Transuranium radionuclides

DOE. 1979a. Biotransport of transuranium radionuclides in dairy animals A data summary. 

Hamilton El, Clifton RJ. 1980. Concentration and distribution of the transuranium radionuclides 239+240pu 238pu anc[241 Am in Mytilus edulis, Fucus vesiculosus and surface sediment of Esk estuary. Mar Ecol Prog Ser 3 267-277. 

Sutton WW, Patzer RG, Potter GD. 1979. Biotransport of transuranium radionuclides. Environmental Monitoring Systems Laboratory, U.S. Environmental Protection Agency, Las Vegas, NV. NHS No. EMSLLV05 3 93 5. 

Waste that contains more than 4 kBq g"1 of alpha-emitting transuranium radionuclides with half-lives greater than 20 y, excluding high-level waste... 

According to strict interpretation of transuranic, these wastes could be so classified only if they contained sufficient amounts of elements having an atomic number greater than 92. Despite this, wastes that contained sufficient amounts of 233U and other alpha-emitting non-transuranium radionuclides often were classified and managed as transuranic waste because their specific activities (activities per unit mass) are more similar to those of the transuranium elements than to natural uranium or thorium. 

High-level waste thus includes the concentrated wastes that arise from reprocessing of commercial or defense nuclear fuel that contain virtually all the fission products and transuranium radionuclides (except plutonium) in spent fuel. However, the definition does not mention the constituents of the waste, and it is only qualitative because concentrated is not quantified and the minimum fuel burnup that would yield high-level waste is not specified. Although the definition given above referred only to liquid (aqueous) waste, it is clear from further discussions in 10 CFR Part 50, Appendix F (AEC, 1970), that AEC intended that high-level waste also would include concentrated solid waste derived from liquid high-level waste that was suitable for permanent disposal. 

The definition of high-level waste in Clause (A) of NWPA given above follows the traditional, source-based description although, for the first time, the presence of fission products is mentioned explicitly. However, the definition remains qualitative because highly radioactive material and sufficient concentrations of fission products are not quantified, nor are the minimum concentrations of alpha-emitting transuranium radionuclides. 

DOE also has used the traditional, source-based definition of high-level waste. In contrast to other definitions, the definition adopted in 1988 was explicit that high-level waste contains transuranium radionuclides (DOE, 1988a). Later, however, DOE essentially adopted the definition in NWPA given above (DOE, 1999a). 

This definition is based on the source of the waste, but certain incidental wastes that arise from fuel reprocessing that contain lower concentrations of fission products and alpha-emitting transuranium radionuclides than the primary reprocessing wastes have been excluded on a case-by-case basis. 

Transuranic waste. As described in Section 4.1.2.2.2, transuranic waste originally was defined by AEC as solid waste that contains long-lived, alpha-emitting transuranium radionuclides or 233U in concentrations greater than 0.4 kBq g A Transuranic waste so defined was not generally acceptable for shallow-land burial. 

In 1982, federal agencies concurred with a recommendation to increase the lower limit on concentrations of long-lived, alpha-emitting transuranium radionuclides in transuranic waste from 0.4 to 4 kBq g 1 (Steindler, 1982). This change in the definition of transuranic waste was made in response to difficulties in routinely measuring levels of alpha activity near 0.4 kBq g 1 in bulk solid waste and analyses which indicated that risks to public health from shallow-land burial of transuranium radionuclides in concentrations up to 4 kBq g 1 should be acceptable. 

In 1985, EPA developed a regulatory definition of transuranic waste in 40 CFR Part 191 (EPA, 1985) that incorporated the increase in the lower limit on concentrations of long-lived, alpha-emitting transuranium radionuclides. This definition was retained when 40 CFR Part 191 was repromulgated in 1993 (EPA, 1993a). EPA s definition is the same as the current statutory definition described below. 

In addition to specifying the lower limit on concentrations of alpha-emitting transuranium radionuclides, this definition specifies their minimum half-life. In contrast to the earliest definition developed by AEC, this definition does not include waste that contains high concentrations of long-lived, alpha-emitting non-transuranium radionuclides (e.g., 233U). 

Although this definition specifies a lower limit on the concentration of particular radionuclides, it also depends on the qualitative, source-based definition of high-level waste and, thus, is not strictly quantitative. Alpha-emitting transuranium radionuclides with half-lives greater than 20 y are expected to be the principal constituents of most transuranic waste, but the definition does not specify any limits on the concentrations of other radionuclides that may occur in transuranic waste, including fission products, alpha-emitting nontransuranium radionuclides, and alpha-emitting transuranium radionuclides with half-lives less than 20 y. 

DOE has defined low-level waste as in Clause (A) above (DOE, 1988c 1999c). In the earlier definition (DOE, 1988c), test specimens of fissionable material irradiated for purposes of research and development could be classified as low-level waste, provided the concentration of long-lived, alpha-emitting transuranium radionuclides was... 

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