Evaluation of new concepts for in situ vitrification: Power system, melt insulation, and off-gas containment

In situ vitrification (ISV) is a thermal process that converts contaminated soil into a highly leach-resistant material resembling natural obsidian. The ISV process was developed by the Pacific Northwest Laboratory (PNL)(a) for the US Department of Energy (DOE) to treat soils contaminated with transuranics. Since 1980, ISV has grown from a concept to an innovative technology through bench-, engineering-, intermediate-, and full-scale tests. Efforts by PNL have developed ISV into a technology considered available for limited deployment to remediate contaminated soil. The technology has been transferred to a licensee for commercial application. In September 1991, PNL conducted an operational acceptance test (OAT) of the modified engineering-scale unit. The OAT provided an opportunity to conduct proof-of-principle testing of new concepts for ISV technology. This additional testing was permitted since it was determined that testing of these new concepts would have no impact on the OAT objective. In discussing the proof-of-principle portion of the engineering-scale test, this report presents conclusions from this work and also describes the conceptual bases of the tested concepts, the engineering-scale test equipment and setup, and test results.