Alternative High-Level Waste Treatments at the Idaho National Engineering and Environmental Laboratory (1999) / Chapter Skim
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7 Other Waste Forms
7 Other Waste Forms
Pages 61-70
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From page 61... ...
Unlike fully vitrified forms, which are composed ideally of a single-phase, chemically homogeneous glass, He glass/ceramic waste forms are composed of a mixture of one or more crystalline phases bonded together, and the partially vitrified waste forms surround these crystals with a glassy phase. Most of the waste forms discussed in this chapter will be physically and chemically heterogeneous on a microscale, so that the overall properties such as leach resistance will depend on the chemical properties of each crystalline and glassy phase.
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From page 62... ...
Much of the equipment already exists for forming pellets approximately 2.5 cm (1 inch) in diameter and height by pressing the existing calcine, sintering the pellets at elevated temperature to increase their strength and chemical durability, and packing and sealing the pellets into metal tubing.
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From page 63... ...
Zoned Unlace heating or multi-staged treatments at controlled temperatures could be used to provide desired waste form properties. Other Waste Forms 63
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From page 64... ...
However, at this time, the absence of current certification for partially vitrified waste forms is a perceived disadvantage for partial vitrification. A common feature of all five procedures listed below is that, as with the vitrification options discussed in Chapter 5, they all use He same type of feed stock, namely, a mixture of 2 That is, a SSF waste form would be analogous to spent fuel material forms primarily in the way it would be produced (as a sintered oxide)
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From page 65... ...
Table 7.1 summarizes He properties of this partially vitrified "sintered glass" waste form and compares Hem to properties reported in INEEL literature for partially vitrified waste forms produced and studied in the past Other Waste Forms 65
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From page 66... ...
to produce partially vitrified waste forms of good chemical durability, he believed that the same results could be obtained for partially vitrified waste forms made by unidirectional hot pressing (i.e., hot uniaxial pressing, or HUP) , which is simpler and less hazardous than HIP, discussed next.
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From page 67... ...
o CQ ~ o.s ~ ~ 8 ~ ~ ~ _ oo cat · ~ I ~ ~.~° ~ 6~ 3 v ;> ~ ~ ~ ~0 ~ r ~ ~ i ~ ld d I Z ·1 J l.- All o ~ ~ ~ ~ V ~ ~ e.= _3 ,: i./ ~ ~ : ~ 7 ~ ~ ~ ~ ~ ~ A ~ ~ " ..
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From page 68... ...
The partially vitrified end product would consist of particles of the unmelted calcine distributed and embedded in a chemically durable glass matrix. Anticipated advantages of this technique are a high waste loading estimated at 50 weight percent or more, a high throughput similar to that of full vitrification processing, and no requirement for high pressure steps.
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From page 69... ...
Glass/ceramic waste forms offer potential advantages of higher waste loading, ease of processing, and potentially lower costs Han options involving chemical processing and complete vitrification. Whether these potential advantages can be realized will depend on regulatory and policy decisions for acceptance of heterogeneous waste forms in permanent repositories.
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From page 70... ...
70 Alternative High-Level Waste Treatments at INEEL
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