PNNL

Abstract

Current estimates indicate that the Hanford tank farm system will run out of available storage space prior to startup of the Pretreatment facility. Deployment of a Near Tank Cesium Removal (NTCR) system could allow LAW processing to begin as soon as WTP LAW Vitrification Facility or supplemental treatment (e.g. bulk vitrification) becomes available, freeing up tank space and beginning waste cleanup several years early. The NTCR will be a mobile, shielded, self-contained system that requires only limited process chemicals and separates the HLW into two process streams. The low activity, Cs-decontaminated waste stream from the NTCR can be vitrified, while the high-activity Cs-rich stream would be stored in the Double Shell Tank system until vitrified by the WTP High Level Waste (HLW) Facility. The NTCR system will be an elutable ion exchange (IX) system based on the Spherical Resorcinol Formaldehyde (SRF) resin, which uses interim storage vessels, process chemical tanks, two IX columns and a resin digestion system. After multiple load-elute cycles the exhausted resin can be dissolved and digested with nitric acid at elevated temperatures, eliminating the need for a separate resin disposal pathway. Rapid deployment of the modular system is enabled by the use of the SRF resin, a simplified flowsheet, resin lifetime extension using cooled nitric acid as the eluant, and resin digestion. Laboratory scale tests of the NTCR resin dissolution and IX processes were conducted to provide data for the design of a demonstration unit (pilot plant) and to make an initial selection of the process conditions. This paper gives a summary of the NTCR process and results of these tests.