05000348/FIN-2010005-02
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Finding | |
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| Title | Failure to Effectively Implement Risk Management Activities Results in Loss of Single Train of Shutdown Core Cooling |
| Description | A self-revealing NCV of 10 CFR 50.65(a)(4) revealed itself when Unit 1 train A RHR was lost because the licensee failed to identify and assess the loss of a plant significant component during plant repairs. On October 15, 2010, Unit 1 was in a refueling outage with fuel in the reactor vessel, the reactor vessel head detensioned, and reactor coolant system (RCS) water level one foot below the reactor vessel flange. The licensee restored power to motor-operated valve (MOV) 8701A during its initial preparations for flooding the refueling cavity and lifting the reactor vessel head to its refueling stand. Concurrent with this evolution, the licensee danger-tagged the train A solid state protection system (SSPS) to perform repairs to the multiplexer test switch. This activity resulted in relay PY402AX being placed in a de-energized state (actuated). Relay PY402AX provides the interlock to MOV 8701A to close if RCS pressure exceeds 402 psig. Once power was restored to MOV 8701A, the active RCS pressure interlock automatically closed the valve. This isolated the suction source of the train A RHR pump, and the control room operators stopped the pump. The licensees failure to effectively implement one of the risk management actions prescribed during the Orange outage risk, which resulted in the loss of a plant significant component during plant repairs, is a performance deficiency. The finding is more than minor because it adversely affected the equipment performance attribute of the MS cornerstone objective of ensuring the availability, reliability, and capability of systems responding to initiating events preventing undesirable consequences (i.e. core damage). Specifically, one of the key safety functions was significantly degraded without sufficient compensation. The significance of this finding was assessed using the Phase 1 screening worksheets of Attachment 4 and Appendix G, Attachment 1, Checklist 3 of MC 0609. Because the finding increased the likelihood that a loss of decay heat removal will occur due to a failure of the system itself or support systems, further review was required by the regional senior risk analyst. A regional Senior Reactor Analyst evaluated the performance deficiency using the Phase 3 protocol of the Significance Determination Process. Based upon this evaluation, the performance deficiency was characterized as of very low safety significance (Green). The dominant accident sequence involved the loss of the operating train of residual heat removal as the initiating event. The rest of the accident sequence involved the loss of the standby residual heat removal train due to the performance deficiency, the failure of operators to recover one these trains before Reactor Coolant System boiling and a failure of operators to initiate emergency core cooling before core damage. The major assumptions of this evaluation included a short time to boil and there was no credit was considered for recovering the standby residual heat removal train. This finding was assigned a cross-cutting aspect in the Resources component of the Human Performance area because training of personnel and sufficient qualified personnel to maintain work hours within working hour guidelines was not accomplished (H.2(b)). Specifically, trained personnel with sufficient knowledge to fully understand the effect of removing power to the Unit 1 train A SSPS were not provided to effectively implement the risk management actions prescribed during the Orange outage risk. (Section 4OA2) One violation of very low safety significance, identified by the licensee, has been reviewed by the NRC. Corrective actions taken or planned by the licensee have been entered into the licensees CAP. This violation and corrective action tracking numbers are listed in Section 4OA7 of this report. |
| Site: | Farley  |
|---|---|
| Report | IR 05000348/2010005 Section 4OA2 |
| Date counted | Dec 31, 2010 (2010Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Nielsen B Caballero B Collins C Dykes E Crowe G Kuzo J Sowa R Carrion S Shaeffer |
| CCA | H.9, Training |
| INPO aspect | CL.4 |
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Finding - Farley - IR 05000348/2010005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Farley) @ 2010Q4
Self-Identified List (Farley)
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