Wastes, radioactive dispersion

Some institutions grind radioactive animal tissue for disposal in the sanitary sewer, although the U.S. NRC requires that all sewer-disposable waste be dispersible. Preventing contamination and exposure of waste handlers to dust or particles is an iir tortant safety measure in this operation. 

Prevent volatile or powdered wastes from dispersing. Package all radioactive powders or volatile liquids into sealed containers in a fume hood to avoid dispersing contaminants to the environment. 

Several modes of waste management are available. The simplest is to dilute and disperse. This practice is adequate for the release of small amounts of radioactive material to the atmosphere or to a large body of water. Noble gases and slightly contaminated water from reactor operation are eligible for such treatment. A second technique is to hold the material for decay. This is appHcable to radionucHdes of short half-life such as the medical isotope technetium-9 9m = 6 h), the concentration of which becomes negligible in a week s holding period. The third and most common approach to waste... 

Technology Descriptions The use of thermoplastic solidification systems in radioactive waste disposal has led to the development of waste containment systems that can be adapted to industrial waste. In processing radioactive waste with bitumen or other thermoplastic material (such as paraffin or polyethylene), the waste is dried, heated and dispersed through a heated, plastic matrix. The mixture is then cooled to solidify the mass. 

Biotic Transport Biotic transport can be defined as the actions of plants and animals that result in the transport of a radioactive material or other substance from a waste site to locations where it can enter pathways that may result in exposure to humans. Small mammals are ubiquitous and inhabit areas containing radioactive contamination or radioactive waste sites. Mammals inhabiting these areas may become contaminated with americium by consuming contaminated soil or plants and disturb americium-contaminated soil through their burrowing and excavating activities. These animals may therefore affect the distribution of americium within the waste site or transport americium to previously uncontaminated areas. In addition, small mammals may be consumed by animals higher in the food chain such as hawks and coyotes, which would add to the dispersal of americium from disposal areas. However, results of... 

Parker, F. L., Churchill, M. A., Andrew, R. W., Frederick, B. J., Carrigan, P. H. Jr., Cragwall, J. S. Jr., Jones, S. L., Struxness, E. G. and Morton, R. J. (1966). Dilution, dispersion and mass transport of radionuclides in the Clinch-Tennessee Rivers, page 35 in Disposal of Radioactive Wastes into Seas, Oceans and Surface Waters, IAEA Publication No. STI/PUB/126 (International Atomic Energy Agency, Vienna). 

Nuclear fuel and associated waste products also include plutonium and enriched uranium (<20% U-235) and associated waste or fission products that emit intense radiation and can pose significant threats if dispersed with conventional explosives (i.e., by a dirty bomb). Industrial sources include a range of devices used in geological investigation and radiography, and may also pose significant hazards if dispersed by a dirty bomb. Examples of radioactive materials that could be used in a dirty bomb include ... 

Disposal Strategy. Two basic strategies for radioactive waste disposal have been developed (1) isolation and (2) dispersion. For isolation, the waste can be stored in a dry geologic respository. Space disposal has been examined but is not considered atrtractive at the present (3, jy. 1Z9I dispersion in the ocean is attractive because of the large volume of the ocean... 

Radioactive waste management involves the treatment, storage, and disposal of liquid, airborne, and solid effluents from the nuclear industry s operations, along with those from other activities that employ the radioactive products. Its strategy involves four approaches limit generation, delay and decay, concentrate and contain, and dilute and disperse. Combinations of all four of these usually are employed to manage each waste stream.39... 

Finally, both dilution and dispersion of large volumes of air and water effluents containing very low quantities of radioactivity generally are necessary. The concentration of radioactivity in these effluents is controlled by federal and international regulations, and such effluents are continuously monitored before release to the environment from the waste treatment and other activities. In a particular operation, the regulations may be reflected by a set of actions that are triggered by successively higher levels of radioactivity. 

Inorganic contaminants are immobilized by washing the waste with soluble phosphates. This treatment uses a very small amount of phosphate, does not change other characteristics of the waste such as its granular nature or volume, and is relatively inexpensive. If the waste contains radioactive contaminants, phosphate washing is not sufficient because the dispersibility of the radioactive contaminant powders needs to be reduced, and hence, the waste needs to be solidified. Solidification requires generating phosphate ceramics of the waste in the form of a CBPC. In the case of radioactive waste, both stabilization and solidification are needed because they not only immobilize the contaminants, but also solidify the entire waste. As we will see in this and the next chapter, whether phosphate treatment is used only for stabilization or for both stabilization and solidification, it is very effective for a wide range of waste streams. 

Radioactivity is significant in the study of environmental phenomena due to its possible effects on living organisms. One finds it for example in the atmosphere (e.g., radon and its decay products), in water near uranium-production sites, in wastes from warfare and nuclear operations, and dispersed as a result of accidents (e.g., the Chernobyl accident, 1986). We will now review some salient features of radioactivity and key radiation properties. 

Composite materials are mechanical dispersions of radioactive solids, for instance ciystalline or vitreous radioactive phases in metal matrix [24], glass-encapsulated Ca-phosphate based ceramics [30] glass-bonded sodalite [31,32] glass-ceramics for plutonium waste immobilization [33] and so on. 

Soil contaminated by biological and chemical weapons would be a different problem than waters contaminated by biological and chemical weapons. Soils contaminated by transuranic waste from RDDs would be a long-lasting problem. The radioactive particles would travel through the air with the soil particles moved by wind. The radioactive particles would travel within the soil if the particles are moved by water. Biological and chemical materials that are sorbed to the soil would move within the soil by convection-dispersion equation (see Chapter 3) or become retransported with the soil in the air or water. 

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