Waste Disposal Into the Ground at Hanford.

Beard, S.J.; Godfrey, W.L.

doi:10.2172/4416879

Cited by 2 publications

(2 citation statements)

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“…Similar results were observed with the sodium silicate-and sodium aluminatetreated soil columns consistent with the similar behavior of Na and K in the general monovalent-divalent cationexchange process within these soil columns. With HUMDINGER's capability to simulate the dynamics of both exchangeable Ca and Mg and their precipitated phases throughout a wide pH range (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), it now becomes possible to describe quantitatively the linked behavior of 90 Sr in alkaline-treated soil columns. In the NaOH treatment scenario modeled in Figures 2 and S3 (Supporting Information), 90 Sr was not initially present in the soil or in the chemical treatment solution but was introduced subsequently with the leaching groundwater; notably, the default groundwater activity was not constant but varied with the cumulative groundwater volume following a measured linear relationship for both 90 Sr activity and hardness (Ca + Mg).…”

Section: Resultsmentioning

confidence: 99%

“…Waste sludge, excess wastewater, and often untreated wastewater were frequently disposed into unlined seepage trenches or lagoons from which contaminants adsorbed to surrounding soil or were allowed to dilute into groundwater while the entrained sludge retained most of the radionuclides. Thus, there are many highly alkaline (high pH and dissolved sodium) and radioactive waste inventories in such shallow subsurface environments at DOE sites including Oak Ridge, TN ( , ), Hanford, WA ( − ), and Savannah River, SC ( , ). The continued retention of radionuclides in these sludges depends on the maintenance of their highly alkaline condi tion.…”

Section: Introductionmentioning

confidence: 99%

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Chemical Equilibria Model of Strontium-90 Adsorption and Transport in Soil in Response to Dynamic Alkaline Conditions

Spalding

2000

Environ. Sci. Technol.

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Strontium-90 is a major hazardous contaminant of radioactive wastewater and its processing sludges at many Department of Energy (DOE) facilities. In the past, such contaminated wastewater and sludge have been disposed in soil seepage pits, lagoons, or cribs often under highly perturbed alkaline conditions (pH > 12) where 90Sr solubility is low and its adsorption to surrounding soil is high. As natural weathering returns these soils to near-neutral or slightly acidic conditions, the adsorbed and precipitated calcium and magnesium phases, in which 90Sr is carried, change significantly in both nature and amounts. No comprehensive computational method has been formulated previously to quantitatively simulate the dynamics of 90Sr in the soil-groundwater environment under such dynamic and wide-ranging conditions. A computational code, the Hydrologic Utility Model for Demonstrating Integrated Nuclear Geochemical Environmental Responses (HUMDINGER), was composed to describe the changing equilibria of 90Sr in soil based on its causative chemical reactions including soil buffering, pH-dependent cation-exchange capacity, cation selectivity, and the precipitation/dissolution of calcium carbonate, calcium hydroxide, and magnesium hydroxide in response to leaching groundwater characteristics including pH, acid-neutralizing capacity, dissolved cations, and inorganic carbonate species. The code includes a simulation of one-dimensional transport of 90Sr through a soil column as a series of soil mixing cells where the equilibrium soluble output from one cell is applied to the next cell. Unamended soil leaching and highly alkaline soil treatments, including potassium hydroxide, sodium silicate, and sodium aluminate, were simulated and compared with experimental findings using large (10 kg) soil columns that were leached with 90Sr-contaminated groundwater after treatment. HUMDINGER's simulations were in good agreement with dynamic experimental observations of soil exchange capacity, exchangeable cations, total 90Sr, and pH values of layers within the soil columns and of column effluents.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical Equilibria Model of Strontium-90 Adsorption and Transport in Soil in Response to Dynamic Alkaline Conditions

Spalding

2000

Environ. Sci. Technol.

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Archaeological Glasses – A Model for the Stability Evaluation of the Vitrified Radioactive Waste

Lytvynenko¹,

Melnychenko²,

Kadoshnikov³

et al. 2022

VKNUGEOL

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This article presents the possibility of usage of the archaeological glasses to predict the behavior of radionuclides incorporated into the glass matrix, under the conditions of the underground storage during prolonged contact with the groundwater. Archaeological glasses, whose age is more than two thousand years old, selected from the cultural horizon of the archaeological reserve "Olvia" were examined. A gel layer was formed on the surface of the glass prolonged contact with the soil, on the outer surface of which layered aluminosilicates are formed. The formation of a protective layer of the glass occurs by the mechanism of the incongruent dissolution. It has been experimentally established that alkaline and alkaline earth cations (Na, Ca), partially silicon and iron, are intensively removed into the soil during leaching from the glass, with the practical immobility of aluminum. Simulation of glass fracture was performed in Soxhlet extractors under conditions of continuous exposure to hot water (t = 75–80 °C) saturated with carbon dioxide for 6 months. The change in the rate of components removal from the glass is connected with an increase in the thickness of the "locking" gel layer, the thickness of which increases over time. Cyclic changes in the dissolution rate of the glass are connected with the partial destruction of the gel layer due to the increase in thickness of the gel layer and, accordingly, a decrease in the adhesion of the gel to the glass. The results of the aluminosilicate (archaeological) glasses fracture study and their comparison with the results of the borosilicate glasses fracture study indicate that archaeological glasses can be a model for the predicting of the behavior in natural conditions of the glass matrices intended for radioactive waste volume reduction for centuries.

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Waste Disposal Into the Ground at Hanford.

Cited by 2 publications

References 0 publications

Chemical Equilibria Model of Strontium-90 Adsorption and Transport in Soil in Response to Dynamic Alkaline Conditions

Chemical Equilibria Model of Strontium-90 Adsorption and Transport in Soil in Response to Dynamic Alkaline Conditions

Archaeological Glasses – A Model for the Stability Evaluation of the Vitrified Radioactive Waste

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