05000282/FIN-2010006-05
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Finding | |
|---|---|
| Title | Errors Found in the Electrical Relay Setting Calculation |
| Description | The inspectors identified a finding having very low safety significance and an associated NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, related to calculation errors found in the licensees relay setting analysis. Specifically, the protective relay setting calculation for Unit 2 4 KV safeguards switchgear failed to include the over-current relay setting calibration tolerance limits and failed to use the actual field measured value for offsite source transformer neutral grounding resistor in calculating the line to ground fault current. This finding was entered into the licensees corrective action program and a preliminary verification performed by the licensee concluded that the relay settings were still acceptable
The inspectors determined that this finding was more than minor because it was associated with the Mitigating Systems cornerstone attribute of equipment performance and affected the cornerstone objective of ensuring availability and reliability of systems that respond to initiating events to prevent undesirable consequences. This finding was of very low safety significance (Green) because the licensee was able to demonstrate that the relay settings were still acceptable. The finding did not have a cross-cutting aspect because it was not reflective of current performance. |
| Site: | Prairie Island  |
|---|---|
| Report | IR 05000282/2010006 Section 1R21 |
| Date counted | Sep 30, 2010 (2010Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems, Barrier Integrity |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | J Chiloyan D Betancourt M Munir A Dahbur D Szwarc C Brown B Sherbin |
| INPO aspect | |
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Finding - Prairie Island - IR 05000282/2010006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2010Q3
Self-Identified List (Prairie Island)
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