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John S. Stuckless

Publications and source records attributed to John S. Stuckless.

At least 19 recordsLinked to original sources
USGS2016

The road to Yucca Mountain—Evolution of nuclear waste disposal in the United States

The generation of electricity by nuclear power and the manufacturing of atomic weapons have created a large amount of spent nuclear fuel and high-level radioactive waste. There is a world-wide consensus that the best way to protect mankind and the environment is to dispose of this waste in a deep geologic repository. Initial efforts focused on salt as the best medium for disposal, but the heat generated by the radioactive waste led many earth scientists to examine other rock types. In 1976, the director of the U.S. Geological Survey (USGS) wrote to the U.S. Energy Research and Development Administration (ERDA), predecessor agency of the U.S. Department of Energy (DOE), suggesting that there were several favorable environments at the Nevada Test Site (NTS), and that the USGS already had extensive background information on the NTS. Later, in a series of communications and one publication, the USGS espoused the favorability of the thick unsaturated zone. After the passage of the Nuclear Waste Policy Act (1982), the DOE compiled a list of nine favorable sites and settled on three to be characterized. In 1987, as the costs of characterizing three sites ballooned, Congress amended the Nuclear Waste Policy Act directing the DOE to focus only on Yucca Mountain in Nevada, with the proviso that if anything unfavorable was discovered, work would stop immediately. The U.S. DOE, the U.S. DOE national laboratories, and the USGS developed more than 100 detailed plans to study various earth-science aspects of Yucca Mountain and the surrounding area, as well as materials studies and engineering projects needed for a mined geologic repository. The work, which cost more than 10 billion dollars and required hundreds of man-years of work, culminated in a license application submitted to the U.S. Nuclear Regulatory Commission (NRC) in 2008.

Environmental & Engineering Geoscience↗
USGS2012

Characterizing the proposed geologic repository for high-level radioactive waste at Yucca Mountain, Nevada: hydrology and geochemistry

This hydrology and geochemistry volume is a companion volume to the 2007 Geological Society of America Memoir 199, The Geology and Climatology of Yucca Mountain and Vicinity, Southern Nevada and California , edited by Stuckless and Levich. The work in both volumes was originally reported in the U.S. Department of Energy regulatory document Yucca Mountain Site Description , for the site characterization study of Yucca Mountain, Nevada, as the proposed U.S. geologic repository for high-level radioactive waste. The selection of Yucca Mountain resulted from a nationwide search and numerous committee studies during a period of more than 40 yr. The waste, largely from commercial nuclear power reactors and the government's nuclear weapons programs, is characterized by intense penetrating radiation and high heat production, and, therefore, it must be isolated from the biosphere for tens of thousands of years. The extensive, unique, and often innovative geoscience investigations conducted at Yucca Mountain for more than 20 yr make it one of the most thoroughly studied geologic features on Earth. The results of these investigations contribute extensive knowledge to the hydrologic and geochemical aspects of radioactive waste disposal in the unsaturated zone. The science, analyses, and interpretations are important not only to Yucca Mountain, but also to the assessment of other sites or alternative processes that may be considered for waste disposal in the future. Groundwater conditions, processes, and geochemistry, especially in combination with the heat from radionuclide decay, are integral to the ability of a repository to isolate waste. Hydrology and geochemistry are discussed here in chapters on unsaturated zone hydrology, saturated zone hydrology, paleohydrology, hydrochemistry, radionuclide transport, and thermally driven coupled processes affecting long-term waste isolation. This introductory chapter reviews some of the reasons for choosing to study Yucca Mountain as a repository site.

Nevada↗
USGS2012

Hydrology of the unsaturated zone, Yucca Mountain, Nevada

The unsaturated zone at Yucca Mountain was investigated as a possible site for the nation's first high-level nuclear waste repository. Scientific investigations included infiltration studies, matrix properties testing, borehole testing and monitoring, underground excavation and testing, and the development of conceptual and numerical models of the hydrologic processes at Yucca Mountain. Infiltration estimates by empirical and geochemical methods range from 0.2 to 1.4 mm/yr and 0.2–6.0 mm/yr, respectively. Infiltration estimates from numerical models range from 4.5 mm/yr to 17.6 mm/yr. Rock matrix properties vary vertically and laterally as the result of depositional processes and subsequent postdepositional alteration. Laboratory tests indicate that the average matrix porosity and hydraulic conductivity values for the main level of the proposed repository (Topopah Spring Tuff middle nonlithophysal zone) are 0.08 and 4.7 × 10 −12 m/s, respectively. In situ fracture hydraulic conductivity values are 3–6 orders of magnitude greater. The permeability of fault zones is approximately an order of magnitude greater than that of the surrounding rock unit. Water samples from the fault zones have tritium concentrations that indicate some component of postnuclear testing. Gas and water vapor movement through the unsaturated zone is driven by changes in barometric pressure, temperature-induced density differences, and wind effects. The subsurface pressure response to surface barometric changes is controlled by the distribution and interconnectedness of fractures, the presence of faults and their ability to conduct gas and vapor, and the moisture content and matrix permeability of the rock units. In situ water potential values are generally less than −0.2 MPa (−2 bar), and the water potential gradients in the Topopah Spring Tuff units are very small. Perched-water zones at Yucca Mountain are associated with the basal vitrophyre of the Topopah Spring Tuff or the Calico Hills bedded tuff. Thermal gradients in the unsaturated zone vary with location, and range from ~2.0 °C to 6.0 °C per 100 m; the variability appears to be associated with topography. Large-scale heater testing identified a heat-pipe signature at ~97 °C, and identified thermally induced and excavation-induced changes in the stress field. Elevated gas-phase CO 2 concentrations and a decrease in the pH of water from the condensation zone also were identified. Conceptual and numerical flow and transport models of Yucca Mountain indicate that infiltration is highly variable, both spatially and temporally. Flow in the unsaturated zone is predominately through fractures in the welded units of the Tiva Canyon and Topopah Spring Tuffs and predominately through the matrix in the Paintbrush Tuff nonwelded units and Calico Hills Formation. Isolated, transient, fast-flow paths, such as faults, do exist but probably carry only a small portion of the total liquid-water flux at Yucca Mountain. The Paintbrush Tuff nonwelded units act as a storage buffer for transient infiltration pulses. Faults may act as flow boundaries and/or fast pathways. Below the proposed repository horizon, low-permeability lithostratigraphic units of the Topopah Spring Tuff and/or the Calico Hills Formation may divert flow laterally to faults that act as conduits to the water table. Advective transport pathways are consistent with flow pathways. Matrix diffusion is the major mechanism for mass transfer between fractures and the matrix and may contribute to retardation of radionuclide transport when fracture flow is dominant. Sorption may retard the movement of radionuclides in the unsaturated zone; however, sorption on mobile colloids may enhance radionuclide transport. Dispersion is not expected to be a major transport mechanism in the unsaturated zone at Yucca Mountain. Natural analogue studies support the concepts that percolating water may be diverted around underground openings and that the percentage of infiltration that becomes seepage decreases as infiltration decreases.

Nevada↗
USGS2010

Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada

Natural analogues are defined for this report as naturally occurring or anthropogenic systems in which processes similar to those expected to occur in a nuclear waste repository are thought to have taken place over time periods of decades to millennia and on spatial scales as much as tens of kilometers. Analogues provide an important temporal and spatial dimension that cannot be tested by laboratory or field-scale experiments. Analogues provide one of the multiple lines of evidence intended to increase confidence in the safe geologic disposal of high-level radioactive waste. Although the work in this report was completed specifically for Yucca Mountain, Nevada, as the proposed geologic repository for high-level radioactive waste under the U.S. Nuclear Waste Policy Act, the applicability of the science, analyses, and interpretations is not limited to a specific site. Natural and anthropogenic analogues have provided and can continue to provide value in understanding features and processes of importance across a wide variety of topics in addressing the challenges of geologic isolation of radioactive waste and also as a contribution to scientific investigations unrelated to waste disposal. Isolation of radioactive waste at a mined geologic repository would be through a combination of natural features and engineered barriers. In this report we examine analogues to many of the various components of the Yucca Mountain system, including the preservation of materials in unsaturated environments, flow of water through unsaturated volcanic tuff, seepage into repository drifts, repository drift stability, stability and alteration of waste forms and components of the engineered barrier system, and transport of radionuclides through unsaturated and saturated rock zones.

Professional Paper↗
USGS1993

Isotopic evidence of complex ground-water flow at Yucca mountain, Nevada, USA

Strontium isotopes (expressed as per mill deviation from mean sea water, ??87Sr) reflect interaction between ground water and the aquifer through which it is flowing. In the Cenozoic aquifer of the Yucca Mountain region, ??87Sr values increase from north to south downgradient in the flow system. The largest ??87Sr values occur in the Amargosa Desert where ground water probably encounters alluvial basin fill derived from Precambrian rocks in the Funeral Range. Similarly, large ??87Sr values for ground water in the Paleozoic aquifer at the western end of the Spring Mountains also probably reflect an encounter with Precambrian rocks. In several wells into the volcanic rocks, apparent isotopic disequilibrium between ground water and the producing units suggests that the ground water probably integrates over a substantial part of the saturated section in attaining its strontium isotope signature.

Conference Paper↗
USGS1993

Strontium isotopic evidence for a higher water table at Yucca Mountain

At Yucca Mountain, calcite occurs as open-space fillings and coatings on fractures within much of the host volcanic rocks in both the saturated and unsaturated zones. Strontium isotope analyses of these calcites divide the samples into two groups corresponding to their location in either the saturated or unsaturated zones. The group of samples from the unsaturated zone corresponds very well with pedogenic carbonate samples, indicating that the strontium came from the surface during infiltration events. However, four samples from the unsaturated zone show strontium isotopic ratios similar to present-day ground water. Since these samples are closest to the water table, they are interpreted as the result of a higher water-table stand (approx.85 m higher than present-day) in the past.

Conference Paper↗
USGS1983

Preliminary assessment of the geochemistry and mineral favorability of the postorogenic granites of the southeastern Arabian Shield, Kingdom of Saudi Arabia

Chemical analyses of samples for 19 postorogenic plutons from the southeastern Arabian Shield show that these rocks have average potassium/rubidium ratios (162) and average rubidium/strontium ratios (11.8) characteristic of highly evolved granites. Most of the analyzed samples are peraluminous. Three plutons are physically similar in terms of shape and megascopic textural zonation to peralkaline complexes in the northeastern part of the Shield, but none of the samples from these plutons is peralkaline. However, these plutons do contain the least-evolved samples. Zinc, yttrium, uranium, thorium, and possibly copper, each occur in anomalously high concentrations in at least one pluton relative to contents typically cited for granite. The average regional concentrations of copper and zinc are anomalously high. These facts suggest at least a moderate potential for mineralization in the southeastern part of the Shield. Good correlations (r of 0.5 to 0.8) between uranium, thorium, yttrium, and rubidium and an excellent correlation (r=0.98) between uranium and radium-equivalent uranium suggest that secondary deposits of these elements are unlikely and that magmatic deposits, especially of a pegmatitic nature, are more likely. Concentrations of some major elements and several trace elements covary with sample location as measured by latitude and longitude. This fact is interpreted to reflect regional variations in the protolith that have been proposed on the basis of lead isotopic data. The chemical variations suggest a largely oceanic crustal component for granites in the southwestern part of the southeastern Shield and a largely continental crustal component to the northeast. Further quantitative analysis is recommended to verify and accurately delineate anomalous concentrations of trace elements. Trend surface analysis of all available data for postorogenic granites from the eastern Arabian Shield is suggested as a method for testing regional variations in the protolith that might control locations of highly favorable areas of ore deposition.

Open-File Report↗
USGS1978

Radiometric results and areal distribution for granitic samples from the Granite Mountains, Wyoming

Analyses of surface samples from the Granite Mountains, Wyoming, generally agree with the findings from drilling at two different localities. The dominant Precambrian granitic rock type is the biotitic phase of the granite of Lankin Dome. This rock type is characterized by high potassium and anomalously high thorium concentrations, and is the most favorable granitic source for the uranium deposits in the surrounding area. Areal distribution patterns for radioelement concentrations show that the most favorable source regions are located closest to known uranium deposits. Most of the granitic rocks in the Granite Mountains region are characterized by high thorium-uranium ratios. These high ratios are interpreted to be the result of uranium loss. Non-gaussian distribution of radioelement contents and poor correlation between radioelement pairs are interpreted to be the result of some redistribution of radioelements during the last phase of granite crystallization and to recent uranium loss. A good correlation between thorium and iron is attributed to the mobilization of thorium into microcrystalline iron oxides during a late portion of the magmatic history. A comparison of sulfur data for surface and shallow drill-hole samples suggests that sulfur has been removed from the granite to at least a depth of 20 m. The loss of uranium and sulfur from these samples suggests that other trace elements found in association with uranium deposits might have been removed from the granite.

Wyoming↗