No abstract

Although the listing that follows represents the majority of documents cited In NRC publications, lt Is not intended to be exhaustive. Referenced documents avalleh!e for Inspection and copying for a fee from the NRC Public Document Room Include NRC correspondence and Internal NRC memoranda; NRC Office of Inspection and Enforcement bulletins, circulars, Information notices, Inspection and Investigation notices; Licensee Event Reports; yender reports and correspondence: Commission papers; and applicant and licensee clocurnents and correspondence. The following documents In the NUREG series are available for purc1_se from the GPO Sales Program: forma, NRC staff and contractor reports, NRC-sponsored conferanm) procoodln_, and NRC booklets and brochures. ASseavailable are Regulatory Guldes, NRC reguPaticns In the Code of Federal Regulatlons, end Nuclear Regulatory Commission Issuances. Documents available from the National Technical information 8_toe Include NUREG series reports end technical reports prepared by other federal agencies and reports prepared by the Atomic Energy Cornrrdssicn, forerunner agency to the Nuclear Regulatory Commission. Documents available from public end special technical Nbrarles Includeld open literature hems, such as books, Jotmnsl and periodical articles, and transactions. Federal Re_lster notices, federal and state leglsleticn, and confessional reports can usually be obtained from these Ibrerles.

Estimates of potential radionuclide releases from HLW storage facilities in geologic formations are an integral part of the technical basis for the regulation of nuclear waste disposal. We have attempted to assess the importance of the variation of several variables and model assumptions to the calculation of radionuclide discharge from hypothetical repositories. The conceptual models of the repository sites are consistent with our current understanding of the characteristics of the geologic environments being studied by the Department of Energy. It must be stressed that we have not attempted to accurately model any real sites; at the present time, the available data are not sufficient for this purpose. Large uncertainties exist in the characterization of the solubilities and sorption of radionuclides, in the description of the regional and local hydrogeology and in the mathematical treatment of contaminant transport in the presence of fracture flow and matrix diffusion. The fraction of waste that could be accessed by breaching the repository, the effects of mixing processes within the facility and the probability of human intrusion are not known. We have completed preliminary calculations of potential radionuclide discharges from hypothetical repositories in tuff and bedded salt [1,2]. Our theoretical approach and computational methods are illustrated in this paper with examples for a repository in volcanic tuff. We also briefly discuss the importance of radionuclide source term assumptions to the calculations for a bedded salt repository.

Prrparrd by Srndir National Laboratorirr Albuqurrqur, New Mrxlco 87185 and Uvermore, Cailfornia 94550 for tho Unltod Statrm Drpartmrnt of Enrrgy undrr Contract DE-ACO4-94Al.85000-. .I Approved for public release; distribution is unlimited.

No abstract