DEVELOPMENT OF THE BULK VITRIFICATION TREATMENT PROCESS FOR THE LOW ACTIVITY FRACTION OF HANFORD SINGLE SHELL TANK WASTES

AMEC Earth & Environmental, Inc. and RWE NUKEM Corporation have teamed to develop and apply a waste pre-treatment and bulk vitrification process for low activity waste (LAW) from Hanford Single Shell Tanks (SSTs). The pretreatment and bulk vitrification process utilizes technologies that have been successfully deployed to remediate both radioactive and chemically hazardous wastes at nuclear power plants, DOE sites, and commercial waste sites in the US and abroad. The process represents an integrated systems approach. The proposed AMEC/NUKEM process follow the extraction and initial segregation activities applied to the tank wastes carried out by others. The first stage of the process will utilize NUKEM's concentrate dryer (CD) system to concentrate the liquid waste stream. The concentrate will then be mixed with soil or glass formers and loaded into refractory-lined steel containers for bulk vitrification treatment using AMEC's In-Container Vitrification (ICV) process. Following the vitrification step, a lid will be placed on the container of cooled, solidified vitrified waste, and the container transported to the disposal site. The container serves as the melter vessel, the transport container and the disposal container. AMEC and NUKEM participated in the Mission Acceleration Initiative Workshop held in Richland, Washington in April 2000 [1]. Anmore » objective of the workshop was to identify selected technologies that could be combined into viable treatment options for treatment of the LAW fraction from selected Hanford waste tanks. AMEC's ICV process combined with NUKEM's CD system and other remote operating capabilities were presented as an integrated solution. The Team's proposed process received some of the highest ratings from the Workshop's review panel. The proposed approach compliments the Hanford Waste Treatment Plant (WTP) by reducing the amount of waste that the WTP would have to process. When combined with the capabilities of the WTP, the proposed approach will accelerate the tank waste remediation program plan and facilitate meeting the regulatory requirements for the remediation of the Hanford tank wastes. Consequently, the DOE Office of River Protection and CH2MHill Hanford Group identified bulk vitrification as one of the technologies to be investigated in FY03 through a demonstration program [2]. In October 2002, CH2MHill issued a request for proposal for the process development testing, engineering and data package for a non-radioactive (cold) pilot bulk vitrification process, and pre-conceptual engineering of a production bulk vitrification system. With AMEC in the lead, AMEC and NUKEM responded with a proposal. Pacific Northwest National Laboratory (PNNL) will support the proposed project as a key subcontractor by providing equipment, facilities, and personnel to support small-scale testing, including the testing on samples of actual tank wastes. This paper will provide an overview of the pre-treatment and bulk vitrification process, summarize the technical benefits the approach offers, and describe the demonstration program that has been developed for the project.« less