Evaluation of atmospheric dispersion of radioactive materials in a severe accident of the BNPP based on Gaussian model

摘要

Regarding the importance of radioactive materials dispersion in the environment and their effect on living organism's well-being, this article examines the atmospheric dispersion of these materials around the Bushehr nuclear power plant (BNPP) in a hypothetical severe accident. One of practical dispersion models is AERMOD which is based on Gaussian distribution. This model which is an extension of Gaussian model is normally used for predicting the gaseous pollution. The aim of this study is to investigate the dispersion of radioactive materials in BNPP's surroundings due to a specific type of Large Break LOCA (LBLOCA) accident. In this study, the wind direction, wind speed, and the topological conditions of the power planes environment are considered. In order to execute this model, the meteorology and topological data of the region have been provided. Besides, using the CONTAIN code, the data about released radioactive materials from the containment have been provided. The double ended cold leg break (DECL) accident in containment has been modeled and its validity has been checked with FSAR. Extracting all required data, the simulation is done in AERMOD and the volumetric concentration and activity of fission products are calculated. The volumetric activity of fission products in Tangestan, BandarE-Bushehr and Delvar cities are evaluated as 7.5658E + 07, 7.5136E + 07 and 2.9655E + 06 (Bq/m(3)), respectively. From results it could be seen that the most dispersion of the radioactive materials are in direction of the non-residential regions, although the pollution of the cities around the power plant is inevitable.