Other Binders - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 119

TABLE 6.2.4
Radiolysis Yield in Various Scenarios and in
Ceramicrete

G(H2) Moles
H2/100ev Material Tested

Pu 239 in water 1.6

Tritiated water in concrete
FUETAP concrete

0.6
0.095

Hanford acid waste in FUETAP cement 0.43

TRU ash in Ceramicrete with 7.87 wt% Pu in ash 0.1

U-Pu alloy in Ceramicrete with 5.2 wt% Pu 0.13

of any organic compounds present in the waste may pressurize sealed containers
during storage of the waste forms. For this reason, Pu-containing waste forms were
subjected to gas generation tests by radiolysis. The results are summarized in Table
6.2.4 in terms of G values defined as the radiation chemical yield to the energy
absorbed, expressed in terms of the number of molecules generated per 100 eV.
Results on the first three examples given in Table 6.2.4 are obtained from the
literature. 17-20 The last two provide the results for Ceramicrete waste forms. The
U-Pu oxide mixture was a result of corrosion of a U-Pu alloy. 6 The TRU combustion
residue was obtained originally from Rocky Flats. It was fully calcined for safe
transport to Argonne; as a result, all organics and combustibles were completely
incinerated and the plutonium concentrated. As Table 6.2.4 indicates, the G values
for Ceramicrete waste forms are lower than for most grout systems and comparable
to that for Formed Under Elevated Temperature and Pressure (FUETAP) concrete.
These observations indicate that the gas yield is acceptable for the Ceramicrete waste
forms.

6.2.6 S UMMARY

The various studies discussed in this section demonstrate that Ceramicrete is a
versatile process for stabilization of hazardous and radioactive waste streams. The
process not only chemically immobilizes the contaminants, but also microencapsu-
lates them with enough leach resistance to pass standard regulatory leach tests and
meet the waste acceptance criteria (WAC) at DOE disposal sites. Ceramicrete is also
an excellent process for macroencapsulation of various contaminated objects. The
waste form is a dense matrix, with good mechanical properties, does not degrade
over time, is neutral to pH, converts flammable waste into nonflammable waste
forms, generates tolerable amounts of gas from self-radiolysis, and can incorporate
a variety of inorganic wastes, including solids, sludge, liquids, and salts. The tech-
nology does not target stabilizing organics at this time, though several tests have
shown that it performs better than some methods. Organics are generally destroyed
by combustion or other chemical means, not stabilized. The resulting ash can be
immobilized in Ceramicrete.