Preliminary Demonstration of GeoMelt Treatment of Hanford’s K-Basin Sludge

The U.S. Department of Energy (DOE) and CH2M Hill Plateau Remediation Company (CHPRC) are seeking a waste treatment solution for sludge stored in the K-Basin spent fuel pond at the Hanford Nuclear Site, in Washington State, USA. This sludge is a Remote Handled Transuranic (RHTRU) waste destined for final disposal at the Waste Isolation Pilot Pant (WIPP) in New Mexico. Removal of the sludge from the K-Basin and transport for interim storage at the Hanford Site is referred to as Phase 1 in this process. Phase 2 is defined as the treatment and packaging of the sludge such that it can be transported and disposed at the WIPP. This paper discusses work in support of Phase 2. ISI’s GeoMelt ICV process is ideally suited to treating a heterogeneous sludge that is rich in uranium metal and which contains a mixture of other fuel derived products, earthen materials, and miscellaneous items (operational debris, resin, etc). GeoMelt can quickly and efficiently treat small drum load batches and will fully destroy organics, oxidize reactive metals, and permanently immobilize radioactive constituents within a high-integrity vitrified product that will meet or exceed all WIPP acceptance criteria. The GeoMelt Technology has an extensive experience base, having treated more waste by vitrification than any other company in the world (25,500 metric tons). The equipment tested for this Project phase constituted the front end, or Sludge Pretreatment and Transport steps, of the proposed GeoMelt process. These components first focused on an engineering scale (22-liter), followed by testing with a full-scale (130-liter), horizontal rotary plow dryer/mixer. The dryer removes water from the sludge, via external heating and under reduced pressure, and mixes it with glass forming minerals (GFM) prior to treatment in the GeoMelt ICV system. Testing was first performed in July and September 2010 using a 22-liter drying system, which demonstrated a baseline drying technique and allowed an assessment of the resulting physical properties before, during, and after drying/mixing. Full-scale testing using a 130-liter dryer and condensate system was then performed in October 2010. An Operational Acceptance Test (OAT) of the equipment, followed by four “Dryer Holdup” tests and three “GFM Cleanout” tests were performed. Each of the Project Test Objectives was successfully met. Both the 22-liter engineering-scale and the 130-liter full-scale steam jacketed, horizontal plow, dryer are shown to dry and mix 5-vol% solids K-Basin sludge and GFM without difficulty. These test results, combined with previous treatability testing in 2004 wherein successful GeoMelt vitrification of a K-Basin sludge simulant was demonstrated, confirm the efficacy of the overall treatment process towards providing an immediate solution to the final disposition of K Basin Sludge.