EXTREME: Expert support tool for responding to a nuclear emergency

Risk Analysis Research Group, Nuclear Safety Research Center

When a nuclear emergency occurs at a nuclear power plant (NPP), protective actions such as evacuation and sheltering are implemented to reduce radiation exposures to the public around the vicinity areas of the NPP. The necessity of the protective actions should be judged, taking into account the various types of information from the on-site and the off-site with reflecting the drastically change of accident situation. In such decision making, the impacts to the public and surrounding environment also should be assessed quickly and consistently through the source-term, which including the amount and timing of release of radioactivity, and the contamination of environment by those. However, it is difficult to provide the information needed to decision-making, because those from the on-site and off-site are enormous. Therefore, expertise for the accident process in the on-site and for exposure assessment, and advance preparation for processing this information are indispensable. In this study, to deal with a huge amount of information and provide the basis for decisions on protective actions in a nuclear emergency, an expert support tool EXTREME (EXpert support Tool for Responding to a nuclear EMErgency) for nuclear emergency response was developed. This tool has a function to evaluate a simplified source term based on in-core information and a function to evaluate exposure doses around a facility based on the results of the evaluation. The system also has a PC-based graphical user interface (GUI) for easy operation by users even in an emergency. This report describes the models implemented the EXTREME, the input/output data files needed, and trial calculation results used in these functions.