ABSTRACT

Early public protection measures play an important role in reducing the health effects of radiation exposure. In particular, a staged evacuation is recognized as the most important strategy. However, studies on segmenting an evacuation region with non-uniform population density are lacking; therefore, the purpose of this study is to gain insight regarding this topic. First, the evacuation region was determined by comparing the level 3 probabilistic safety assessment (PSA) results with the generic-dose limit. Second, we performed mathematical approaches to calculate the evacuation and delay time. We then scored staged evacuation strategies and selected the best strategy. Through this study, we found some features as follows: (1) the evacuation and delay time have a trade-off relationship, (2) there is no significant difference in total evacuation time except for the preparation time, and (3) there is a big difference in total delay time despite the same segmentations. Namely, even if the evacuation time may be the same, the delay time may differ. The delay time can be defined as the period that people spend on the road, and so the longer the delay time, there is an increased likelihood of receiving unnecessary exposure.

摘要

早期的公共保护措施在减少辐射照射对健康的影响方面发挥着重要作用。特别是，分阶段疏散被认为是最重要的策略。然而，缺乏对人口密度不均匀的疏散区域进行分割的研究；因此，本研究的目的是深入了解这一主题。首先，通过将 3 级概率安全评估 (PSA) 结果与通用剂量限值进行比较来确定疏散区域。其次，我们使用数学方法来计算疏散和延迟时间。然后我们对分阶段疏散策略进行评分并选择最佳策略。通过本次研究，我们发现了以下几个特点：（1）疏散时间与延迟时间存在权衡关系，（2）除准备时间外，总疏散时间没有显着差异；（3）尽管分段相同，总延迟时间差异很大。即，即使疏散时间相同，延迟时间也可能不同。延迟时间可以定义为人们在路上花费的时间，因此延迟时间越长，接受不必要暴露的可能性就越大。