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| Entered date | Event description | |
|---|---|---|
| ENS 50871 | 7 March 2015 16:55:00 | On March 7, 2015, at 0830 EST, the NCNR (NIST Center for Neutron Research) discovered a probable violation of the Limiting Condition for Operations of the TR-5 Technical Specifications (TS), 3.3.2, Specification (1), while performing maintenance during the scheduled reactor shutdown period. This initial report is being made in accordance with TR-5 TS 6.7.2.d. The TS is as follows: TS 3.3.2 Emergency Core Cooling; Specification: The reactor shall not be operated unless: (1) The D2O (deuterium oxide) emergency core cooling system is operable, and (2) A source of makeup water to the D2O emergency cooling tank is available. The discovery was made at 0830 EST on March 7, 2015, that the local disconnect switch for the emergency sump pump was in the disconnect position. The last time that it was verified operable was on July 2, 2014, when the annual surveillance of operability was performed. There was no maintenance performed on the emergency sump pump, nor is there any other known reason that the switch would have been placed in the disconnect position since July 2, 2014. After the discovery the sump pump disconnect switch was immediately placed in the connect position. The emergency core cooling system, in the event of loss of core coolant, provides sufficient D2O, to passively provide adequate coolant for ~ 2.5 hours to cool the fuel and protect against the release of fission products. That part of the emergency core cooling system was and remains operable and is not part of this violation. The emergency core cooling system employs one sump pump to return spilled coolant to the overhead storage tank. There is only enough D2O in the overhead storage tank to provide cooling for 2.5 hours on a once through basis. Because there is only one sump pump, it must be operational whenever the reactor is operational (TS 3.3.2 (1)). In the event that that pump fails or is inoperable and the D2O supply in the overhead storage tank is exhausted, domestic water or a suitable alternative would be used to furnish water for once through cooling (TS 3.3.2 (2)). A source of makeup water to the D2O emergency cooling tank was and remains available and is not part of this violation. The violation that is the subject of this report is that the sump pump was discovered inoperable and may have been inoperable since July 2, 2014, which includes periods of reactor operation. That is a violation of TS 3.3.2 (1). The licensee is conducting an investigation into this event. |