About this Abstract |
| Meeting |
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Symposium
|
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Presentation Title |
Simulation of Xenon and Silver Diffusion in Irradiated TRISO (UO2 and UCO) Fuel Kernels |
| Author(s) |
David Andersson, Xiang-Yang Liu, Christopher Matthews, Michael Cooper |
| On-Site Speaker (Planned) |
David Andersson |
| Abstract Scope |
In this talk, diffusion of fission gases (e.g., Xe) and fission products (e.g., Ag) in Tristructural isotropic coated (TRISO) fuel particles with uranium oxide (UO2) or oxy-carbide (UCO) fuel kernels will be reviewed. TRISO fuels are used in high-temperature gas-cooled reactors (HTGR) and are being developed for fluoride salt-cooled high temperature reactors (FHR) as well as for several micro-reactor designs. Diffusion of fission gases and fission products in the UO2 or UCO fuel kernels leads to a source term at the carbon and silicon carbide layers of the TRISO particles. The latter serve to protect against release from the particle. It is important to understand both the source term and transport through the SiC layers. The present study focuses on diffusion through the fuel kernels, but efforts of understanding the behavior of the TRISO layers will be briefly reviewed for context. Density functional theory (DFT) and empirical potential calculations are utilized to interrogate the diffusion mechanisms in UO2 and UCO TRISO fuel kernels. The properties (migration barriers, formation and binding energies) describing the fundamental diffusion steps are then adopted in the Centipede cluster dynamics code to predict effective diffusivities under irradiation. The diffusivities in TRISO fuel kernels differ from the case of standard UO2 in pellet form due to the reducing conditions caused by the presence of carbon and/or uranium carbide. Finally, the use of the effective diffusivities provided by Centipede in fuel performance simulations are demonstrated by implementing correlations in the Bison. |
| Proceedings Inclusion? |
Undecided |