Corporate Information

Press Release (May 11,2009)
Performing a Series of Functional Tests for the Entire Plant of the Kashiwazaki-Kariwa Nuclear Power Station Unit No.7 after the Niigata-Chuetsu-Oki Earthquake(Evaluation After Raising the Reactor Pressure to Approx. 3.5MPa)
The Kashiwazaki-Kariwa Nuclear Power Station Unit No.7 (ABWR: 1,356MW) had been shut down 
since the Niigata-Chuetsu-Oki Earthquake occurred on July 16, 2007.  On May 8, 2009, we started 
a series of functional tests for the entire plant, and started up the reactor on May 9. 
(Already publicized on May 9.)

After the reactor pressure was raised to approx. 3.5MPa, the reactor was once brought down to 
subcriticality.  Then we performed various pre-planned tests and confirmed these results to be 
satisfactory by 6:00pm of May 10.

Based on these results of the tests, we brought the reactor up to criticality and raised the 
reactor pressure to rated pressure of approx. 7.0MPa at 3:12am of May 11.

Subsequently, at 6:43am of May 11, while performing an activation test of the reactor core 
isolation cooling system (RCIC), water level of the suppression pool went beyond the normal 
level, leading to a departure from the "Limiting Condition for Operation (LCO)," stipulated 
in the Technical Specification.  Following the operation of lowering the water level of the 
suppression pool, the plant returned to a normal condition within the LCO at 6:53am.  

Also, at around 6:53am, the RCIC could not be shut down by normal procedure and had to be shut 
down manually at the site.  While the RCIC was put out of service to examine the cause, 
a departure from LCO occurred.  After the RCIC was returned to a stand-by mode, the plant was 
declared to have returned to normal condition within the LCO at 7:31am.
No radioactive materials were released to the atmosphere and there is no effect of radioactivity 
due to these events.

We are now performing examination of the causes of these events.
Since water injection function into the reactor has been secured and since the RCIC pump was 
safely stopped by the operation at the site, we have determined that these events were not 
caused by the Niigata-Chuetsu-Oki Earthquake.

We will disclose test evaluation results accordingly.
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