05000338/FIN-2015007-02
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Finding | |
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| Title | Failure to Consider Potential Water Hammer Impact Loading on AFW piping |
| Description | The team identified a non-cited violation (NCV) of 10 Code of Federal Regulations (CFR) Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to control deviations from their piping design code of record for the auxiliary feedwater (AFW) system discharge lines. The licensee failed to consider the impact forces from a potential water hammer event as required by USA Standard (USAS) B31.1.0. The licensee entered this issue into their corrective action program as CR1003896. The licensee measured the discharge line temperatures of the AFW system to verify that current seat leakage past the check valves did not support steam void formation based on the recorded temperature and pressure in the discharge line such that water hammer was avoided. Additionally, the licensee implemented weekly temperature monitoring for continued operability of the AFW discharge lines in CA3003072. This performance deficiency was more than minor because it was associated with the mitigating systems cornerstone attribute of design control and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensee did not ensure the capability of the AFW piping because they did not consider that an undiscovered steam pocket in any of the AFW pumps discharge lines could lead to a water hammer in the line when AFW is initiated during an event. The team used IMC 0609, Att. 4, Initial Characterization of Findings, issued June 19, 2012, for Mitigating Systems, and IMC 0609, App. A, The Significance Determination Process (SDP) for Findings At-Power, issued June 19, 2012, and determined the finding to be of very low safety significance (Green) because the finding was a deficiency affecting the design of a mitigating structure, system, or component (SSC), and the SSC maintained its operability or functionality (as shown through review of documentation related to prior identified leakage). The team determined that no cross-cutting aspect was applicable because the finding was not indicative of current licensee performance. |
| Site: | North Anna  |
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| Report | IR 05000338/2015007 Section 1R21 |
| Date counted | Sep 30, 2015 (2015Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Baron G Ottenberg J Bartley M Riley O Mazzoni S Herrick T Skaggs-Ryan |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - North Anna - IR 05000338/2015007 | ||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2015Q3
Self-Identified List (North Anna)
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