05000382/FIN-2011005-02
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Finding | |
|---|---|
| Title | Failure to Identify and Correct a Condition Adverse to Quality Associated with the Main Feedwater Isolation Valves |
| Description | The inspectors identified a non-cited violation of 10CFR50, Appendix B, Criterion XVI because the licensee failed to identify and correct a condition adverse to quality associated with the main feedwater isolation valve. Specifically, the licensee did not identify that varnish deposits were causing the main feedwater isolation valve to fail its inservice testing. As a result, corrective actions that were implemented did not address the adverse condition, leading to a subsequent test failure. The licensee entered this issue into their corrective action program as CR-WF3-2011-2005 and CR-WF3-2011-8140. The corrective actions included the replacement of the actuator, a shortening of the replacement frequency of the four-way hydraulic valves to a 36 month interval, and an evaluation of the current methods of gathering and implementing operating experience. The performance deficiency is more than minor because it is associated with the equipment performance attribute of the Mitigating Systems cornerstone and affects the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the main feedwater isolation valve is credited for closure during a main feedwater line break. The inspectors performed the initial significance determination using the NRC Inspection Manual 0609, Attachment 0609.04, Phase 1 Initial Screening and Characterization of Findings. The finding screened to a Phase 2 significance determination because it involved a loss of one train of safety related equipment for longer than the technical specification allowed outage time. A Region IV senior reactor analyst performed a Phase 2 significance determination and used the pre-solved worksheet from the Risk Informed Inspection Notebook for the Waterford-3 Nuclear Power Plant, Revision 2.01a. However, the main feedwater isolation valves were not included in the pre-solved worksheet and the valves did not appear as components in the Phase 2 significance determination worksheets. The senior reactor analyst performed a Phase 3 significance determination for this issue. The analyst noted that the main feed isolation valves were not a significant contributor to core damage frequency and were not included in the NRCs SPAR model. These valves close to mitigate core overcooling events or to isolate feedwater flow to a ruptured feedwater line inside containment. Overcooling events do not lead to core damage. A ruptured feedwater line could challenge containment integrity, but without core damage there would be no potential for a large early release. If a valve failed to close on demand, the licensee had other means to isolate feedwater flow to a steam generator or into containment. Operators could secure feedwater pumps, close a block valve, or close the main feedwater flow control valves. Accordingly, the contribution to core damage was much less than E-6. Therefore, the inspectors determined that this finding had very low safety significance (Green). This finding has a cross-cutting aspect in the operating experience component of the problem identification and resolution area in that the licensee did not collect and evaluate relevant external operating experience to identify that other sites experienced similar failures of feedwater isolation valves due to varnish deposits on the interior surface |
| Site: | Waterford  |
|---|---|
| Report | IR 05000382/2011005 Section 1R12 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | L Ricketson G Guerra C Smith P Elkmann M Davis G George L Carson D Allen D Overland B Correll S Hedger N Greene D Bradley |
| CCA | P.5, Operating Experience |
| INPO aspect | CL.1 |
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Finding - Waterford - IR 05000382/2011005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2011Q4
Self-Identified List (Waterford)
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