Radioactive Wastes Dispersed in Stabilized Ash Cements

摘要

Although cementation is a standard S/S treatment process, many cemented wasteforms are failing to qualify for underground disposition because of transport and/or disposal requirements. We have been evaluating supercritical CO_2 carbonation of OPC to alter the bulk phase chemistry, which accelerates the natural aging (carbonation) reactions. This treatment process produces a chemically stable form having substantially-reduced levels of free liquids and organics, as well as reduced porosity, permeability and pH. The promising results obtained with SCCO_2 treatment of OPC leads us to speculate that fly ash-modified OPC may produce a highly efficient immobilization matrix. The structural and chemical changes produced by the treatment process should allow for a reduction on waste volume and a reduced mobility of anions, cations, and radionuclides in aboveground and underground repositories.