05000338/FIN-2015002-01
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Finding | |
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| Title | Failure To Maintain An Adequate Maintenance Procedure For The Turbine Driven Auxiliary Feedwater Pump |
| Description | Green. A self-revealing NCV of 10 CFR 50 Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified for the licensees failure to maintain an adequate maintenance procedure to set the governor valve on the Unit 1 Turbine Driven Auxiliary Feedwater (TDAFW) pump to the fully closed position. Specifically, the licensee failed to clarify key measurements in Maintenance Procedure 0-MCM-0412-02, Repair of the Terry Turbine Governor Valve, Revision 11, section 6.4.6, which sets the fully closed position of the governor valve that also adversely impacted the performance of the TDAFW system, and the TDAFW system suction source, the Emergency Condensate Storage Tank (ECST). This issue was entered this into the licensees corrective action program as CR 572803. The licensee failed to maintain an adequate maintenance procedure to set the governor valve on the Unit 1 TDAFW pump to the fully closed position was a performance deficiency (PD). Using Manual Chapter 0612, Appendix B, Issue Screening, dated September 7, 2012, the inspectors determined that the PD was more than minor because it was associated with the procedure quality attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage) and is therefore a finding. The finding was screened in accordance with NRC Inspection Manual Chapter (IMC) 0609, Attachment 4, Initial Characterization of Findings, dated June 19, 2012, and was determined to affect the short term secondary system heat removal safety function within the Mitigating Systems Cornerstone. The finding was determined to represent a loss of system function of the auxiliary feedwater (AFW) system as the incorrectly set governor caused the TDAFW pump to run at higher discharge pressure under low flow conditions, lifting the TDAFW discharge relief valve, which bypassed approximately 200 gpm flow to the ground. With the loss of 200 gpm the ECST could not have met its mission time which represented a loss of system function requiring a detailed risk analysis. A detailed risk analysis was performed by a regional senior reactor analyst (SRA) in accordance with the guidance of NRC IMC 0609, Appendix A, The Significance Determination Process (SDP) for ndings At-Power, dated June 19, 2012, using the NRC North Anna SPAR model. The major analysis assumptions included: the ECST failed for a one year exposure period, no additional failure modes from the incorrectly set TDAFW pump governor valve other than the early depletion of the ECST, and no recovery for the condition other than to align to alternate suction source which remained at nominal failure probability. The dominant sequence was a loss of offsite power with success of reactor protection system, success of the emergency power system and late failure of AFW and late failure of feed and bleed leading to core damage. The risk was mitigated by the availability of other suction sources. The result of the analysis was that the PD represented an increase in core damage frequency of < 1.0 E-6/year, a GREEN finding of very low safety significance. The finding has a cross-cutting aspect in the area of human performance associated with resources attribute because leaders failed to ensure that personnel, equipment, procedures, and other resources were available and adequate to support nuclear safety to maintain the ECST inventory during the mission time. |
| Site: | North Anna  |
|---|---|
| Report | IR 05000338/2015002 Section 1R12 |
| Date counted | Jun 30, 2015 (2015Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | C Fontana G Kolcum R Hamilton R Kellner S Rose S Sanchez T Skaggs-Ryan W Pursley |
| Violation of: | 10 CFR 50 Appendix B Criterion V |
| CCA | H.1, Resources |
| INPO aspect | LA.1 |
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Finding - North Anna - IR 05000338/2015002 | |||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2015Q2
Self-Identified List (North Anna)
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