05000454/FIN-2015008-11
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Finding | |
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| Title | Operability Evaluation Relied on Probabilities of Occurrence of the Associated Event |
| Description | The team identified a finding of very-low safety significance (Green), and an associated NCV of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, for the failure to make an operability determination without relying on the use of probabilistic tools. Specifically, an operability evaluation for an SXCT degraded condition used probabilities of occurrence of tornado events which was contrary to The requirements of the licensee procedure established for assessing operability of structures, systems, and components (SSCs). The licensee captured the teams concern in their CAP to revise the affected operability evaluation without using probability of occurrence of tornado events. The performance deficiency was more than minor because it was associated with the Mitigating Systems cornerstone attribute of protection against external events, and affected the cornerstone objective of ensuring the availability, reliability, and capability of mitigating systems to respond to initiating events to prevent undesirable consequences. The finding screened as of very-low safety significance (Green) using a detailed evaluation because a loss of SXCT during a tornado event would degrade one or more trains of a system that supports a risk-significant system or function. The bounding change to the core damage frequency was less than 5.4E-8/year. The team determined that this finding had a cross-cutting aspect in the area of human performance because the licensee did not ensure knowledge transfer to maintain a knowledgeable and technically competent workforce. Specifically, the licensee did not ensure personnel were trained on the prohibition of the use of probabilities of occurrence of an event when performing operability evaluations, which was contained in licensee procedure established for assessing operability of SSCs. [H.9] |
| Site: | Byron  |
|---|---|
| Report | IR 05000454/2015008 Section 4OA2 |
| Date counted | Sep 30, 2015 (2015Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Della Grecab Palagi C Lipa D Betancourt J Leivo M Jones N Feliz-Adorno |
| Violation of: | 10 CFR 50 Appendix B Criterion V |
| CCA | H.9, Training |
| INPO aspect | CL.4 |
| ' | |
Finding - Byron - IR 05000454/2015008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2015Q3
Self-Identified List (Byron)
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