Multidimensional multiphysics modeling of TRISO particle fuel with SiC/ZrC coating using modified fission gas release model

TRISO particle is adopted in the design of various types of reactors and accident tolerant fuel (ATF) due to its excellent accident tolerant performance under high temperature and other severe conditions. This study presents a multidimensional thermomechanical analysis of TRISO particle fuel with SiC/ZrC coating under typical operation conditions in reactor. Key fuel performance phenomena were considered including thermal performance (heat generation, conduction, irradiation gap heat transfer, etc.), mechanics (thermal expansion, elastic strain, densification, fission product swelling strain, contact, and thermal, irradiation creep, etc.), also irradiation behaviors (burnup, fission gas production and release, gap/plenum pressure with plenum volume, etc.). All these models have been integrated and solved via finite-element method. As for results, several complicated models were implemented and proved to successfully predict the thermomechanical behaviors of TRISO coated fuel compared with the existing experimental or numerical results. An enhanced fission gas behavior model considering grain boundary diffusion was established, which could complete detailed calculation on fission gas release at both grain size and fuel particle pellet scales. Based on the preliminary thermomechanical analysis, in terms of structural strength and heat transfer efficiency, ZrC appears to be a candidate material of SiC. Moreover, failure mechanisms and effective thermal conductivity have been analyzed using the current modified analysis technique.