Other Binders - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 145

TABLE 6.5.5
TCLP of HC Concrete Made with Sugar-Calcined
INEEL SBW

μ g/g in the
Leachate

UTS Limit
( μ g/g)

Concentration in Calcine
( μ g/g) Metal

As < 0.002 5 10.8

Ba 0.35 7.6 48

Cd 0.13 0.14 1372

Cr 0.023 0.86 950

Pb < 0.1 0.37 1500

Se < 0.002 0.16 6.9

Ag < 0.1 0.3 1510

chemically inhomogeneous, intrinsically porous material (most calcines and calcine-
containing concretes); and c) since the nominal purpose of performing this test is
to compare one material to another (e.g., concrete vs. EA glass), assuming vastly
different surface areas will produce misleading (grossly biased) results.

6.5.4.2.2 Toxicity Characteristic Leaching Procedure (TCLP)
Most INEEL reprocessing wastes, calcined or raw, fail the TCLP, 13 typically for
cadmium, mercury, chromium, and lead. Table 6.5.5 lists the results of a TCLP test
of an HC made with a sugar-calcined INEEL “sodium bearing waste” simulant,
which had been doped with unrealistically high levels of several RCRA metals.

6.5.4.2.3 MCC-1 Leach Test
FUETAP concrete performed poorly at retaining 137 Cs as measured by the MCC-1
leach protocol. 14 Consequently, improving 137 Cs leach performance measured by that
particular test was a key goal during the HC development. The MCC-1 exposes a
small monolith of known composition and geometric surface area to a relatively
large volume of 90°C distilled water for 28 days. Normalized leach rates
(gram/m 2 /day) for each constituent are calculated from the concentrations measured
in the leachates.
Table 6.5.6 compares 28-day MCC-1 leach performance of two HC-type con-
cretes with those of four radwaste glasses and a recently developed “glass bonded
sodalite” ceramic. 15 The first HC specimen (HC#1) contained 42 wt% of a repre-
sentative INEEL zirconia-type calcine, crude metakaolin (a cement-extender poz-
zolan produced at a local cement plant), vermiculite, a small amount of sodium
sulfide, plus sodium hydroxide. The second (HC#2) was similar except that the waste
simulant was a mix of all three major types of INEEL calcines (alumina, zirconia,
and fluorinel-blend). The HCs surpassed all of the vitrified materials with respect
to Cs leach performance.
The relative ranking of glasses and HCs with respect to sodium dissolution is
often different with the PCT and MCC-1 tests. The reason for this is that a chunk
of HC presents several orders of magnitude more surface area to the leach water