DEVELOPMENT OF A ROTARY MICROFILTER FOR SAVANNAH RIVER SITEHIGH-LEVEL WASTE APPLICATIONS

摘要

The processing rate of Savannah River Site (SRS) high-level waste decontamination processesrnare limited by the flow rate of the solid-liquid separation. The baseline process, using arn0.1 micron cross-flow filter, produces ~0.02 gpm/sq. ft. of filtrate under expected operatingrnconditions. Savannah River National Laboratory (SRNL) personnel identified the rotaryrnmicrofilter as a technology that could significantly increase filter flux, with throughputrnimprovements of as much as 10X for that specific operation. With funding from the U. S.rnDepartment of Energy Office of Cleanup Technology, SRNL personnel are evaluating andrndeveloping the rotary microfilter for radioactive service at SRS.rnThis work includes pilot-scale and actual waste testing to evaluate system reliability, the impactrnof radiation on system components, the filter flux for a variety of waste streams, and relativernperformance for alternative filter media. Personnel revised the design for the disks and filter unitrnto make them suitable for high-level radioactive service. Work to date provides the followingrnconclusions and program status.rn? The actual waste testing conducted with Tank 37H supernate and Tank 51H sludgernshowed a 10X increase in flux over similar tests conducted with cross-flow filters.rn? Pilot-scale simulant testing showed a 1.5 – 3X increase in flux over similar testsrnconducted with cross-flow filters.rn? The pilot-scale rotary filter operated for over 3000 hours without significant mechanicalrnproblems.rn? Pilot-scale testing with irradiated filter disks (at ~5 year equivalent dose) showed nornadverse impact on filter flux, but some weakening of the epoxy-Ryton? bond. Arnreduction in flux was observed, but the reduction is believed to be due to differences inrnfeed particle size.rn? The authors modified the design of the filter disks to remove epoxy and Ryton?. Thernnew design includes welding both stainless steel and ceramic filter media to a stainlessrnsteel support plate. The welded disks were tested in the pilot-scale unit. They showedrngood reliability and met filtrate quality requirements.rn? The authors modified the design of the unit, making removal and maintenance easier.rnFabrication of the unit for remote, nuclear service is in progress.rn? The project team plans to use the rotary microfilter as a filter in advance of a smallrncolumn ion exchange process under development for potential deployment in SRS wasterntank risers.