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Noble gas isotope measurements for spent nuclear fuel reprocessing. IAEA Task 90/0A211 interim report

Description: The nuclear fission of actinides in reactor fuel produces large quantities of Kr and Xe as fission products. Because of the high levels of fission Kr and Xe, sample collection and analysis of noble gases for spent fuel diagnostic measurements is a simple, straight-forward technique. In modern reprocessing plants with continuous dissolvers, it will not be possible to use traditional methods for isolating input batches of fuel. This study investigates the feasibility of using noble gas isotope abundance measurements (isotope correlation techniques - ICT) to solve safeguards requirements. Noble gas measurements might be able to provide an independent analysis of Pu contained within dissolves fuel, on an individual fuel assembly basis. The isotopic composition of Kr and Xe in spent fuel reflects both the composition (isotope abundance ratios) of the fission products and the effects of neutron capture on those fission products. We have reviewed the available literature for noble gas analyses of spent reactor fuel. While references are made to noble gas isotope correlations over the last 20 years, we have found little if any detailed analysis of large data sets. The literature search did find several useful reports. Of these papers, one is particularly useful for evaluating noble gas isotopic compositions. The ``Benchmark-paper`` (1) contains 54 Kr and 56 Xe isotopic composition analyses for 4 different reactors with a variety of fuel enrichment factors. Burnup ranges from 8000 to 37000 MWd/tU. Besides the noble gas measurements, a variety of other measurements are reported (actinides and fission products).
Date: February 17, 1993
Creator: Hudson, G. B.
Partner: UNT Libraries Government Documents Department

Excess /sup 129/Xe in terrestrial samples: A non-primordial hypothesis

Description: Excesses of /sup 129/Xe relative to the isotopic composition in air are observed in some terrestrial samples. Traditionally these /sup 129/Xe excesses have been thought to be related to /sup 129/I that was present in abundance in the early solar system. We propose an alternative hypothesis to explain terrestrial /sup 129/Xe excesses based on the production of /sup 129/I from the spontaneous fission of /sup 238/U.
Date: March 1, 1987
Creator: Caffee, M.W. & Hudson, G.B.
Partner: UNT Libraries Government Documents Department

Using Groundwater Age and Other Isotopic Signatures to Delineate Groundwater Flow and Stratification

Description: Isotopic tracers, such as stable isotopes of the water molecule and tritium, have been used in investigations of groundwater flow and transport and recharge water source for several decades. While these data can place hard constraints on groundwater flow rates, the degree of vertical flow between aquifers and across aquitards, and recharge source area(s), they are rarely used, even for validation, in conceptual or numerical models of groundwater flow. The Groundwater Ambient Monitoring and Assessment Program, sponsored by the California State Water Resources Control Board, and carried out in collaboration with the U.S. Geological Survey, has provided the means to gather an unprecedented number of tritium-helium groundwater ages in the basins of California. As the examples below illustrate, a collection of groundwater ages in a basin allows delineation of recharge areas (youngest ages), bulk flow rates and flowpaths, as well as a means of assessing susceptibility to anthropogenic contaminants.
Date: August 31, 2005
Creator: Moran, J E & Hudson, G B
Partner: UNT Libraries Government Documents Department

Surface studies and implanted helium measurements following NOVA high-yield DT experiments

Description: This paper presents the results of three March 6, 1996 direct-drive high-yield DT NOVA experiments and provides `proof-of-principal` results for the quantitative measurement of energetic He ions. Semiconductor quality Si wafers and an amorphous carbon wafer were exposed to NOVA high-yield implosions. Surface damage was sub-micron in general, although the surface ablation was slightly greater for the carbon wafer than for the Si wafers. Melting of a thin ({approx} 0.1{mu}) layer of Si was evident from microscopic investigation. Electron microscopy indicated melted blobs of many different metals (e.g. Al, Au, Ta, Fe alloys, Cu and even Cd) on the surfaces. The yield measured by determining the numbers of atoms of implanted {sup 4}He and {sup 3}He indicate the number of DT fusions to be 9.1({plus_minus}2.3) X 10{sup 12} and DD fusions to be 4.8({plus_minus}1.0) x 10{sup 10}, respectively. The helium DT fusion yield is slightly lower than that of the Cu activation measurement, which was 1.3({plus_minus}0.l) x 10{sup 13} DT fusions.
Date: February 18, 1997
Creator: Stoyer, M.A. & Hudson, G.B.
Partner: UNT Libraries Government Documents Department

Analysis of Radionuclide Migration through a 200-m Vadose Zone Following a 16-year Infiltration Event

Description: The CAMBRIC nuclear test was conducted beneath Frenchman Flat at the Nevada Test Site on May 14, 1965. The nuclear device was emplaced in heterogeneous alluvium, approximately 70 m beneath the ambient water table, which is itself 220 m beneath the ground surface. Approximately 10 years later, groundwater adjacent to the test was pumped steadily for 16 years to elicit information on the migration of residual radionuclide migration through the saturated zone. The pumping well effluent--containing mostly soluble radionuclides such as tritium, {sup 14}C, {sup 36}Cl, {sup 85}Kr, {sup 129}I, and {sup 106}Ru--was monitored, discharged to an unlined ditch, and allowed to flow towards Frenchman Lake over one kilometer away. Discharged water and radionuclides infiltrated into the ground and created an unexpected second experiment in which the migration of the effluent through the unsaturated zone back to the water table could be studied. In this paper, the pumping and effluent data are being utilized in conjunction with a series of geologic data, new radionuclide measurements, isotopic age-dating estimates, and vadose zone flow and transport models to better understand the movement of radionuclides between the ditch and the water table. Measurements of radionuclide concentrations in water samples produced from a water table monitoring well 100 m away from the ditch indicate rising levels of tritium since 1993. The detection of tritium in the monitoring well occurs approximately 16 years after its initial discharge into the ditch. Modeling and tritium age dating have suggested 3 to 5 years of this 16-year transit time occurred solely in the vadose zone. They also suggest considerable recirculation of the pumping well discharge back into the original pumping well. Notably, there have been no observations of {sup 14}C or {sup 85}Kr at the water table, suggesting their preferential retention or volatilization during transit to the water ...
Date: September 21, 2004
Creator: Tompson, A B; Hudson, G B; Smith, D K & Hunt, J R
Partner: UNT Libraries Government Documents Department

Measurement of 3H in soil cores from the Hyrax Event (U3bh) subsidence crater

Description: Core samples were collected from two boreholes drilled in the subsidence crater of the Hyrax event (U3bh). The moisture in the core samples was extracted via freeze drying and tritiw-n was measured in the extracted moisture via `He accumulation mass spectrometry or liquid scintillation counting. Elevated tritium concentrations (IE4 - IE6 pCi/L extracted moisture as of the time of measurement) were observed in the extracted moisture from virtually all of the core samples with significant increases beginning at about 30 ft depth. No longer-lived fission products (144 Ce) or activation products (`OCo, `Eu, 114 En) were observed by gamma-ray spectroscopy in a subset of the core samples. This likely indicates that a catastrophic failure of containment (if it occurred) did not release significant radioactivities to this shallow depth (30 ft). The presence of `Cs at much greater depths (@210 ft, 64 m) may indicate that gaseous and/or vapor products were released shortly after the Hyrax event to a depth of about 210 ft. The relatively shallow depth where the elevated tritium is observed makes highly improbable any significant linkage between the elevated tritium concentrations and a Hyrax event containment failure. This may indicate that an additional source of enriched `H was introduced at this site.
Date: July 1, 1996
Creator: Kreek, S.; Hudson, G.B. & Ruth, M.
Partner: UNT Libraries Government Documents Department

Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada

Description: The hydrology of Honey Lake Basin was studied using environmental isotope measurements of approximately 130 water samples collected during 1995 and 1996. The principal analytical methods included hydrogen, oxygen and carbon stable isotope ratio measurements, radiocarbon and tritium dating, and measurements of dissolved noble gas abundances.
Date: July 1, 1997
Creator: Rose, T.P.; Davisson, M.L.; Hudson, G.B. & Varian, A.R.
Partner: UNT Libraries Government Documents Department

Report on the feasibility of using isotopes to source and age-date groundwater in Orange County water district`s Forebay region

Description: From March to September 1995, the Isotope Sciences Division of Lawrence Livermore National Laboratory performed isotopic measurements on water in the Orange County Forebay region. The goal was to test the applicability of isotope techniques for determining the current groundwater flow paths and flow rates in the OCWD spreading facilities. Successful results could then be used to predict the fate of proposed reclaimed waste water recharge. Stable isotope measurements in surface waters and groundwaters in the Forebay region of the Orange County groundwater basin provided a general source indicator. The data defined three general groups: (1) groundwater derived from recharged Santa Ana River water (SAR),(2) groundwater resulting from a mixture of recharged Colorado River water and the SAR, and (3) groundwater recharged from the Santiago basin area. In the first group of data, recharge directly from the SAR flow was not readily distinguishable from groundwater recharged via the spreading ponds. Some groundwater samples from Forebay wells showed significant temporal variability in stable isotope values, while others remained constant throughout the study period. The temporal changes in the groundwater stable isotope signatures are believed to be controlled by similar variations in the stable isotope signatures of the surface water recharge. With further sampling, these seasonal isotopic variations may provide a viable tracer for young (<2 years) groundwater.
Date: May 1, 1996
Creator: Davisson, M.L.; Hudson, G.B.; Niemeyer, S.; Beiriger, J. & Herndon, R.
Partner: UNT Libraries Government Documents Department

Characterization of contaminant transport by gravity, capillarity and barometric pumping in heterogeneous. 1998 annual progress report

Description: 'The intent of this research program is to obtain an improved understanding of vadose zone transport processes and to develop field and modeling techniques required to characterize contaminant transport in the unsaturated zone at DOE sites. For surface spills and near-surface leaks of chemicals, the vadose zone may well become a long-term source of contamination for the underlying water table. Transport of contaminants can occur in both the liquid and gas phases of the unsaturated zone. This transport occurs naturally as a result of diffusion, buoyancy forces (gravity), capillarity and barometric pressure variations. In some cases transport can be enhanced by anisotropies present in hydrologic regimes. This is particularly true for gas-phase transport which may be subject to vertical pumping resulting from atmospheric pressure changes. For liquid-phase flows, heterogeneity may enhance the downward transport of contaminants to the water table depending on soil properties and the scale of the surface spill or near-surface leak. Characterization techniques based upon the dynamics of transport processes are likely to yield a better understanding of the potential for contaminant transport at a specific site than methods depending solely on hydrologic properties derived from a borehole. Such dynamic-characterization techniques can be useful for evaluating sites where contamination presently exists as well as for providing an objective basis to evaluate the efficacy of proposed as well as implemented clean-up technologies. The real-time monitoring of processes that may occur during clean-up of tank waste and the mobility of contaminants beneath the Hanford storage tanks during sluicing operations is one example of how techniques developed in this effort can be applied to current remediation problems. In the future, such dynamic-characterization methods might also be used as part of the site-characterization process for determining suitable locations of new DOE facilities that have the potential of introducing contamination into the ...
Date: June 1, 1998
Creator: Carrigan, C.R. & Hudson, G.B.
Partner: UNT Libraries Government Documents Department

Reduction of multielement mass spectra

Description: Even though the spectra obtained by inductively coupled plasma source spectrometry (ICP-MS) are relatively simple, their interpretation can be complicated by the presence of molecular and isobaric interferants. To the extent that isotopic abundances are known and constant, one can treat observed spectra as sums of known components. A linear decomposition approach for determining the concentrations of the components in a spectrum and correctly propagating uncertainties is presented. This technique differs from linear regression in that an exact fit is made to a subset of isotopes and goodness-of-fit is evaluated from the deviations between the predicted and measured intensities of the other, unfit isotopes. This technique can be applied to a wide range of spectral fitting problems. In this paper, its applicability to ICP-MS spectra is used to demonstrate the use and utility of the technique. 2 refs., 9 figs.
Date: June 29, 1990
Creator: Russ, G.P. III; Caffee, M.W.; Hudson, G.B. & Storch, N.A.
Partner: UNT Libraries Government Documents Department

The early solar system abundance of /sup 244/Pu as inferred from the St. Severin chondrite

Description: We describe the analysis of Xe released in stepwise heating of neutron-irradiated samples of the St. Severin chondrite. This analysis indicates that at the time of formation of most chondritic meteorites, approximately 4.56 x 10/sup 9/ years ago, the atomic ratio of /sup 244/Pu//sup 238/U was 0.0068 +- 0.0010 in chondritic meteorites. We believe that this value is more reliable than that inferred from earlier analyses of St. Severin. We feel that this value is currently the best available estimate for the early solar system abundance of /sup 244/Pu. 42 refs., 2 tabs.
Date: March 1, 1987
Creator: Hudson, G.B.; Kennedy, B.M.; Podosek, F.A. & Hohenberg, C.M.
Partner: UNT Libraries Government Documents Department

Sources of groundwater nitrate revealed using residence time and isotope methods

Description: Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources. Nitrate isotope data are effective in determining contaminant sources, especially when combined with other isotopic tracers such as stable isotopes of water and tritium-helium ages to give insight into the routes and timing of nitrate inputs to the flow system. This combination of techniques is demonstrated in Livermore, CA, where it is determined that low nitrate reclaimed wastewater predominates in the northwest, while two flowpaths with distinct nitrate sources originate in the southeast. Along the eastern flowpath, {delta}{sup 15}N values greater than 10{per_thousand} indicate that animal waste is the primary source. Diminishing concentrations over time suggest that contamination results from historical land use practices. The other flowpath begins in an area where rapid recharge, primarily of low-nitrate imported water (identified by stable isotopes of water and a tritium-helium residence time of less than 1 year), mobilizes a significant local nitrate source, bringing groundwater concentrations up to 53 mg NO{sub 3} L{sup -1}. In this area, artificial recharge of imported water via local arroyos increases the flux of nitrate to the regional aquifer. The low {delta}{sup 15}N value (3.1{per_thousand}) in this location implicates synthetic fertilizer. In addition to these anthropogenic sources, natural nitrate background levels between 15 and 20 mg NO{sub 3} L{sup -1} are found in deep wells with residence times greater than 50 years.
Date: October 7, 2004
Creator: Moore, K B; Ekwurzel, B; Esser, B K; Hudson, G B & Moran, J E
Partner: UNT Libraries Government Documents Department

Barometric gas transport along faults and its application to nuclear test-ban monitoring

Description: Underground nuclear explosions produce a unique but evanescent set of radionuclide gases that potentially can be used in the context of an on-site, test-ban monitoring program to differentiate them from other detected events such as earthquakes or mining activity. In Part I of this report we describe an experiment to evaluate the upward transport of gases from an underground explosion using two gas tracers with very different diffusivities that were released in a 400- m-deep, chemical explosive detonation. The less diffusive (more massive) tracer was detected on a nearby geologic fault 50 days following the detonation while the more diffusive tracer was-- detected 375 days after release. Computer simulations indicate that the arrival time and the chromatographic behavior of transport are characteristic of barometrically induced flow in a fractured, porous matrix regime. For a hypothetical 1-kiloton fission explosion subject to the same weather and gas transport conditions of the chemical explosion, simulations predict the delectability of argon-37 after 80 days in spite of depletion by radioactive decay. Largely because of the earlier arrival of xenon-133, owing to its lower binary gas diffusivity, the exceedingly short lived isotope should also be detectable-arriving about 30 days earlier than argon. in Part II we consider that our prediction of the delectability of argon and xenon is based upon the small volume (0.00001 M3) sampling technique of the NPE tracer-gas sampling study while actual sampling for radionuclides would involve drawing much larger volume (possibly 0.1- 1 M3) gas samples from the near-surface.
Date: June 1, 1997
Creator: Carrigan, C. R.; Heinle, R. A.; Hudson, G. B.; Nitao, J. J. & Zucca, J. J.
Partner: UNT Libraries Government Documents Department

Preliminary report on isotope abundance measurements in groundwater samples from the Talbert Injection Barrier Area, Orange County Water District

Description: This report discusses isotope abundance measurements made on a collection of groundwater samples from the Orange County Water District. The water samples were collected in May, 1994 as part of a preliminary study conducted by LLNL to assess the feasibility of tracing and dating reclaimed water used in the Talbert Injection Barrier. A set of samples were collected both near to and far from the barrier and also at different depths in available monitoring wells. A variety of elements were selected for isotopic analysis; hydrogen (tritium), helium, neon, carbon, chlorine and strontium. The tritium abundance combined with the {sup 3}He and {sup 20}Ne abundance provides a method for age dating young (< 40 yr.) groundwater. The abundance of {sup 14}C provides an age dating technique for older (1,000--50,000 yr.) groundwater. The concentrations of {sup 36}Cl and {sup 87}Sr/{sup 86}Sr give information on sea water mixing and water-rock chemical interactions.
Date: February 1, 1995
Creator: Hudson, G.B.; Davisson, M.L.; Velsko, C.; Niemeyer, S.; Esser, B. & Beiriger, J.
Partner: UNT Libraries Government Documents Department

Isotope tracer approaches for characterizing artificial recharge and demonstrating regulatory compliance

Description: Potable reuse of groundwater from wastewater origins requires new methods to quantify proposed regulatory criteria such as subsurface residence times, dilution, and water quality transitions. Isotope tracers oxygen-18 ({sup 18}O), tritium ({sup 3}H), dissolved noble gases, and radiocarbon ({sup 14}C) have been used together in Orange County to age-date groundwater, quantify mixing, and characterize changes in total organic carbon (TOC). Simultaneous measurements of {sup 3}H and helium-3 ({sup 3}He) are used to determine groundwater ages between 1 and 40 years with uncertainties of plus/minus one year. These ages map preferred groundwater flowpaths and identify groundwater ages of less than or equal to 1 year. Wells recharged from the Anaheim Lake spreading basin were used to monitor arrival times and dilution of 6000 acre-ft of {sup 18}O-distinct Colorado River (COR) water introduced during a controlled recharge experiment. In addition, isotopically enriched Xe was introduced into the basin to quantify COR dilution of greater than 90%. The COR arrived at 7 wells between 30 and 200 days after recharge commenced. The COR was diluted up to 90% at distances and depths less than 1000 feet from the lake. Results suggest that dilution of 50% is obtained within 6 months from time or recharge. {sup 14}C measured in TOC of Anaheim Lake bottom water was 3 pmc higher than the DOC. The same water collected one month later in a nearby monitoring well, as confirmed by {sup 18}O, showed a 50% reduction in TOC concentration, and a 7 pmc decrease in {sup 14}C relative to the surface water. This result suggests that older carbon components increase in TOC after recharge.
Date: May 1, 1998
Creator: Davisson, M.L.; Hudson, G.B.; Moran, J.E.; Neimeyer, S. & Herndon, R., LLNL
Partner: UNT Libraries Government Documents Department

Tracing and age-dating injected groundwater of the west basin barrier project, Los Angeles, CA

Description: This preliminary report summarizes results from isotopic data recently generated on water collected for the West Basin Municipal Water District (WBMWD). Samples comprised monitoring and production wells up to 3.5 miles form the injection barrier, in addition to barrier product and blend water.
Date: March 26, 1999
Creator: Davisson, M L; Eaton, Gp; Hudson, G B & Koester, C
Partner: UNT Libraries Government Documents Department

Compilation of the Dakota Aquifer Project isotope data and publications: The Isotope Hydrology Program of the Isotope Sciences Division

Description: In FY92 the then Nuclear Chemistry Division embarked on a scientific collaboration with the Kansas Geological Survey (KGS) to characterize with isotope techniques groundwater of the Dakota Formation of Kansas. The Dakota Formation is a Cretaceous-aged marine sandstone hosting potable groundwater in most regions of Kansas whose use will serve to partially offset the severe overdraft problems in the overlying Ogallala Formation. The isotope characterization of the Dakota groundwater has generated data that delineates sources, ages, and subsurface controls on the water quality. Initial interpretations of the data have been published in abstract volumes of (1) the 1993 Geological Society of America National Meeting, (2) the 8th International Conference on Geochronology, Cosmochronology and Isotope Geology, and (3) the 1994 Dakota Aquifer Workshop and Clinic. Copies of all abstracts are included in this brief review. One report will focus on the sources and ages of the groundwater, and the other will focus on the subsurface controls on the natural water quality.
Date: January 1, 1995
Creator: Davisson, M.L.; Smith, D.K.; Hudson, G.B.; Niemeyer, S.; Macfarlane, P.A. & Whittemore, D.O.
Partner: UNT Libraries Government Documents Department

An integrated approach to monitoring a field test of in situ contaminant destruction

Description: The development of in situ thermal remediation techniques requires parallel development of techniques capable of monitoring the physical and chemical changes for purposes of process control. Recent research indicates that many common contaminants can be destroyed in situ by hydrous pyrolysis/oxidation (HPO), eliminating the need for costly surface treatment and disposal. Steam injection, combined with supplemental air, can create the conditions in which HP0 occurs. Field testing of this process, conducted in the summer of 1997, indicates rapid destruction of polycyclic aromatic hydrocarbons (PAHs). Previous work established a suite of underground geophysical imaging techniques capable of providing sufficient knowledge of the physical changes in the subsurface during thermal treatment at sufficient frequencies to be used to monitor and guide the heating and extraction processes. In this field test, electrical resistance tomography (ERT) and temperature measurements provided the primary information regarding the temporal and spatial distribution of the heated zones. Verifying the in situ chemical destruction posed new challenges. We developed field methods for sampling and analyzing hot water for contaminants, oxygen, intermediates and products of reaction. Since the addition of air or oxygen to the contaminated region is a critical aspect of HPO, noble gas tracers were used to identify fluids from different sources. The combination of physical monitoring with noble gas identification of the native and injected fluids and accurate fluid sampling resulted in an excellent temporal and spatial evaluation of the subsurface processes, from which the amount of in situ destruction occurring in the treated region could be quantified. The experimental field results constrain the destruction rates throughout the site, and enable site management to make accurate estimates of total in situ destruction based on the recovered carbon. As of October, 1998, over 400,000 kg (900,000 lb) of contaminant have been removed from the site; about 18% of ...
Date: December 1, 1998
Creator: Aines, R D; Carrigan, C; Chiarappa, M; Eaker, C; Elsholtz, A; Hudson, G B et al.
Partner: UNT Libraries Government Documents Department

Preliminary on the isotope hydrology investigations at the Nevada test site: Hydrologic resources management program; FY 1992--1993

Description: A comprehensive isotope data base of the NTS groundwaters collected during FY 92-93 is presented with preliminary interpretations. Multiple samples were collected from over 30 sites on pumped wells and open-holes by wireline bailing. Field water level measurements indicate essentially a bimodal distribution separated by water levels at higher elevations (e.g. Pahute Mesa) from water levels of lower elevations (e.g. Yucca and Frenchman Flats). Down hole temperature measurements have confirmed anomalous temperature gradients in the eastern Yucca Flat area and on Pahute Mesa, where horizontal temperature gradients up to 0.33{degrees}F/100ft are found. Consistent with previous reports by others, the major ion geochemistry of the NTS groundwater are dominated by Na-K-HCO{sub 3} and Ca-Mg-HCO{sub 3} water types, where the Na-rich water appears to be related to dissolution in the volcanic tuffs and the Ca-rich water to the Paleozoic carbonates. Increases in dissolved Si also seems to be indicative of groundwater that resides in the volcanic tuffs. Processes controlling the Na/Ca ratios are complex and may include ion exchange reactions with clays, evaporative concentration in the vadose zone, and lithological heterogeneities in addition to simple differential dissolution between the volcanic tuffs and the Paleozoic carbonates. Apparent {sup 14}C ages range between 4000 and 38,000 years for groundwaters at the NTS. The uncertainty is large for exact age determinations at this time. The {sup 14}C abundance decreases with increased dissolved HCO{sub 3}, and {sup 13}C suggests dissolution of the ``dead`` Paleozoic carbonates significantly influence the ages, but more work is needed to investigate the influence of vadose zone carbonate.
Date: January 1994
Creator: Davisson, M. L.; Kenneally, J. M.; Smith, D. K.; Hudson, G. B.; Nimz, G. J. & Rego, J. H.
Partner: UNT Libraries Government Documents Department

FY-92 report on the isotope hydrology characterization of the Faultless test site, Nye County, Nevada

Description: In January of 1968 the Faultless test shot at 975m below the surface had an estimated magnitude range between 200kt to 1Mt. The detonation resulted in a surface crater estimated at 1km in diameter accompanied by a > 3m collapse escarpment at the surface. Careful monitoring of outlying observation wells before, during and after the shot has provided valuable data on the hydrodynamic response of the groundwater. This report of FY92 investigations at Faultless by the Nuclear Chemistry Division at LLNL serves to outline new and previous isotopic data of natural and shot-related nuclides measured in the drillback hole and the two closest satellite wells. The goals of this study are: (1) to investigate and characterize the geochemical and isotopic variabilities of groundwater, as a function of groundwater source and age, (2) to determine concentrations of event-related nuclide activity and investigate any possible migration of the hydrologic source term. A more comprehensive source and age characterization from isotopic and geochemical variations of natural groundwater in the Hot Creek Valley would require a regional scale investigation.
Date: February 1, 1994
Creator: Davisson, M. L.; Nimz, G. J.; Hudson, G. B.; Smith, D. K.; Rego, J. H. & Kenneally, J. M.
Partner: UNT Libraries Government Documents Department

Hydrologic Resources Management Program and Underground Test Area Project FY2005 Progress Report

Description: This report describes FY 2005 technical studies conducted by the Chemical Biology and Nuclear Science Division (CBND) at Lawrence Livermore National Laboratory (LLNL) in support of the Hydrologic Resources Management Program (HRMP) and the Underground Test Area Project (UGTA). These programs are administered by the U.S. Department of Energy, National Nuclear Security Administration, Nevada Site Office (NNSA/NSO) through the Defense Programs and Environmental Restoration Divisions, respectively. HRMP-sponsored work is directed toward the responsible management of the natural resources at the Nevada Test Site (NTS), enabling its continued use as a staging area for strategic operations in support of national security. UGTA-funded work emphasizes the development of an integrated set of groundwater flow and contaminant transport models to predict the extent of radionuclide migration from underground nuclear testing areas at the NTS. The report is organized on a topical basis and contains five chapters that highlight technical work products produced by CBND. However, it is important to recognize that most of this work involves collaborative partnerships with the other HRMP and UGTA contract organizations. These groups include the Energy and Environment Directorate at LLNL (LLNL-E&amp;E), Los Alamos National Laboratory (LANL), the Desert Research Institute (DRI), the U.S. Geological Survey (USGS), Stoller-Navarro Joint Venture (SNJV), and Bechtel Nevada (BN).
Date: March 23, 2007
Creator: Eaton, G F; Genetti, V; Hu, Q; Hudson, G B; Kersting, A B; Lindvall, R E et al.
Partner: UNT Libraries Government Documents Department

California GAMA Program: Sources and Transport of Nitrate in Groundwater in the Livermore Valley Basin, California

Description: A critical component of the State Water Resource Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program is to assess the major threats to groundwater resources that supply drinking water to Californians (Belitz et al., 2004). Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources Source attribution and nitrate fate and transport are therefore the focus of special studies under the GAMA program. This report presents results of a study of nitrate contamination in the aquifer beneath the City of Livermore, where high nitrate levels affect both public supply and private domestic wells. Nitrate isotope data are effective in determining contaminant sources, especially when combined with other isotopic tracers such as stable isotopes of water and tritium-helium ages to give insight into the routes and timing of nitrate inputs to the flow system. This combination of techniques is demonstrated in Livermore, where it is determined that low nitrate reclaimed wastewater predominates in the northwest, while two flowpaths with distinct nitrate sources originate in the southeast. Along the eastern flowpath, {delta}{sup 15}N values greater than 10{per_thousand} indicate that animal waste is the primary source. Diminishing concentrations over time suggest that contamination results from historical land use practices. The other flowpath begins in an area where rapid recharge, primarily of low nitrate imported water (identified by stable isotopes of water and a tritium-helium residence time of less than 1 year), mobilizes a significant local nitrate source, bringing groundwater concentrations above the MCL of 45 mg NO{sub 3} L{sup -1}. In this area, artificial recharge of imported water via local arroyos induces flux of the contaminant to the regional aquifer. The low {delta}{sup 15}N value (3.1{per_thousand}) in this location implicates synthetic fertilizer. Geochemical modeling supports the hypothesis of separate ...
Date: November 18, 2005
Creator: Beller, H; Eaton, G F; Ekwurzel, B E; Esser, B K; Hu, Q; Hudson, G B et al.
Partner: UNT Libraries Government Documents Department

Nitrate Biogeochemistry and Reactive Transport in California Groundwater: LDRD Final Report

Description: Nitrate is the number one drinking water contaminant in the United States. It is pervasive in surface and groundwater systems,and its principal anthropogenic sources have increased dramatically in the last 50 years. In California alone, one third of the public drinking-water wells has been lost since 1988 and nitrate contamination is the most common reason for abandonment. Effective nitrate management in groundwater is complicated by uncertainties related to multiple point and non-point sources, hydrogeologic complexity, geochemical reactivity, and quantification of denitrification processes. In this paper, we review an integrated experimental and simulation-based framework being developed to study the fate of nitrate in a 25 km-long groundwater subbasin south of San Jose, California, a historically agricultural area now undergoing rapid urbanization with increasing demands for groundwater. The modeling approach is driven by a need to integrate new and archival data that support the hypothesis that nitrate fate and transport at the basin scale is intricately related to hydrostratigraphic complexity, variability of flow paths and groundwater residence times, microbial activity, and multiple geochemical reaction mechanisms. This study synthesizes these disparate and multi-scale data into a three-dimensional and highly resolved reactive transport modeling framework.
Date: February 24, 2006
Creator: Esser, B K; Beller, H; Carle, S; Cey, B; Hudson, G B; Leif, R et al.
Partner: UNT Libraries Government Documents Department