The team identified a noncited violation of
10 CFR Part 50, Appendix B, Criterion III, Design Control. The calculation EE2-14-3 Diesel Generator Overcurrent Protection, Revision 1, does not document sufficient design bases for the setting of the IGCV-51 overcurrent with voltage control relays for the
emergency diesel generators. Specifically, the licensee failed to perform an adequate evaluation of new setpoint values identified in Engineering Report ER-W3-99-0174-00-00, which provided the bases for relay tap setpoint changes for
emergency diesel generator overcurrent protection while the diesel was in test mode. The primary purpose of the IGCV-51V relays was to protect the
emergency diesel generator against external faults and prevent the output breaker from closing foilowing a breaker trip associated with a fault. If the faulted bus had been isolated by the operation of the under-voltage relays instead of the IGCV-51 relays, the
emergency diesel generator output breaker would be allowed to electrically reclose onto this faulted bus and potentially damage the
emergency diesel generator and the associated switchgear. The issue has been entered into the licensee\'s corrective action program as Condition Report
CR-WF3-2009-04780. The failure to have sufficient design bases for the
emergency diesel generator overcurrent protection IGCV-51V relays without an adequate verification of the setpoint modification for the IGCV-51V relay, Voltage Controlled, Time-Overcurrent Relay, for
emergency diesel generator overcurrent protection while the diesel was in test mode, was a performance deficiency. Specifically, failure to verify the adequacy of a design modification for the IGCV-51V relay could result in reduced reliability of the
emergency diesel generators. The finding was determined to be greater than minor because it affected the
mitigating systems cornerstone attribute of design control to ensure the availability, reliability, and capability of safety systems that respond to
initiating events to prevent undesirable consequences. Using Manual Chapter 0609.04, the finding was determined to have a very low safety significance (Green) because the failure did not result in loss of operability or functionality and because the finding did not screen as potentially risk significant due to a seismic, flooding, or severe weather initiating event. This finding was reviewed for crosscutting aspects and none were identifie
