Summary of Hanford Site Groundwater Monitoring for Fiscal Year 2003

Hartman, Mary J.; Morasch, Launa F.; Webber, William D.

doi:10.2172/15007190

Cited by 7 publications

(14 citation statements)

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“…Spectral gamma logging of uranium in boreholes at Hanford is performed on an ongoing basis (Hartman et al 2007). Gamma emissions from the decay of uranium isotopes are generally of too-low energy and activity to detect in borehole geophysical logging, so logging of uranium is based on gamma emissions from daughter isotopes.…”

Section: Methodsmentioning

confidence: 99%

“…At sufficiently high levels, U-235 can also be detected with the high-resolution logging system directly through one of its gamma emissions. Therefore, U-235/U-238 activity ratios can be estimated (Hartman et al 2007;McCain et al 2006). …”

Section: Methodsmentioning

confidence: 99%

“…This correlation is not expected to be exact because the waste sites exhibit markedly different hydrologic (e.g., process-water disposal and natural or enhanced recharge) and waste-chemical histories, and the underlying vadose zones display great differences in lithologic, geochemical, and hydrophysical properties, influencing both physical and chemical retardation and migration vectors. The principal U plumes reside in three areas: 1) the north-northwest of the 200 East Area in WMA B-BX-BY, with a localized hot spot near 241-BX-102, 2) the south portion of the 200 West Area (200-UP-1 Operable Unit) near the 216-U1,2 Crib, and 3) along the Columbia River shoreline in the 300 Area, beneath and surrounding 316-1 and 316-2 (Hartman et al 2007). …”

Section: 674mentioning

confidence: 99%

“…The large inventory of U released to the vadose zone, combined with its sometimes significant mobility under the oxidizing, circumneutral-to-mildly-basic geochemical conditions found at Hanford has led to the creation of three identified groundwater plumes (Hartman et al 2007). These plumes have a combined area of 1.6 square kilometers with dissolved U concentrations that are above the U.S. Environmental Protection Agency's established maximum-contaminant level (MCL) of 30 ppb (1.2 x10 -7 mol/L).…”

Section: Introductionmentioning

confidence: 99%

“…The migration of U to groundwater was facilitated by large volumetric releases of process waters, and by magnified natural infiltration, as a result of ponding and the use of gravel covers that enhanced transport through the vadose zone. The groundwater-U plume near Waste Management Area (WMA) B-BX-BY continues to grow in size (Hartman et al 2007), indicating sustained flux from the vadose zone. A significantly larger number of vadose-zone plumes of U exist beneath cribs, trenches, and retention basins that have not yet migrated to groundwater.…”

Section: Introductionmentioning

confidence: 99%

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A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Zachara¹,

Brown²,

Christensen³

et al. 2007

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Executive SummaryUranium (U) is an important risk-driving contaminant at the Hanford Site. Over 200,000 kg have been released to the vadose zone over the course of site operations, and a number of vadose zone and groundwater plumes containing the uranyl cation [UO 2 2+ , U(VI)] have been identified. U is recognized to be of moderate-to-high mobility, conditions dependent. The site is currently making decisions on several of these plumes with long-lasting implications, and others are soon to come.Uranium is one of nature's most intriguing and chemically complex elements. The fate and transport of U(VI) has been studied over the long lifetime of the Hanford Site by various contractors, along with the Pacific Northwest National Laboratory (PNNL) and its collaborators. Significant research has more recently been contributed by the national scientific community with support from the U.S. Department of Energy's (DOE) Office of Science through its Environmental Remediation Sciences Division (ERSD). This report represents a first attempt to integrate these findings into a cohesive view of the subsurface geochemistry of U at the Hanford Site. The objective is to inform all interested Hanford parties about the in-ground inventory of U and its geochemical behavior. This report also comments on the prospects for the development of a robust generic model to more accurately forecast future U(VI) migration at different Hanford waste sites, along with further research necessary to reach this goal.To accomplish the report objectives, the environmental geochemistry of U at the Hanford Site is discussed in terms of both the vadose and saturated zone, to the extent that it is known. Hexavalent uranium [U(VI)] is the dominant valence form of U under the predominantly oxidizing subsurface conditions at the Hanford Site, and the researchers' analyses consequently emphasize this species. The nature and concentration of background U in Hanford subsurface sediments is identified to place contaminant U(VI) concentrations and behavior in perspective to the natural system. In-ground U-waste inventories are quantified and characterized with regard to source term, to the extent possible, and the most important sites from an inventory perspective are identified. The U-isotopic content of various waste streams are discussed from the perspective of waste-source tracking. The geochemical attenuation processes responsible for slowing the rate of subsurface U migration, relative to the transporting water front, are illustrated through careful consideration of both field characterization studies of existing U vadose-zone and groundwater plumes, and laboratory studies of derived contaminated and uncontaminated sediments. Both empirical and more mechanistic models of these attenuation processes are considered as well as the parameters that define attenuation magnitude. Attention is given to the behavior of contaminant U(VI) that has been in contact with Hanford sediments for extended periods (circa 10-50 years), as long contact imparts unique characte...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: 674mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Zachara¹,

Brown²,

Christensen³

et al. 2007

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Quantification of Technetium-99 in Complex Groundwater Matrixes Using a Radiometric Preconcentrating Minicolumn Sensor in an Equilibration-Based Sensing Approach

2009

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A preconcentrating minicolumn sensor for technetium-99 detection in water consists of a packed bed containing a mixture of anion-exchange resin and scintillating plastic beads. The column materials are contained in a transparent plastic flow cell placed between two photomultiplier tubes for radiometric detection. Upon retention of pertechnetate anions, the radioactive decay of Tc-99 results in detectable scintillation pulses that are counted in coincidence. In equilibration-based sensing mode, the sample is pumped through the packed bed until complete chromatographic equilibrium is achieved between the activity concentration in the water sample and the concentration on the anion-exchange resin. The analytical signal is the observed steady-state count rate at equilibrium. The sensitivity is related to a measurement efficiency parameter that is the product of the retention volume and the absolute radiometric detection efficiency. This sensor can readily detect pertechnetate to levels 10 times below the drinking water standard of 0.033 Bq/mL. The potential for other anions in natural groundwater and contaminated groundwater plumes to interfere with pertechnetate detection and quantification has been examined in detail, with reference to the groundwater chemistry at the Hanford site in Washington state. Individual anions such as nitrate, carbonate, chloride, and iodide, at natural or elevated concentrations, do not interfere significantly with pertechnetate uptake on the anion-exchange resin. Elevated chromate or sulfate anion concentrations can interfere with pertechnetate uptake by the resin, but only at levels substantially higher than typical concentrations in groundwater or contamination plumes. Nevertheless, elevated anion concentrations may reduce pertechnetate uptake and sensitivity of the sensor when present in combination. Chromate is retained on the anion-exchange resin from water at parts-per-billion levels, leading to an orange stain that interferes with pertechnetate detection by the absorption of scintillation light pulses (color quench). Radioactivity from radioiodine, tritium, and uranium is not expected to create a significant positive bias in groundwater analyses. A method of automated fluidic standard addition is demonstrated that corrects for matrix interferences leading to accurate analyses over a wide range of groundwater compositions. This method is developed for automated groundwater monitoring applications.

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The Geochemistry of Technetium: A Summary of the Behavior of an Artificial Element in the Natural Environment

Icenhower¹,

Qafoku²,

Martin³

et al. 2008

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Summary of Hanford Site Groundwater Monitoring for Fiscal Year 2003

Cited by 7 publications

References 0 publications

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Quantification of Technetium-99 in Complex Groundwater Matrixes Using a Radiometric Preconcentrating Minicolumn Sensor in an Equilibration-Based Sensing Approach

The Geochemistry of Technetium: A Summary of the Behavior of an Artificial Element in the Natural Environment

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