Leach testing of in situ stabilization grouts containing additives to sequester contaminants

This document discusses laboratory testing performed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford Company (WHC) of special grout formulations that incorporate specific sequestering agents to help improve the ability of the cement to resist contaminant leaching. To enhance the sequestering of contaminants we chose five additives to introduce (singly) to the control cement. The additives were Florida pebble phosphate, clinoptilolite (a natural zeolite), ferrous sulfide (a reductant), a mixed bed organic ion exchange resin and a proprietary anion-adsorbing mixed metal oxide. These additives were added one per test to the standard formulation and used to encapsulate a diluted high-salt alkaline liquid waste that is produced after various processes to remove uranium and plutonium from spent nuclear fuel. This report documents the testing of these additives.