Preliminary numerical investigation of TRISO-matrix interface debonding characteristics in fully ceramic microencapsulated fuel

The bonding mode of NITE-SiC matrix and TRISO particles has a great impact on the fracture mechanisms of the Fully Ceramic Microencapsulated (FCM) fuel. Combination strength and interface debonding characteristics are of great significance when evaluating the thermo-mechanical behavior of a FCM fuel. In this study, a finite element method (FEM) model for TRISO-matrix debonding characteristics analysis was presented based on the cohesive zone model (CZM). The CZM was coupled with several irradiation behaviors (burnup, fission gas release, gap/plenum pressure, etc.) and thermo-mechanical behaviors (irradiation-induced dimensional change (IIDC), contact, heat generation, conduction, gap heat transfer, thermal expansion, and creep etc.), and developed to investigate the interface debonding characteristics of TRISO coated FCM Fuel preliminarily. A 3-dimensional multiphysics modeling approach has been successfully applied to realize simulations of a representative FCM fuel unit, also a uniformly distributed FCM layer. The NITE-SiC and OPyC interface debonding characteristics model was well performed, and was validated with CZM theory. Moreover, the effects of burnup, particle spacing, stress distributions of matrix, interfacial bonding strength and other key parameters in CZM model, were studied and investigated.