Waste treatment - Treatment Stabilization and Transmutation...

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1 Treatment, Stabilization, and Transmutation of High-Level Wastes “My uncle’s enthusiasm, always a little more than was required, was now excusable.” —Henry Lawson in “Journey to the Center of the Earth” by Jules Verne. Composition of reprocessing wastes per 1,000 kg of SNF (Murray, 2003) Fission products 28.8 kg U4 . 8 Pu 0.04 Np 0.48 Am 0.14 Cm 0.04 Reprocessing chemicals 68.5
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2 Reprocessing wastes The weight of reprocessing waste is about one-tenth of the weight of SNF. Sr-90 and Cs-137 are the major problems during the first few centuries of waste storage. Can they be eliminated from HLW? Will be discussed later. For now. . . by definition, reprocessing wastes are HLW Reprocessing wastes Aqueous/nitric acid solutions that contain fission products such as Cs, Sr, Zr, Ni, La and others. Derived from SNF from military applications in the US. Because we do not reprocess SNF, HLW treatment research has not been a major priority in the US. In general, these are high-level liquid wastes that are stored in underground tanks.
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3 Typical first-cycle raffinate
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4 Treating High-Level Liquid Wastes Reduce the volume of waste Calcination—heat the liquid at a high temperature to evaporate moisture and volatile constituents without fusing the residue (a granular form is easier to handle). Fixation, immobilization, —adding some agent to the calcinate to reduce the potential for leaching (waste stabilization) as another safety factor. Immobilization of calcinate/HLW Basic approach is to mix and isolate the calcinate with 1. Amorphous glass 2. Ceramic-formation minerals 3. Glass-ceramic combinations 4. Basalt glass-ceramic combinations 5. Cements and concretes
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5 Immobilization of calcinate/HLW Immobilization of calcinate/HLW Concrete and cement are used for the immobilization of LLRW such as in the Netherlands. Problems with radiolysis of water when used with HLW: H 2 O + alpha, beta, and gamma radiation yields H + , OH - , H 2 (gas), O - , H 2 O 2 , H 3 O, and H 2 O + Low-moisture concretes have been proposed, but application is complicated. Research abandoned.
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6 Immobilization of calcinate/HLW Best understood and widely used additive is borosilicate glass. 70 to 81% SiO 2 7 to 13% B 2 O 3 4 to 8% Na 2 O 2 to 7% Al 2 O 3 Immobilization of calcinate/HLW Borosilicate glass is more resistant to thermal shock such as from the heat from radioactive decay than ordinary glass. Also called “Pyrex glass” as in lab glassware.
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This note was uploaded on 12/04/2011 for the course NPRE 442 taught by Professor Stubbins during the Fall '08 term at University of Illinois, Urbana Champaign.

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Waste treatment - Treatment Stabilization and Transmutation...

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