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A Conceptual Model of Groundwater Flow at the Midway, Utah Fish Hatchery as Constrained by Geochemical, Physical Hydrogeological, and Geophysical MethodsDurrant, Camille 11 March 2005 (has links) (PDF)
In addition to a loss of potential revenues from Utah's $393 million sport fishing industry, the state expends millions of dollars every year on costs associated with whirling disease mitigation and prevention. A state fish hatchery at Midway, Utah was closed when the shallow unconfined aquifer being used for fish culture by spring discharge was deemed to be contaminated by whirling disease. An alternative water source may exist in a confined aquifer below this contaminated unconfined aquifer. However, the complex hydrostratigraphy presents a challenge in determining if this source is a viable resource for fish culture. Geological, physical, chemical, geophysical, and isotopic data were combined to create a conceptual model of the groundwater flow at the site and to determine the interactions this confined aquifer may have with the contaminated aquifer. This model divides groundwater at the hatchery into a shallow unconfined system, an upper confined system, and a lower confined system. The shallow unconfined system is characterized by a water table ~1m below ground surface, several active springs, fast travel times, modern water mixed with ancient hydrothermal water, relatively high TDS, and relatively enriched isotopic values. The confined aquifers have a smaller hydrothermal component, relatively depleted isotopic values, lower TDS, and modern recharge components. Two orthogonal shallow high-resolution seismic reflection profiles indicate substantial heterogeneity in the subsurface at the level of the confined systems at the hatchery. Several north-south trending normal discontinuities were interpreted as possible faults from the seismic profile oriented as a dip line, whereas the strike profile shows discontinuous layering without noticeable faulting. A well log profile for the site shows discontinuous tufa layers amid heterogeneous alluvium material. These tufa layers separate upward leaking confined aquifers from the unconfined system. It is only through the integration of several methods that such mixed systems, can be understood. In this study, the lower confined aquifer was found to be a sufficient and safe resource through the integration of numerous methods.
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A System Approach to Fission-Fusion SymbiosisGordon, Charles William 04 1900 (has links)
<p> Three symbiotic systems are considered. These include the
possibility of coupling the tritium production in a fission reactor
with the fertile conversion in a fusion blanket. Equations for the
fuel dynamics, power output, efficiency and costs of a symbiotic, selfcontained power station are developed and evaluated for a specific,
1500 MWe fission reactor operating on a thorium cycle and some fusion
parameters. It is concluded that a system using the tritium produced
in a fission reactor has lower costs and increased power output when
compared to an alternate system. </p> / Thesis / Master of Engineering (MEngr)
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Émissions gazeuses issues de déchets radioactifs solidesLeduc, Sophie 11 April 2018 (has links)
Le compactage, l'emballage et l'entreposage des déchets faiblement radioactifs d'une centrale nucléaire sont des opérations susceptibles de produire des émissions de composés à risque radiologique ou chimique. L'objectif de ce projet de maîtrise était de caractériser les composés radioactifs que sont l'eau tritiée (HTO) et le dioxyde de carbone14 (14CO2), ainsi que les composés organiques volatils (COV), dans l'air autour de déchets soumis au compactage, fraîchement mis en ballot ou entreposés dans des fosses depuis quelques années. Le suivi des émissions d'un ballot de déchets a été réalisé grâce à un montage expérimental comprenant une enceinte, ainsi qu'un système d'échantillonnage et de séparation des composés. Une technique de concentration cryogénique a été utilisée pour échantillonner des traces de composés organiques volatils. Les résultats des analyses d'air, et ceux de modélisations de diffusion et de dispersion, indiquent que les émissions de composés à risque sont faibles durant les opérations de compactage et d'emballage, mais qu'elles se poursuivent durant plusieurs années, selon un taux de diminution prévisible.
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Application of biological sample oxidiser and low-level liquid scintillation counter for the determination of ¹⁴C and ³H content in water from the Hartbeespoort Dam in North-West ProvinceKhumalo, Lamlile Hlakaniphile Ntando 02 1900 (has links)
The aim of the research study was to evaluate the levels of 14C and 3H radionuclides in Hartbeespoort Dam water and to determine if these radionuclides are within regulatory concerns. Water samples from Hartbeespoort Dam were prepared using the Sample Oxidiser Method and measurements of selected radionuclides were done using Liquid Scintillation Counter Quantulus 1220. The results evaluated suggest that water from Hartbeespoort Dam contains levels of 14C and 3H radionuclides that are within regulatory limits. The highest average concentration for 14C measured was 3.77E+01 (+/-2.47E-01) Bq/L, whereas the highest average concentration measured for 3H was 2.74E+01 (+/- 2.30E-01) Bq/L. The observations made regarding the impacts of climate on the 14C radionuclide were that, the concentration levels were higher during winter season when there was a rain than during rainy seasons. Tritium results showed that the climate conditions did not have any significant impacts on the concentration levels. When the concentrations of these radionuclides are above regulatory levels (14C is 100 Bq/L and 3H is10000 Bq/L), their impacts may cause harm to public`s health and the environment. Therefore, Necsa as a nuclear facility owner and National Nuclear Regulator (NNR) as a regulator are responsible for ensuring the public protection from radioactive effluents that contain not just 3H and 14C, but any radionuclide which may cause harm to public`s health. / Environmental Sciences / M. Sc. (Environmental Science)
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FW-CADIS variance reduction in MAVRIC shielding analysis of the VHTRFlaspoehler, Timothy Michael 27 September 2012 (has links)
In the following work, the MAVRIC sequence of the Scale6.1 code package was tested for its efficacy in calculating a wide range of shielding parameters with respect to HTGRs. One of the NGNP designs that has gained large support internationally is the VHTR. The development of the Scale6.1 code package at ORNL has been primarily directed towards supporting the current United States' reactor fleet of LWR technology. Since plans have been made to build a prototype VHTR, it is important to verify that the MAVRIC sequence can adequately meet the simulation needs of a different reactor technology. This was accomplished by creating a detailed model of the VHTR power plant; identifying important, relevant radiation indicators; and implementing methods using MAVRIC to simulate those indicators in the VHTR model.
The graphite moderator used in the design shapes a different flux spectrum than water-moderated reactors. The different flux spectrum could lead to new considerations when quantifying shielding characteristics and possibly a different gamma-ray spectrum escaping the core and surrounding components. One key portion of this study was obtaining personnel dose rates in accessible areas within the power plant from both neutron and gamma sources. Additionally, building from professional and regulatory standards a surveillance capsule monitoring program was designed to mimic those used in the nuclear industry. The high temperatures were designed to supply heat for industrial purposes and not just for power production. Since tritium, a heavier radioactive isotope of hydrogen, is produced in the reactor it is important to know the distribution of tritium production and the subsequent diffusion from the core to secondary systems to prevent contamination outside of the nuclear island.
Accurately modeling indicators using MAVRIC is the main goal. However, it is almost equally as important for simulations to be carried out in a timely manner. MAVRIC uses the discrete ordinates method to solve the fixed-source transport equation for both neutron and gamma rays on a crude geometric representation of the detailed model. This deterministic forward solution is used to solve an adjoint equation with the adjoint source specified by the user. The adjoint solution is then used to create an importance map that can weight particles in a stochastic Monte Carlo simulation. The goal of using this hybrid methodology is to provide complete accuracy with high precision while decreasing overall simulation times by orders of magnitude. The MAVRIC sequence provides a platform to quickly alter inputs so that vastly different shielding studies can be simulated using one model with minimal effort by the user. Each separate shielding study required unique strategies while looking at different regions in the VHTR plant. MAVRIC proved to be effective for each case.
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Geovisualization of boreal peatland architecture in a three dimensional hydrogeological framework using ground penetrating radar and LiDAR at Mariana Lakes, Alberta, CanadaShulba, William Paul 07 June 2021 (has links)
Communicating science in three-dimensional (3D) multimedia is an immersive and interactive way to explore scientific processes (Signals and Communication Technology, 2019). Geovisualization is an emerging 3D multimedia method for visual analysis, synthesis, and presentation of geospatial, geologic, and geophysical data (MacEachren & Kraak, 2001). There is an identified need to develop scientific communication tools to further understand boreal peatland evolution, hydrogeology, ecology, and geochemistry (Bubier et al., 2003) since the International Union of Conservation of Nature asserts that peatlands are among the most valuable ecosystems on Earth, critical for preserving global biodiversity, providing drinking water, minimising flood risk, preventing wildfire, and mitigating climate change (Hama et al., 2000).
The intention of this thesis is to communicate a novel approach to geovisualize boreal peatland architecture using Light Detection and Ranging (LiDAR) and Ground Penetrating Radar (GPR). GPR and LiDAR have been used to create 3D subsurface geovisualizations for archaeology (Kenady et al., 2018; Schultz & Martin, 2011) and resource geology (Corradini et al., 2020; Koyan & Tronicke, 2020) although application to peatland hydrogeology is uncommon.
Point-source hydrogeological and geochemical data were integrated with 3D geological models to estimate carbon and nitrogen storage in an archetypal boreal peatland near Mariana Lakes, Alberta. Peatland geometry resembled a shallow lake basin with depths greatest in fens (>10 m) and thinnest in bogs (<2 m). Hydraulic conductivity was only a few meters per year and vertical groundwater movement was limited. Sequestered carbon and nutrients increased with depth. The average concentration of dissolved ammonium was 3 grams per cubic metre of peat (g/m3), 5g/m3of Total Kjeldahl Nitrogen, 60g/m3 of dissolved organic carbon and 200g/m3 of dissolved inorganic carbon. Tritium detection from atmospheric atomic weapons radionuclide fallout revealed that in deeper anaerobic peat (catotelm), tritium was absent, signifying groundwater was older than 50 years and not mixed with meteoric waters. Fen catotelm channels are likely acting as gravity-driven hydraulic traps (Tóth, 1999). / Graduate
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<b>FACTORS AFFECTING THE PRESERVATION OF THE ISOTOPIC FINGERPRINT OF GLACIAL MELTWATER IN MOUNTAIN GROUNDWATER SYSTEMS</b>Ayobami O Oladapo (19218853) 26 July 2024 (has links)
<p dir="ltr">Alpine glacier meltwater is an important source of recharge supporting groundwater flow processes in the high mountains. In the face of rapid ice loss, knowledge of response times of mountain aquifers to loss of glacial ice is critical in evaluating the sustainability of alpine water resources for human communities and alpine ecosystems. Glaciers are very sensitive to changes in climate, they advance during periods of global or regional cooling, and they retreat in response to global or regional warming conditions. When the glaciers grow, the equilibrium-line altitude separating the zone of accumulation and zone of ablation on the glacier moves downslope; it moves upslope when they retreat. The latter is not a sustainable condition for the glacier. Previous studies have shown that glacial meltwater is an important source of groundwater recharge. However, we lack fundamental information on the importance of glacial meltwater in mountain groundwater processes such as supporting baseflow generation to alpine streams, perennial flow to alpine springs, and the geochemical evolution of groundwater in mountain aquifers. Thus, continued glacial ice loss may have severe consequences for alpine hydrological and hydrogeological systems.</p><p dir="ltr">Glacier National Park (GNP) and Mount Hood National Forest (MH), both have alpine glaciers. These two study sites show different responses to climate change since their glaciers are in different states of retreat. GNP glaciers are in advanced stages of retreat compared to MH glaciers. Groundwater samples were collected from springs, seasonal snow, glacial ice, and glacial melt (subglacial flow) in GNP and MH. The samples were analyzed for a suite of environmental isotopes and geochemical tracers to address the following questions: 1) How are isotopic fingerprints of glacial meltwater preserved in mountain-block aquifers? What does the isotopic fingerprint of subglacial flow tell us about melting, meltwater processes, and mixing processes? 2) Is the preservation of the isotopic fingerprint of glacial meltwater affected by aspect controls on ice preservation? Aspect is defined as the compass direction of the slope where the glacier is found. 3) What controls groundwater flow and flowpath connectivity from high elevations (near glacier) to lower elevations? What geologic units support groundwater flow to local- and regional-scale springs and flowpath connectivity across spatial scales in each study site?</p><p dir="ltr">The flow of groundwater in mountainous terrain is heavily dependent on the hydraulic properties of the bedrock including presence/absence of dipping layers and structural features, primary and secondary porosity, and presence/absence of ongoing tectonic activity. Strontium isotopes (<sup>87</sup>Sr/<sup>86</sup>Sr) were used to identify the rock units that host groundwater flowpaths and to quantify flowpath connectivity across spatial scales in both study sites. The <sup>87</sup>Sr/<sup>86</sup>Sr data show that flowpaths in GNP are primarily hosted in the Helena Formation and permeable facies in the Snowslip Formation. Groundwater also flows through alluvium and younger bedrock units, and there is some flow along or through the volcanic sill in the Helena Formation. Hydrostratigraphy also affects groundwater flow and the spatial distribution of alpine springs in GNP. At MH, the rock units hosting flowpaths are young reworked volcanic rock units that are Quaternary in age. Flowpaths in MH appear to be connected across spatial scales since warm springs emerging along the lower southern slopes of Mount Hood preserve stable isotopic signatures of glacial meltwater. In comparison, nearly all the sampled springs in GNP emerge on south-facing slopes. This is not an indication of ice preservation, instead it’s controlled by hydrostratigraphy. In fact, it’s unlikely that high-elevation groundwater is strongly connected to low-elevation sites due to hydrostratigraphy. There are more springs on south-facing slopes at MH as well; however, they do not preserve an isotopic signature of recharge from glacial meltwater except for the warm springs. Springs on north-facing slopes in MH, however, do preserve the signature.</p><p dir="ltr">Tritium (<sup>3</sup>H) and chlorine-36 (<sup>36</sup>Cl/Cl) were measured to assess how the isotopic fingerprint of glacial meltwater is preserved in mountain aquifers. The <sup>3</sup>H activities in spring water are elevated in GNP and it’s difficult to differentiate between modern precipitation and glacial meltwater. Tritium activities are lower in MH, but it’s also difficult to differentiate between potential endmembers. This discrepancy could imply that glacial meltwater doesn’t contribute to groundwater recharge, but this doesn’t support the Bayesian stable isotope mixing model results of an earlier study. Instead, I infer that englacial mixing processes are affecting the isotopic fingerprint of subglacial melt. An englacial mixing model (EMM) was developed to explain how the isotopic fingerprint of subglacial flow (glacial meltwater) changes in relation to the stage of retreat. The stage of retreat is important because it controls the proportion of glacial meltwater to runoff from snowmelt and rain that enters the englacial network from the surface of the glacier. Mixing occurs in the englacial network, and the mixed water is transported to the base of the glacier. Englacial mixing in conduits, fractures, and moulins affects the <sup>3</sup>H and <sup>36</sup>Cl/Cl fingerprint of subglacial flow and will, in turn, affect the isotopic fingerprint of recharge from glacial meltwater. For this study, the <sup>3</sup>H is not robust by itself; however, <sup>36</sup>Cl/Cl shows some additional benefits over <sup>3</sup>H. The EMM suggests that the impact of englacial mixing and the influence of modern precipitation on the isotopic composition of subglacial flow increases as the glacier retreats in both GNP and MH. This model is novel to the best of our knowledge. Additional testing of the EMM should be prioritized in the near future.</p>
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The •OH scavenging effect of bromide ions on the yield of H[subscript 2]O[subscript 2] in the radiolysis of water by [superscript 60]Co γ-rays and tritium β-particles at room temperature : a Monte Carlo simulation study / Effet de capture des radicaux •OH par les ions bromure Br- sur le rendement de H[indice inférieur 2]O[indice inférieur 2] dans la radiolyse de l'eau par les rayons γ de [indice supérieur 60]Co et les électrons β du tritium à la température ambiante: une étude par simulation Monte CarloMustaree, Shayla January 2016 (has links)
Abstract: Monte Carlo simulations were used here to compare the radiation chemistry of pure water and aqueous bromide solutions after irradiation with two different types of radiation, namely, tritium β-electrons (~7.8 keV) and [superscript 60]Co γ-rays/fast electron (~1 MeV) or high energy protons. Bromide ions (Br-) are known to be selective scavengers of hydroxyl radicals •OH precursors of hydrogen peroxide H[subscript 2]O[subscript 2]. These simulations thus allowed us to determine the yields (or G-values) of H[subscript 2]O[subscript 2] in the radiolysis of dilute aqueous bromide solutions by the two types of radiations studied, the first with low linear energy transfer (LET) (~0.3 keV/μm) and the second with high LET (~6 keV/μm) at 25 °C. This study was carried out under a wide range of Br- concentrations both in the presence and the absence of oxygen. Simulations clearly showed that irradiation by tritium β-electrons favored a clear increase in G(H[subscript 2]O[subscript 2]) compared to [superscript 60]Co γ-rays. We found that these changes could be related to differences in the initial spatial distributions of radiolytic species (i.e., the structure of the electron tracks, the low-energy β-electrons of tritium depositing their energy as cylindrical “short tracks” and the energetic Compton electrons produced by γ-radiolysis forming mainly spherical “spurs”). Moreover, simulations also showed that the presence of oxygen, a very good scavenger of hydrated electrons (e-[subscript aq]) and H• atoms on the 10[superscript-7] s time scale (i.e., before the end of spur expansion), protected H[subscript 2]O[subscript 2] from further reactions with these species in the homogeneous stage of radiolysis. This protection against e-[subscript aq] and H• atoms therefore led to an increase in the H[subscript 2]O[subscript 2] yields at long times, as seen experimentally. Finally, for both deaerated and aerated solutions, the H[subscript 2]O[subscript 2] yield in tritium β-radiolysis was found to be more easily suppressed than in the case of cobalt-60 γ-radiolysis, and interpreted by the quantitatively different chemistry between short tracks and spurs. These differences in the scavengeability of H[subscript 2]O[subscript 2] precursors in passing from low-LET [superscript 60]Co γ-ray to high-LET tritium β-electron irradiation were in good agreement with experimental data, thereby lending strong support to the picture of tritium-β radiolysis in terms of short tracks of high local LET. / Résumé: Les simulations Monte Carlo constituent une approche théorique efficace pour étudier la chimie sous rayonnement de l'eau et des solutions aqueuses. Dans ce travail, nous avons utilisé ces simulations pour comparer l’action de deux types de rayonnement, à savoir, le rayonnement γ de [indice supérieur 60]Co (électrons de Compton ~1 Me V) et les électrons β du tritium (~ 7,8 keV), sur la radiolyse de l’eau et des solutions aqueuses diluées de bromure. Les ions Br- sont connus comme d’excellents capteurs des radicaux hydroxyles •OH, précurseurs du peroxyde d’hydrogène H[indice inférieur 2]O[indice inférieur 2]. Les simulations Monte Carlo nous ont donc permis de déterminer les rendements (ou valeurs G) de H[indice inférieur 2]O[indice inférieur 2] à 25 °C pour les deux types de rayonnements étudiés, le premier à faible transfert d'énergie linéaire (TEL) (~0,3 keV/μm) et le second à haut TEL (~6 keV/μm). L’étude a été menée pour différentes concentrations d’ions Br-, à la fois en présence et en absence d'oxygène. Les simulations ont montré que l’irradiation par les électrons β du tritium favorisait nettement la formation de H[indice inférieur 2]O[indice inférieur 2] comparativement aux rayons γ du cobalt. Ces changements ont pu être reliés aux différences qui existent dans les distributions spatiales initiales des espèces radiolytiques (i.e., la structure des trajectoires d'électrons, les électrons β du tritium déposant leur énergie sous forme de «trajectoires courtes» de nature cylindrique, et les électrons Compton produits par la radiolyse γ formant principalement des «grappes» de géométrie plus ou moins sphérique). Les simulations ont montré également que la présence d'oxygène, capteur d’électrons hydratés et d’atomes H• sur l'échelle de temps de ~10[indice supérieur -7] s (i.e., avant la fin des grappes), protégeait H[indice inférieur 2]O[indice inférieur 2] d’éventuelles réactions subséquentes avec ces espèces. Une telle «protection» conduit ainsi à une augmentation de G(H[indice inférieur 2]O[indice inférieur 2]) à temps longs. Enfin, en milieu tant désaéré qu’aéré, les rendements en H[indice inférieur 2]O[indice inférieur 2] obtenus lors de la radiolyse par les électrons β du tritium ont été trouvés plus facilement supprimés que lors de la radiolyse γ. Ces différences dans l’efficacité de capture des précurseurs de H[indice inférieur 2]O[indice inférieur 2] ont été interprétées par les différences quantitatives dans la chimie intervenant dans les trajectoires courtes et les grappes. Un excellent accord a été obtenu avec les données expérimentales existantes.
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Migration of Recharge Water Downgradient from the Santa Catalina Mountains into the Tucson Basin AquiferBarger, Erin E. January 1996 (has links)
Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams within the basins and by water entering along the margins of the basins from surrounding mountains (mountain -front recharge). The Tucson Basin of Southeastern Arizona is such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much precipitation (about 70 cm/yr) as the basin does (about 30 cm/yr). In this study environmental isotopes were employed to investigate the migration of precipitation basinward through joints and fractures. Water samples were obtained from springs in the Santa Catalina Mountains. Stable isotopes and thermonuclear bomb-produced tritium enabled qualitative characterizations of flow paths and flow velocities. Stable isotopic measurements fail to display a direct altitude effect. Tritium values indicate that although a few springs discharge pre-bomb water, most springs discharge waters from the 1960's or later.
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LIFE IN THE RAIN SHADOW: UNDERSTANDING SOURCES OF RECHARGE, GROUNDWATER FLOW, AND THEIR EFFECTS ON GROUNDWATER DEPENDENT ECOSYSTEMS IN THE PANAMINT RANGE, DEATH VALLEY, CALIFORNIA, USACarolyn L. Gleason (5930639) 16 January 2019 (has links)
<div>
<p>Despite
its location in the rain shadow of the southern Sierra Nevada, the Panamint
Range within Death Valley National Park, CA hosts a complex aquifer system that
supports numerous springs. These springs, in turn, support unique
groundwater-dependent ecological communities. Spring emergences range in
elevation from 2434 m above sea level (within the mountain block) to 77 m below
sea level (in the adjacent basins). Waters were collected from representative
Panamint Range springs and analyzed for environmental isotopes and geochemical
tracers to address the following questions: 1) What is the primary source of
recharge for the springs? How much
recharge occurs on the Panamint Range? 2) What groundwater flowpaths and
geologic units support springflow generation? and 3) What are the residence
times of the springs? The stable isotopic composition (δ<sup>18</sup>O and δ<sup>2</sup>H) of spring
water and precipitation indicate that localized high-elevation snowmelt is the
dominant source of recharge to these perennial springs, though recharge from
rainfall is not wholly insignificant. Geochemical evolution was evaluated using
principle component analysis to compare the concentrations of all major spring
cations and anions in a multidimensional space and group them according to
dominant geochemical signatures. These resulting geochemical groups are controlled
primarily by topography. The Noonday Dolomite and other carbonate units in the
range are identified as the water-bearing units in the mountain block based on
the <sup>87</sup>Sr/<sup>86</sup>Sr of spring
waters and rock samples. These units also offer higher hydraulic conductivities
than other formations and are chemically similar. Radiocarbon- and <sup>3</sup>H derived residence
times of these spring waters range from modern to approximately 1840 years,
with the shortest residence times at higher altitudes and Hanaupah Canyon and
increasing residence times with decreasing altitude. This residence time-altitude
relationship is likewise likely topography-driven though there are significant
disparities in mountain block storage between the various canyons of the range
resulting in variable residence times between drainages. Lower Warm Springs A
and B, however, are the exceptions to this trend as they emerge at lower
altitudes (750m above sea level) and are likely driven by the transport of
groundwater to the surface along faults which increases both the temperature
and groundwater residence times of waters from these springs. Benthic
macroinvertebrates and benthic and planktonic microbes were also sampled for
each spring studied. BMI and microbial community structure in the Panamint Range
is likewise topography-controlled with more tolerant communities at lower
elevations (within more chemically evolved waters) and less tolerant species in
the unevolved waters at higher elevations.</p></div>
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