Calculated Distributions of Pu Concentrations within Spent Fuel Assemblies of Fugen Reactor

JAEA and USDOE (LANL) have been collaborating on spent fuel measurements with a PNAR/SINRD NDA instrument at Fugen, in the course of the NGSI Spent Fuel Non- destructive Assay Project. In this collaboration, JAEA and LANL have just finished measurements of Fugen (ATR: Advanced Thermal Reactor) spent fuel assemblies. For evaluation of the data measured by the PNAR/SINRD detector, we need data on the Pu content distribution in the measured assemblies. For nuclear material accountancy, JAEA has data on the quantity of Pu in each spent fuel assembly that is based on burn-up calculations. However, this calculation is just for the total amount of Pu in an assembly. Therefore, we have done burn-up calculations for two MOX-B type assemblies with high burn-up and very low burn-up to obtain Pu content distributions along the vertical axis of an assembly and also distribution differences among inner, intermediate and outer fuel rods. The data of the Pu content distributions within an assembly will be useful for evaluating the measured data.