Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials (1999) / Chapter Skim
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3 Major Sources of Technologically Enhanced Naturally-Occurring Radioactive Materials
3 Major Sources of Technologically Enhanced Naturally-Occurring Radioactive Materials
Pages 61-74
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From page 61... ...
, which are the ore residues discharged to a waste pond after extraction of the uranium, typically by sulfuric acid leaching. Although 90-95% of the uranium in the ore is extracted, most of the uranium-decay-product activity remains with 61
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62 GUIDELINES FOR EXPOSURE TO TENORM e' o A set V Em Cat 4, _ _ C~ as ·~ C)
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Two distinct manufacturing processes, a wet process and a thermal process, are involved. The wet process treats the ore with sulfuric acid to yield phosphoric acid and hydrated calcium sulfate (gypsum)
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From page 65... ...
are a low-volume, discrete TENORM waste at wet-process plants. The thermal process involves heating the phosphate rock to about 1300 °C to yield an elemental phosphorous product and a calcium silicate vitreous slag waste containing 226Ra at about 0.7-2 kBq/kg (20-50 pCi/g)
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From page 66... ...
Such differential behavior and the resulting concentration differences should be considered in dose assessments. Radon emanation from ash is a possible exposure pathway from both ash disposal piles and use of fly ash as a concrete aggregate.
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From page 67... ...
Chemical decontamination methods that use salts of amino carboxylic acids and proprietary reagents are available for the dissolution of scale and other surficial TENORM materials; radium can be precipitated from the spent solutions and the solid concentrate disposed of (Coil 1997; Lancee and others 1997~. Sludges are related deposits, typically found settled on the bottoms of equipment and storage tanks at various points in the oil-gas-water separation processing stream.
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From page 68... ...
MUNICIPAL WATER TREATMENT Conventional water-treatment processes designed to remove suspended solids and dissolved chemical contaminants from drinking-water supplies also remove radionuclides. During the period of atmospheric nuclear-weapons testing, the US Public Health Service and others did much work on removal of fission products, such as strontium-89 and strontium-90, from water supplies (Straub 1971~.
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From page 69... ...
Indeed, at some municipal wastewater-treatment plants, elevated concentrations of radium in sewage sludge have been attributed to residual materials discharged to the sewer systems by drinking-water treatment plants (Nuclear Regulatory Commission 1997b)
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From page 70... ...
The foundry sands~ined from deposits in Florida, South Africa, Australia, India, and Brazil contain elevated concentrations of uranium and thorium that occur in heavy accessory minerals, such as zircon and monazite. State regulations restricting the disposal of radioactive material and the use of portal radiation monitors at landfills have in some cases made it difficult for the industry to dispose of discarded casting molds (Anonymous 1995~.
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From page 71... ...
The use of scale inhibitors or in situ removal of radionuclides from oil-field production fluids by the introduction of sorbents downhole can limit the buildup of TENORM in piping and equipment (Lancee and others 1997~. The removal of uranium as an economic product from phosphoric acid production circuits will decrease the exposure of people who obtain foodstuffs from fertilized soils.
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From page 72... ...
72 GUIDELINES FOR EXPOSURE TO TENORM h~ _ 2 ~ ~ i, ~ , ~ _ ~ ~ _ ~ f ~ . ~ ~ ~ I ' 3 ~ 0~ ~ ~ roll Ha R i LD1~
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From page 74... ...
For example, metal-mining wastes can contain a wide variety of inorganic contaminants associated with the ores and their processing; sludges with elevated radium concentrations at oil-water separators can also contain appreciable concentrations of oil. In establishing groundwater standards for remedial actions at inactive uranium-processing sites (40 CFR Part 192)
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