05000454/FIN-2015008-07
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Finding | |
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| Title | Failure to Evaluate the Adverse Effects of Changing the SXCT Tornado Analysis as Described in the UFSAR |
| Description | The team identified a Severity Level IV NCV of 10 CFR 50.59(d)(1), Changes, Tests, and Experiments, and an associated finding of very-low safety significance (Green) for the licensees failure to perform a written evaluation that provided the bases for the determination that the changes to the emergency service water cooling tower (SXCT) tornado analysis as described in the UFSAR did not require a license amendment. Specifically, the associated 10 CFR 50.59 Evaluation did not address the introduction of a new failure mode, the resulting loss of heat removal capacity during worst postulated conditions, and addition of operator actions that have not been demonstrated can be completed within the required time to restore the required SXCT heat removal capacity during worst case conditions. The licensee captured this issue in their CAP with a proposed action to revise the 10 CFR 50.59 Evaluation and submit a Licensee Amendment Request. The performance deficiency was determined to be 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. In addition, the associated tradition enforcement violation was determined to be more than minor because the team could not reasonably determine that the changes would not have ultimately required prior NRC approval. 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 did not identify a cross-cutting aspect associated with this finding because the finding was not representative of current performance due to the age of the performance deficiency. |
| Site: | Byron  |
|---|---|
| Report | IR 05000454/2015008 Section 1R21 |
| Date counted | Sep 30, 2015 (2015Q3) |
| Type: | TEV: Severity level IV |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | A Della Grecab Palagi C Lipa D Betancourt J Leivo M Jones N Feliz-Adorno |
| Violation of: | 10 CFR 50.59 |
| INPO aspect | |
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Finding - Byron - IR 05000454/2015008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2015Q3
Self-Identified List (Byron)
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