The inspectors identified a noncited
Severity Level IV violation of
10 CFR 50.59 after Pacific Gas and Electric failed to perform an adequate safety evaluation of Unit 1 containment
sump modifications. As a result, the licensee failed to obtain prior NRC approval for a change to the technical specifications incorporated in the license. On March 6, 2007, the licensee identified that the current refueling water storage tank minimum technical specification level was not adequate to ensure that the new containment
sump would perform the required safety function. On April 20, 2007, Pacific Gas and Electric completed a
10 CFR 50.59, Licensing Basis Impact Evaluation Screen of the Containment
Sump Modification. The licensee concluded that the modification did not involve a change to the plant technical specifications and that the required refueling water storage tank level was unaffected by the modification. On May 25, 2007, Pacific Gas and Electric placed Unit 1 into Mode 4 without an approved technical specification change. The inspectors concluded that the finding was more than minor because the modification required prior NRC approval. Because the issue affected the NRCs ability to perform its regulatory function, this finding was evaluated using the traditional enforcement process. The issue was classified as
Severity Level IV because the violation of
10 CFR 50.59 involved conditions evaluated as having very low safety significance by the
Significance Determination Process. The finding was determined to be of very low safety significance because the safety function was maintained since Pacific Gas and Electric had administratively maintained the refueling water storage tank at an adequate level during plant operation. On this basis, the item impacts the
mitigating systems cornerstone and screens to Green, using the
Inspection Manual Chapter 0609,
Significance Determination Process, Phase 1 evaluation, Appendix A, because (a) the finding is not a design or qualification deficiency, (b) there is no loss of safety function for the mitigating system; and, (c) there are no seismic, fire, flooding or severe weather initiating implications associated with the finding. This finding has a crosscutting aspect in the area of problem identification and resolution associated with the corrective action program component because the licensee did not appropriately prioritize and evaluate the problem of an inadequate refueling water storage tank level after the problem was entered into the corrective action program,
P.1(c). This issue was entered into the licensees corrective action program as Action Request A07145625
