概率截断值对先进轻水堆核电厂应急计划区划分的影响

Impact of Cut-Off Probability on Emergency Planning Zone Sizing for Advanced Light Water Reactors

1997年,美国核管会(NRC)在对被动与改进型先进轻水堆的应急计划进行评估后指出,在现有的技术框架下先进轻水堆的应急计划应当保持不变,但也表明如果考虑到严重事故发生概率更低,事故的延迟时间更长,则有可能简化对先进轻水堆的应急计划要求,减小应急计划区。这意味着,如果在事故选择时不考虑低于某一概率截断值的事故,则有可能对先进轻水堆核电厂应急计划区的划分产生较大的影响。本文以AP1000核电机组为例,参考美国NUREG-0396的方法,使用MACCS程序对选取不同事故概率截断值可能产生的影响进行研究。研究结果表明,只有当概率截断值高于某些相对概率较大、而后果较为严重的事故的发生概率时,才会对先进轻水堆应急计划区的划分产生较大影响。

In 1997,NRC performed an evaluation of emergency planning for the evolutionary and advanced light water reactors,and indicated that no changes to emergency planning（EP） requirements were warranted in the existing technical framework.However,NRC also recognized if the lower probability of severe accidents or the longer time period between accident initiation and release of radioactive material was considered,the changes to EP requirements for advanced light water reactors might be warranted and the emergency planning zone（EPZ） sizing might be reduced.This means that if the accidents which probabilities are lower than a cut-off probability are not considered,there may be a significant impact on the EPZ sizing.AP1000 was selected as an example in this study and the probable impacts of different cut-off probabilities were studied by using MACCS code in accordance with the NUREG-0396 method.The results show that,only if the cut-off probability is higher than the occurrence probability of the accident which has relatively serious consequence and high probability,there will be a significant impact on the EPZ sizing for the advanced light water reactor.