05000410/FIN-2014007-01
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Finding | |
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| Title | |
| Description | The team identified a Green NCV of Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix B, Criterion III, Design Control, for failure to verify and assure, in Nine Mile Point Unit 1 design basis calculations, that adequate voltages would be available to Class 1E accident initiated motors, motor-operated valves (MOV), and control circuits powered from the 4160 V, 600 V, and 120 V distribution systems during a design basis loss-of-coolant accident (LOCA) with offsite power available. Specifically, Exelon did not identify and evaluate the minimum transient voltage for the design basis LOCA event regarding accident initiated motors, MOVs, and control circuits, and did not evaluate the capability of the safety-related main steam isolation valve motor brakes. Immediate corrective action included preliminary calculations using the design grid voltage sag, which determined the Reserve Service Station Transformer load tap changers, motor control center (MCC) control circuits, MOVs, and the main steam isolation valve motor brakes would have adequate voltage to remain capable of performing their safety functions. Exelon entered the issues into their corrective action program as issue reports 2386719, 2386824, 2387652, 2387888, 2392928, and 2393299. This finding was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The team determined the finding was of very low safety significance because it was a design deficiency confirmed not to result in a loss of safety-related MCC MOV operability or functionality. This team assigned a cross-cutting aspect associated with this finding because the long-standing performance deficiency continued during and after Exelons review of related internal and external operating experience from 2012 to 2014. The team determined this finding had a cross-cutting aspect in the area of Problem Identification and Resolution, Operating Experience (Aspect P.5), because Nine Mile Point Unit 1 staff did not effectively collect, evaluate, and implement relevant internal and external operating experience in a timely manner. |
| Site: | Nine Mile Point  |
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| Report | IR 05000410/2014007 Section 1R21 |
| Date counted | Dec 31, 2014 (2014Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Edwards D Kern F Arner J Ayala J Brand J Nicely N Floyd W Sherbin |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | P.5, Operating Experience |
| INPO aspect | CL.1 |
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Finding - Nine Mile Point - IR 05000410/2014007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Nine Mile Point) @ 2014Q4
Self-Identified List (Nine Mile Point)
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