基于ASTEC的压水堆严重事故下碘行为不确定性量化研究  

Uncertainty Quantification on the PWR Severe Accident Iodine Behavior via ASTEC

作　　者：欧平文 陈勇征 陈鹏 OU Pingwen;CHEN Yongzheng;CHEN Peng(China Nuclear Power Technology Research Institute,Shenzhen of Guangdong Prov.518000,China)

机构地区：[1]中广核研究院有限公司,广东深圳518000

出　　处：《核科学与工程》2023年第6期1266-1272,共7页Nuclear Science and Engineering

基　　金：“国家重点研发计划”资助(2019YFB1900702)。

摘　　要：在严重事故源项分析中,碘作为最危险的放射性核素之一,在被人体吸入和摄入后会对人体甲状腺造成威胁.碘行为相关模型中存在的不确定性会对严重事故源项评估产生了影响。本文的目的是用严重事故一体化程序ASTEC和不确定性分析工具SUNSET,以事故进程较快的大破口失水事故为代表序列,对典型第三代压水堆严重事故中碘行为进行不确定性量化研究。选择I_(2)在干燥油漆结构表面的吸附率、安全壳内置换料水箱中的pH、安全壳内置换料水箱中的额外剂量率、冲刷效应的滞留比例以及一回路释放到安全壳的气态碘份额作为不确定性参数,分析不同形式的碘释放到环境中的质量,并给出了3天内的偏相关系数、边界值、百分位数和概率密度函数。结果表明,冲刷效应的滞留比例和一回路释放到安全壳的气态碘份额对结果影响较大,且碘化银与冲刷效应对碘的影响有待进持续研究。In severe accident source term analysis,iodine,one of the most dangerous radionuclides,poses a threat to human thyroid after inhalation and ingestion.The existing uncertainty of iodine behavior modeling has an impact on the severe accident source term evaluation.The purpose of this paper is to quantify the uncertainty of iodine behavior in severe accident of typical Gen Ⅲ pressurized water reactor by using AS TEC(Accident Source Term Evaluation Code) and the uncertainty analysis tool SUNSET,in the representative sequence of large break loss of coolant accident(LBLOCA) with rapid accident progress.Adsorption rate of I_(2) in the painted dry structure surface,pH value in the in-containment refueling water storage tank(IRWST),additional dose rate in the IRWST,retained fraction of wash-down effect and gaseous fraction of iodine release from the primary circuit to containment are selected as uncertainty parameters and the released iodine mass to the environment in different forms are analyzed.The partial correlation coefficient,the bound,the percentile and the probability density function in 3 days are presented.The results indicate the important role of the retained fraction of wash-down effect and the gaseous fraction of iodine release from primary circuit to the containment.Besides,the silver iodide reaction and wash-down should be continuously investigated.

关 键 词：不确定性量化 碘 ASTEC SUNSET 

分 类 号：TL48[核科学技术—核技术及应用]