Plutonium-contaminated wastes

Plutonium-contaminated waste, principally from weapons materials processing. There are two classes of plutonium wastes the transuranic, containing mostly plutonium and other transuranics, and the high-level wastes that contain significant heat-generating products, strontium, and cesium. 

Plutonium-contaminated wastes, which mainly comprise paper, gloves, and contaminated, unserviceable equipment fix)m the maintenance of plants handling plutonium, can be treated in the following ways combustible waste—incineration and acid digestion and noncombustible waste— decontamination by electropolishing or ultrasonic washing. 

Although incineration is used widely for volume reduction of industrial and household combustible waste, the incineration process for plutonium-contaminated waste has required very special development to ensure protection of the operators, efficient ofiF-gas cleaning to protect the environment, and the avoidance of criticality owing to the concentration of plutonium in the ash. An incinerator for this duty now has been operated successfully in the United Kingdom on a pilot-plant scale and it... 

Viewed under a microscope, the incinerator ash of plutonium-contaminated waste sample consists of primarily dark crystallites 10-50 /im in size with a small amount of clear and orange particles. The primary interest in this study was to identify the plutonium species present and their relationship to other elements or molecular components in the sample. 

A decision had been made in 1972, however, that PFR fuel would be reprocessed at Dounreay and studies of modifications to the existing DFR fuel reprocessing plant were begun. A need to increase plutonium throughput by a factor of 1000, and a factor of 10 increase in fission product activity, demonstrated the need for an extensive change to the plant and the construction of additional waste management facilities for the treatment and storage of plutonium contaminated waste. 

Plutonium (Pu) is an artificial element of atomic number 94 that has its main radioactive isotopes at 2 °Pu and Pu. The major sources of this element arise from the manufacture and detonation of nuclear weapons and from nuclear reactors. The fallout from detonations and discharges of nuclear waste are the major sources of plutonium contamination of the environment, where it is trapped in soils and plant or animal life. Since the contamination levels are generally very low, a sensitive technique is needed to estimate its concentration. However, not only the total amount can be estimated. Measurement of the isotope ratio provides information about its likely... 

Allhough Ihe ceramification and SYNROC lechnologies are being researched to develop a final waste form for plutonium-contaminated materials, no experiments with plutonium have been performed. The SMITE process is designed for the treatment of solid, inorganic materials. The final waste form will leach in acidic solutions so storage in a basic environment is recommended. 

Komatsu, F., Sawada, Y., Ohtsuka, K. OHUCHI, J. 1981. Development of a new solidification method for wastes contaminated by plutonium oxides. In Management of Alpha-Contaminated Wastes. IAEA, Vienna, 325-337. 

A lthough the levels of plutonium in environmental waters are generally - low, there is the possibility of plutonium contamination from weapons testing, nuclear reactor operations, laundry and decontamination wastes, fuel reprocessing, and accidental release during transportation. It has been estimated that by 1980 the United States will be producing 15,000-20,000 kg. of plutonium per year (12). Its growing use will increase the probability of environmental contamination. 

Alpha-bearing wastes (also called transuranic, plutonium-contaminated material, or alpha wastes) include wastes that are contaminated with enough long-lived, alpha-emitting nuclides to make near-surface disposal unacceptable. They arise principally from spent fuel reprocessing and mixed-oxide fuel fabrication. The wastes may he disposed of in a similar manner to HLW. 

Plutonium wastes from the Los Alamos National Laboratory in northern New Mexico were trucked for the first time to the federal Waste Isolation Pilot Plant in Carlsbad in March 1999. The 600 pounds (270 kg) of waste consisted of plutonium-contaminated clothing and metal cans, packed in boxes and stainless steel containers. Most of the material was from the laboratory s manufacture of nuclear batteries used in NASAs deep space probes and will be buried in the depository carved out of ancient salt caverns about half a mile (0.8 km) below ground. 

Contaminated wastes derive from the fabrication of weapon components and related activities also. Further, the end of Cold War resulted in closing weapons production facilities and the creation of decontamination products, surplus plutonium, and other radioactive materials. These materials have to be safely disposed so that they do not cause any harm to public health or the environment. Moreover, they have to be secured so that they carmot be easily recovered and reused. 

The primary issue is to prevent groundwater from becoming radioactively contaminated. Thus, the property of concern of the long-lived radioactive species is their solubility in water. The long-lived actinides such as plutonium are metallic and insoluble even if water were to penetrate into the repository. Certain fission-product isotopes such as iodine-129 and technicium-99 are soluble, however, and therefore represent the principal although very low level hazard. Studies of Yucca Mountain, Nevada, tentatively chosen as the site for the spent fuel and high level waste repository, are underway (44). 

These observations contrast with some of the results obtained in natural waters. In the experiments where contaminated sediments were equilibrated with Lake Michigan water for a number of days, the Pu(IV) that was on the sediments and was transferred to the water was oxidized to Pu(V), with the oxidation occurring either during or after desorption (15). The studies in the Irish Sea near Windscale show that although no more than 1 percent of the waste effluent stream is oxidized plutonium, approximately 5 percent of the plutonium released leaves the area in the currents of the Irish Sea as oxidized plutonium. Most of the plutonium, therefore, must be oxidized fairly rapidly in sea water. 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

As a manufactured element, americium is not naturally present in rocks and soils. Contamination of the soil can occur either from deposition of americium or precursor plutonium originally discharged into the atmosphere, or from waste products discharged directly into or on the ground. Except for the reentry into... 

Long-lived ty = 2.1 x 10 years) Tc, present as TCO4 in Purex process HNO3 feed solutions, is partially coextracted with uranium and plutonium in the first cycle. Unless separated in the Purex process, Tc contaminates the uranium product subsequent processing of the U02(N03)2 solution to UO2 can release some of the technetium to the environment. The presence of technetium in the purification steps as well as in the uranium product causes several other complications. Thus it is desirable to route all Tc into the high-level waste. Efforts in this direction have been described in some recent flow sheets [37]. 

Disposal of spent nuclear fuel and other radioactive wastes in the subsurface and assessment of the hazards associated with the potential release of these contaminants into the environment require knowledge of radionuclide geochemistry. Plutonium (Pu), for example, exhibits complex environmental chemistry understanding the mechanism of Pu oxidation and subsequent reduction, particularly by Mn-bearing minerals, is of major importance for predicting the fate of Pu in the subsurface. 

Subsurface contamination by uranium wastes and contaminant speciation during transport from a wastewater pond (originating from a plutonium production plant) to groundwater were studied by Catalano et al. (2006). Land disposal of basic sodium aluminates and acidic U(VI)-Cn(ll) and their redistribution in the vadose zone resulted in development of a groundwater nraninm plume. The solid phase speciation of nraninm from the base of the pond, throngh the subsurface, to the... 

The Army plans to leave Johnston Island following completion of the destruction of the chemical stockpile. To complete the closure of JACADS, the Army must demonstrate to EPA that its portion of the island is acceptable for future use (whatever that use is determined to be). Other parts of Johnston Island will require cleanup by appropriate government agencies to address contamination by non-JACADS wastes. These include plutonium, Agent Orange,... 

Aqueous biphasic systems offer the potential for highly selective and low-cost separations. Aqueous biphasic extraction for soil decontamination is based on the selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. Both soluble and particulate uranium contaminants can be separated from soil using this technique. Aqueous biphasic extraction may also have application for separation of plutonium and thorium from soil or waste. 

Figure 4. Comparative accumulation of actinides by small mammals from contaminated soil or sediment relative to the accumulation of plutonium-239. Accumulation factor (AF) = concentration of nuclide in the internal small mammal body -- concentration of nuclide in dry soil. Twelve shrews and seven rats and mice from a floodplain forest were composited to yield four and three separate analyses, respectively. Twelve cotton rats inhabiting the banks of a liquid waste pond (3513) also were analyzed.

Citnbacter sp. uptake of lanthanum and a strategy for the biological treatment of liquid wastes containing plutonium. Bulletin of Environmental Contamination and Toxicology, 44, 173-80. 

DOE — Organics, PCBs, petroleum/fuel hydrocarbons, solvents, TCE, unspecified VOCs, and unspecified SVOCs are among the contaminants found. Metals cited most often include lead, beryllium, mercury, arsenic, and chromium. Radioactive contaminants are present at most installations the most frequently cited are uranium, tritium, thorium, and plutonium. In addition, mixed waste containing both radioactive and hazardous contaminants is of particular concern to the DOE because of the lack of an acceptable treatment technology. 

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