Effect of Fuel Structure on Performance of Unified Spent fuel Attribute Tester

The Unified Spent fuel Attribute Tester (USAT) is a verification device for the spent fuel assemblies and non fuel items in the LWR spent fuel pond. USAT started from the concept of combinations of two devices. One is the Spent Fuel Attribute Tester(SFAT) for spent fuel assembly verification. The other is the IRradiated fuel Attribute Tester(IRAT) for non fuel item verification. Both of them have the same theoretical concept in respect of using a gamma spectroscopy, which can analyze the specific spectrum of the gamma ray from the target. The linearity between CZT detector and source was one of the crucial considerations. The structural difference between WH type and KSNP type fuel assemblies possibly produce the oblique of radiation path and it may affect the counts of radiations from spent fuel passing through 1 m length air pipe and tungsten collimator. In order to optimize the design of USAT, not only maintaining alignment between fuel zone and radiation collimation zone but also positioning air pipe on top plate of fuel assembly should be redetermined to maximize the entering radiation counts