Preliminary Study of the Emergency Planning Zone Evaluation for the Nuclear Power Plant in Taiwan by Using MACCS2 Code

INTRODUCTION The purpose of this preliminary study is to perform the evaluation of the emergency planning zone of nuclear power plants in Taiwan by using MACCS2 (MELCOR Accident Consequence Code System version 2) code. MACCS code series were developed by SNL (Sandia National Laboratory) for replacing the CRAC (Calculations of Reactor Accident Consequences) code series. The function of these codes is to estimate the radiological doses, health effects and economic consequences that could result from postulated accidental release of radioactive materials to the atmosphere. This preliminary study has not only provided an opportunity to establish our capability to use MACCS2, but also helped us know better the deference between MACCS and CRAC code series. The Reactor Safety Study presented the first comprehensive assessment of the consequences and risks to society from PRA evaluated nuclear power plant accidents in 1975. As part of the Reactor Safety Study, the CRAC code was developed to calculate the consequences from accidental release of radioactive material to the atmosphere. Since the Reactor Safety Study, consequence modeling has received widespread attention and application throughout the world and a significant number of consequence models have been developed. CRAC2, released in 1982, incorporated major improvements over CRAC in the areas of weather sequence sampling and emergency response modeling. Because CRAC2 was not portable across computer systems and did not offer sufficient flexibility for the evaluation of alternative parameter values for its models, the goal of the MACCS development effort was to produce a portable code with a modular architecture and flexible database. In order to implement a number of other changes that enhance the code’s usefulness for all types of reactor and nonreactor facilities, the MACCS2 development effort was initiated at SNL in 1991. The purpose of this effort was to develop a generally applicable analysis tool for use in assessing potential accidents at a broad range of reactor and nonreactor nuclear facilities. The version we used to perform the emergency planning zone evaluation is MACCS2 V.1.12. Since NUREG-0396 report introduced the concept of the emergency planning zone as a basis for the planning of response actions in the event of a severe power reactor accident in 1978, this concept has been accepted all over the world. According to government regulation in Taiwan, the emergency planning zone of nuclear power plant must be designated before operation. The related emergency response planning in the emergency planning zone must be planned to guarantee all necessary resources available under the postulated accidents of nuclear power plant. Thus the pre-planned necessary actions will be helpful to protect inhabitants from the damage during the possible accident. Up to now, there are three nuclear power plants operating in Taiwan, and the fourth one is to be constructed. We evaluated the emergency planning zone of the three operating nuclear power plants by using CRAC2 code in 1992 and designated it with a conservative value, 5.0km. According to government regulation, we have to finish the evaluation of the fourth one’s emergency planning zone by 2004, because the plant will be operated at that time if everything goes right by schedule. This preliminary study focuses on performing the evaluation of the emergency planning zone of all the four nuclear power plants by using MACCS2 code. We have established our capability to use MACCS2 code, rechecked the emergency planning zone of the three operating nuclear power plants and confirmed that 5.0km is still a conservative value for all the four nuclear power plants in Taiwan.