核电厂LOCA事故下衰变链对主控室内剂量计算影响研究

Study of Decay Chain Influence on Dose Assessment of Control Room Under LOCA in Nuclear Power Plants

主控室是对核电厂正常运行和事故状态实施控制的场所,为了保护控制室内操作人员,法规要求对控制室进行可居留性分析。在一般计算模型中,为了简化模型,没有考虑衰变子核对于人员剂量的贡献。本文中,针对通用主控室模型在考虑了衰变链对人员剂量的影响的基础上,建立了核素平衡方程,并开发了主控室可居留性剂量评价程序CROSS进行计算。基于RG1.183规定的冷却剂丧失事故(LOCA)源项,使用CROSS程序分别在非放射性通风系统新风模式和应急可居留系统通风模式下对主控室可居留性进行了分析。计算中对比了是否考虑衰变子核对个人剂量的影响。计算结果表明,考虑衰变链后,对于非放射性通风系统新风模式:个人有效剂量增到了1.28倍,其中主要增加为内照射有效剂量,增到了1.64倍;对于应急可居留系统通风模式:个人有效剂量增到了1.27倍,其中主要增加为内照射有效剂量,增到了1.30倍。在核电厂事故工况下计算主控室人员剂量时,需要考虑衰变链对个人有效剂量的影响。

The control room is where the nuclear power plant operations are taken control under both normal and abnormal conditions. The control room habitability analysis is required by the Regulatory to guarantee operators safety. In conventional calculation models,the daughter nucleus are not considered in dose assessment. In this article, a nuclide balance differential equation is set up based on a general control room model, considering daughter nucleus. A dose assessment code CROSS is developed based on this model and used in dose assessment. In the hahit^hilitv ~n^l,,~i~ ,1~,~ r t c,^^1__,Accident（LOCA） source from RG1. 183 is used. The analysis is carried out under nonradioactive ventilation system（VBS） new wind model and the emergency habitability system（VES） model. In the analysis, two cases with or without daughter nucleus are compared. In VBS new wind model,the results show that individual effective dose raises 1.28 times and inner effective dose raised 1.64 times considering daughter nucleus against cases without daughter nucleus. In VES model,the results show that individual effective dose raises 1.27 times and inner effective dose raised 1.30 times considering daughter nucleus against cases without daughter nucleus. In dose assessment of control room under accident condition in nuclear power plants, the decay chain influence must be considered.