05000454/FIN-2007009-05
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Finding | |
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Title | Failure to Identify Corroded 0SX138B Valve Bolting During VT-2 Examination |
Description | The team identified a finding of very low safety significance and a Non-Cited Violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for the licensees failure to identify severely corroded bolts (condition adverse to quality) on the 0B SX basin suction supply isolation valve 0SX138B. The cause of this finding was related to the Corrective Action Program Component (Item P.1(a) of IMC 305) for the cross-cutting area of Problem Identification and Resolution, because the licensee staff failed to adopt an appropriate threshold for identifying issues. Specifically, the failure of the licensee VT-2 examiner to identify these degraded bolts was related to an excessively high threshold for problem identification. The licensee entered this issue into the corrective action program and replaced the bolts on the lower half of this valve which were subjected to the most severe corrosion. This finding was determined to be more than minor in accordance with IMC 0612, Power Reactor Inspection Reports, Appendix B, Issue Screening because the finding was associated with the Equipment Performance attribute of the Mitigating Systems Cornerstone and 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). Absent NRC intervention, the inappropriate threshold for identification of bolt corrosion as a condition adverse to quality would have gone uncorrected. This condition, if uncorrected, could lead to undetected corrosion failures in carbon steel components, affecting the reliability or capability of mitigating systems. The team evaluated the finding in accordance with IMC 0609.04, Phase 1 Initial Screening and Characterization of Findings. Under the Mitigating Systems Cornerstone Column of Table 4a, the team answered No to each of the screening questions, because the corrosion of the 0SX138B valve bolts had not yet challenged structural integrity or operability of the system. Therefore, the finding screened as having very low safety significance |
Site: | Byron ![]() |
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Report | IR 05000454/2007009 Section 4OA3 |
Date counted | Mar 31, 2008 (2008Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71153 |
Inspectors (proximate) | C Moore D Hills J Mcghee L Kozak M Holmberg T Bilik V Meghani |
CCA | P.1, Identification |
INPO aspect | PI.1 |
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Finding - Byron - IR 05000454/2007009 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2008Q1
Self-Identified List (Byron)
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