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Failure to ensure proper configuration of … Failure to ensure proper configuration of 1A EDG light socket On March 10, 2013, during a monthly surveillance of the 1A EDG, the output breaker failed to close while attempting to parallel the 1A EDG to the grid. Two more breaker closures were attempted and again, the breaker failed to close (total of 3 times). The electrician reported the breaker cycled, current on the ammeter increased, but the breaker did not latch and immediately tripped. The control room operators noted that during the three closure attempts, the red light never energized. No trip flags were noted at the breaker cubicle. Bench testing of the breaker outside of its cubicle was performed and the breaker was able to be closed seven times without incident. Subsequent troubleshooting revealed the circuit breaker was exposed to a standing trip signal. The cause of the trip signal was an electrical short across the red-indicating light that resulted in the energization of the trip coil. This short effectively bypassed the internal resistor which allowed enough current in the circuit to energize the trip coil. The short was attributed to a failure of the red-indicating-light-socket assembly. The specific cause of the broken light socket was deemed to be age-related distortion of the plastic socket where under a high temperature environment (behind operating panel) successive retightening of the retaining nut can induce enough stress to exceed the yield stress of the socket material. In addition, the licensee noted that the vendor tech manual for the light-socket assembly recommended bending of the rear terminal tab up to 90 degrees (if necessary) to best suit the wiring configuration. Given a failure of the light-socket assembly, pre-bending of the tab could have decreased (or eliminated) the likelihood of a short circuit. 10CFR50 Appendix B, criterion III, requires in part, established measures shall ensure the design bases for safety-related components are translated into procedures and instructions. Contrary to the above, the licensee failed to incorporate vendor guidance into plant maintenance procedures to ensure the EDG could have performed its design function. The light-socket assembly was replaced and the 1A EDG was successfully tested and declared back in service on March 10, 2013. The licensee entered the issue into the CAP and developed several corrective actions including the initiation of a preventative maintenance program to periodically inspect the light sockets to ensure their continued operability. A risk analysis for this event was performed by the licensee. An exposure time of 15 days (one-half the time from the last successful EDG run, or 30 days) was utilized for this analysis. The results were reviewed by the inspectors and the conclusion was that the failure was of very low safety significance (Green).s of very low safety significance (Green).

Discovered date

23:59:59, 30 June 2013 +

Docket

05000327 + and 05000328 +

Event date

23:59:59, 30 June 2013 +

Finding integer

2 +

Finding type

Non-cited violation +

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Identified by

Licensee-identified +

Inspection report

IR 05000327/2013003 +

Inspector

R Hamilton +, Scott Shaeffer +, Wesley Deschaine +, Galen Smith + and Jonathan Rivera +

Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.

15:47:33, 30 May 2018 +

Person