The team determined that the licensees failure to develop and implement corrective actions for a repetitive problem of excavating and digging activities damaging buried components was a performance deficiency warranting a significance evaluation. The team concluded that the finding was of greater than minor risk significance in accordance with
IMC 0612, Power Reactor Inspection Reports, Appendix B, Issue Disposition Screening. This conclusion was based on the licensees failure to develop and implement corrective actions for several previous similar events. When the loss of offsite power event occurred the plant was shutdown with the reactor vessel head removed and the reactor cavity flooded to about 6 feet above the reactor vessel
flange.
Inspection Manual Chapter 0609,
Significance Determination Process, Appendix A,
SDP Phase 1 Screening Worksheet for
IE [Initiating Events], MS [Mitigating Systems], and B [Barrier Integrity] Cornerstones, states that if the finding is assumed to degrade the safety of a shutdown reactor then use Appendix G, Shutdown Operations
Significance Determination Process. Utilizing
IMC 0609, Appendix G worksheet,
PWR [Pressurized Water Reactor] Cold Shutdown and Refueling Operation
RCS [Reactor Coolant System] Open and Refueling Cavity Level <23 Feet, the team determined this was a finding that increased the likelihood of a loss of offsite power and therefore required a Phase 2 analysis. In addition, a Phase 3 analysis was required since the potential for this event to occur also existed when the plant was operating at power.
