Research Needs for High-Level Waste Stored in Tanks and Bins at U.S. Department of Energy Sites Environmental Management Science Program (2001) / Chapter Skim
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Appendix G: Glossary
Appendix G: Glossary
Pages 126-132
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From page 126... ...
Following dissolution of the aluminum cladding in hot sodium hydroxide solution, the uranium metal fuel slugs were dissolved in nitric acid. The dissolved fuel solution was treated with several successive cycles of precipitation to separate plutonium from uranium and other elements.
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From page 127... ...
Electrode: The conducting material used in electric melters to pass an alternating current through the preheated glass batch so as to cause internal resistive heating and melt formation. Electric melters for commercial glass production typically employ molybdenum or tin oxide electrodes.
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From page 128... ...
In loose terms, HLW is the waste containing fission products and actinides that results from the reprocessing of spent nuclear fuel and requires permanent isolation in a geologic repository. On-exchange: Chemical reaction in which mobile hydrated ions of a solid are exchanged, equivalent for equivalent, for ions of like charge in solution.
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From page 129... ...
In the case of wasteform leaching, these will probably include some or all of the following: · H+ or H3O+ diffusion into the glass surface; · diffusion of leachable species (particularly alkali ions) out of the glass surface; · subsequent diffusion of ions across the external leached layer; · dissolution of the leached layer itself (i.e., matrix dissolution)
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From page 130... ...
This process had major advantages over the bismuth phosphate process: it reduced the waste volume, provided for nearly complete recovery of both uranium and plutonium, and allowed continuous operation, which favored higher production rates. One disadvantage was that large amounts of aluminum nitrate had to H ~ G H - L E V E E W A S T E
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From page 131... ...
Refractories used in electric melters must also exhibit high electrical resistivities. The glass contact refractories used in the Jouleheated melters at DWPF and WVDP are bricks of chrome-rich Monofrax K3@, a fusion-cast refractory material that shows excellent corrosion resistance, but with a trend toward decreasing electrical resistivity with increasing temperature that can be problematic much above 11 50°C.
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From page 132... ...
in the waste form or the amount of equivalent oxides that will be formed by thermal decomposition during waste form production. A further ambiguity arises from use of the term at different HEW sites to either include or exclude nonradioactive waste components (e.g., Na, Al, Si)
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