Estimating radionuclide releases from low-level radioactive wastes

Performance assessments of low-level radioactive waste (LLW) disposal facilities are particularly sensitive to assumed radionuclide source terms and release models. The U.S. Nuclear Regulatory Commission (NRC) is currently evaluating alternative approaches for estimating radionuclide releases from LLW. As part of a more comprehensive performance assessment methodology, the NRC is developing source term models to estimate radionuclide releases for safety assessments of LLW disposal facilities. These models range from simple, empirical approaches to more complex models that attempt to simulate the processes of leaching, dissolution, sorption, corrosion, diffusion, and advection. Preliminary results indicate that relatively simple, deterministic approaches are preferable provided that they can be demonstrated to be reasonably conservative. The NRC staff intends to select an approach for estimating radionuclide releases that provides demonstrably conservative estimates and sufficient flexibility to consider releases on a facility-specific basis