Study on the decision-making of the protective action for residents at the early phase of nuclear disaster

Abstract

ABSTRACT In the nations which have nuclear facilities, the precautionary urgent protective action based on the emergency action levels (EALs) is adopted for the decision-making in the early phase of nuclear disaster in line with the strategy introduced in the Safety Standards of International Atomic Energy Agency (IAEA). In this phase, the decision-makers are forced to make choices from the evacuation or the sheltering-in-place as more effective action to reduce the radiation risk of nearby residents, reading situations by EALs. In most cases, the procedure to select these two actions is monotonously set across the whole of region in those nations. Therefore, we developed the decision-making method which can reflect the accident scenarios and the regional characteristics such as population and geographic aspects in evaluating the risk of the exposure during evacuation. The method consists of two procedures; the procedure to evaluate the containment vessel (CV) failure time and the evacuation time , and the procedure to determine the time allowance from EALs, and . We confirmed the rational treatments of uncertainties on the time allowance which deduced by integrating the severe accident analysis and the evacuation time estimate. We also found the effectiveness of this method by applying it to two sample areas.