There is no update from the release issued at 1:00 am
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, there was an alarm indicating that one of the control rods was
not properly inserted, however, at 10:43am 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.
- At 6:08pm, we announced the increase in reactor containment vessel
pressure, assumed to be due to leakage of reactor coolant. However, we
do not believe there is leakage of reactor coolant in the containment
vessel at this moment.
- At 5:22am, the temperature of the suppression chamber exceeded 100
degrees. As the reactor pressure suppression function was lost, at 5:22am,
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 and finished at 6:00pm.
- 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, the temperature of the suppression chamber exceeded 100
degrees. As the reactor pressure suppression function was lost, at 5:32am,
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 and finished at 10:58pm.
- 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 and finished at 12:13pm.
- Reactor cold shutdown at 12:15pm
Unit 4 (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.
- 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, the temperature of the suppression chamber exceeded 100 degrees.
As the reactor pressure suppression function was lost, at 6:07am, 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 and finished at around 11:52am.
- 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.