Development of Optical Fiber System for CANDU Spent Fuel Verification in Korea

CANDU spent fuels, which are required for a gross defect verification in the safeguards of nuclear materials, have being verified by a NDA equipment or an under water viewing device. Current equipment, SCAV and SCAI-II, however, is difficult to measure of the spent fuel bundles being placed at lower layer of the pond. Thus, an optical fiber system has been developed. The system was done for a laboratory test and a field test. The results of the laboratory test showed that the optic detector kept its durability up to 107 rad of 60Co, and the linearity and reproducibility for the relative average deviation were within 4.3% and 1.3 %, respectively. The results of the field test showed that the bundles being placed lower layer were verified by detecting the gamma profile corresponding to individual bundle. Therefore, the optical fiber system is considered that it can be utilized as a NDA equipment for the verification of the spent fuel bundles.