AP1000 adapts Passive Core Cooling System to improve the safety. However, it is found that static diffusion under the difference of the boron concentration and sampling lead to boron loss, which makes the boron concentration in core makeup tank lower than the specification limits. Corresponding to this problem, replenishing high concentration boron water is a way to meet the requirements for boron concentration. Under this circumstance, this study numerically investigates the effect of static boron diffusion, sampling and replenishing on boron concentration. The results show that static diffusion and sampling have a slight impact on boron dilution, but in different ways. A larger replenishing flow rate is useful to enhance the boron mixture. However, that will result in a heavy heat load on the “T" connection of reactor coolant system and core makeup tank.

AP1000采用被动式核心冷却系统以提高安全性。然而，发现在硼浓度和取样的差异下的静态扩散导致硼损失，这使得堆芯补充罐中的硼浓度低于规格极限。对应于此问题，补充高浓度的硼水是满足硼浓度要求的一种方法。在这种情况下，本研究数值研究了静态硼扩散，采样和补给对硼浓度的影响。结果表明，静态扩散和取样对硼稀释有轻微影响，但方式不同。较大的补充流速可用于增强硼混合物。但是，这将导致“ T”上的热负荷过大