基于弥散燃料颗粒开裂的裂变气体释放模型

Releasing Model of Fission Gas Based on Dispersion Fuel Particle Cracking

根据弥散燃料颗粒开裂后裂变气体的3种释放途径,分别建立了裂纹连通释放模型、气泡连通释放模型以及原子扩散释放模型,综合得到了基于弥散燃料颗粒开裂的裂变气体释放模型,并采用该模型对裂变气体释放量进行了计算。结果表明:裂变气体释放量主要由裂纹连通释放途径贡献;燃耗深度越高,裂变气体释放量的增加速率会越大;随着退火温度的增加,裂变气体释放量迅速增加,而退火时间越长,裂变气体释放量的增加速率越低。通过裂变气体释放量模型计算得到的裂纹宽度与实验观察到的裂纹宽度符合较好,对比结果验证了基于弥散燃料颗粒开裂的裂变气体释放模型的合理性。

According to three releasing approaches of fission gas after the cracking of the dispersion fuel particles, the releasing models of crack connection, bubble connection and atom diffusion were established respectively, resulting in the releasing model of fission gas based on the dispersion fuel particle cracking. The releasing amount of fission gas was calculated by this model. Results show that the releasing amount of fission gas is mainly attributed to the releasing approach of crack connection, and the increasing rate of releasing amount gradually increases with the burn-up. With the increase of annealing temperature, the releasing amount rapidly raises, while the increasing rate gradually decreases with the annealing time. The crack widths calculated from the releasing model of fission gas are consistent with the experimental data, which verify the releasing model of fission gas based on the dispersion fuel particle cracking.