Dose Assessment for Setting of EPZ in Emergency Plan for Decommissioning of Nuclear Power Plant

In emergency plan for a nuclear power plant, taking enough measures in EPZ boundary (Emergency Planning Zone) is one of priority matters, to have protection against the release of radioactive materials in accident efficiently and quickly to minimize environmental impacts. EPZ is set as the zone which emergency plans should be mainly prepared on emergency conditions. The criteria of EPZ is that dose value in the area between plant and EPZ boundary have to be less than 10mSv, even if very conservative release mechanisms and path are supposed. The released amount of radioactive material from a nuclear power plant is calculated to the accident scenario were supposed with the each phase of decommissioning. Moreover, the dose value is calculated as the evaluation of environmental impacts, using atmospheric diffusion parameters are determined by the plume concentration Gaussian type distribution model at steady state, and annual meteorological data of the reference plants. Both of ‘the spent fuel storage phase’ and ‘the safe maintenance and dismantling phase’ on each of the expected accident scenario, the dose value in EPZ boundary is much less than safety criteria (10mSv), and there is no need to plan offsite emergency plan, such as the Sheltering and Escape for a reference plant. This result is agreeing with the opinion of Waste and decommission working group 2006 of Western European Nuclear Regulator’s Association (WENRA).