Management of Commercially Generated Radioactive Waste - U.S. ...

4.24
1) vitrification by in-can melting following spray calcination and 2) fluidized bed
calcination. These processes are described in detail in DOE/ET-0028. They produce a
borosilicate glass product and a granular powder product, respectively.
Spray Calciner/In-Can Melting (Example Method)
A flow diagram for the in-can melting process, the example high-level waste solidifica-
tion process of this Statement, is shown in Figure 4.3.5. The liquid HLW is dried and cal-
cined in a spray-calciner, the resultant calcine is mixed with about twice its weight of
glass-forming materials, and the mixture is melted within a steel canister. The filled can-
ister is cooled and sealed by welding. The output of the example process amounts to about
2.2 m 3 of waste glass per GWe-yr; higher volumes would result from lower waste loadings.
The number of canisters used to contain this volume of glass depends on a number of factors,
among which are the heat generation rate of the contained waste and the heat generation rate
per canister allowed by disposal considerations. For canister heat loadings of 1.2 to
3.2 kW (typical of those allowed in geologic repositories) and 6.5-year aged (out-of-
reactor) waste, the number of canisters would amount to 44 and 17, respectively, per GWe-yr.
A large variety of other glass-making processes have been developed; the output of these
processes would be similar to that described here.
Fluidized Bed Calcination
In the fluidized bed calcination process (other calcination processes are also fea-
sible), the liquid HLW is atomized as it enters the calciner vessel, which is heated by an
in-bed combustion system. When the atomized HLW is injected into the hot bed, the waste
constituents are converted to solids (primarily oxides) that adhere to the surface of par-
ticles already in the bed. The bed is fluidized by heated air entering through perforations
in the bottom support plate. Calcined product is removed continuously so that the bed
AIR
SPRAY CALCINER TOFF-GAS TREATMENT
FRIT ADDITION
FFILTERS
STORAGE RACK
DIVERTER r I I
Si MDECONTAMINATION
I STATION
STATION
FIGURE 4.3.5. Flow Diagram for Spray Calciner/In-Can Melting Process