The research reactor radiation emergency countermeasure system in Korea

A disaster prevention system was established for a radiation emergency from an operation of a research reactor with a thermal power of 30 MWth in Korea. A national radiation disaster countermeasure organization was set up to cope with the radiation emergency classified into three cases whose effective doses were more than 1 mSv/h inside the nuclear facility, inside the site boundary and outside the site boundary. Its role consists of the proclamation and consequent withdrawal of a disaster, a general assessment, an emergency medical service, a field control, radiation protection, resident protection implement, an accident analysis, a security plan, a radiation environmental investigation plan and probe, a radiation environmental effect assessment, and others. The emergency planning zone (EPZ) was settled to be within a radius of 800 m, the average distance between the site boundary and the center of a research reactor in operation, as a quick and effective early countermeasure from the result of the radiation environmental effect assessment. The environmental probing zone was chosen to extend to a radius of 2 km from a research reactor according to the moving path of the radioactive cloud so that a densely populated area could be considered and would be extended to 10 km according to the radiation level of the research reactor and atmospheric diffusion. Practically, the environmental probing is implemented at 22 points inside the site and eight points outside the site considering the geography, population and the wind direction. The gamma radiation dose and atmospheric radioactivity are analyzed during an effluence, and the radioactivity of a ground surface deposit and an environmental sample are analyzed after an effluence. The environmental laboratory covers the analysis of the gamma radioisotopes, tritium, strontium, uranium, gross alpha and beta. It is estimated that the habitability can be recovered when the radiation dose rate is less than 1 mSv/h inside the site and around the environmental laboratory with the no sign of an effluence of the radioactive material. As a conclusion, it is thought that this emergency countermeasure system is effective in a real radiation emergency situation.