Analytical results and effective dose estimation of the operational Environmental Monitoring Program for the radioactive waste repository in Abadia de Goiás from 1998 to 2008

Abstract

This paper presents the results of the Environmental Monitoring Program for the Radioactive waste repository of Abadia de Goiás, which was originated from the accident of Goiania, conducted by the Regional Center of Nuclear Sciences (CRCN-CO) of the National Commission on Nuclear Energy (CNEN), from 1998 to 2008. The results are related to the determination of 137Cs activity per unit of mass or volume of samples from surface water, ground water, depth sediments of the river, soil and vegetation, and also the air-kerma rate estimation for gamma exposure in the monitored site. In the phase of operational Environmental Monitoring Program, the values of the geometric mean and standard deviation obtained for 137Cs activity per unit of mass or volume in the analyzed samples were (0.08 ± 1.16) Bq.L −1 for surface and underground water, (0.22 ± 2.79) Bq.kg −1 for soil, and (0.19 ± 2.72) Bq.kg −1 for sediment, and (0.19 ± 2.30) Bq.kg −1 for vegetation. These results were similar to the values of the pre-operational Environmental Monitoring Program. With these data, estimations for effective dose were evaluated for public individuals in the neighborhood of the waste repository, considering the main possible way of exposure of this population group. The annual effective dose obtained from the analysis of these results were lower than 0.3 mSv.y −1, which is the limit established by CNEN for environmental impact in the public individuals indicating that the facility is operating safely, without any radiological impact to the surrounding environment.