As the technical criteria，it is required that the severe accident sequences should be considered in the partition of nuclear power plants Emergency Planning Zone (EPZ). In the relevant national standards and nuclear safety guide rules, the dose criteria involving 'majority severe accident sequences' and 'the severest accident sequences' are proposed. However, in the actual applications of these criteria, there might be some different understanding to the concept of 'majority severe accident sequences' and 'the severest accident sequences'. The source terms of PWR1—PWR7 release categories in WASH1400 are selected as the referenced source terms, and the individual consequence of each source term and the weighted average of these consequences are calculated and analyzed by using MACCS code. Then the impacts of the results of two different calculation approaches on EPZ size are compared with each other. The conclusion shows that the weighted average of the severe accident spectrum consequences can basically reflect the assessment results of each severe accident consequence and the consideration for emergency planning cost to a certain extension. This means that using the weighted average of the severe accident spectrum consequences as the technical criteria for the partition of EPZ can better embody the trade-off principle between the risk mitigation and cost.
