Waste Management Analysis

Non-Newtonian modeling combined with component tracking, generic fluid property framework, and hydrogen modeling capabilities already included in GOTHIC make the software an effective tool for waste tank storage applications. Modeling of solid particles includes settling into a sediment layer, bed load, resuspension of the settled material due to shear and turbulence, and release/absorption of dissolved gas Non-Newtonian physics covering both yield-pseudoplastic and thixotropic materials, considering non-zero yield stress, non-zero shear strength, non-linear relationship between the shear stress and strain rate, temperature dependence, particle concentration dependence and a time dependence (thixotropic). Previous experience includes evaluating hydrogen generation, venting and explosions and associated loads for waste tanks.
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The NAS staff has extensive dose, aerosol and containment modeling experience utilizing several different types of software. For example, RADTRAD-NAI has been used to perform Alternative Source Term (AST) dose analyses, ORIGEN was utilized to assess the concentrations and source terms of isotopes and MICROSHIELD and MICROSKYSHINE were applied to complete shielding and dose calculations for several different nuclear power plants. GOTHIC is capable of fission product tracking, dry aerosol transport and ventilation assessments. In addition to tracking solid particles, GOTHIC can track user defined tracer elements (including radioactive decay and daughtering of nuclides) in the liquid, vapor and droplet fields as well as on surfaces and filters. GOTHIC includes components such as fans, filters, charcoal filters, dryers/demisters, etc. in which aerosols and other filtered material is removed or accumulated. Moreover, NAS has developed a GOTHIC model of a medical isotope facility including the irradiation unit, hot cells and glove boxes, and the facility ventilation including dampers, filters, forced flow to maintain pressure differential and hydraulic connections between areas and to the environment. More information can be found here.

NAS has supported detailed analyses of spent fuel pools (SFP), independent spent fuel storage installation facilities (ISFSI), spent fuel shipping and storage casks and operating procedures associated with loading and unloading casks and shipping fuel.

Waste cleanup sites have the potential for the migration of pollutants and hazardous wastes from groundwater transport. GOTHIC can be used as a predictive analysis tool to evaluate mitigating actions intended to minimize impact on the environment and public exposure. Any number of contaminants, radioactive isotopes and other species of interest can be tracked by GOTHIC. Moreover, GOTHIC is developed and maintained under a Quality Assurance program in compliance with the requirements of 10CFR50 Appendix B. The multi-region modeling approach used by GOTHIC simplifies model construction for regions of varying hydrologic characteristics and focuses the computational effort on regions of particular interest while simultaneously capturing the macroscopic response and any feedback effects across the larger domain, as demonstrated here. Custom add-on modules expand the modeling capabilities of GOTHIC and can be used to account for chemistry effects in groundwater transport.
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