严重事故熔融池实验热工水力特性仿真分析

Simulation Study on Thermal Hydraulic Characteristics for Corium Pool Experiment of Reactor Severe Accident

本文基于LIVE(Late In-Vessel Phase Experiments)三维压水堆熔融池模拟实验,采用COMSOL Multiphysics软件建立了适用于熔融池的仿真计算模型。通过非等温流动模块耦合流体传热和湍流流动过程,使用相变材料模型模拟实验中的非共晶摩尔比例20%NaNO_(3)-80%KNO_(3)熔盐,湍流模型设置为低雷诺数k-ε模型。仿真结果表明,稳态下熔融池内存在较强的沿冷却壁面向下的自然对流,同时还伴随着大量的涡流,在涡流搅拌作用下温度场形成了明显的热分层结构。仿真得到的熔融池中部和顶部区域温度分布以及冷却壁面上的结壳厚度与实验值十分接近,说明COMSOL软件适用于熔融池仿真工作。

Based on 3D PWR corium pool experiments LIVE,a computational model for corium pool simulation was built by COMSOL Multiphysics.The non-isothermal flow calculation module was employed to couple the turbulent flow field and heat transfer in the corium pool,the non-eutectic binary mixture of 20%NaNO_(3)-80%KNO_(3)was simulated by phase-change material model,the Low Reynolds number k-εturbulence model was selected to calculate the velocity field.The simulation results show that,a strong downward flow natural convection is formed near the cooling wall.Besides,many vortexes are existed in the corium pool,which lead to the thermal stratification of the temperature field in a steady-state condition.Since the simulated temperature distribution in the middle and top area of the corium pool,and the simulated thickness of the crust on the cooling wall are very close to the experimental data,the COMSOL software is suitable for the simulation of the corium pool.