Development and validation of CFDT code for fission product release analysis of spherical and cylindrical TRISO-based fuel element in HTGRs

High-Temperature Gas-Cooled Reactors (HTGRs) that use TRi-structural ISOtropic (TRISO) fuel particles are Generation IV nuclear reactors known for their safety and efficiency in producing nuclear energy. An effective approach is needed to calculate fission product retention during normal operation and potential accidents. This paper presents an efficient method for evaluating the release of fission products from TRISO fuel elements. A software package named CFDT (Codes for Fission-product Diffusion in Triso-fuel) has been developed to analyze fission-product diffusion in HTGR TRISO fuel elements. The software uses a numerical model based on the Finite Volume Method (FVM) to solve diffusion equations in one and two dimensions. The versatility of CFDT is enhanced by incorporating the release of fission products for spherical and cylindrical fuel geometries. Our results are consistent with benchmark cases from the IAEA CRP-6 project and the AGR-1 heating tests, confirming the accuracy of the CFDT code.