一种快堆边界下的裂变气体释放数值模型

裂变气体释放(FGR)对燃料元件的热力演化过程有着极其重要的影响，准确地模拟反应堆中裂变气体释放是燃料元件性能分析程序开发的最基本内容之一, 也是重要的评价准则. 本文围绕快堆边界下的裂变气体释放行为展开详细论述，基于气体原子与气泡行为模型，模拟了晶内气体原子的产生、自由扩散、俘获-再溶解等行为，以及晶内气泡的形成、生长、融合、移动等行为.模拟了晶界气泡的生长、连接、通道形成与气体释放等过程. 通过数值方程组离散和迭代计算，建立了一种快堆边界下的裂变气体释放数值模型. 经过与理论及实验数据对比，结果显示该模型能准确预测燃料元件的裂变气体释放份额与气体肿胀量，能较好地模拟晶内气泡浓度与尺寸. 表明该模型可以用于快堆燃料元件性能分析.

A numerical fission gas release model in fast reactors

Fission gas release (FGR) has an extremely important influence on the thermo-mechanical behavior of a fuel element. Accurate simulation of FGR in reactors is one of the most basic contents in the development of fuel element performance analysis program, and it is also an important evaluation criterion. In this paper, we discuss the FGR behaviors in fast reactors in detail. The FGR model is based on the equations modeling the behavior of gas atoms and bubbles. The behaviors such as the generation, free diffusion, capture and re-dissolution of gas atoms in the grain are modeled in detail, and the nucleation, growth, coalescence, and migration of bubbles in the grain are simulated. Moreover, the growth, connection, channel formation, and gas release of intergranular bubbles are modeled. We develop a model for FGR calculation, using a method of numerical discrete and iteration calculation. The calculated results are compared with those of experiments and physical theories, which shows very good agreement. Therefore, the model can predict the gas release and swelling in the fuel and the concentration and size of intragranular bubbles, indicating that this model is appliable in a fuel element analysis code.