one line from the cesium adsorption 
  instrument to the decontamination instrument and the other treatment 
  line of the cesium adsorption instrument No.2. 
- At 2:06 pm on October 7, 2011, we started to spray purified accumulated 
  water brought from Unit 5 and 6 continually in order to prevent dust 
  scattering and potential fire outbreaks from the cut down trees. 
- On October 28, 2011, we started installation of the water proof wall at 
  the sea side, in front of the existing shore protection, Units 1-4, in 
  order to contain marine pollution by underground water. 
- At 12:25 pm on December 13, 2011, we started the re-circulating 
  operation of desalination facility (reverse osmosis membrane type) for 
  the purpose of suppression of condensed water after desalination 
  treatment. 
- At 9:18 am on January 31, we started transfer of Sub-drain Water of 
  Unit 6 to the temporary tank. We will conduct transferring to the 
  temporary tank appropriately. 
- From 2:00 pm on February 28 to 10:09 am on March 5, we conducted the 
  transfer of accumulated water from basement of unit 2 turbine building 
  to Centralized Radiation Waste Treatment Facility Process Main building. 
- At 3:26 am on March 4, we found the figure for Monitoring Post No.3 
  showing a message of "Transmission Error" from the system inside the 
  Main Anti-earthquake Building. When we checked out the indicator of MP3 
  directly, we could confirm the figure. Therefore, we estimated that 
  there was an error in the transmission system between the Main Anti- 
  earthquake Building and Monitoring Post. At 8:31 pm on the same day, we 
  switched the transmission route and could restored the system. From 
  8:40 pm on the same day, the data sampling in the Main Anti-earthquake 
  Building was restarted. Regarding the data until finishing restoring, 
  we had checked the figure on the site once an hour. We confirmed that 
  there no significant changes or variations in the figure of this 
  Monitoring Post and the same types of Monitoring Post. 
- At 10:00 am on March 5, we started transferring accumulated water from 
  basement of unit 6 turbine building to the temporary tank.  
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