Assessing Postulated Accidental Releases of Radioactive Liquid Effluents from Nuclear Power Plants

Licensing of commercial nuclear power reactors requires an assessment of a postulated accidental release of radioactive liquid effluent in ground and surface waters to demonstrate that the dose to an individual member of the public does not exceed regulatory limits. The radioactive liquid effluent with the highest potential exposure consequences to offsite water users is associated with the liquid waste management system and is comprised of a mixture of fission and activation products with a wide range of half-lives. The liquid effluent containing tanks postulated to fail are located below ground such that a liquid release would enter the groundwater and then be subject to groundwater transport offsite with radionuclide concentrations being attenuated by the processes of radioactive decay, adsorption, and dispersion. Evaluations of these postulated releases have been completed and included in the license applications for 17 new nuclear power reactor sites. Results of these analyses indicate that groundwater travel times vary widely from site to site and that groundwater to surface water pathways are present for many of the sites. Comparisons of predicted radionuclide concentrations at offsite receptor locations to regulatory limits indicate compliance with the dose limits for an individual member of the public, with tritium having the potential for the greatest dose contribution.