冷却剂丧失条件下钠冷快堆棒束传热的三维蒙特卡罗模拟方法

Three Dimensional Monte-Carlo Simulation Method for LMFBR Fuel Bundle Heat Transfer Under Loss of Coolant Accident Conditions

采用蒙特卡罗方法分析钠冷快堆在假想冷却剂丧失条件下燃料棒束的钠两相流传热。以分子运动理论的基本定律为基础,开发出替代宏观经验模型来分析反应堆棒束中的钠蒸发率和冷凝率的微观模型,且采用三维蒙特卡罗方法模拟分子的运动轨迹,分子间的碰撞率以及分子与棒束、分子与棒束组件盒壁的碰撞率。对包壳干涸区的再浸润现象用动力膜模型描述,并计算了通过液膜的液体速度分布和平均液膜速度,对于从冷凝液膜蒸发的钠分子则被重新记为蒙特卡罗计算的源项。用微观和宏观模型相结合的方法数字模拟了德国卡尔斯鲁厄核研究中心的堆外钠沸腾实验。

3-D Monte-Carlo method was employed for analyzing Liquid Metal Fast Breeder Reactor（LMFBR） sodium two-phase flow in fuel bundle under hypothetical loss of coolant accident（LOCA） conditions. Based on molecular kinetic theory, a microscopic model was developed for determining the evaporation and condensation rates of sodium in a reactor bundle. Three dimensional Monte-Carlo methodology was applied to simulate the molecular trajectories, collision rates among vapor molecules and between molecules and surfaces of pins as well as bundle canning wall. Re-wetting of dried out regions of the cladding surfaces was simulated with a dynamic liquid film model. The source of molecules re-entering into the Monte-Carlo calculation of molecular dynamics due to the evaporation of sodium from the condensed liquid film was computed. The nu- merical simulation of an out-of pile sodium boiling experiment made at Karlsruhe Research Center （Forschungszentrum Karlsruhe） of Germany was carried out.