POTENTIAL ENVIRONMENTAL HAZARD TO THE PUBLIC FROM THE OPERATION OF URANIUM MINING AND MILLING FACILITY

Abstract

Mining and milling processes could cause potential radiological exposures to the public. The objective of this study was to estimate the off-site radiological doses expected to be received by the public as a result of uranium mining and milling activities at Mkuju River Project in the United Republic of Tanzania. MILDOS-AREA was used to estimate off-site doses along with RESRAD-OFFSITE for comparison and verification. Since the mining has not yet started, the conceptual scenario was chosen. Using the concept of the most exposed individual, the location of the nearest residence (receptor) was chosen at 2.5 km from the site with other receptors being the fence boundary and grazing area being at 1.0 and 1.8 km, respectively. Yellowcake stack (point source), ore pad and two tailing piles where each had an area of 2.5 × 105 m2 were chosen to be the source of radiological contamination. The radiological source term was obtained from the concentration of 226Ra and 232Th in soil obtained from the previous studies of environmental impact assessments. Meteorological and site-specific data were used for this analysis. The estimated total effective dose equivalent (TEDE) for the nearest residence which was calculated by MILDOSE-AREA ranged from 2.5 × 10-2 to 4.45 × 10-2 mSv/y during the operation of 13 y. The result of RESRAD-OFFSITE ranged from 7.19 × 10-2 mSv/y for the first year to 7.43 × 10-2 mSv/y in the final year. This implied all the estimated TEDEs were below the dose limit and dose constraint of 1 and 0.3 mSv/y, respectively, as suggested by the International Atomic Energy Agency. Hence, it was found that there was no potential radiological concern of uranium mining at Mkuju River Project. It was found that using MILDOS-AREA it is possible to estimate dose at different distances from the facility. Therefore, this study apart from estimating the off-site doses, it can be used for planning of public and social premises before the commencement of the project. That is the distance from the facility where the public should be located as well as other locations for social activities.