Importance of waste form-specific leach modeling in low-level waste source term analysis

Abstract

The purpose of this study was to examine the importance of waste form-specific leach modeling in low-level radioactive waste (LLW) source term analysis. The tasks performed include: 1) detailed characterization of radionuclide inventory distributions in LLW to identify major waste forms and their leach characteristics, 2) development of a new source term computer model to support waste form-specific analysis, and 3) quantifying uncertainty due to the use of alternative modeling approaches for the major waste forms. The analyses were performed for 14C, 129I, 99Tc, 36Cl, 226Ra, 238U, and 239Pu. Results indicated that detailed waste form-specific modeling was not critical in reducing uncertainty in LLW source term analysis. Investigation of parameter uncertainty for the K d values of nuclides, water infiltration rate, and the inventory in the surface-contaminated waste remains important to better characterize the uncertainty in LLW source term analysis.