The U.S. Department of Energy (DOE) Office of Environmental Management (EM) has received a shipment of replacement centrifugal contactors for the Salt Waste Processing Facility (SWPF) at Savannah River Site (SRS), which should increase production at the facility by reducing the amount of downtime for maintenance.
Office of Environmental Management
August 6, 2024
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The bank of contactors inside the Salt Waste Processing Facility at Savannah River Site removes radioactive cesium from salt waste. However, the contactors have collected unwanted solids and require frequent chemical cleaning to operate efficiently, resulting in lengthy downtime for the facility. The arrival of 16 new contactors is expected to significantly reduce that downtime and will enable the facility to make extensive run times at higher flow rates.
AIKEN, S.C. — The U.S. Department of Energy (DOE) Office of Environmental Management (EM) has received a shipment of replacement centrifugal contactors for the Salt Waste Processing Facility (SWPF) at Savannah River Site (SRS), which should increase production at the facility by reducing the amount of downtime for maintenance.
The specially engineered contactors are used to remove radioactive cesium from the liquid salt waste stored in underground, carbon-steel tanks at SRS.
By purchasing 16 spare contactors, Savannah River Mission Completion (SRMC), the SRS liquid waste contractor, can now change out an entire bank of extraction contactors instead of replacing individual contactors as they show signs of wear. By having the spare bank of contactors, EM has the best opportunity for longer run times at higher flow rates.
Jim Folk, EM’s assistant manager for waste disposition, said the contactors are vital to the success of the SRS liquid waste mission.
“With the arrival of these spare contactors, we expect SWPF will make great strides in the effort to process liquid waste in a timely and safe manner,” Folk said. “Shorter outages will help keep the liquid waste mission on schedule to finish in 2037 to reduce risk to our community, environment and workers.”
The contactors operate in the Central Processing Area of SWPF. A solvent is fed to one end of a bank of centrifugal contactors while the waste is fed to the other end in a counter-current flow.
The solvent extracts the cesium, with each successive contactor stage extracting more, resulting in a decontaminated salt solution stream and a cesium-laden solvent stream. The solvent stream is stripped of its cesium and washed, and the solvent is reused. The cesium-laden solution, known as strip effluent, is transferred to the Defense Waste Processing Facility to be combined with sludge from the tank farm — a grouping of underground waste tanks — and stabilized through vitrification, or immobilization in glass. The decontaminated salt solution continues through the remainder of the SWPF process and eventually goes to the Saltstone Production Facility, where it is mixed with dry ingredients to form a grout that is pumped into Saltstone Disposal Units for permanent disposal.
SRMC’s Steve Howell, SWPF and End Stream Delivery director, said replacing an entire bank of contactors would previously eliminate a month from the processing schedule because in-service contactors had to be removed, overhauled and then reinstalled during the outage.
"While pauses in processing provide our staff the ability to perform other routine maintenance also, the pauses were considerably longer than we would have liked,” Howell said. “These additional contactors will give us more control over our processing schedule.”
Since coming online in October 2020, SWPF has processed more high-activity liquid waste than the former system processed in 11 years. SRMC’s goal is to improve SWPF’s processing rate so that all liquid waste tanks can be emptied, cleaned and closed by 2037.
-Contributor: Jim Beasley
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