A generic method to evaluate the reasonable upper-bound dose from near-surface radioactive waste disposal facilities through drinking water pathway

摘要

A generic method has been developed to evaluate the reasonable upper-bound (RUB) dose from near-surface radioactive waste disposal facilities through a drinking water pathway. This generic method has been developed by applying a safety assessment model to seven near-surface radioactive waste disposal sites in India. The concentrations and effective radiation dose rates due to different radionuclides are evaluated at different distances from the disposal facilities. The peak dose rates received by members of the public at these distances are given per unit nuclear power capacity at the site [mSv/yr per GW(electric) center dot yr]. The product of these normalized peak dose rates and the total existing or projected nuclear power capacity at a site [GW(electric) center dot yr] will indicate the RUB dose rates from the near-surface disposal facility through a drinking water pathway at different distances. Results indicate that the sites can be grouped into two categories: (a) sites having ground-water velocity >10 cm/day (category 1) and (b) sites having groundwater velocity <10 cm/day (category 2). The variation in the dose rates between each category of sites is found to be small. Based on this finding, a generic method has been developed to evaluate the RUB dose rates to members of the public from the near-surface radioactive waste disposal facilities as a function of distances and nuclear power capacity. It is observed that the RUB dose rates at 1, 2, and 3 km are similar to 0.03, 0.02, and 0. 01 mSv/yr, respectively, for category 1 sites for a nuclear power capacity of 1 GW(electric). These dose rates are reduced by, a factor of 2 for category 2 sites. This generic method is found useful for the screening analysis of proposed low-level radioactive waste disposal sites as it estimates the RUB effective dose rates as a function of distance and nuclear power capacity for different categories of sites.