OPG fuel surveillance program

The Ontario Power Generation (OPG) fuel surveillance program was initiated in response to a Canadian Nuclear Safety Commission (CNSC) Generic Action Item to verify the condition of CANDU fuel irradiated in Canadian reactors. As part of a comprehensive response, OPG committed to performing in-bay fuel inspection and hot-cell examinations. Based on the in-bay inspection results, a selection of fuel was shipped from each reactor site to Chalk River Laboratories (CRL) for post-irradiation examination (PIE). Typically, 15 loose elements (from a variety of fuel bundles) or a single bundle are sent to CRL. The PIE is intended to: provide data for assessment of fuel performance; check compliance of operating fuel with design and operating limits; determine the defect root cause for failed fuel elements; provide data to characterize the actual condition of fuel during operations, for use in licensing analyses; and, provide longer-term assurance that measurable fuel operating parameters are not deviating from the established norms. Since 1999, a total of 103 individual fuel elements from 40 fuel bundles and two intact fuel bundles have been sent to CRL for PIE. The examinations are used to monitor several fuel performance parameters (i.e., fission gas release, grain growth, and residual sheath strains). Fuel performance has been good and representative of what has been previously observed. A total of 9 defected fuel elements from 9 fuel bundles have been examined. The majority of these fuel bundles (7) failed as a result of debris fretting. The fuel bundle defect rate at OPG remains well below 0.01 percent for the last five years. Details of the PIE results are presented in this paper. (author)