RICHLAND, Wash. – Observing COVID-19 safety protocols, workers recently started construction of concrete pads that will hold a waste pretreatment system vital to the Hanford Site cleanup mission.
The concrete pads are located next to the underground tank storage area called AP Tank Farm and will hold the Tank-Side Cesium Removal system. The system will pretreat tank waste for vitrification at the nearby Waste Treatment and Immobilization Plant’s Low-Activity Waste Facility.
Hanford tank operations contractor Washington River Protection Solutions worked with subcontractor AVANTech to design and fabricate the cesium removal system at an offsite facility. Testing this spring confirmed mechanical, electrical, and instrument systems work properly, and the system removes radioactive cesium and solids as intended.
“Completing acceptance testing was the culminating achievement of 18 months of design and fabrication,” said Janet Diediker, acting federal project director for the EM Office of River Protection. “Kudos to the tank operations contractor and its subcontractor on achieving this major success while observing pandemic safety requirements.”
The pretreatment system is a key component of the treatment of tank waste using the Direct-Feed Low-Activity Waste (DFLAW) approach, which will send the pretreated waste directly from the tank farms to the Low-Activity Waste Facility for vitrification. Progress on the project supports EM’s 2020 priority of completing DFLAW construction and turnover for commissioning.
“The cesium removal system is a critical part of the approach to treat low-activity tank waste,” said Kim Smith, the contractor’s project manager for demonstration of the cesium removal system. “The teams put in a lot of hard work to take this from concept to design to reality, and we’re confident of the result.”
The system process enclosure holds two filters for straining out solids and three ion exchange columns for removing cesium from tank waste. During acceptance testing, the team ran simulated waste through the system to test operating conditions. Workers will move the system components from the AVANTech facility to the new concrete pads later this summer, with additional onsite testing to follow.
During pretreatment operations, tank waste will flow through the columns at about five gallons per minute. A double-shell tank at the AP Tank Farm will store the pretreated waste until it is fed via underground piping to the Low-Activity Waste Facility, where it will be vitrified — heated to 2,100 degrees Fahrenheit, mixed with glass-forming materials, and poured into stainless steel containers for disposal.
During testing of the pretreatment system, the team also demonstrated the removal and installation of the ion exchange columns using a forklift. Forecasted to be full every 25 days, the ion exchange columns will weigh about 26,000 pounds each when replaced by the system operator teams. These “spent” columns will be placed on a nearby concrete pad — also under construction — for interim storage.
Familiarization and training of both maintenance workers and cesium removal system operators has recently begun to prepare for the full activation of the new system.