Classification of Radioactive Waste

The simplest way to classify radioactive waste is by its physical state, that is, whether it is a gas, liquid, or solid. Gaseous waste arises from gas evolution, 

The most important liquid wastes are the high-level effluents, containing fission products from fuel reprocessing. They contain 99% of the fission products in the fuel with small quantities of U and Pu. Medium-level liquid waste has an activity of 4 GBq/L and results from various steps in fuel reprocessing. Low-level ( 0.1GBq/m3) waste is treated or concentrated. Liquid organic waste is usually incinerated or chemically destroyed. 

Solid waste comes from the mining and milling of uranium ore and the sludge from spent fuel storage. It also includes contaminated equipment and structures. High-level solid waste includes the hulls from the dissolving of spent fuel, ion exchange resin, and the like. 

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Classification of radioactive waste has been facilitated by two considerations. The first is that radiation dose provides a common measure of potential health impacts from exposure to any radionuclide and for any exposure situation (see Section 3.2.2). All classification systems for radioactive waste take into account, at least to some... 

IAEA has been developing recommendations on classification of radioactive waste and principles for exempting radioactive waste from regulatory requirements for radioactive material for more than 30 y. This Section briefly reviews these developments. 

IAEA (1994). International Atomic Energy Agency. Classification of Radioactive Waste, Safety Series No. 111-G-l.l (International Atomic Energy Agency, Vienna). 

For the purpose of this document, the definitions below will be adopted. Some definitions are adopted from the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management [1]. If no appropriate definition is found in the above reference, the definitions are adopted from the IAEA s Radioactive Waste Management Glossary, 2003 Edition [2], the Safety Guide on Classification of Radioactive Waste [3] and the IAEA Safeguards Glossary, 2001 Edition [4]. Some other definitions are adapted from the mentioned documents. 

INTERNATIONAL ATOMIC ENERGY AGENCY, Classification of Radioactive Waste — A Safety Guide, Safety Series No.l 11-G-l.l, IAEA, Vienna (994) 39 p. 

INTERNATIONAL ATOMIC ENERGY AGENCY,Classification of Radioactive Waste, lAEA-Safety Series No.lll-G-1.1, Vienna (1994). 

The classification of radioactive waste proposed by the IAEA [1] combines concerns about long-term safety with those about present-day (operational) safety. In die proposed classification, wastes are characterized by hazardous lifetime (short-lived, long-lived) and by increasing intensity of radiation (LLW, ILW, HLW). 

Details of the purpose, methods and approaches to the classification of radioactive waste are provided in Ref. [19]. The distinction between radioactive waste and waste that can be cleared from regulatory control is addressed in Ret [18]. 

Second, waste that contains hazardous substances is classified based on considerations of health risks to the public that arise from waste disposal. The existing classification systems for radioactive and chemical wastes in the United States are not based primarily on considerations of health risks to the public. Rather, classification of hazardous wastes has been based primarily on the source of the waste or the presence of particular hazardous substances. The absence of risk-based waste classifications has had a number of undesirable ramifications ... 

Over the last several decades, separate classification systems have been developed for radioactive and hazardous chemical wastes based on a variety of considerations, the most prevalent being the source of the waste. These classification systems have served their intended purpose of facilitating development of health-protective strategies for waste management and disposal reasonably well. However, they have exhibited a number of shortcomings and undesirable ramifications, which indicate that a new approach to classification of hazardous wastes would be beneficial. 

The primary purpose of this Report is to present NCRP s recommendations on classification of hazardous wastes. The Report is directed at a multidisciplinary audience with different levels of technical understanding in the fields of radiation and chemical risk assessment and radioactive and chemical waste management. Anew hazardous waste classification system is proposed that differs from the existing classification systems for radioactive and hazardous chemical wastes in two fundamental respects. First, hazardous waste would be classified based on considerations of health risks to the public that arise from disposal of waste. Hazardous waste would not be classified based, for example, on its source. Second, the classification system would apply to any hazardous waste, and separate classification systems for radioactive and hazardous chemical wastes would not be retained. In the proposed system, waste would be classified based only on its properties, and the same rules would apply in classifying all hazardous wastes. 

The classification system lacks a set of principles for determining when a waste contains sufficiently small amounts of radionuclides that it can be exempted from regulatory control as radioactive material. The lack of a general class of exempt waste increases in importance as the resources required for management and disposal of radioactive waste increase compared with the resources required for management and disposal of these materials as nonradioactive waste, and it may foreclose possible beneficial uses of slightly contaminated materials. 

Table 1.2—Summary of characteristics of radioactive wastes and disposal options in waste classification system... 

NCRP s recommendations on classification of hazardous wastes are intended to address deficiencies and inconsistencies in the separate systems for classification and disposal of radioactive and hazardous chemical wastes in the United States summarized previously. The most important of these include ... 

As part of this study, NCRP investigated how the recommended waste classification system would affect the current classifications of radioactive and hazardous chemical wastes. The results of this investigation are summarized as follows ... 

A general class of exempt waste, which could be regulated as nonhazardous material, would be established. Development of an exempt class of waste that contains low levels of hazardous substances has been controversial and currently is banned by law in the case of radioactive waste. Some radioactive and hazardous chemical wastes have been exempted on a case-by-case basis, but general principles for exempting radioactive or hazardous chemical wastes have not been established. In spite of these difficulties, however, a meaningful risk-based waste classification system must include a general class of exempt waste. 

Wastes have been classified for decades for a variety of purposes. This Section discusses the historical development of classification systems for radioactive and hazardous chemical wastes and the resulting classification systems in use at the present time. The relationship between waste classification and requirements for disposal of different classes of hazardous waste is emphasized. The framework for this discussion is the top-level system for waste classification in the United States shown in Figure 4.1. Within this framework, it is first determined whether a waste is nonhazardous (e.g., municipal waste) these wastes are not addressed in this Report. If a waste is deemed hazardous, it is so classified due to the presence of radionuclides or hazardous chemicals. Mixed radioactive and hazardous chemical waste is not a separate class of waste. However, mixed waste has been an important concern as a result of differences in requirements for management and disposal of radioactive and hazardous chemical wastes. Section 4.1 addresses classification and disposal of radioactive waste, and is followed by discussions of classification and disposal of hazardous chemical waste in Section 4.2 and approaches to management of mixed radioactive and hazardous chemical waste in Section 4.3. Finally, Section 4.4 summarizes previous NCRP recommendations relevant to waste classification. 

The discussions of classification of radioactive and hazardous chemical wastes and management of mixed waste in Sections 4.1 to 4.3 are presented in considerable detail to facilitate understanding of these issues by readers who may not be knowledgeable in these areas. The existing hazardous waste classification systems and the historical developments underlying them are complex. NCRP believes that an appreciation of these complexities is important in gaining an understanding of the need for a new hazardous waste classification system and the benefits it would provide. 

This Section discusses the historical development and current approaches to classification and disposal of radioactive waste. Classification and requirements for disposal of different radioactive wastes in the United States are emphasized, particularly the relationship between waste classification and requirements for disposal much of this discussion is adapted from a previous paper (Kocher, 1990). Proposals for alternative radioactive waste classification systems are reviewed. Classification systems developed by the International Atomic Energy Agency (IAEA) and the relationship between waste classification and disposal requirements in IAEA recommendations are discussed in some detail. Waste classification systems developed in other countries are briefly mentioned. 

Classification and Disposal of Wastes from the Nuclear Fuel Cycle. This Section discusses the different classes of radioactive waste that arise from operations of the nuclear fuel cycle that have been defined in laws and regulations over the last three decades and... 

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