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Press Release (Mar 12,2012)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, March 12)

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. 1.7 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. 
-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. 2.8 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 12, the temperature of the lower part of the RPV 
  (top of the lower head 135°) : approximately 42.3 °C 
 ·At 11:00 am on March 12, the temperature of the lower part of the RPV 
  (top of the lower head 270°) : approximately 40.1 °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. In the display for the noble gas monitoring system for
 PCV of Unit 2, both A and B system had not worked due to the failure of
 the transmission system which connected the site and the Central
 Monitoring Station in the Main Anti-Earthquake Building. Because we could
 not conduct the monitoring from the monitoring station, we have conducted
 remote monitoring by a camera installed at the site since February 20,
 2012 for B system and February 21, 2012 for A system. After we revised 
 software for the transmission system for B system on March 9, 2012 and A 
 system on March 12, 2012, the monitoring from the Main Anti-Earthquake 
 Building became available. Since 2:00 pm on the same day, we restarted 
 data sampling at the Central Monitoring Station in the Main 
 Anti-Earthquake Building. 
-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. 1.8 m3/h and that from the core spray system is approx. 5.2m3/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 8:47 am on March 11, we started transferring the accumulated water
 from the basement of Turbine Building of Unit 2 to the centralized
 radiation waste treatment facility (Miscellaneous Solid Waste Volume
 Reduction Treatment Building [High Temperature Incinerator Building]).
-At 10:10 am of March 10, 2012, we started transferring the accumulated
 water from the basement floor of the turbine building of Unit 3 to the
 centralized radiation waste treatment facility (Miscellaneous Solid Waste
 Volume Reduction Treatment Building [High Temperature Incinerator
 Building]).
-At 8:37 am on March 12, 2012, we started transferring the water
 accumulated in the site banker building to the process main building in
 the centralized waste treatment facilities. At 1:31 pm on the same day, 
 we stopped transferring. 
-At 10:00 am on March 12, 2012, we started transferring the water
 accumulated in the basement of Unit 6 Turbine Building to temporary
 tanks.
-At around 11:47 am on March 12, 2012, our staff confirmed by over current 
 alarm of fan motor of compressor at the site, that the nitrogen supply 
 equipment (nitrogen gas separator A), which supplied nitrogen to the PCVs 
 and the RPVs of Unit 1-Unit 3, stopped. At 12:09 pm on the same day, we 
 started the waiting nitrogen supply equipment (nitrogen gas separator B) 
 and at 12:19 pm, nitrogen injection started again. Regarding the pressure 
 of PCVs of Unit 1 ? Unit 3 and hydrogen density, we did not confirm any 
 significant fluctuation (hydrogen density of Unit 3 is monitored as 
 reference data because the PCV gas control system is now under test 
 operation). 
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