An extensive program of characterization of several inactive uranium tailings piles has been carried out in the past year. The geotechnical engineering program conducted a drilling program at the Salt Lake City and Grand Junction sites. The locations of slimes and sands in these sites hve been characterized. In general, it was found that slimes exist in the impoundments in lower percentages than normally produced from mill tailings. Permeability tests were conducted yielding values ranging from 10/sup -3/ cm/sec to 10/sup -6/cm/sec. The geochemical studies made considerable progress in the past year. Extensive sampling of several sites was conducted. Sampling programs have been completed for seven sites and are underway for nine other sites. The work to date has indicated the importance of salts in controlling the direction and rate of movement of contaminants. The work has also indicated that a number of non-radioactive elements such as As are of environmental importance. The work also indicates the importance of the fact that the tailings piles are out of chemical equilibrium with their environment. Computer software was developed and implemented for data storage and retrieval. Automation hardware was installed and tested for the Inductively Coupled Plasma Emission Spectrometer. A number of …

The uranium-mill tailings at Green River, Utah, are relatively low in /sup 226/Ra content and concentration (20 Ci and 140 pCi/g, respectively) because the mill was used to upgrade the uranium ore by separating the sand and slime fractions; most of the radium was transported along with the slimes to another mill site. Spread of tailings was observed in all directions, but near-background gamma exposure rates were reached at distances of 40 to 90 m from the edge of the pile. Water erosion of the tailings is evident and, since a significant fraction of the tailings pile lies in Brown's Wash, the potential exists for repetition of the loss of a large quantity of tailings such as occurred during a flood in 1959. In general, the level of surface contamination was low at this site, but some areas in the mill site, which were being used for nonuranium work, have gamma-ray exposure rates up to 143 ..mu..R/hr.

Results of a study of the content of radium-226 in plants growing on inactive uranium mill tailings sites in the Four Corners Region of the southwestern United States and in plants grown under greenhouse conditions with minimal surficial contamination are reported. Field plant samples and associated substrates were analyzed from two carbonate tailings sites in the Grants Mineral Belt of New Mexico. Radium activities in air-cleaned samples ranged from 5 to 368 pCi/g (dry weight) depending on species and location: activities in plants growing on local soils averaged 1.0 pCi/g. The talings and local soils contain 140 to 1400 pCi/g and 2.1 pCi/g, respectively. An evaluation of cleaning methods on selected samples showed that from 17 to 79% of the radium activity measured in air-cleaned samples was due to surficial contamination, which varied with species and location. A survey of 18 inactive uranium mill sites in the Four Corners Region was performed. Radium activity in plant tissues from nine species ranged from 2 to 210 pCi/g on bare tailings and from 0.3 to 30 pCi/g on covered tailings The radium content in most of the soil overburdens on the covered tailings piles was 10 to 17 pCi/g. An experiment was …

Pacific Northwest Laboratory, is investigating the use of an asphalt emulsion admix seal to reduce the release of radon from uranium mill tailings. A key requirement of any cover system is its long-term stability; the cover must withstand failure over very long periods of time. An important determinant of overall cover system stability is the integrity of the 6.35-cm (2.5-in.) thick asphalt admix seal. Therefore, the physical stability of this seal was examined. The investigation considered the mechanical interaction between the tailings pile and cover. The potential effect of differential settlement of the tailings pile on the integrity of the seal system was also examined. Results indicate that the minimum span length the seal could withstand without failing is 0.34 m (1.1 ft). This assumes a differential settlement of 4.92 cm (1.94 in.) at the center resulting from the application of a 0.76-m (2.5-ft) cover. At spans greater than 0.60 m (1.97 ft), no tensile strain would develop.

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This report briefly discusses how seismic activity, erosion, climatic change, slope stability, differential settlement, and cover design could affect the long-term integrity of multilayer earthen cover systems. In addition, the report suggests ways to design and construct covers so that adverse impacts can be avoided or minimized. The stability of multilayer earthen barriers used to isolate uranium mill tailings depends on the morphology of the disposal site, the engineering of the barrier, the condition of the tailings, and the possible impacts of earthquakes, erosion, and climatic changes. When designing a cover for or siting a tailings pile, one must take into account both geologic and geotechnological variables. To alleviate the adverse effects of possible seismic activity, tailings piles should never be located on or near active or capable faults. Existing piles near faults should be moved to safer sites or engineered to withstand possible displacement and shaking. Liquefaction generally can be prevented if the tailings and their underlying material are compacted to a relative density of 60% or greater, or if they are kept dry. If the tailings are saturated, dewatering schemes may have to be used. Erosion may be caused by streams, glaciers, or wind, depending on the geomorphic …

Uranium mill tailings are a source of low-level radiation and radioactive materials that may be released into the environment. Stabilization or disposal of these tailings in a safe and environmentally sound way is necessary to minimize radon exhalation and other radioactive releases. One of the most promising concepts for stabilizing uranium tailings is being investigated at the Pacific Northwest Laboratory: the use of asphalt emulsion to contain radon and other potentially hazardous materials in uranium tailings. Results of these studies indicate that radon flux from uranium tailings can be reduced by greater than 99% by covering the tailings with an asphalt emulsion that is poured on or sprayed on (3.0 to 7.0 mm thick), or mixed with some of the tailings and compacted to form an admixture seal (2.5 to 15.2 cm) containing 18 wt % residual asphalt.

During the period 1947 through 1970, the Atomic Energy Commission (AEC) fostered the rapid development and expansion of the domestic uranium mining and milling industry by providing a market for uranium. Some thirty-two mills were constructed during that period to produce U/sub 3/O/sub 8/ concentrates for sale to the AEC. In addition, there were various pilot plants, concentrators, upgraders, heap leach, and solution mining facilities that operated during the period. The purpose of this report is to compile a short narrative history of the AEC's uranium concentrate procurement program and to describe briefly each of the operations that produced uranium for sale to the AEC. Contractual arrangements are described and data are given on quantities of U/sub 3/O/sub 8/ purchased and prices paid. Similar data are included for V/sub 2/O/sub 5/, where applicable. Mill and other plant operating data were also compiled from old AEC records. These latter data were provided by the companies, as a contractual requirement, during the period of operation under AEC contracts. Additionally, an effort was made to determine the present status of each facility by reference to other recently published reports. No sites were visited nor were the individual reports reviewed by the companies, many …

The energy saving potential and refining capability of three copper(I)/electrolyte systems for the electrorefining of copper were compared experimentally. The alternative electrolyte systems studied were copper(I)/acid chloride, copper(I)/acetonitrile and sulfuric acid, and copper(I)/ammonia solutions. These were compared to the conventional copper(II)/sulfuric acid electrolyte. All of the alternative electrolyte systems demonstrated at least some potential for saving energy when run at an equal deposition rate to the conventional process; the chloride electrolyte showed the greatest energy saving potential, about 70%, and the ammonia electrolyte showed the least, about 25%. All of the alternative electrolyte systems, however, exhibited performance problems, primarily with regard to inadequate separation of impurities. A preliminary capital cost estimate was made for the copper(I)/chloride system. This estimate showed that, for the alternative electrolyte system to be cost competitive (that is, a reduction of capital cost of about 15 to 20%) with the conventional electrorefining process, the refining cells would have to be operated at a current density of about 25 to 30 mA-cm/sup -2/. At this current density, the estimated energy saving potential for the copper(I)/chloride system was still about 50%.

This report is a review and evaluation of soil consolidation theories applicable for evaluating settlement during dewatering and subsequent covering of uranium-mill tailings. Such theories may be used to predict both consolidation and water flow related effects in uranium-mill tailings during drainage, following sluicing into burial pits. A consolidation theory to be useful must consider the effect of time-dependent loads, nonhomogeneous soil mass, nonlinear variation of soil properties with the stress-state parameters, large strain, and saturated and unsaturated flow. Constitutive relations linking the stress-deformation-state variables with void ratio should be adopted for predicting both consolidation and fluid-flow interaction in unsaturated uranium-mill tailings.

From Abstract: "This bulletin summarizes the results of Bureau of Mines investigations of a technique for dewatering clay waste that consists of flocculation with polyethylene oxide (PEO)followed by screening of the resulting flocs. Results of the laboratory tests and small and large scale field tests are described."

Progress is reported on the following studies dealing with mill tailings: long-term stabilizaton; interim stabilization of mill tailings piles; tailings dewatering techniques; tailings neutralization and other alternatives in immobilizing toxic materials in tailings; evaluation of seepage and leachate transport from tailings disposal facilities; effluent and environmental monitoring methods and equipment and instrument testing; attenuation of radon emissions; assessment of leachate movement from uranium mill tailings; and methods of minimizing ground water contamination in in-situ leach uranium mining.

Progress is reported on the following studies dealing with mill tailings: long-term stabilization; interim stabilization of mill tailings piles; tailings dewatering techniques; tailings neutralization and other alternatives in immobilizing toxic materials in tailings; evaluation of seepage and leachate transport from tailings disposal facilities; effluent and environmental monitoring methods and equipment and instrument testing; attenuation of radon emissions; assessment of leachate movement from uranium mill tailings; and methods of minimizing ground water contamination in in-situ leach uranium mining. 1 figure.

An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques.

The phosphate industry in the United States includes three major activities, namely, mining and milling of phosphate rock, phosphate product manufacture, and phosphate product use. Phosphatic materials contain uranium, thorium, and their decay products in greater than background amounts. This assessment of the radiological impacts associated with the redistribution of radioactive components of phosphate materials may provide insight into the effects of uranium extraction from phosphate materials for use in the nuclear fuel cycle.

Weekly student newspaper from McMurry College in Abilene, Texas that includes local, state and campus news along with advertising.

This study evaluates leachate-soil interactions that will take place at the Morton Ranch for certain disposal alternatives. Laboratory tests were conducted to evaluate the following: 1) physical and chemical characteristics of geologic materials from the Morton Ranch. 2) physical and chemical characteristics of acid leach tailings and tallings solution, 3) leaching tests with selected tailings materials and leach solutions to evaluate the leachability of contaminants with time under specific disposal alternatives, 4) adsorption studies measuring the sorption characteristics of heavy metals and radionuclides on the geologic materials at Morton Ranch, 5) clay liner stability tests to evaluate effects of acid leachate on clay mineralogy and clay permeability.

This document contains primarily reproductions of slides presented at the 1986 Annual Doe Remedial Action Programs Meeting, Oak Ridge, Tennessee.

Pacific Northwest Laboratory (PNL), under contract to the US Department of Energy (DOE) Uranium Mill Tailings Remedial Action Project (UMTRAP) office, has developed an asphalt emulsion cover system to reduce the release of radon from uranium mill tailings. The system has been field tested at Grand Junction, Colorado. Results from laboratory and field tests indicate that this system is effective in reducing radon release to near-background levels (<2.5 pCi m/sup -2/s/sup -1/) and has the properties required for long-term effectiveness and stability. Engineering specifications have been developed, and analysis indicates that asphalt emulsion covers are cost-competitive with other cover systems. This report summarizes the technology for asphalt emulsion radon barrier systems. 59 references, 45 figures, 36 tables.

This appendix is an assessment of the present conditions of the inactive uranium mill site near Mexican Hat, Utah. It consolidates available engineering, radiological, geotechnical, hydrological, meteorological, and other information pertinent to the design of the Remedial Action Plan. Plan is to characterize the conditions at the mill and tailings site so that the Remedial Action Contractor may complete final designs of the remedial action.

Three years of laboratory and field testing have demonstrated that asphalt emulsion seals are effective radon diffusion barriers. Both laboratory and field tests in 1979, 1980 and 1981 have shown that an asphalt emulsion seal can reduce radon fluxes by greater than 99.9%. The effective diffusion coefficient for the various asphalt emulsion admix seals averages about 10/sup -6/ cm/sup 2//s. The 1981 joint field test is a culmination of all the technology developed to date for asphalt emulsion radon barrier systems. Preliminary results of this field test and the results of the 1980 field test are presented. 18 figures, 6 tables.

The objective of this study is to identify potential material supply constraints due to the large-scale deployment of five advanced photovoltaic (PV) cell designs, and to suggest strategies to reduce the impacts of these production capacity limitations and potential future material shortages. The Critical Materials Assessment Program (CMAP) screens the designs and their supply chains and identifies potential shortages which might preclude large-scale use of the technologies. The results of the screening of five advanced PV cell designs are presented: (1) indium phosphide/cadmium sulfide, (2) zinc phosphide, (3) cadmium telluride/cadmium sulfide, (4) copper indium selenium, and (5) cadmium selenide photoelectrochemical. Each of these five cells is screened individually assuming that they first come online in 1991, and that 25 Gwe of peak capacity is online by the year 2000. A second computer screening assumes that each cell first comes online in 1991 and that each cell has a 5 GWe of peak capacity by the year 2000, so that the total online capacity for the five cells is 25 GWe. Based on a review of the preliminary baseline screening results, suggestions were made for varying such parameters as the layer thickness, cell production processes, etc. The resulting PV cell characterizations …

The Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, Public Law 95-604 (PL95-604), grants the Secretary of Energy the authority and responsibility to perform such actions as are necessary to minimize radiation health hazards and other environmental hazards caused by inactive uranium mill sites. This Technical Approach Document (TAD) describes the general technical approaches and design criteria adopted by the US Department of Energy (DOE) in order to implement remedial action plans (RAPS) and final designs that comply with EPA standards. It does not address the technical approaches necessary for aquifer restoration at processing sites; a guidance document, currently in preparation, will describe aquifer restoration concerns and technical protocols. This document is a second revision to the original document issued in May 1986; the revision has been made in response to changes to the groundwater standards of 40 CFR 192, Subparts A--C, proposed by EPA as draft standards. New sections were added to define the design approaches and designs necessary to comply with the groundwater standards. These new sections are in addition to changes made throughout the document to reflect current procedures, especially in cover design, water resources protection, and alternate site selection; only minor revisions were made to …

This study examined the type and level of wastes that would be generated in the mining and milling of U/sub 3/O/sub 8/ from four potential domestic sources of uranium. The estimated costs of the technology to control these wastes to different degrees of stringency are presented.