ANALYSES OF INSPECTION REPORTS AT FUEL CYCLE FACILITIES TO DERIVE INSIGHTS FOR A SIGNIFICANCE DETERMINATION PROCESS

摘要

Inspections carried out at nuclear fuel cycle facilities by USNRC inspectors are used to analyze and improve the safe operation of these facilities. With advances in risk-informed methodologies to analyze facility safety, a significance determination process (SDP) based on categorizing inspection findings according to their risk significance would allow an enhanced focus on findings more significant to risk and hence safety. Defining a SDP that can consistently evaluate the events and inspection findings is expected to foster objectivity, transparency, and predictability which are desirable features of an oversight process for fuel cycle facilities. This paper provides a summary of an attempt to characterize events and inspection reports at fuel cycle facilities to derive insights for such a process. A two- phased SDP was considered where Phase 1 was used to screen out findings of minimal risk significance and Phase 2 was used to characterize the (risk) significance of the inspection finding. This paper discusses evaluations to be conducted as part of the two phases in the SDP for inspection findings related to criticality safety, i.e., those findings that have the potential to increase the likelihood of a criticality accident in a facility. Screening criteria for Phase 1 evaluations for inspection findings affecting criticality safety are presented and event tree analyses for Phase 2 evaluations are performed. Further needs in developing guidance documents for conducting Phase 2 evaluations for SDP are also recommended. This work was carried out in support of NRC's effort to develop an improved fuel cycle oversight process (FCOP).