| Abstract Scope |
TRi-structural ISOtropic (TRISO) fuel is a cornerstone of several advanced reactor designs due to its enhanced safety and resilience under extreme conditions. Despite the robust nature of TRISO, significant challenges remain in translating the particle’s failure mechanisms into high-fidelity fuel performance models, particularly phenomena such as irradiation-induced dimensional changes and creep, layer fracturing and debonding, and chemical degradation. For the phenomenon of Pd attack on the SiC layer, the current approach employs empirical models to account for the Pd penetration rate into the SiC layer. When the penetration depth reaches half of the SiC layer thickness, the particle is considered failed. This estimate does not account for Pd generation within the fuel kernel, nor does it capture the explicit presence of the inclusion and its impact on the mechanical behavior of the SiC layer. Recent work aimed to alleviate the first issue by employing advanced diffusion models in BISON, Idaho National Laboratory's (INL) fuel performance code, to model Pd transport while maintaining Pd conservation across the particle. The latter has not been extensively explored and thus presents a notable gap in accurately modeling the thinning of SiC layers. This research aims to address this by dynamically modeling second-phase inclusions, particularly Pd compounds, by leveraging BISON’s Extended Finite Element (XFEM) and Level Set Method (LSM) capabilities, which are well-suited for representing discontinuities and evolving geometries within a coupled thermo-mechanical framework. The inclusion growth velocity will be governed by current empirical models, with flexibility to incorporate ongoing developments in lower-length-scale mechanistic modeling. |