10 research outputs found
Recommended from our members
Post-test comparison of thermal-hydrologic measurements and numerical predictions for the in situ single heater test, Yucca Mountain, Nevada
The Single Heater Test (SHT) is a sixteen-month-long heating and cooling experiment begun in August, 1996, located underground within the unsaturated zone near the potential geologic repository at Yucca Mountain, Nevada. During the 9 month heating phase of the test, roughly 15 m{sup 3} of rock were raised to temperatures exceeding 100 C. In this paper, temperatures measured in sealed boreholes surrounding the heater are compared to temperatures predicted by 3D thermal-hydrologic calculations performed with a finite difference code. Three separate model runs using different values of bulk rock permeability (4 microdarcy to 5.2 darcy) yielded significantly different predicted temperatures and temperature distributions. All the models differ from the data, suggesting that to accurately model the thermal-hydrologic behavior of the SHT, the Equivalent Continuum Model (ECM), the conceptual basis for dealing with the fractured porous medium in the numerical predictions, should be discarded in favor of more sophisticated approaches
Recommended from our members
Sensitivity of hydrological performance assessment analysis to variations in material properties, conceptual models, and ventilation models
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface- based and underground testing. Analyses have been performed to support the design of an Exploratory Studies Facility (ESF) and the design of the tests performed as part of the characterization process, in order to ascertain that they have minimal impact on the natural ability of the site to isolate waste. The information in this report pertains to sensitivity studies evaluating previous hydrological performance assessment analyses to variation in the material properties, conceptual models, and ventilation models, and the implications of this sensitivity on previous recommendations supporting ESF design. This document contains information that has been used in preparing recommendations for Appendix I of the Exploratory Studies Facility Design Requirements document
The FEBEX benchmark test: case definition and comparison of modelling approaches
The FEBEX (Full-scale Engineered Barriers Experiment in Crystalline Host Rock) ââin situââ test was installed at the Grimsel Test
Site underground laboratory (Switzerland) and is a near-to-real scale simulation of the Spanish reference concept of deep geological
storage in crystalline host rock. A modelling exercise, aimed at predicting field behaviour, was divided in three parts. In Part A,
predictions for both the total water inflow to the tunnel as well as the water pressure changes induced by the boring of the tunnel
were required. In Part B, predictions for local field variables, such as temperature, relative humidity, stresses and displacements at
selected points in the bentonite barrier, and global variables, such as the total input power to the heaters were required. In Part C,
predictions for temperature, stresses, water pressures and displacements in selected points of the host rock were required. Ten
Modelling Teams from Europe, North America and Japan were involved in the analysis of the test. Differences among approaches
may be found in the constitutive models used, in the simplifications made to the balance equations and in the geometric symmetries
considered. Several aspects are addressed in the paper: the basic THM physical phenomena which dominate the test response are discussed, a comparison of different modelling results with actual measurements is presented and a discussion is given to explain the
performance of the various predictions.Peer Reviewe
Recommended from our members
Estimation of the impact of water movement from sewage and settling ponds near a potential high level radioactive waste repository in Yucca Mountain, Nevada; Yucca Mountain Site Characterization Project
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, which may include underground shafts, drifts, and ramps, and the accompanying ponds used for the storage of sewage water and muck water removed from construction operations. The information in this report pertains to the two-dimensional numerical calculations modelling the movement of sewage and settling pond water, and the potential effects of that water on repository performance and underground experiments. This document contains information that has been used in preparing Appendix I of the Exploratory Studies Facility Design Requirements document (ESF DR) for the Yucca Mountain Site Characterization Project
Recommended from our members
Evaluation of the effects of underground water usage and spillage in the Exploratory Studies Facility; Yucca Mountain Site Characterization Project
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level radioactive waste repository. Analyses reported herein were performed to support the design of site characterization activities so that these activities will have a minimal impact on the ability of the site to isolate waste and a minimal impact on underground tests performed as part of the characterization process. These analyses examine the effect of water to be used in the underground construction and testing activities for the Exploratory Studies Facility on in situ conditions. Underground activities and events where water will be used include construction, expected but unplanned spills, and fire protection. The models used predict that, if the current requirements in the Exploratory Studies Facility Design Requirements are observed, water that is imbibed into the tunnel wall rock in the Topopah Springs welded tuff can be removed over the preclosure time period by routine or corrective ventilation, and also that water imbibed into the Paintbrush Tuff nonwelded tuff will not reach the potential waste storage area
Recommended from our members
Estimations of the extent of migration of surficially applied water for various surface conditions near the potential repository perimeter; Yucca Mountain Site Characterization Project
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to support the design of site characterization activities so to have minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. Two examples of site characterization activities are the construction of an Exploratory Studies Facility, which may include underground shafts, drifts, and ramps, and surface-based testing activities, which may require borehole drilling, excavation of test pits, and road watering for dust control. The information in this report pertains to two-dimensional numerical calculations modeling the movement of surficially applied water and the potential effects of that water on repository performance and underground experiments. This document contains information that has been used in preparing recommendations for two Yucca Mountain Site Characterization Project documents: Appendix I of the Exploratory Studies Facility Design Requirements document, and the Surface-Based Testing Field Requirements Document
Recommended from our members
Estimation of the limitations for surficial water addition above a potential high level radioactive waste repository at Yucca Mountain, Nevada; Yucca Mountain Site Characterization Project
The Yucca Mountain Site Characterization Project is studying Yucca Mountain in southwestern Nevada as a potential site for a high-level nuclear waste repository. Site characterization includes surface-based and underground testing. Analyses have been performed to design site characterization activities with minimal impact on the ability of the site to isolate waste, and on tests performed as part of the characterization process. One activity of site characterization is the construction of an Exploratory Studies Facility, consisting of underground shafts, drifts, and ramps, and the accompanying surface pad facility and roads. The information in this report addresses the following topics: (1) a discussion of the potential effects of surface construction water on repository-performance, and on surface and underground experiments; (2) one-dimensional numerical calculations predicting the maximum allowable amount of water that may infiltrate the surface of the mountain without affecting repository performance; and (3) two-dimensional numerical calculations of the movement of that amount of surface water and how the water may affect repository performance and experiments. The results contained herein should be used with other site data and scientific/engineering judgement in determining controls on water usage at Yucca Mountain. This document contains information that has been used in preparing Appendix I of the Exploratory Studies Facility Design Requirements document for the Yucca Mountain Site Characterization Project
Recommended from our members
Results of the Single Heater Test at Yucca Mountain, Nevada
The Yucca Mountain Project conducted a Single Heater Test (SHT) in the Exploratory Studies Facility at Yucca Mountain. During the nine month-long heating phase, approximately 4 m{sup 3} of in situ, fractured, 92% saturated, welded tuff was heated to temperatures above 100 C by a 5 m long, 3.8 kW, horizontal, line heater. In this paper, the thermal data collected during the test (Sandia National Laboratories, 1997) are compared to three numerical simulations (Sobolik et al., 1996) in order to gain insight into the coupled thermal-hydrologic processes. All three numerical simulations rely on the Equivalent Continuum Model (ECM) for reasons of computational efficiency. The ECM assumes that the matrix and the fractures are in thermodynamic equilibrium which allows the thermal and hydrologic properties of the matrix and the fractures to be combined into single, bulk values. The three numerical simulations differ only in their bulk permeabilities and are referred to as the High, Low and Matrix Permeability Models, respectively. In the Matrix Permeability Model, the system behaves as an unfractured porous medium with the properties of the rock matrix
The FEBEX benchmark test: case definition and comparison of modelling approaches
The FEBEX (Full-scale Engineered Barriers Experiment in Crystalline Host Rock) ââin situââ test was installed at the Grimsel Test
Site underground laboratory (Switzerland) and is a near-to-real scale simulation of the Spanish reference concept of deep geological
storage in crystalline host rock. A modelling exercise, aimed at predicting field behaviour, was divided in three parts. In Part A,
predictions for both the total water inflow to the tunnel as well as the water pressure changes induced by the boring of the tunnel
were required. In Part B, predictions for local field variables, such as temperature, relative humidity, stresses and displacements at
selected points in the bentonite barrier, and global variables, such as the total input power to the heaters were required. In Part C,
predictions for temperature, stresses, water pressures and displacements in selected points of the host rock were required. Ten
Modelling Teams from Europe, North America and Japan were involved in the analysis of the test. Differences among approaches
may be found in the constitutive models used, in the simplifications made to the balance equations and in the geometric symmetries
considered. Several aspects are addressed in the paper: the basic THM physical phenomena which dominate the test response are discussed, a comparison of different modelling results with actual measurements is presented and a discussion is given to explain the
performance of the various predictions.Peer Reviewe