VERIFICATION OF CANDU-TYPE SPENT FUEL BUNDLES WITHOUT FUEL MOVEMENT

Movement of CANDU spent fuel in the storage pond for safeguards verification purposes is highly intrusive and constitutes an extreme burden for both the Agency and the State considering the effort and time it demands and the cost. In this report, methods and techniques for the verification of CANDU-type spent fuel in underwater storage without the isolation of individual bundles or trays are proposed. The task is defined - in-situ verification by item counting and by NDA attribute test, and criteria for acceptance of such verification are given. The first test results of the proposed methods are reported including a proposed simplified procedure for the verification measurements during an actual inspection. It has been demonstrated that CANDU bundles stored in stacks under water can be verified without movement using optical devices for item counting and NDA equipment for qualitative attribute measurements. Possible impact of the test results on the direction of future improvements in the instrumentation and methods are discussed. This impact may subsequently be of significance to Agency safeguards measures applied to all CANDU reactors and to light water reactors as well. Possible limitations of the new techniques are also pointed out.