05000454/FIN-2010006-03
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Finding | |
|---|---|
| Title | Failure to Periodically Test 125 Vdc Molded Case Circuit Breakers |
| Description | A finding of very low safety significance and associated NCV of the Byron Station facility operating licensee conditions for fire protection was identified by the inspectors for the licensees failure to periodically test samples of molded case circuit breakers (MCCBs) at the 125 Volt direct current (Vdc) level. The licensee subsequently entered the issue into their corrective action program and verified that sufficient design margin existed such that breaker coordination would not be adversely affected.
The inspectors determined that this finding was more than minor because the failure to test the MCCBs would result in a failure to detect excessive set-point drift which impacted breaker coordination. This finding was of very low safety significance (Green) because the licensee verified that sufficient design margin existed such that breaker coordination would not be adversely affected. In addition, no failures of 125 Vdc MCCBs to trip due to set-point drift had been identified. The finding did not have a cross-cutting aspect because it was not reflective of current performance. |
| Site: | Byron  |
|---|---|
| Report | IR 05000454/2010006 Section 1R05 |
| Date counted | Dec 31, 2010 (2010Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.05 |
| Inspectors (proximate) | R Daley R Langstaff R Winter A Dahbur L Kozak G Gulla N Melly |
| INPO aspect | |
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Finding - Byron - IR 05000454/2010006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2010Q4
Self-Identified List (Byron)
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