AP1000核电厂安全壳内气溶胶自然去除分析

AP1000等非能动压水堆核电厂依靠自然的原理清除事故后安全壳气空间内的放射性气溶胶,可靠性较高,但对其进行分析较为复杂。事故后安全壳内气溶胶的主要运动形式有凝聚、重力沉降、扩散泳及热泳等,本文研究确定了合适的机理模型、假设条件和主要参数等,完成了AP1000核电厂的分析。分析结果表明,AP1000核电厂LOCA后,主要气溶胶去除机制中扩散泳贡献最大,其次是热泳和重力沉降;安全壳内气溶胶自然去除系数约为0.4~0.9h~(-1),堆芯裸露5h后变化较小;基于RG1.183源项、包络大气弥散因子及本文给出的安全壳气溶胶自然去除系数,计算得到的LOCA后厂外及主控室人员所受剂量可满足10CFR50中规定的限值要求。

Aerosol Natural Removal Analysis in Containment for AP1000 Nuclear Power Plant

For passive nuclear power plants,such as AP1000,the radioactive aerosols in containment are removed by natural processes after accidents.This method has the advantage of high reliability.However,it is very complicated to analyze the behaviors of aerosols in natural processes.The dominant processes include coagulation,sedimentation,diffusionphoresis and themophoresis.The aerosol natural removal for AP1000 was analyzed in this study.The results indicate that diffusionphoresis makes the biggest contribution to aerosol removal while the themophoresis and sedimentation are the next two important processes for LOCA.After LOCA,the aerosol natural removal coefficient in containment of AP1000 is about 0.4-0.9 h-1,and it does not change much after core uncover 5 h.Based on RG1.183,with atmospheric dispersion factor and aerosol removal coefficient given in this study,the calculated offsite and control-room dose for AP1000 after LOCA meets the regulation requirements in 10CFR50.