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Press Release (Mar 13,2011)
Plant Status of Fukushima Daini Nuclear Power Station (as of 8pm March 13th)
 
[There is no update from the press release issued at 7:00 pm]
Unit 1 (shut down at 2:48pm on March 11th) 
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- At 8:19am, Mar 12th, there was an alarm indicating that one of
  the control rods was not properly inserted, however, at 10:43am,
  Mar 12th the alarm was spontaneously called off. Other control rods has
  been confirmed that they are fully inserted (reactor is in subcritical
  status)
- Status of main steam isolation valve: closed
- Injection of water into the reactor is done by Make-up Water Condensate
  System.
- We do not believe there is leakage of reactor coolant in
  the containment vessel at this moment.
- At 5:22am, Mar 12th, the temperature of the suppression chamber
  exceeded 100 degrees. As the reactor pressure suppression function was
  lost, at 5:22am, Mar 12th, it was determined that a specific incident
  stipulated in article 15, clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
  the reactor containment vessel (partial discharge of air containing
  radioactive materials) in order to fully secure safety.
  This preparation work started at around 9:43am, Mar 12th and finished
  at 6:30pm, Mar 12th.
- Restoration work in reactor cooling function is in progress to achieve
  reactor cold shutdown.
Unit 2 (shut down at 2:48pm on March 11th) 
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- Control rods are fully inserted (reactor is in subcritical status)
- Status of main steam isolation valve: closed
- Injection of water into the reactor is done by Make-up Water Condensate
  System.
- We do not believe there is leakage of reactor coolant in 
  the containment vessel.
- At 5:32am, Mar 12th, the temperature of the suppression chamber
  exceeded 100 degrees. As the reactor pressure suppression function was
  lost, at 5:32am, Mar 12th, it was determined that a specific incident
  stipulated in article 15, clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
  the reactor containment vessel (partial discharge of air containing
  radioactive materials) in order to fully secure safety.
  This preparation work started at around 10:33am, Mar 12th and finished
  at 10:58pm, Mar 12th.
- Restoration work in reactor cooling function is in progress to achieve
  reactor cold shutdown.
Unit 3 (shut down at 2:48pm on March 11th) 
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- Control rods are fully inserted (reactor is in subcritical status)
- Status of main steam isolation valve: closed
- We do not believe there is leakage of reactor coolant in 
  the containment vessel.
- We decided to prepare implementing measures to reduce the pressure of
  the reactor containment vessel (partial discharge of air containing
  radioactive materials) in order to fully secure safety. The preparation
  woke started at around 12:08pm, Mar 12th and finished at 12:13pm,
  Mar 12th.
- Reactor cold shutdown at 12:15pm, Mar 12th
Unit 4 (shut down at 2:48pm on March 11th) 
- Reactor is shut down and reactor water level is stable.
- Offsite power is available.
- At 0:43PM, there was a signal indicating that one of the control rods
  may have not properly inserted. However, we confirmed that it was
  inserted completely by another signal. We will inspect the reason
  of this.
- Status of main steam isolation valve: closed
- Injection of water into the reactor is done by Make-up Water Condensate
  System.
- We do not believe there is leakage of reactor coolant in 
  the containment vessel.
- In order to cool down the reactor, injection of water into the reactor
  had been done by the Reactor Core Isolation Cooling System, however,
  At 6:07am, Mar 12th, the temperature of the suppression chamber
  exceeded 100 degrees. As the reactor pressure suppression function was
  lost, at 6:07am, Mar 12th, it was determined that a specific incident
  stipulated in article 15, clause 1 has occurred.
- We decided to prepare implementing measures to reduce the pressure of
  the reactor containment vessel (partial discharge of air containing
  radioactive materials) in order to fully secure safety. The preparation
  woke started at around 11:44am, Mar 12th and finished 
  at around 11:52am, Mar 12th.
- Restoration work in reactor cooling function is in progress to achieve
  reactor cold shutdown. 
 
Indication from monitoring posts installed at the site boundary did
not show any difference from ordinary level.
No radiation impact to the external environment has been confirmed.
We will continue to monitor in detail the possibility of radioactive
material being discharged from exhaust stack or discharge canal. 
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