saltstone

Saltstone is a cementitious waste form used to immobilize certain low-activity radioactive wastes at the Savannah River Site in South Carolina, United States. It is produced by mixing a salt-containing waste solution with cementitious materials and pouring the resulting grout into large vaults where it cures to a stable solid.

The grout recipe typically combines cement, fly ash, and ground granulated blast furnace slag with the concentrated waste salt solution. After mixing, the grout is poured into engineered structures and allowed to cure, producing a durable, low-permeability solid that helps limit the release of radionuclides to the environment.

Saltstone is disposed of in the Saltstone Disposal Facility, a near-surface facility adjacent to the Savannah River Site. The facility is designed to meet regulatory requirements for containment, monitoring, and long-term performance, and operates under ongoing oversight by federal and state authorities. The program began in the 1990s as a means to stabilize and isolate liquid radioactive waste by converting it into a solid form suitable for near-surface disposal.

In addition to its primary meaning, the term saltstone can be encountered in other, less common contexts in geology or construction. However, in contemporary practice, the Saltstone program at Savannah River Site is the most widely recognized reference, describing a concrete-based method for stabilizing and disposing of radioactive salt wastes.