The inspectors identified a noncited violation of
10 CFR 50.59 after Pacific Gas and Electric failed to perform an adequate evaluation of a thermal hydraulic analysis to determine if prior NRC approval was required for a 30-minute delay time to align offsite power. This analysis, Calculation STA-274, RETRAN Evaluation of
GDC-17 Loss of
AC Scenario, Revision 0, demonstrated that the 30-minute delayed offsite power source was acceptable. On December 31, 2008, a Pacific Gas and Electric
10 CFR 50.59 screen concluded that Calculation STA-274 was not required to be evaluated to determine if prior NRC approval was required for the delay time. On March 31, 2009, the inspectors concluded that the licensee was required to evaluate Calculation STA-274 to determine if prior NRC approval was needed. On May 27, 2009, Pacific Gas and Electric completed the 50.59 evaluation and concluded that prior NRC approval was required for the 30-minute delay time to align offsite power. The inspectors concluded that the finding is more than minor because the changes made to the facility required prior NRC review and approval. The finding affected the
Mitigating Systems Cornerstone because the change described how the delayed offsite power source met the design basis. The inspectors concluded the finding is of very low safety significance because the finding was a design deficiency that did not result in the loss of operability or functionality. Because the issue affected the NRCs ability to perform its regulatory function, the inspectors evaluated this finding using the traditional enforcement process. This issue was classified as
Severity Level IV because the violation of
10 CFR 50.59 involved conditions resulting in very low safety significance by the
significance determination process. This finding had a crosscutting aspect in the area of problem identification and resolution associated with the corrective action program component because Pacific Gas and Electric did not thoroughly evaluate the change to the facility as described in the Final Safety Analysis Report Update to determine if prior NRC approval was required
P.1(c)(Section 40A5)
