05000346/FIN-2016003-02
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Finding | |
|---|---|
| Title | Inadequate Modification Design Control Measures Result in Reactor Protection System Inoperability |
| Description | A self-revealed finding of very low safety significance and an associated NCV of Title 10, Code of Federal Regulations (CFR), Part 50, Appendix B, Criterion III, Design Control, were identified for the licensees failure to have adequately prepared and implemented a permanent plant modification associated with steam generator (SG) replacement during the units 18th RFO in 2014. Specifically, in conjunction with SG replacement the licensee had also replaced a significant amount of reactor coolant system (RCS) piping and instrumentation, including all RCS hot leg resistance temperature detectors (RTDs). The RTD housings were improperly insulated during the modification, such that over the ensuing reactor operating cycle the RTD wiring insulation degraded to the extent that nearly all the RTDs were rendered inoperable. This issue was entered into the licensees CAP. Corrective actions by the licensee included replacement of the degraded RTDs. This finding was of more than minor safety significance because it affected the attribute of design control of the Mitigating Systems cornerstone of reactor safety, and adversely impacted the cornerstone objective of ensuring the availability, reliability, and capability of the units RPS. Specifically, the inspectors determined that the licensees failure to have properly designed and implemented the insulation packages for the RTD housings ultimately resulted in the overheating and degradation of the RTD wiring insulation and inoperability of the RTDs associated with the RCS high temperature and RCS pressure/temperature reactor trips. The finding was determined to be of very low safety significance based on a detailed risk analysis that yielded a change in core damage frequency (CDF) of less than 1E7 events per year. The inspectors determined that the finding had a cross-cutting aspect in the area of human performance. The inspectors assigned the cross-cutting aspect of Field Presence to the finding because the licensees SG replacement project management team failed to reinforce the importance of close communication between responsible engineers with overlapping and interfacing modification packages, and did not adequately promote effective work execution through the use of clearly defined work documents that were written and structured to minimize the likelihood for human error. (H.2) |
| Site: | Davis Besse  |
|---|---|
| Report | IR 05000346/2016003 Section 4OA3 |
| Date counted | Sep 30, 2016 (2016Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | D Kimble J Cameron J Cassidy J Rutkowski M Garza N Valos T Briley |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | H.2, Field Presence |
| INPO aspect | LA.2 |
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Finding - Davis Besse - IR 05000346/2016003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2016Q3
Self-Identified List (Davis Besse)
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