05000315/FIN-2016003-02
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Finding | |
|---|---|
| Title | Charging System Thru-Wall Leak |
| Description | A finding of very low safety significance with an associated NCV of Title 10 of the Code of Federal Regulations (CFR) 50 Appendix B, Criterion III, Design Control, was self-revealed when a thru-wall leak was identified on a branch connection off of the Unit 1 west coolant charging pump (CCP) discharge piping while it was in-service. The licensee failed to ensure the branch line design would remain intact when subjected to the vibratory conditions in the line. As a result, a vibration induced fatigue crack developed. This design issue caused a thru-wall leak on a similar line associated with the opposite-train charging pump in 2011. When the licensee addressed the prior leak, assumptions were made regarding the Unit 1 west CCP line. Since the length was slightly different, the belief was it would not be subject to the same increase in vibrations. However, when measuring the vibrations after the recent leak was identified, the results indicated the same elevated vibrations existed. The licensee secured the pump to stop the leak, declared the B train of the emergency core cooling system (ECCS) inoperable, and repaired the leaking weld. The issue was more than minor because it adversely affected the Design Control Attribute of the Mitigating Systems cornerstone, whose objective is to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). The finding screened as Green, or very low safety significance, because there was no loss of system function and the repairs were completed within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> timeframe allowed by Technical Specifications (TS). No cross-cutting aspect was assigned because the issue occurred in 2011 and was not reflective of current licensee performance. |
| Site: | Cook  |
|---|---|
| Report | IR 05000315/2016003 Section 1R12 |
| Date counted | Sep 30, 2016 (2016Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | J Bozga J Ellegood K Riemer T Go T Taylor |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control Technical Specification |
| INPO aspect | |
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Finding - Cook - IR 05000315/2016003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Cook) @ 2016Q3
Self-Identified List (Cook)
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