UNANNOUNCED INSPECTIONS FOR SPENT FUEL TRANSFER VERIFICATION AT MULTI-UNIT CANDU STATIONS IN CANADA: EVALUATION OF A FIRST YEAR OF IMPLEMENTATION

Unannounced inspections (UIs) for the verification of spent fuel (SF) transfers are an important component of the integrated safeguards (IS) approach for multi-unit CANDU stations (MUCS) in Canada. Within the framework of the IS implementation, UIs provide a more effective and efficient coverage of the SF flow from nuclear generating stations to dry storages, due to its time unpredictability and human resource savings. The paper analyzes the results of a first year of implementing UIs at the MUCS. The performance indicators of interest for safeguards are the Person Day of Inspection (PDI) and the Calendar Day in the Field (CDF). These performance indicators are used to illustrate the savings achieved in 2007 associated with introducing UIs for the verification of SF transfers for multi-unit CANDU stations in Canada under integrated safeguards. The predicted savings of 60-70% in PDI effort have been exceeded. Experience shows that further optimization of inspection effort at multiunit CANDU stations is possible by combining inspection activities and by developing new sealing and surveillance strategies.