核电厂液态流出物排放数模计算域分析

Numerical Simulation Domain Analysis of Liquid Effluent Discharge from NPPs

针对核电厂液态流出物在受纳水体中的稀释扩散问题,常采用平面二维数值模拟法进行分析,计算所得流场往往有水文测验资料进行验证,但对于半衰期较长的核素,衰变减少的份额较少,计算范围的大小对计算结果的影响较大。本文结合工程实例,选取大小不同的两个计算域,分别进行数值模拟计算,并对计算所得流态、浓度场分布、浓度通量以及总量守恒进行分析。结果表明,在计算能力范围内,应选取较大的计算域;在满足计算精度和效率的条件下,排放口距计算边界宜大于80 km的范围。该结果可供核电厂液态流出物排放选择计算范围时进行参考。

In view of the dilution and diffusion of liquid effluents from NPPs in the receiving water, the twodimensional numerical simulation method is often used for analysis. And the calculated flow field is often verified by hydrological test data. However, for radionuclides with longer half-life, the reduced fraction resulted from decay is smaller, and the size of calculation range has a greater impact on the calculation results. Combined with engineering examples, two computational domains with different sizes are selected, numerical simulations are carried out respectively, and the calculated flow regime, concentration, flux and total conservation are compared and analyzed. It turned out that within the scope of computing power, a larger computational domain should be selected;under the condition of satisfying the calculation accuracy and efficiency, the range between the discharge outlet and the calculation boundary should be more than 80 km. The results can be used as a reference for calculating the computational range of NPP liquid effluents.