Sizing Cooling Water Discharge System to Control Water Quality Impacts of Tritium Releases

Nuclear power plants with re-circulating cooling water systems routinely release controlled quantities of tritium with plant water discharge to on-site cooling lakes. Computations are required to evaluate the impacts of tritium releases on the water quality of the cooling lake. A mass balance equation is developed to compute the build up of tritium activity in the cooling lake with specified amounts of tritium discharged from the plant and varying amounts of fresh water withdrawn from and blowdown water discharged to a perennial source, e.g., a river. Different scenarios are evaluated for varying quantities of fresh water withdrawal and blowdown discharges and maximum tritium activity expected in the water in the cooling lake. Limitations on withdrawals from and blowdown discharges into the river are addressed so that the water quality of the receiving stream is not impaired due to unacceptable tritium concentrations.