Alternative High-Level Waste Treatments at the Idaho National Engineering and Environmental Laboratory (1999) / Chapter Skim
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5 Vitrification
5 Vitrification
Pages 47-54
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From page 47... ...
They are essentially free from an undissolved crystalline phase but can contain some precipitated crystalline phases and separated amorphous phases as minor phases to the extent that their overall chemical durability is not affected adversely. This chapter begins by evaluating the vitrification plans for the INEEL HEW and associated developmental studies that were contained in presentations to the committee and in various technical reports cited below.
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From page 48... ...
will be feed with glass with a waste loading of approximately 20 to 30 percent by weight. Waste Compositions and Characteristics The base glass composition developed for use with Savannah River and West Valley HLW is a borosilicate type, with the relative abundance of frit constituents tailored to the waste composition to ensure production of a vitrified form with adequate waste loading.
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From page 49... ...
In particular, blends of pilot-plant alumina calcine and SBW can be immobilized using the same high-silica borosilicate glass compositions that were developed for the SBW only (Vinjamuri, 1995~. For example, a blend of the simulated waste consisting of 57 percent by weight alumina calcine and 43 percent by weight SBW was mixed with a frit consisting of 88 percent by weight SiO2 and 12 percent by weight ~03 with the waste loading ranging from 20 to 35 percent by weight.
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From page 50... ...
Waste Compositions and Characteristics As with the nonseparations option, development work has been initiated on glass formulations that would be suitable for the compositions of waste to be vitrified. Because the above-mentioned HAW compositions resulting from the separation process are unconventional, a group effort was instituted to develop appropriate nuclear waste glass compositions (Staples, et al., 1998~.
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From page 51... ...
Since 1970, however, only borosilicate glasses have been investigated on a large scale in He United States, with two exceptions: phospho-borosilicate glass compositions for a separation option (Staples et al., 1998) and lead-iron phosphate glass development (Sales and Boatner, 1988~.
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From page 52... ...
While borosilicate-based nuclear waste glasses appear to exhibit phase separation that leads to chemical durability deterioration when the P2Os content exceeds 5 to 7 percent by weight (Staples et al., 1998) , depending on the final waste form composition, phosphate-based glass should be able to avoid this problem.
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From page 53... ...
batch materials, as compared to melter designs such as in-can or in-crucible melting that cannot use cold caps. In experience to date, although some phosphate glasses exhibit higher corrosion, iron-based phosphate glasses do not corrode common glass contact refractories any more than the Savannah River borosilicate glasses (Chen and Day, 1999; Day et al., 1999)
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