05000397/FIN-2017002-01
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Finding | |
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| Title | Mechanism Operated Cell Switch Failure |
| Description | Green . The inspectors reviewed a self -revealed finding for the licensees failure to follow plant Procedure SWP -CA P-01, Corrective Action Program, that ensures corrective actions are timely. As a corrective action for failures associated with mechanism operated cell switches for nonsafety 4160 VAC circuit breakers in 2013 and 2015, the licensee assigned modifications to the mechanism operated cell switches but failed to implement t hem in a timely manner. Consequently, on July 20, 2016, circuit breaker E -CB -S/3 mechanism operated cell switches failed to change state resulting in a loss of a main feed pump and an unplanned runback to 70 percent reactor power. As corrective action, the licensee declared the startup transformer inoperable, modified the mechanism operated cell assembly for circuit breaker E -CB -S/3 to remove one switch, and performed post -maintenance testing. The licensee also initiated Action Request 352504 to perform an apparent cause review and address long -term corrective actions. The failure to follow plant Procedure SWP -CAP -01, Corrective Action Program, that ensures corrective actions are timely was a performance deficiency. The performance deficiency was more than minor because it affected the equipment performance attribute of the Initiating Event Cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the loss of major loads on E -SM -3 upset plant stability by causing a loss of feed and reactor runback transient. The inspector performed the initial significance determination using NRC Inspection Manual Chapter 0609, Appendix A, Exhibit 1, Initiating Events Screening Questions. The inspectors determined that the finding was of very low safety significance (Green) because the finding did not cause a reactor trip and the loss of mitigation equipment relied upon to transition the plant from the onset of the trip to a stable shutdown condition. Specifically, the licensee remained at power and maintained diverse feed and condensate pumps. This finding had a cross -cutting aspect in the area of human performance, consistent process, in that the licensee failed to use a systematic approach to make decisions including incorporating risk insights. Specifically, circuit breaker E -CB -S/3 is utilized at least monthly 3 for emergency diesel generator surveillance testing and a failure could render the startup transformer inoperable. The mechanism operated cell assembly modification, recommended in 2013 and assigned for action in 2015, was not planned or scheduled as a work order at the time of the failure in 2016 [H.13]. |
| Site: | Columbia  |
|---|---|
| Report | IR 05000397/2017002 Section 1R12 |
| Date counted | Jun 30, 2017 (2017Q2) |
| Type: | Finding: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.12 |
| Inspectors (proximate) | G Kolcum R Alexander D Bradley L Brandt L Carson J Drake S Money J O'Donnell M Haire |
| CCA | H.13, Consistent Process |
| INPO aspect | DM.1 |
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Finding - Columbia - IR 05000397/2017002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Columbia) @ 2017Q2
Self-Identified List (Columbia)
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