Press Release (Mar 14,2011)
Plant Status of Fukushima Daini Nuclear Power Station (as of 8:00 am March 14th)
[New Items are underlined]
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 that was conducted to
achieve reactor cold shutdown has been completed and cooling of the
reactor has been commenced at 1:24 am, Mar 14th.
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.
- Restoration work in reactor cooling function that was conducted to
achieve reactor cold shutdown has been completed and cooling of the
reactor has been commenced at 7:13 am, Mar 14th.
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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