05000261/FIN-2016001-04
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Finding | |
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| Title | Failure to Control Deviations from Design Specifications for the Service Water System |
| Description | A self-revealing Green NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, was identified for the licensees failure to assure that appropriate quality standards are specified and included in design documents and that deviations from such standards are controlled. Specifically, the failure to control a modification of the service water (SW) system led to the installation of a non-conforming valve and resulted in the inoperability of the motor-driven auxiliary feedwater (MDAFW) system. As corrective action, the licensee performed a modification to replace the SW-115 valve. The licensee entered this issue into their CAP as CR 1993790. The failure to control deviations from design specifications for a modification to the SW system was the performance deficiency. The performance deficiency was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the installation of a valve outside of design specifications for the SW system contributed to the failure of SW-115 and reduction of cooling water flow to the MDAFW system. This degraded condition rendered the A train of the MDAFW system inoperable for greater than its TS AOT from December 15, 2015, to January 19, 2016. In addition, both trains of MDAFW were inoperable for greater than the TS AOT from January 19, 2016, to January 22, 2016. The inspectors used NRC IMC 0609, Attachment 4, Phase 1 - Initial Screening and Characterization of Findings, to evaluate the significance of this issue and determined the finding required a Detailed Risk Evaluation because the finding represented an actual loss of function of at least a single train of MDAFW for greater than its TS AOT. A detailed risk evaluation was performed by a regional SRA in accordance with NRC IMC 0609 Appendix A using the NRC Robinson SPAR model and input from the licensees Robinson Fire PRA model. The major analysis assumptions included exposure periods for loss of a single train of MDAFW for 38 days and loss of both trains of MDAFW for a period of three hours. No recovery was assumed. The SDAFW and C AFW trains were not affected. The dominant sequence was a loss of main feedwater initiator followed by failures of both trains of MDAFW due to the performance deficiency, the SDAFW pump, the C train of AFW, and failure of the operator to implement feed and bleed cooling. The risk associated with this performance deficiency was mitigated by the availability of alternate AFW trains. The detailed risk evaluation determined that the increase in core damage frequency due to the performance deficiency was less than 1.0 E-6 per year and therefore the performance deficiency was characterized as a GREEN finding of very low safety significance. The finding does not have a cross-cutting aspect since the installation of a valve outside of design specifications into the SW system occurred prior to 1978 and, as a result, is not indicative of current licensee performance. |
| Site: | Robinson  |
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| Report | IR 05000261/2016001 Section 1R22 |
| Date counted | Mar 31, 2016 (2016Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.22 |
| Inspectors (proximate) | A Nielsen C Scott D Bacon G Hopper J Parent K Ellis W Loo |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control Technical Specification |
| INPO aspect | |
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Finding - Robinson - IR 05000261/2016001 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Robinson) @ 2016Q1
Self-Identified List (Robinson)
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