Evaluation of thermo-hydrological performance in support of the thermal loading systems study

Buscheck, T.A.; Nitao, John J.; Saterlie, S.F.

doi:10.2172/145594

Cited by 18 publications

(22 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This assumption is made primarily to avoid numerical instabilities caused by oscillations in gas pressures at nodes in the neighborhood of the water table. Previous studies (Lingineni et al, 1994, Buscheck et al, 1994 have shown that the effect of including the water table is significant at late time periods 4-3 (after about do00 years) after the thermal front reaches the water table. In the absence of the saturated zone in the model, the thermal boundary condition at the lower boundary plays an important role.…”

Section: Model Assumptionsmentioning

confidence: 95%

Total system performance assessment - 1995: An evaluation of the potential Yucca Mountain repository

Atkins¹,

Lee²,

Lingineni³

et al. 1995

View full text Add to dashboard Cite

Section: Model Assumptionsmentioning

confidence: 95%

Total system performance assessment - 1995: An evaluation of the potential Yucca Mountain repository

Atkins¹,

Lee²,

Lingineni³

et al. 1995

View full text Add to dashboard Cite

“…These benefits include formation of a large dry-out zone around the repository horizon, with the possibility of associated condensate drainage, for times extending well beyond 1000 y. These recent models suggest that liquid saturation in much of the repository horizon will remain below initial values (>68%, Buscheck et al 1994) for at least 100,000 y at an A M L of 110.5 MTU/acre. Obviously, such a large and persistent dry-out zone will greatly reduce the potential for aqueous-phase transport of radionuclides from a repository.…”

Section: Introductionmentioning

confidence: 99%

“…The baseline APD used in the Yucca Mountain Site Characterization Plan is 57 kW/acre (an A M L of 55.3 MTU/acre for 22.5-year-old fuel). However, more recent models of the thermal behavior of a repository at Yucca Mountain have considered the benefits of higher loadings, up to an A M L of 110.5 MTU/acre (Buscheck et al 1994). These benefits include formation of a large dry-out zone around the repository horizon, with the possibility of associated condensate drainage, for times extending well beyond 1000 y.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium Modeling of Clinoptilolite-Analcime Equilibria at Yucca Mountain, Nevada, USA

Bish

1997

Clays and clay miner.

View full text Add to dashboard Cite

Abstract--Yucca Mountain, Nevada, is being investigated to determine its suitability to host a potential high-level radioactive waste respository. An important reason for its choice as a potential repository site was the presence of thick zeolite-rich horizons in the altered volcanic tufts that compose the mountain. Clinoptilolite is the most abundant zeolite at Yucca Mountain and may be important in radionuclide retardation and in determining hydrologic properties. Therefore, it is necessary to understand the geochemical conditions affecting its long-term stability. For example, it has been suggested that long-term, repository-induced heating of the rocks at Yucca Mountain may lead to the transformation of clinoptilolite to analcime, thereby significantly affecting the hydrologic properties and retardation capabilities of the rock.Thermodynamic modeling of clinoptilolite-analcime equilibria was conducted with the program Ge0-Calc PTA-SYSTEM using estimated thermodynamic data for measured chemical compositions of clinoptilolite and analcime at Yucca Mountain. Log[(aK+)2/aCa 2+] versus log[(aNa+)2/aCa 2 § diagrams were calculated to model the conditions under which clinoptilolite may transform to analcime. Temperature, relative cation abundances and silica activity are all important factors in determining clinoptilolite-analcime equilibria. Increased Na § concentrations in either clinoptilolite or the fluid phase, increased clinoptilolite K § concentration, increased temperature and decreased aqueous silica activity all stabilize analcime relative to clinoptilolite, assuming present-day Yucca Mountain water compositions. However, increased Ca 2 § concentrations in either clinoptilolite or the fluid phase, increased aqueous K § concentration and increased AI:Si ratios in clinoptilolite (heulandite) all stabilize clinoptilolite with respect to analcime.Assuming well J-13 water as the analog chemistry for Yucca Mountain water, clinoptilolite should remain stable with respect to analcime if temperatures in the clinoptilolite-bearing horizons do not significantly exceed 100 ~ Even if temperatures rise significantly (for example, to 150 ~ not all clinoptilolite should alter to analcime. Perhaps more importantly, thermodynamic modeling suggests that some Yucca Mountain clinoptilolites, particularly those rich in Ca and A1, will remain stable at elevated temperatures, even with an aqueous silica activity at quartz saturation.

show abstract

“…Because of the large spatial and temporal scales involved in such characterization, quantitative modeling 3 evaluation of the coupled fluid-flow and heat-transfer processes has proven to be essential. Quantitative investigation of TH processes at the Yucca Mountain repository site have motivated a continual effort to develop and apply different scale fluid and heat flow models [25,20,21,19,5,29,26,9,10,1,6,13,14,2]. These numerical models have played a crucial role in understanding coupled fluid and heat flow as well as in assessing how TH conditions affect on various aspects of the overall UZ waste disposal system.…”

Section: Introductionmentioning

confidence: 99%

A mountain-scale thermal–hydrologic model for simulating fluid flow and heat transfer in unsaturated fractured rock

Mukhopadhyay

Zhang

et al. 2006

Journal of Contaminant Hydrology

View full text Add to dashboard Cite

A multidimensional, mountain-scale, thermal-hydrologic (TH) numerical model is presented for investigating unsaturated flow behavior in response to decay heat from the radioactive waste repository in the Yucca Mountain unsaturated zone (UZ), Nevada. The model, consisting of both two-dimensional (2-D) and three-dimensional (3-D) representations of the UZ repository system, is based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climate conditions. This mountain-scale TH model evaluates the coupled TH processes related to mountain-scale UZ flow. It also simulates the impact of radioactive waste heat release on the natural hydrogeological system, including heat-driven processes occurring near and far away from the emplacement tunnels or drifts. The model simulations predict thermally perturbed liquid saturation, gas-and liquid-phase fluxes, and water and rock temperature elevations, as well as the changes in water flux driven by evaporation/condensation processes and drainage between drifts. These simulations provide mountain-scale thermally perturbed flow fields for assessing the repository performance under thermal loading conditions. Key Words: thermal-hydrologic processes in subsurface, thermal load, Yucca Mountain, fluid and heat flow in porous media, heat pipe, reservoir simulation, fractured unsaturated rock * Corresponding author. Tel.: +1-510-486-7291; fax: +1-510-486-5686, E-Mail address: YSWu@lbl.gov. 2 IntroductionIn the past decade, the 500-700 m thick Yucca Mountain unsaturated zone (UZ) has been extensively investigated as a potential subsurface repository for storing high-level radioactive wastes. While the site characterization has been mostly carried out for analyzing unsaturated flow and radionuclide transport in ambient, isothermal conditions [30,31], the inherent nature of nonisothermal flow and transport processes, created by repository heating from radioactive decay, has also motivated many research efforts to understand thermal-hydrologic (TH) behavior and its impact on the repository performance within the UZ. In particular, significant progress has been made in quantitative TH modeling studies at Yucca Mountain [9,10,6].Emplacement of heat-generating high-level radioactive waste in the UZ system of unsaturated welded and unwelded fractured tuff at Yucca Mountain will perturb the ambient condition and create complex multiphase fluid flow and heat-transfer processes.The physical phenomena associated with repository heating include conduction and convection heat transfer, phase change (boiling and condensation), two-phase flow of liquid and gas phases under variably saturated conditions, enhanced fracture-matrix interaction caused by rapid matrix drying and subsequent imbibition, diffusion and dispersion of vapor and gas, and vapor-pressure-lowering effects. These TH processes will last hundreds to thousands of years after waste emplacement, and will significantly redistribute the in-situ moisture content and alter the per...

show abstract

Evaluation of thermo-hydrological performance in support of the thermal loading systems study

Cited by 18 publications

References 5 publications

Total system performance assessment - 1995: An evaluation of the potential Yucca Mountain repository

Total system performance assessment - 1995: An evaluation of the potential Yucca Mountain repository

Equilibrium Modeling of Clinoptilolite-Analcime Equilibria at Yucca Mountain, Nevada, USA

A mountain-scale thermal–hydrologic model for simulating fluid flow and heat transfer in unsaturated fractured rock

Contact Info

Product

Resources

About