[2O11-14] Advanced Reactor

[2O12] Study on Diffusion Release of Cesium from Coated Fuel Particles for High Temperature Gas-cooled Reactors

*Masaki Yoshino¹, Kazuhiro Sawa¹, Jun Aihara² (1. Hokkaido Univ., 2. JAEA)

Keywords:High Temperature Gas-cooled Reactor, Coated fuel particle

In HTGR fuel, the release of fission products is prevented by coated fuel particles, but for some metallic FP nuclides such as cesium, it is necessary to consider diffusion release from particles with an intact coating layer in addition to release from particles with a failed coating layer. In the previous study, the calculated release fraction of cesium was evaluated to be about one order of magnitude larger than that in the experimental value. In this study, we will develop a more detailed model to improve the prediction accuracy of the release fraction. A calculation code based on Fick's law of diffusion called FORNAX-A is used as the analysis method, and results from calculation and previous irradiation tests will be compared to confirm the validity of the model. As a result, it was confirmed that the calculated results are overestimated compared to the experimental values, which may be due to the computational assumptions used in FORNAX-A, and we will work to improve this.