Exemption Levels for Radioactive Waste

2 Exemption levels for radioactive waste. This Section discusses exemption levels for radionuclides in waste materials that have been established or were proposed by NRC. Exemption levels for radioactive waste have not been established by DOE or EPA. 

Established Exemption Levels. NRC s radiation protection standards in 10 CFR Part 20 (NRC, 1991) include limits on concentrations or annual releases of radionuclides for unrestricted discharge into sanitary sewer systems, except any excreta from individuals undergoing medical treatment with radioactive material are exempt from the limits. These regulations also include an exemption for land disposal of liquid scintillation materials and animal carcasses that contain 2 kBq g 1 (0.05 pCi g-1) or less of 3H or 14C, although the exempted scintillation materials must be managed in accordance with RCRA requirements due to the presence of toluene. 

Current NRC regulations for source material in 10 CFR Part 40 (AEC, 1961) and byproduct material in 10 CFR Part 30 (AEC, 1965a) specify conditions for exemption of many products or materials that contain small amounts of radioactive material (see also Schneider et al, 2001). These exemptions apply to commercial or specialized industrial uses of radioactive materials, as well as their disposal, and they include many common consumer products e.g., timepieces, smoke detectors, thorium gas mantles). These exemptions were established based on judgments by AEC and NRC that the benefits of exempt uses far outweighed the risks to public health. 

NRC regulations described above represent a case-by-case approach to establishing exemption levels for radioactive material. Although the various exemption levels are expected to correspond to low doses from use and disposal of materials compared, for example, with dose limits in radiation protection standards for the public 

In addition to the exemptions established in regulations, NRC issued guidance on concentration limits for disposal of residual thorium or uranium from past operations with no restrictions on burial method (NRC, 1981). There wouldbe no restrictions on burial method if the concentrations were less than (1) 0.4 Bq g 1 for natural thorium or uranium with its decay products present and in activity equilibrium, (2) 1.3 Bq g 1 for depleted uranium, and (3) 1 Bq g 1 for enriched uranium. These concentration limits were intended to provide criteria for remediation of contaminated sites to permit unrestricted use by the public, but they could be applied to waste disposal as well. 

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This Section describes the concepts used in exempting waste that contains radioactive material and discusses efforts in the United States to establish exemption levels for radioactive waste. 

Concepts and definitions. Two concepts are potentially useful in establishing exemption levels for radioactive waste. The first is the concept of a generally applicable negligible (de minimis) dose or risk, and the second is the concept of amounts of radionuclides that are exempt or below regulatory concern (BRC) for particular practices or sources. 

NCRP has developed a recommendation on a negligible individual dose that could be used to establish exemption levels for radioactive waste for such purposes as disposal and recycle/reuse, but this recommendation has not been adopted by regulatory authorities. Indeed, NRC is prohibited by law from implementing a proposed generic policy on exemption of radioactive materials that was consistent with the NCRP recommendation. 

The provision of the National Energy Policy Act (NEPA, 1992) that prohibits NRC from establishing dose criteria that could be used to exempt radioactive wastes from licensing requirements for disposal clearly is an impediment to development of generally applicable exemption levels for radioactive waste. An exempt class of radioactive and hazardous chemical waste is the cornerstone of the risk-based waste classification system developed in this Report, and any legal and regulatory impediments to establishment of generally applicable exemption levels would need to be removed. 

On July 18, 2000, the Agency released HWIR-waste exemption levels for 36 chemicals that were developed using a risk model known as the Multimedia, Multi-pathway and Multi-receptor Risk Assessment (3MRA) Model.17 The May 16, 2001, HWIR-waste rule revised and retained the hazardous waste mixture and derived-from rules as previously discussed in this module. In addition, the rule finalized provisions that conditionally exempt mixed waste (waste that is both radioactive and hazardous), if the mixed waste meets certain conditions in the rule.5... 

Summary of exemptions for radioactive waste in the United States. At the present time, exemption levels for radionuclides in waste materials, or materials intended for beneficial use,... 

Based on the negligible annual dose to individuals of 10 pSv and assumed scenarios for unrestricted disposal of waste, IAEA has developed recommendations on exemption levels for radionuclides in solid waste (IAEA, 1995) the recommended exempt concentrations have values in the range of about 0.1 to 104 Bq g 1 depending on the radionuclide. IAEA also has issued recommendations on total activities and activity concentrations of radionuclides that could be exempted from any requirements for notification, registration, or licensing of sources or practices, based on the same exemption principles and assumed scenarios for exposure of the public (IAEA, 1996). The recommended exemption levels for naturally occurring radionuclides are limited to their incorporation in consumer products, use as a radioactive source, or use for their elemental properties. 

A striving to embody all the desired attributes of the new system, while recognizing that this may take many years and that a number of important benefits can be obtained by interim implementation of parts of the system. The most important areas in which interim implementations are likely to be beneficial include the establishment of exemption levels for radionuclides and hazardous chemicals in waste, to allow hazardous wastes to be managed as nonhazardous material or to allow mixed waste to be managed as radioactive or hazardous chemical waste only, and the elimination of source-based definitions of hazardous wastes, especially radioactive wastes. 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

As part of this study, proposed radioactive waste classification systems that differ from the existing classification system in the United States were reviewed and evaluated. Of particular interest is the classification system currently recommended by the International Atomic Energy Agency (IAEA). This classification system and the disposal options for each waste class are summarized in Table 1.2. The basic waste classification system consists of exempt waste, low-and intermediate-level waste, and high-level waste. 

Management and disposal of hazardous chemical waste under RCRA is based on detailed and prescriptive technical requirements that apply to any facility for waste treatment, storage, or disposal, whereas management and disposal of low-level radioactive waste is more flexible because AEA allows consideration of waste- and site-specific factors. As a consequence, acceptable approaches to management and disposal of mixed low-level waste probably will be determined primarily by RCRA requirements, unless exempt levels of hazardous chemicals are established that render the waste nonhazardous under RCRA. 

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. 

The fundamental objective is to isolate the radioactive waste from the accessible enviroiunent for as long as is needed to prevent unacceptable radiation exposure. In practice, some releases may occur and it is therefore necessary to limit die associated risk to individuals. This leads to a hierarchy of possible protection levels from exemption from control (unrestricted release) through to active institutional controls. 

Technical requirements on treatment and disposal of spent fuel, high-level waste, and transuranic waste established under AEA should be largely unaffected by the presence of waste classified as hazardous under RCRA Some of these wastes meet technology-based treatment standards for hazardous chemical waste established by EPA (e.gvitrified high-level waste is an acceptable waste form under RCRA). Alternatively, a finding that disposal of the radioactive component of the waste complies with applicable environmental standards established by EPA under AEA can serve to exempt the disposal facility from prohibitions on disposal of restricted hazardous chemical wastes under RCRA [e.g., disposal of mixed transuranic waste at the Waste Isolation Pilot Plant (WIPP)]. 

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