Case Studies: Full-Scale Operations and Delivery Systems - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 361

TABLE 13.9
Nominal Saltstone composition

wt% of the
Saltstone Product Component

Waste salt solution containing 29 wt% dissolved sodium salts 46

Premixed reagents

Portland cement 6

Ground granulated blast furnace slag 24

Fly ash 24

cementitious reagents (cement, slag, and fly ash) per hour. Mixing is accomplished
in a twin-shaft Readco continuous processor. The resulting waste form slurry is
pumped over 2000 ft through a 3-in carbon steel line and is disposed of in a concrete
vault. The centrifugal pumps and transfer line are cleaned after each production run
with a small amount of water and pigs launched by compressed air. The facility is
typically operated continuously for one shift (6 to 10 hours).

13.4.4.3 High-Level Waste (HLW) Tank Fill

In 1997, two single-shell carbon steel tanks (17-F and 20-F) were emptied and filled
with grout at the SRS to reduce the mobility of residual contaminants and to provide
structural stability to the empty tanks. 9,10 Each tank had a capacity of 1.3 million
gallons and each was originally used to store low-heat waste (no cooling coils or
other obstructions). The waste tank closure strategy required three different fill
materials. Figure 13.14 illustrates the three different fill materials required by the
waste tank closure strategy.
All of the material used to close these radioactive waste tanks was prepared
from non-radioactive ingredients in two portable batching plants. The dry solids
storage silos for each plant are shown in Figure 13.15. Each plant was equipped
with an auger grout/concrete mixer. The auger mixers for both plants discharged

Strong grout
Intruder barrier

CLSM

Reducing grout for encapsulation
Tank heel partially mixed, mostly encapsulated

FIGURE 13.14 Schematic diagram illustrating the three different grout materials designed
to close high-level waste tanks at the Savannah River Site for Case Study #4.