The licensee identified a finding of very low safety significance (Green) and associated
NCV of
10 CFR Part 50, Appendix B, Criterion XVI, Corrective Actions. Criterion XVI requires, in part, that measures shall be established to assure that
conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected. Contrary to this requirement, on February 11, 2014, the licensee identified that they had failed to identify and correct a
condition adverse to quality where a single failure could result in the
EDGs picking up load on the essential busses in a time frame longer than what is required by TS
SR 3.8.1.12.
Surveillance Requirement 3.8.1.12 states that when required, the
EDGs auto-start and energize permanently connected loads in approximately 10 seconds. Specifically, after the NRC identified an
NCV on May 8, 2012, where required time delay limits would be exceeded in the sites EDG/1AR degraded voltage transfer logic, the licensees extent of condition failed to identify and correct a deficiency where relays in the EDG/1AR loss of voltage transfer logic could result in the
EDGs energizing the connected loads in a slightly longer time period than allowed (< 11 seconds). The performance deficiency was determined to be more than minor because it was associated with the
Mitigating Systems Cornerstone attributes of Design Control and Equipment Performance, and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences (i.e., core damage). Using
IMC 0609, the inspectors determined that the finding represented a loss of system and/or function as defined for the
EDGs in the TS bases; however, a detailed risk evaluation determined that there was no change in core damage frequency because exceeding the time delay would not impact the
Probabilistic Risk Assessment function to respond to a loss of offsite power event. As a result, the inspectors concluded that the finding had very low safety significance. The licensee entered this issue into their
CAP, and declared both
EDGs inoperable until action was taken to remove 1AR from service, and relays with acceptable time delays could be installed.
