Radioactive wastes examples

Approach to Example Analysis. Similar to the previous examples involving radioactive wastes, these residues were assumed to be placed in a typical near-surface disposal facility having a RCRA Subtitle C permit. In this example, it is assumed that an inadvertent intruder excavates an area of the disposal site of approximately 200 m2. This excavation is sufficient to reach the waste, and the exposure pathways considered involve inhalation of resuspended waste, ingestion of waste, and dermal absorption. The intrusion is identified and halted prior to any structures being constructed on the disposal site and before any farming activity can be developed. As in the similar scenarios used in the radioactive waste examples, exposure is assumed to continue for 1,000 h. 

Nuclear utiUties have sharply reduced the volume of low level radioactive waste over the years. In addition to treating wastes, utiUties avoid contamination of bulk material by limiting the contact with radioactive materials. Decontamination of used equipment and materials is also carried out. For example, lead used for shielding can be successfully decontaminated and recycled using an abrasive mixture of low pressure air, water, and alumina. 

A new class of solvents called ionic liquids has been developed to meet this need. A typical ionic liquid has a relatively small anion, such as BF4, and a relatively large, organic cation, such as l-butyl-3-methylimidazolium (16). Because the cation has a large nonpolar region and is often asymmetrical, the compound does not crystallize easily and so is liquid at room temperature. However, the attractions between the ions reduces the vapor pressure to about the same as that of an ionic solid, thereby reducing air pollution. Because different cations and anions can be used, solvents can be designed for specific uses. For example, one formulation can dissolve the rubber in old tires so that it can be recycled. Other solvents can be used to extract radioactive waste from groundwater. 

Sorption can significantly diminish the mobility of certain dissolved components in solution, especially those present in minor amounts. Sorption, for example, may retard the spread of radionuclides near a radioactive waste repository or the migration of contaminants away from a polluting landfill (see Chapters 21 and 32). In acid mine drainages, ferric oxide sorbs heavy metals from surface water, helping limit their downstream movement (see Chapter 31). A geochemical model useful in investigating such cases must provide an accurate assessment of the effects of surface reactions. 

Both uncalcined and calcined LDHs have also been used as sorbents for decontamination of radioactive wastewater [150,151]. For example, Toraishi et al. [151] reported the adsorption behavior of lOs" in radioactive waste-water by LDHs with interlayer or NOs" anions. It was found that the... 

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. 

The beneficial use of radiation is one of the best examples of how careful characterization of the hazard is essential for its safe use. A radioactive substance can be safely stored or transported if appropriately contained. Depending on the characteristics of the radioactive material, it can be safely handled by using appropriate shielding and safety precautions. Laboratory workers usually wear special badges that quantify radiation exposure to ensure that predetermined levels of exposure, which are considered safe, are not exceeded. Unfortunately, after more than 50 years, society has not yet been able to design and implement a safe way to dispose of radioactive waste. The hazardous properties of radiation are explored further in a subsequent chapter. 

The Applications of Laser-induced Time-resolved Spectroscopic Techniques chapter starts with a short description of laser-induced spectroscopies, which may be used in combination with laser-induced luminescence, namely Breakdown, Raman and Second Harmonic Generation. The chapter contains several examples of the application of laser-based spectroscopies in remote sensing and radiometric sorting of minerals. The proljlem of minerals as geomaterials for radioactive waste storage is also considered. 

Such studies are sometimes criticized because they appear to be based on the concept of a global analogy between the specific example studied and a waste repository site (e.g., Miller et al. 1994). Clearly no geological site fully resembles a radioactive waste repository site. Confusion also seems to arise from the fact that analogy has sometimes been considered as a particular... 

Note that a solution more concentrated than the original one also results from the reverse osmosis process. This means that the method of reverse osmosis may also be used as a method for concentrating solutions. Fruit juices and radioactive wastes, for example, have been concentrated by this method. 

Variations, which avoid the use of radioisotopes, are replacing RIA. Some utilize stable isotopes. However, 14C at such low levels that there is no radioactive waste can be coupled with accelerator mass spectrometry to provide very sensitive immunoassays.1 A great variety of other procedures are available. Some involve coupling to antibodies that carry fluorescent labels. Many are now automated. Often protein A from Staphylococcus aureus is utilized in various ways that take advantage of its ability to bind to the Fc portion of IgG from virtually all mammals. For example, it may fix antibodies to a surface or to a label)... 

In the past, a number of polluters have used temporary waste storage means, such as aboveground tanks. Storage of radioactive wastes at nuclear power facilities is another example. In-plant storage or nearby polluter-owned sites must meet all current pollution regulations These practices have been costly in retrospect. They have comprised many of the targets of the so-called Superfund. 

Discuss the disposal of the following examples of radioactive waste ... 

Harmful chemical spills can often be cleaned up by treatment with another chemical. A spill of H2SO4, for example, can be neutralized by adding NaHC03. Why can t harmful radioactive wastes from nuclear power plants be cleaned up just as easily ... 

Legal impediments to development of a new waste classification system would be ignored. These include, for example, the distinction between radioactive waste that arises from operations of the nuclear fuel-cycle and NARM waste, which is based on provisions of AEA, the distinction between radioactive and hazardous chemical wastes, which is based on provisions of AEA and RCRA, and the provision in the National Energy Policy Act that prohibits NRC from establishing a general class of exempt radioactive waste. 

NCRP believes that subclassification of the basic waste classes would be appropriate as long as it is based on properties of waste that are related to health risks from disposal or considerations of the cost-benefit of different options for waste management and disposal. Other factors that have influenced waste classification in the past should not be used as a basis for waste subclassification. For example, the present distinction between radioactive waste that arises from operations of the nuclear fuel cycle and NARM waste should not be maintained in subclassifying waste, because this distinction is based solely on the source of the waste rather than significant differences in health risks from waste disposal or considerations of cost-benefit in waste management and disposal. 

The best example of this is wastes that are classified based solely on the nature of the generating process or facility e.g., high-level radioactive waste, chemical wastes from certain industries), irrespective of the content and concentration of hazardous substances. This results in resources being used unnecessarily on lower-risk situations when they could be better applied to higher-risk situations (hazardous waste disposal or otherwise). For example, billions of dollars have been spent in managing... 

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