Probabilistic performance-assessment modeling of the mixed waste landfill at Sandia National Laboratories [electronic resource].
- Published
- Washington, D.C. : United States. Dept. of Energy, 2005.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy. - Physical Description
- 80 pages : digital, PDF file
- Additional Creators
- Sandia National Laboratories, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
Access Online
- Restrictions on Access
- Free-to-read Unrestricted online access
- Summary
- A probabilistic performance assessment has been conducted to evaluate the fate and transport of radionuclides (americium-241, cesium-137, cobalt-60, plutonium-238, plutonium-239, radium-226, radon-222, strontium-90, thorium-232, tritium, uranium-238), heavy metals (lead and cadmium), and volatile organic compounds (VOCs) at the Mixed Waste Landfill (MWL). Probabilistic analyses were performed to quantify uncertainties inherent in the system and models for a 1,000-year period, and sensitivity analyses were performed to identify parameters and processes that were most important to the simulated performance metrics. Comparisons between simulated results and measured values at the MWL were made to gain confidence in the models and perform calibrations when data were available. In addition, long-term monitoring requirements and triggers were recommended based on the results of the quantified uncertainty and sensitivity analyses. At least one-hundred realizations were simulated for each scenario defined in the performance assessment. Conservative values and assumptions were used to define values and distributions of uncertain input parameters when site data were not available. Results showed that exposure to tritium via the air pathway exceeded the regulatory metric of 10 mrem/year in about 2% of the simulated realizations when the receptor was located at the MWL (continuously exposed to the air directly above the MWL). Simulations showed that peak radon gas fluxes exceeded the design standard of 20 pCi/m²/s in about 3% of the realizations if up to 1% of the containers of sealed radium-226 sources were assumed to completely degrade in the future. If up to 100% of the containers of radium-226 sources were assumed to completely degrade, 30% of the realizations yielded radon surface fluxes that exceeded the design standard. For the groundwater pathway, simulations showed that none of the radionuclides or heavy metals (lead and cadmium) reached the groundwater during the 1,000-year evaluation period. Tetrachloroethylene (PCE) was used as a proxy for other VOCs because of its mobility and potential to exceed maximum contaminant levels in the groundwater relative to other VOCs. Simulations showed that PCE reached the groundwater, but only 1% of the realizations yielded aquifer concentrations that exceeded the regulatory metric of 5 {micro}g/L. Based on these results, monitoring triggers have been proposed for the air, surface soil, vadose zone, and groundwater at the MWL. Specific triggers include numerical thresholds for radon concentrations in the air, tritium concentrations in surface soil, infiltration through the vadose zone, and uranium and select VOC concentrations in groundwater. The proposed triggers are based on U.S. Environmental Protection Agency and Department of Energy regulatory standards. If a trigger is exceeded, then a trigger evaluation process will be initiated which will allow sufficient data to be collected to assess trends and recommend corrective actions, if necessary.
- Report Numbers
- E 1.99:sand2005-6888
sand2005-6888 - Subject(s)
- Other Subject(s)
- Americium 241
- Aquifers
- Cadmium
- Cesium 137
- Cobalt 60.
- Containers
- Metrics
- Monitoring
- Organic Compounds
- Plutonium 238
- Plutonium 239
- Radioisotopes
- Radium 226
- Radon
- Radon 222
- Sanitary Landfills
- Strontium 90.
- Thorium 232
- Transport
- Tritium
- Uranium
- Uranium 238
- Us Epa
- Volatile Matter
- Wastes
- Performance Standards
- Sandia National Laboratories
- Radioactive And Mixed Waste Management Facility
- Environment
- New Mexico
- Environmental Sciences-Computer Simulation
- Note
- Published through SciTech Connect.
11/01/2005.
"sand2005-6888"
Ho, Clifford Kuofei; Peace, Gerald L.; Goering, Timothy James; Miller, Mark Laverne. - Funding Information
- AC04-94AL85000
View MARC record | catkey: 13802514