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| Entered date | Event description | |
|---|---|---|
| ENS 48644 | 2 January 2013 18:42:00 | At 1308 hours (CST) on January 2, 2013, Arkansas Nuclear One Unit 2 (ANO-2) experienced an inadvertent safety injection actuation signal (SIAS), containment cooling actuation signal (CCAS) and containment isolation actuation signal (CIAS) during matrix testing on 'C' channel plant protective system (PPS). All components actuated as designed for the stated actuation signals. After verification that the actuation signal was not valid the high pressure safety injection (HPSI) pumps and low pressure safety injection (LPSI) pumps were secured and their hand switches placed in pull-to-lock as directed by the abnormal operating procedure for inadvertent SIAS at 1312 hours. The HPSI and LPSI pumps were the restored to normal standby condition and available for automatic operation at 1352 hours. The unit did down power to approximately 87% power when all three coolant charging pumps ran with suction aligned to the boric acid makeup tanks. The unit currently remains in mode 1. SIAS, CCAS, and CIAS have been reset. The cause of the inadvertent actuation signals is under investigation. The NRC Resident Inspector has been informed. Unit 2 entered Technical Specification 3.0.3 for approximately 40 minutes while the LPSI and HPSI pumps were in pull-to-lock. |