The NRC identified a non-cited violation of
10 CFR 50, Appendix B, Criterion III, Design Control, for the licensees failure to correctly evaluate the heat-up of the
Main Steam Valve House (MSVH), which contains the auxilliary
feedwater pumps as well as other safety-related
mitigating systems. The violation was entered into the licensees corrective action program as Condition Reports 1077007 and 1077684 and the licensee conducted a preliminary calculation and evaluation to determine the actual temperature increase and determined that the equipment located in MSVH remained
operable. The performance deficiency was determined to be more than minor because it was associated with the Design Control attribute of the
Mitigating Systems cornerstone and adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the failure to evaluate worst-case design conditions resulted in a decreased margin for reliability and capability of
mitigating systems contained in the MSVH. The inspectors determined the finding to be of very low safety significance (Green) because the finding was a deficiency affecting the qualification of a mitigating structure, system, or component (
SSC), and the
SSC maintained its operability or functionality. This finding was not assigned a cross-cutting aspect because the underlying cause was a legacy issue and not indicative of current performance.
