Radionuclide accumulation in a reactor cooling lake

In the utilization of a cooling lake for a commercial power reactor, low-level quantities of liquid waste are released to the lake water. Due to the retention and recycling of water for condenser cooling purposes, concentrations of radionuclides can increase to levels which are directly measurable in the water. Such a site design is represented by the H. B. Robinson Unit 2 operated by the Carolina Power and Light Company at Hartsville, SC. For a 4-year period lake water and other lake components such as fish, aquatic vegetation, and benthic sediments were sampled and analyzed to determine if any long-term buildup occurred. Results indicated that the lake water concentrations followed general mixing equations and that turnover rates in the individual components of the lake were too short to quantitate with this study design. This indicates that concentrations of radionuclides in the lake would be primarily a function of parameters such as radioactivity released and lake flow for the previous year and essentially independent of earlier parameters. An estimate of annual external doses to an individual utilizing the lake for recreation (i.e., swimming, boating, and fishing) would be about 5 microrem