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DOE OSTI · 3377885

Multiscale, mechanistic calculation of the effective silver diffusion coefficient in polycrystalline silicon carbide: application to silver release in AGR-1 TRISO particles

Simon, Pierre-Clement A·Aagesen Jr, Larry K·Jiang, Chao·Jiang, Wen·Ke, Jia-Hong
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Abstract

The silicon carbide (SiC) layer in tristructural isotropic (TRISO) fuel particles serves as a barrier to prevent the escape of fission from the fuel kernel. The release of silver (Ag) is a concern due to the long half-life of the 110mAg isotope. In this study, the effective diffusion coefficient of the fission product Ag through the grain boundary (GB) network is calculated using a combination of atomistic and phase-field methods. Atomistic calculations of Ag diffusivity in SiC bulk and GBs are leveraged to develop a mesoscale effective Ag diffusion coefficient (Deff) in SiC. Since GBs serve as pathways for Ag diffusion, Deff is defined as a function of temperature, microstructure variables, and fluence. Deff is implemented in the fuel performance code Bison to predict Ag release from AGR-1 TRISO fuel particles. We hereby quantify the impact of SiC grain size and irradiation on Ag release and improve Bison's predictions.

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11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS36 - MATERIALS SCIENCE97 - MATHEMATICS AND COMPUTINGAGR-1BisonEffective diffusion coefficientFission gas releaseTRISO fuelValidation

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Simon, Pierre-Clement A, Aagesen Jr, Larry K, Jiang, Chao, Jiang, Wen, Ke, Jia-Hong. 2022-10-09. Multiscale, mechanistic calculation of the effective silver diffusion coefficient in polycrystalline silicon carbide: application to silver release in AGR-1 TRISO particles. https://www.osti.gov/biblio/3377885

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