05000220/FIN-2014007-02
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Deficient Design Control of NMP Unit 1 Electrical Protection Design to Ensure Survivability of Safety-Related Loads |
| Description | The team identified a Green NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for failure to verify the adequacy of the Nine Mile Point Unit 1 electrical design during a design basis loss of coolant accident (LOCA) event with sustained degraded grid voltage (DGV). Specifically, Exelon did not verify Class 1E loads would not be damaged or become unavailable for a design basis LOCA with a degraded voltage condition between the degraded voltage setpoint and the loss of voltage setting for the degraded voltage time delay of 21 +/- 3 seconds and subsequent reconnection to the emergency diesel generator. Immediate corrective actions included preliminary evaluation of the safetyrelated MOV that operate during the first 21 seconds of the accident, which determined there was reasonable assurance the MOV protective devices would not actuate during sustained DGV concurrent with a design basis LOCA. Exelon entered this issue into their corrective action program as issue reports 2387818 and 2392780. The 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 (Green) because it was a design deficiency confirmed not to result in loss of operability or functionality. The team determined this issue had a cross-cutting aspect in the area of Problem Identification and Resolution, Operating Experience (Aspect P.5), because the organization did not effectively collect, evaluate, and implement relevant internal and external operating experience in a timely manner. Despite NRC Regulatory Issue Summary 2012-11, Adequacy of Station Electric Distribution System Voltages, and NRC Component Design Bases Inspections identifying similar performance deficiencies at other Exelon facilities during the last 3 years, the Nine Mile Point staff did not effectively evaluate and resolve this operating experience. |
| Site: | Nine Mile Point  |
|---|---|
| Report | IR 05000220/2014007 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 |
| ' | |
Finding - Nine Mile Point - IR 05000220/2014007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Nine Mile Point) @ 2014Q4
Self-Identified List (Nine Mile Point)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||