TS 5.4.1, Procedures states in part that written procedures shall be established, implemented, and maintained covering activities recommended in
RG 1.33, Revision 2, Appendix A.
RG 1.33, Appendix A, section 6a, requires procedures for loss of coolant emergencies. Contrary to the above, from August 27, 2012 to February 9, 2013, licensee procedures FNP-1/2-ECP-1.1, Loss of Emergency Coolant Recirculation, used a non-conservative value of 100 psig instead of the vendor recommended 160 psig as the lower limit during
steam generator pressure reduction to allow the safety injection (
SI)
accumulators to inject to the
RCS. At 100 psig,
nitrogen gas could be injected into the
RCS cold leg and inhibit natural recirculation. The licensee entered this condition into their
CAP as CR 585797. The inspectors assessed the finding using
IMC 0609 Attachment 4, and Appendix A, and determined that additional analysis by the regional senior reactor analyst (
SRA) was required. The regional
SRA performed a Phase 3 analysis for the finding. Cutsets were developed for small and medium loss of coolant accident scenarios which represented postulated conditions. A human reliability analysis (
HRA) was developed that conservatively overestimated the failure rate for plant operators to perform a continuous action step that would have prevented
nitrogen intrusion prior to the point in the procedure that contained the incorrect setpoint for isolating
accumulators. This
HRA was used as a screening value to evaluate the nonrecovered cutsets, and the value was totaled. The impact of the finding on core damage frequency was determined to be less than
1E-6 and the finding determined to be Green.
