Risk, general considerations Waste classification system

Development of a waste classification system based on considerations of risks to the public requires assumptions about generic exposure scenarios (i.e., exposure scenarios that are generally applicable at any disposal site). 

The waste classification system presented in this Report would apply to all radioactive and hazardous chemical wastes from any source, and it would be based on considerations of health risks to the public that arise from waste disposal. The recommended classification system differs from the existing waste classification systems in three respects radioactive and hazardous chemical wastes would be included in the same classification system all waste would be classified based on its properties, rather than its source and the classification system would include a general class of exempt waste. 

The waste classification system developed in this Report includes a general class of exempt waste. Waste in this class would contain sufficiently small amounts of hazardous substances that it could be managed in all respects as if it were nonhazardous (e.g., as household trash). NCRP intends that exempt materials could be used or disposed of in any manner allowed by laws and regulations addressing disposition of nonhazardous materials. However, exempt waste would not necessarily be exempt for purposes of beneficial use without further analysis of the risks associated with anticipated uses. Materials could be exempted for purposes of disposal or beneficial use based on similar considerations of acceptable risk. However, based on differences in exposure scenarios for the two dispositions, limits on the amounts of hazardous substances that could be present in exempt materials intended for beneficial use could be substantially lower than the limits for disposal as exempt waste. Thus, disposal may be the only allowable disposition for some exempt materials based on considerations of risk. In addition, some exempt materials may consist of trash, rubble, and residues from industrial processes that would have no beneficial uses and must be managed as waste. 

The basic framework for the waste classification system developed in this Report is depicted in Figure 6.1. Starting with the objectives that the classification system should apply to any waste that contains radionuclides or hazardous chemicals and that all such waste should be classified based on risks to the public posed by its hazardous constituents, the fundamental principle of the proposed system is that hazardous waste should be classified in relation to disposal systems (technologies) that are expected to be generally acceptable in protecting public health. This principle leads to the definitions of three classes of waste, and to quantification of the boundaries of the different waste classes based on considerations of risks that arise from different methods of disposal. The boundaries normally would be specified in terms of limits on concentrations of hazardous substances. At the present time, nearly all hazardous and nonhazardous wastes are intended for disposal in a near-surface facility or a geologic repository, and these are the two types of disposal systems assumed in classifying waste. The three waste classes and their relationship to acceptable disposal systems are described in more detail in Section 6.2. 

The risk-based waste classification system developed in this Report is based fundamentally on the concepts of negligible (de minimis) and acceptable (barely tolerable) risks from exposure to radionuclides and hazardous chemicals, with the crucial distinction that acceptable risks generally can be considerably higher than negligible risks. Therefore, in implementing the waste classification system, decisions would need to be made by regulatory authorities about... 

NCRFs recommendations on classification of hazardous wastes are based on two principles. First, a classification system should be generally applicable to any waste that contains radionuclides, hazardous chemicals, or mixtures of the two (i.e., the system should be comprehensive). Second, waste that contains hazardous substances should be classified based on considerations of health risks to the public that arise from waste disposal, because permanent disposal is the intended disposition of materials having no further use. 

---