Nuclear waste classification

Classification of wastes may be according to purpose, distinguishing between defense waste related to military appHcations, and commercial waste related to civiUan appHcations. Classification may also be by the type of waste, ie, mill tailings, high level radioactive waste (HLW), spent fuel, low level radioactive waste (LLW), or transuranic waste (TRU). Alternatively, the radionucHdes and the degree of radioactivity can define the waste. Surveys of nuclear waste management (1,2) and more technical information (3—5) are available. 

The most usual route of waste classification is by radioactivity and thermal emission, mainly between high-level nuclear waste (HLNW) and low-level nuclear waste (LLNW). Depending on the countries there are other categories, such as intermediate-level nuclear waste (ILNW) and more recently another category has been introduced in order to avoid unnecessary saturation of LLNW repositories these are the so-called very low activity nuclear wastes (VLNW). 

Deficiencies in the Radioactive Waste Classification System. The classification system for radioactive waste in the United States summarized in Table 1.1 is based primarily on the earliest descriptions of different classes of waste that arises from chemical reprocessing of spent nuclear fuel and subsequent processing of nuclear materials that were developed beginning in the late 1950s. These wastes were considered to be the most important in regard to potential radiological impacts on workers. 

The basic waste classification system does not distinguish between radioactive waste associated with the nuclear fuel-cycle and other waste i.e., fuel-cycle and NARM wastes are included in the same classification system. 

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. 

A number of alternatives to the qualitative and source-based classification system for radioactive waste in the United States have been proposed. The alternative waste classification systems have three important features in common. First, they are comprehensive, in that NARM waste and nuclear fuel-cycle waste are included in the same classification system. Second, they are based on the concept that waste classes should be defined primarily on the basis of risk, particularly the risk resulting from waste disposal. Finally, to some degree, they associate waste classes with particular disposal systems that are expected to be generally acceptable. None of these features is embodied in the radioactive waste classification system in the United States. In addition, some proposed classification systems include an exempt class of radioactive waste that contains negligibly small amounts of radionuclides. Waste in this class would be regulated in all respects as if it were nonhazardous. A general class of exempt waste is not included in the radioactive waste classification system in the United States. 

The existing waste classification systems for radioactive and hazardous chemical wastes clearly are not comprehensive. At a fundamental level, entirely separate and quite different classification systems have been developed for the two types of hazardous waste. In addition, each classification system is not comprehensive in the context of the general type of waste to which each system applies. In the existing radioactive waste classification system, waste that arises from operations of the nuclear fuel cycle is classified separately from NARM waste. The existing classification system for hazardous chemical waste excludes many potentially important wastes that contain hazardous chemicals. 

The extent to which differences in waste classification and approaches to waste management may impede the disposal of high-level radioactive waste and spent nuclear fuel is not yet clear because of uncertainties in the final waste forms intended for disposal and the fact that siting and licensing of a repository is still in the investigative phase. 

The hazardous waste classification system recommended by NCRP is depicted in Figure 6.1 at the beginning of Section 6. This proposal was developed with two fundamental objectives in mind. First, all wastes that contain radionuclides, hazardous chemicals, or mixtures of the two should be included in the same classification system. A comprehensive hazardous waste classification system should be developed to replace the separate, and quite different, classification systems for radioactive and hazardous chemical wastes, as well as the separate classification systems for radioactive waste that arises from operations of the nuclear fuel cycle and NARM waste. Second, all hazardous wastes should be classified based on considerations of risks to the public that arise from disposition of the material. In this Report, permanent disposal in a permitted facility for hazardous or nonhazardous waste is the assumed disposition of waste containing hazardous substances that has no further use to its present custodian. An important consequence of these two objectives is that the same rules should apply in classifying any waste that contains hazardous substances. 

KING, W.C. and COHEN, J.J. (1977). Interim Report to the Nuclear Regulatory Commission on Radioactive Waste Classification, Lawrence Livermore National Laboratory Report UCID-17497 (National Technical Information Service, Springfield, Virginia). 

NRC. 20011. Waste classification. U.S. Nuclear Regulatory Commission. Code of Federal Regulations. 10 CFR 61.55. Http //www. nrc.gov/NRC/CFR/PART06 l/part06 l-0055.html. 

Note These hazard levels are not to be confused with the DOE classification of nuclear waste into high-level, low-level, mixed low-level, transuranic and 1 le(2) byproduct material categories. These nuclear waste categories are established by DOE Order 5820.2A, which can be viewed online at http //www.directives.doe.gov (Dec. 2005). See DOE/EM (1997) for more information on nuclear waste. To reiterate, waste hazard levels are different than laboratory hazard levels, although the defining terminology is similar. 

U.S. Nuclear Regulatory Commission (NRC). 1983. Final waste classification and waste form technical position papers, Washington, DC. 

Another important feature of the classification system for nuclear fuel-cycle wastes in the United States is the definition of low-level waste only by exclusion there is no definition of what low-level waste is, only a definition of what it is not. As a result, in contrast to the earliest descriptions of low-level waste prior to the establishment of definitions in law, this class is not restricted to waste that contains relatively low concentrations of radionuclides compared with high-level waste. Rather, low-level waste can range from virtually innocuous to highly hazardous over long time frames. 

The classification system for nuclear fuel-cycle wastes in the United States can be characterized in the following way. First, as a consequence of the definition of high-level waste as waste from fuel reprocessing, all waste classes, including mill tailings, are defined based essentially on the source of the waste, rather than its radiological properties, and most of the definitions are not explicit in regard... 

As summarized below, however, the classification system that encompasses nuclear fuel-cycle and NARM waste also has exhibited a number of deficiencies that call into question its continued suitability. 

There also are two important differences. First, the classification system for radioactive waste from the nuclear fuel cycle includes different classes that are defined based essentially on the source of the waste. In addition, some classes of fuel-cycle waste (e.g., high-level waste) often, but not always, contain higher concentrations of radionuclides than other classes (e.g., low-level waste) and, thus, pose a greater hazard in waste management and disposal. The classification system for hazardous chemical waste does not distinguish between hazardous wastes based on their source, with the exception of the K list of wastes from specific sources. Additionally, hazardous chemical wastes are not further classified based on their relative hazard (i.e., there is only one class of hazardous chemical waste). 

Inclusion of NARM waste in the same classification system with radioactive waste that arises from operations of the nuclear fuel cycle would require a change in the scope of AEA, because management and disposal of commercial NARM waste cannot be regulated under AEA. 

Radioactive wastes that arise from operations of the nuclear fuel cycle are divided into five classes, called spent nuclear fuel, high-level waste, transuranic waste, low-level waste, and uranium or thorium mill tailings. At the present time, NARM wastes are not formally divided into different classes (see Section 4.1.2.4). The division of all radioactive waste into fuel-cycle and NARM waste and the division of fuel-cycle waste into five classes constitutes the basic classification system for radioactive waste in the United States. 

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