Sensitivity analysis of cesium and strontium release from TRISO particle under irradiation and high temperature conditions

Abstract

This paper presents a systematic sensitivity analysis of the diffusivity parameters of cesium and strontium inside Tristructural isotropic (TRISO) fuel particle and their dependence on irradiation and high temperature annealing conditions. The BISON fuel performance code was used to model the base irradiation and the high temperature tests performed within the AGR-1 experiment. The sensitivity analysis results quantified the contributions of the various diffusion parameters to BISON predictions of Cs and Sr release from compacts exposed to a number of different irradiation and thermal conditions. Informed by the Sobol indices, a calibration study provided an optimized set of diffusion parameters that improved the accuracy of BISON predictions. Finally, we describe an analysis of the influence of irradiation and thermal conditions on the Cs and Sr release and characterize their dependence on the testing conditions. The systematic approach in this study allows us to better understand the transport mechanism of Cs and Sr inside TRISO particle, and to identify a number of future needs to fully resolve the discrepancy between BISON predictions of Cs and Sr release with the AGR-1 experimental observations.