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Corporate Information

 
Press Release (Feb 02,2012)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 4:00 pm, February 2)
* The 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, 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. To improve reliability of water injection 
  to a reactor, line connecting to injection piping in water injection 
  line of reactor injection pump on the hill of Unit 1 had replaced with 
  polyethylene piping. So at 10:35 am, we changed injection route from 
  injection pump in turbine building to reactor injection pump on the hill. 
  We confirmed the decrease in volume of injecting water to reactors, so 
  at 3:15 pm on February 2, we adjusted volume of water injection in each 
  reactor as follows: Feed water system from approx. 4.2 m3/h to approx. 
  4.5 m3/h, Reactor core spray system from approx. 1.5 m3/h to approx. 2.0 
  m3/h. 
  The current water injection amount from the reactor feed water system is
  approx. 4.5m3/h and that from  the core spray system is approx. 2.0m3/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
  water feeding system, we started water injection from piping of core
  spray system to the reactor. To improve reliability of water injection 
  to a reactor, line connecting to injection piping in water injection 
  line of reactor injection pump on the hill had replaced with 
  polyethylene piping.. At 10:55 am in February 2, we adjusted water 
  injection volume to the reactor of Unit 2 through the feed water system 
  from approx. 3.9 m3/h to approx. 3.0 m3/h, and the volume from the 
  reactor core spray system from approx. 5.1 m3/h to approx. 6.0m3/h. We 
  confirmed the decrease in volume of injecting water to reactors, so at 
  3:15 pm on February 2, we adjusted volume of water injection in each 
  reactor as follows: Feed water system from approx. 2.5 m3/h to approx. 
  3.0 m3/h, Reactor core spray system from approx. 5.2 m3/h to approx. 5.5 
  m3/h. 
  The current water injection amount from the reactor feed water system is 
  approx. 3.0m3/h and that from the core spray system is approx. 5.5m3/h.
- 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-scale operation of the PCV gas
  management system started. On February 1 2012, we conducted sampling of
  the gas of the PCV gas management system. As a result of the analysis,
  we confirmed that at the entrance of the system Xenon 135 was below
  detection limit (9.5x10-2Bq/cm3), and below the re-criticality
  criterion which is 1Bq/cc.
- 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. To improve reliability of water injection to 
  a reactor, line connecting to injection piping in water injection line 
  of reactor injection pump on the hill had replaced with polyethylene 
  piping. At 11:10 am on February 2 , we adjusted water injection volume 
  to the reactor of Unit 3 through the feed water system from approx. 3.8 
  m3/h to approx. 3.0 m3/h, and the volume from the reactor core spray 
  system from approx. 5.2 m3/h to approx. 6.0m3/h. We confirmed the 
  decrease in volume of injecting water to reactors, so at 3:15 on 
  February 2, we adjusted volume of water injection in each reactor as 
  follows: Feed water system from approx. 2.5 m3/h to approx. 3.0 m3/h, 
  Reactor core spray system from approx. 5.2 m3/h to approx. 5.5m3/h. 
  The current water injection amount from the reactor feed water system is
  approx. 3m3/h and that from the core spray system is approx. 5.5m3/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. 
- At 4:26 pm on November 30, 2011, we started operation to inject nitrogen
  into the reactor pressure vessel.
- At 3:18 pm on January 14, we started operation of the radioactive
  material removal instrument for the spent fuel pool in Unit 3 
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 approx. 10:30 pm on January 31, we found that the water was leaking
  from the indicator test line in the rack instruments for jet pumps were
  stored. At 10:43 pm, the leakage was stopped after the main valve
  leading to the rack was closed. Debris were scattered around on the
  floor, and the volume of leaked water was approx. 6 litters as far as we
  could confirmed. Please note that it didn't run off outside of the
  reactor building. We sampled the water in the test line and measured the
  radioactivity concentration. From the results, we estimated the water
  leaked from the reactor well (analysis result: 35.5 Bq/cm3). We 
  estimated the amount of water leaked is 8,500 litters by measuring 
  decrease in water level of skimmer surge tank 
- At 3:20 pm on February 2 , a Tepco worker on patrolling at reactor 
  building of Unit 4 found the very small flow(just as much as lead in 
  pencil) of water in north west corner in first floor of the reactor 
  building. This leakage seemed to be occurred at make up water system in 
  reactor well because the valve at reactor well is closed totally and so 
  the leakage seemed not be from reactor well. We are investigating 
  further. No water leakage to out side of reactor building. 
- 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.
- At this moment, we don't think there is any reactor coolant leakage
  inside the primary containment vessel. 
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.
- At this moment, we do not think there is any reactor coolant leakage
  inside PCV. 
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.
- As finding of accumulated water containing radioactive materials at the
  trench between the Process Main Building and the Miscellaneous Solid
  Waste Volume Reduction Treatment Building [High Temperature Incinerator
  Building] (December 18, 2011), we started the inspection of other
  trenches at the site on January 11.
- At 4:05 pm on January 30, we started to transfer the accumulated water
  from the basement of T/B, Unit 2 to the Centralized Waste Treatment
  Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building
  [High Temperature Incinerator Building] and Process Main Building)
  through newly installed polyethylene pipes.
- At 4:12 pm on January 30, we started to transfer the accumulated water
  from the basement of T/B, Unit 3 to the Centralized Waste Treatment
  Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building
  [High Temperature Incinerator Building] and Process Main Building)
  through newly installed polyethylene pipes.
- 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 10:00 am to 4:00 pm on February 1, we conducted transferring the
  accumulated water from Unit 6 Turbine Building to temporary tanks. From
  10:00 am to 4:00 pm on February 2, we transferred the accumulated water
  from Unit 6 Turbine Building to temporary tanks.
- At 8:36 am on February 2, second Cesium adsorption apparatus was stopped
  to backwash the filter because there was a gradual downward tendency. At 
  11:12 am of the same day, we restarted the apparatus and at 11:15 am, 
  reached to steady volume of water flow (36m3/h) 
- Newly found water leakage caused by congelation after the latest report 
  (at 10:00 am February 1) are as follows:  
  · two valves in discharged water piping at water treatment building 
    where filtrate water purified(Found at 3:30 pm on February 2 ) 
  · (Filtrate water(water taken from dam): approx. 0.5 litters) 
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