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Press Release (Dec 15,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, December 15)
 
*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 on March 12. It was assumed to be hydrogen explosion.
-At 3:37 pm on March 25, 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, 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 volume is approx 4.5 m3/h from the reactor 
 feed water system and approx. 1.7 m3/h from the core spray system.
-We commenced injection of nitrogen gas into Primary Containment Vessel at 
 1:31 am on April 7.
-At 11:22 am on August 10, 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, 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, we started operation to inject nitrogen into 
 the reactor pressure vessel. 
Unit 2 (Shut down) 
-At approximately 6:00 am on March 15, an abnormal noise began emanating 
 from nearby Pressure Suppression Chamber and the pressure within the 
 chamber decreased. 
-At 10:10 am on March 26, 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, 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 volume is approx. 2.9 m3/h from the reactor 
 feed water system and approx. 6 m3/h from the core spray system.  
-At 5:21 pm on May 31, 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. 
 6:54 am on December 14, the alert that indicates the flow difference is 
 big at the inlet and outlet of primary pump was issued on the alternative 
 cooling system of sent fuel pool. No abnormalities such as leaking etc. 
 were found by field inspection. Then, as we sounded the instrument piping, 
 we confirmed that alert stopped. Hereafter we will check flow rate once 
 an hour. In addition to this, keeping operation of spent fuel pool 
 alternative cooling system so there is no problem on cooling   
-At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
 Containment Vessel.
-From 6:00 pm on October 28, we put the gas management system of the 
 reactor containment vessel in operation.
-At 10:46 am on December 1, we started the nitrogen injection to the 
 Reactor Pressure Vessel. 
Unit 3 (Shut down) 
-Explosive sound and white smoke were confirmed at approximately 11:01 am 
 on March 14. It was assumed to be hydrogen explosion.
-At 6:02 pm on March 25, 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, 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 volume is approx 2.7 m3/h from the reactor 
 feed water system and approx. 6.0 m3/h from the core spray system.
-At 7:47 pm on June 30, 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, injection of nitrogen gas into the Primary 
 Containment Vessel started. 
-At 4:26 pm on November 30, 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, 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, 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, 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, we started the Residual Heat Removal System Pump 
 in order to cool the spent fuel pool.
-At 2:30 pm on March 20, the reactor achieved cold shutdown.
-At 2:45 pm on July 15, we started the operation of the original Residual 
 Heat Removal System (System B) by its original seawater pump.
-At this moment, we don't think there is any reactor coolant leakage 
 inside the primary containment vessel.
-With recovery work of residual heat removal sea water pump (B) which was 
 unavailable caused by Tsunami, we stopped residual heat removal pump (B) 
 and residual heat removal sea water pump (D) sequentially from 6:29 am on 
 December 14. The stop time will be approx. 10 hours and we expect that 
 the elevation of temperature is about 1.6 degree C/ hour, so we expected 
 there is no impact on reactor. After completion of the work, we started 
 the suspended pumps, and at 4:29 pm on the same day, we restarted cooling 
 the reactor. (The temperature of the reactor core at the time of 
 suspension was 26.5 °C and the temperature at the time of restart was 
 38.2 °C) 
Unit 6 (Outage due to regular inspection) 
-Sufficient level of reactor coolant to ensure safety is maintained.
-At 10:14 pm on March 19, we started the Residual Heat Removal System Pump 
 of Unit 6 to cool down Spent Fuel Pool.
-At 7:27 pm on March 20, the reactor achieved cold shutdown. 
-At 2:33 pm on September 15, 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.
-At this moment, we do not think there is any reactor coolant leakage 
 inside PCV. 
Others 
-At around 10 am on June 13, we started the operation of the circulating 
 seawater purification facility installed at the screen area of Unit 2 and 
 3.
-At 8 pm on June 17, 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, 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, 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, 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 6:03 pm on November 30, we started transfer of the accumulated water 
 from the basement of Unit 2 turbine building to Centralized Radiation 
 Waste Treatment Facility High Temperature Incinerator Building. At 7:51 
 am on December 13, we stopped the transfer of 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]) in order to 
 stop power supply to Unit 2 accumulated water transfer pump for power 
 supply enhancing work. With the stoppage of the water transfer, the 2nd 
 Cesium adsorption apparatus was shutdowned for replacing vessels at 8:44 
 am on December 12, and will be kept outage until December 14 in order to 
 adjust the water level of the centralized radiation waste treatment 
 facility (miscellaneous solid waste Volume reduction treatment building 
 [high temperature incinerator building]). The Cesium adsorption apparatus 
 is continued its operation. Water injection to the Reactors will not be 
 affected since the cooling is continued by using processed water in the 
 buffer tank.
-At 12:25 pm on December 13, we started the re-circulating operation of 
 desalination facility (reverse osmosis membrane type) for the purpose of 
 suppression of condensed water after desalination treatment.
-We plan to establish the system injecting water into the reactor in Unit 
 1 to 3 using the condensate storage tank of Unit 3. In preparation of 
 such establishment, the stored water in the tank was transferred to the 
 basement of turbine building of Unit 3 from 10:22 am on November 21 to 
 9:45 am on November 24. As the calibration of water level gauge is 
 required if all the water is transferred, approx. 200 ton was left in the 
 tank. During the measurement of salt concentration in the left water, it 
 turned out that concentration was high. In order to secure the space for 
 additional water injection to decrease such concentration, at 10:00 am on 
 December 6, the left water was transferred from the tank to the basement 
 of the turbine building of Unit 3.
 At 8:54 on December 7, we stopped transferring, and at approx. 9:19 am on 
 the same day, we started filling water in the tank, but afterwards, we 
 confirmed water leakage (approx. 5 liter) at the joint section of hose 
 connecting to the tank, at approx. 9:52 am, we stopped filling water and 
 confirmed the leakage has stopped. We plan to consider such measures as 
 repair etc. in future. The leaked water was treated as to be free of 
 radioactive materials and desalinated. At 9:05 am on December 9, we 
 restarted filling the water in the tank after completing the replacement 
 of the transfer hose. At 7:00 pm on the same day, we finished the filing. 
 At 9:30 am on December 12, we started transferring of the accumulated 
 water in the condensate storage tank of Unit 3 to the basement of Turbine 
 Building of Unit 3 before feeding water to reduce salt level in the tank. 
 After that we confirmed decrease of transferring quantity of water from 
 the water level fluctuation, at 0:00 pm on December 14, we stopped 
 transferring of the accumulated water in the tank. Also we confirmed that 
 there was no water leakage at the site. Currently we are investigating 
 the cause.
-At 10:00 am on December 15, we started transferring accumulated water 
 from the Turbine Building of Unit 6 to the temporary tank. 
-At 2:22 pm on December 15, we started transferring accumulated water from 
 the basement of Unit 3 turbine building to Centralized Radiation Waste 
 Facility (Process Main Building). 
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