05000338/FIN-2010005-04
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Finding | |
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| Title | Failure to Promptly Correct Conditions Adverse to Quality for Valve Actuator Diaphragms |
| Description | A non-cited violation of 10 CFR 50, Appendix B, Criterion XVI, Corrective Action, was identified by the inspectors for two examples of the failure to promptly identify and correct a condition adverse to quality present in the actuator diaphragms of 1-CH-HCV-1200C, letdown orifice isolation, and 1-RC-PCV-1456, reactor coolant system (RCS) pressurizer power operated relief valve (PORV). The licensee entered these problems into their corrective action program as condition reports 355000 and 387916. The inspectors determined that the failure to promptly correct conditions adverse to quality for 1-CH-HCV-1200C and 1-RC-PCV-1456 was a performance deficiency (PD). The NRC Enforcement Manual allows for the grouping of multiple examples of the same violation during an inspection period and the assignment of an issue to that example which is most significant. The inspectors determined that the second example, involving 1-RC-PCV-1456, was the more significant issue. The inspectors reviewed IMC 0612, Appendix B and determined the finding was more than minor because it affected the Barrier Integrity cornerstone objective of providing reasonable assurance that physical design barriers (e.g. RCS) protect the public from radionuclide releases caused by accidents or events. Specifically, the pressurizer PORVs provide protection to the RCS by preventing brittle fracture at low temperature conditions and protect RCS integrity at high temperature conditions. The inspectors reviewed IMC 0609, Attachment 4 and determined that since the finding involved a degradation of the Barriers Cornerstone, specifically the RCS barrier, a phase 3 analysis was required. The NRCs SPAR model was utilized to assess the risk significance of the finding modeling the impact of an increased likelihood of failing-to-open. The analyst calculated new failure probabilities for the Unit 1 PORVs (1-RC-PCV-1455C/1456) based on actual/observed failures of the valves. The analyst confirmed that the other valves affected by the performance deficiency (e.g., loop drain valves) were of negligible risk significance and were not included in the North Anna SPAR model. The dominant sequences were transients where a loss of the Condensate Storage Tank occurs and one/both of the PORVs fail to open when called upon, in order to initiate feed and bleed, subsequently leading to core damage. The analyst determined that the risk increase in core damage frequency was <1E-6 per year, a finding of very low safety significance, Green. The cause of this finding involved the cross-cutting area of problem identification and resolution, the component of corrective action program, and the aspect of implementation of corrective action (P.1(d)), because the licensee failed to correct the safety issue that existed with 1-RC-PCV-1456 in a timely manner, commensurate with its safety significance and complexity. |
| Site: | North Anna  |
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| Report | IR 05000338/2010005 Section 4OA5 |
| Date counted | Dec 31, 2010 (2010Q4) |
| Type: | NCV: Green |
| cornerstone | Barrier Integrity |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Nielsen W Loo J Reece E Lea G Mccoy R Clagg J Caruso G Johnson D Dempsey J Furia G Dentel E Knutson M Schneider M Balazik A Rao |
| CCA | P.3, Resolution |
| INPO aspect | PI.3 |
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Finding - North Anna - IR 05000338/2010005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2010Q4
Self-Identified List (North Anna)
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