05000482/FIN-2010005-02
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Finding | |
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Title | Failure to Account for Water Hammer Stresses in Essential Service Water System Calculations |
Description | The inspector identified a Green noncited violation of 10 CFR 50, Appendix B, Criterion III, having very low safety significance for the licensees failure to ensure that applicable regulatory requirements and the design basis were correctly translated into specifications, drawings, procedures and instructions. Wolf Creek failed to properly account for essential service water piping membrane stress and impact loads as required by the 1974 ASME Code,Section III, paragraphs ND-3112.4 and ND-3111. Specifically, the licensees design calculations for the essential service water system did not account for the pressure fluctuations caused by a known column closure water hammer phenomena which occurs during a loss of offsite power or load sequencer testing. Wolf Creek has written Condition Report 33253 and plans to address the issue. The licensees failure to account for the pressure fluctuations caused by a known column closure water hammer phenomena in the design calculations for the essential service water system was a performance deficiency. This performance deficiency was more than minor and therefore a finding because it was associated with the human performance attribute of the Mitigating Systems Cornerstone, and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The inspector determined the significance of the finding using IMC 0609.04, Phase 1 - Initial Screening and Characterization of Findings, and determined that the finding was of very low safety significance (Green) because it did not represent an actual loss of safety function of a single train for greater than its technical specification allowed outage time. This finding has a crosscutting aspect in the human performance cross-cutting area, associated with the decision making component, because the licensee used nonconservative values without adequate engineering justification to conclude that essential service water system piping met minimum wall thickness criteria for operability. |
Site: | Wolf Creek |
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Report | IR 05000482/2010005 Section 1R04 |
Date counted | Dec 31, 2010 (2010Q4) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.04 |
Inspectors (proximate) | G Apger J Groom B Correll N Greene T Farina W Strickland K Clayton D Stearns L Carson D Allen J Adams C Long C Peabody |
CCA | H.14, Conservative Bias |
INPO aspect | DM.2 |
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Finding - Wolf Creek - IR 05000482/2010005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Wolf Creek) @ 2010Q4
Self-Identified List (Wolf Creek)
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