摘要
Five marine organisms in Daya Bay are selected for estimating the dose rates. Internal exposure and its 5 pathways are also considered. The concentrations of 43 kinds of background and additional radionuclides in seawater are from the survey of background radioactivity and the prediction of routine radioactive releases of the 4 reactors. Point source dose distribution functions are used to estimate the dose rates to various organisms from a and β radiation.
Five marine organisms in Daya Bay are selected for estimating the dose rates. Internal exposure and its 5 pathways are also considered. The concentrations of 43 kinds of background and additional radionuclides in seawater are from the survey of background radioactivity and the prediction of routine radioactive releases of the 4 reactors. Point source dose distribution functions are used to estimate the dose rates to various organisms from α and β radiation. Monte-Carlo method is used to determine the absorbed fractions in the organisms from γ radiation. Results indicate that the background dose rates are 2.72 mGya · a-1 to phytoplankton and 1.75 mGy · a-1 to zooplankton. The dose rates to other organisms are in the range of 0.31–0. 49 mGy · a-1. The additional dose rates from the routine releases are varied to different organisms. They reach the range of 5.7–6.1 times of the background dose rates to benthic crustaceans and mollusks, which are 8.3%–15.3% to fishes, and only 0.2% to plankton. β internal irradiation from additional radionuclides is the critical pathway to plankton.131I and60Co are the major contributors to zooplankton, while103Ru,60Co and58Co are the main contributors to phytoplankton. γ external irradiation from sediment is the critical pathway to benthic organisms.58Co and60Co are the main contributors. The main pathways to fishes are internal β and γ irradiation.124Sb is the critical radionuclide.
