05000528/FIN-2014004-03
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Finding | |
|---|---|
| Title | Inadequate Calculations to Support the Degraded Voltage Relay Setpoint |
| Description | The team identified a Green non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the licensees failure to assure the adequacy of degraded voltage relay (DVR) setpoints. Specifically, the team identified that the licensee failed to perform calculations to demonstrate the voltage setpoints for the installed degraded voltage relays would afford adequate voltage to safety-related loads during worst case accident loading. The failure to assure the adequacy of DVR setpoints for voltage and the time delay by performing adequate voltage drop calculations was a performance deficiency. This finding is more than minor because it was associated with the design control attribute of the Mitigating Systems cornerstone and it adversely impacted to the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events. Specifically, the failure to properly ensure that safety-related electrical devices had adequate voltage could impact their safety function. The basis for this conclusion was that despite the non-conservative voltage inputs to voltage calculations and, therefore, loss of design margin for available voltage, there was still adequate voltage for the circuits to perform their safety function based on worst case voltage as demonstrated in the updated calculations. The licensee developed design basis calculations for its DVR voltage setpoints and committed to develop a plant design change and an associated license amendment to shorten the existing time delay in Technical Specication 3.3.7.3(a). There is no cross-cutting aspect associated with this finding because it is a historical condition and not indicative of current performance. |
| Site: | Palo Verde  |
|---|---|
| Report | IR 05000528/2014004 Section 1R21 |
| Date counted | Sep 30, 2014 (2014Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | B Parks D Reinert D You J Watkins M Hay S Makor T Brown |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Palo Verde - IR 05000528/2014004 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Palo Verde) @ 2014Q3
Self-Identified List (Palo Verde)
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