"September 1996 ...Radiological Dose Assessment Related to Management of Naturally Occurring Radioactive Materials Generated by the Petroleum Industry by K.P. Smith, D.L. Blunt, G.P. Williams, and C.L. Tebes Environmental Assessment Division Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439"
Estimated doses to the general public from both smelter stack emissions and use of products made from recycled steel and slag are lower by at least two orders of magnitude than estimated doses related to unrestricted shallow burial of the same quantity of NORM-contaminated equipment. Furthermore, doses resulting from smelting contaminated equipment can be controlled by limiting the contamination level of the initial feed.
At the present time, regulatory limits on the release of radioactively contaminated metals have not been established. .....
The IAEA is proposing a clearance level (i.e., unrestricted release criterion) of 0.3 becquerel per gram 7 (i.e., 8 picocuries per gram [pCi/g]) for Ra-226, Ra-228, Th-228, and Pb-210; metals contaminated 8 with higher activity levels could not be released from the generator to a commercial smelter or other facility. The IAEA has no regulatory authority over the petroleum industry, and the petroleum industry would not be subject to this limit if adopted....
Although smelting currently is not employed to dispose of NORM-contaminated equipment, it has been considered by the petroleum industry as a potentially viable disposal option. For equipment that cannot be easily cleaned and reused (i.e., scrap metal), smelting might be a preferable disposal option to landfilling or indefinite storage. The bulk of this scrap metal is likely to consist of scale-encrusted tubing that cannot be easily cleaned because of its small diameter....
8.4.2 Doses to the Public from Smelter Emissions Dose estimates from smelting 50,000 t of NORM-contaminated scrap metal are presented in Table 6. Doses are presented for the maximally exposed individual, who is located approximately 500 m away from the stack release. The total dose from smelting 50,000 t of contaminated metal is estimated to be on the order of 4 ◊ 10 mrem/yr. Doses to the maximally exposed individual from -4 smelter emissions are estimated to be two orders of magnitude lower than doses estimated for other public end-use scenarios."
www.evs.anl.gov/pub/doc/anlead2.pdf
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