IDAHO FALLS, Idaho – EM's Idaho Site workers recently completed improvements to the Integrated Waste Treatment Unit (IWTU), including the challenging task of welding a stainless steel alloy designed to withstand high temperatures.
Welders and pipefitters with EM cleanup contractor Fluor Idaho successfully finished initial welds and other modifications to the waste treatment facility’s primary reaction vessel known as the Denitration Mineralization Reformer (DMR). They modified the vessel from a hemispherical bottom to a conical shape, and installed directional nozzles, or gas distributors, to improve the movement of billions of tiny beads inside the vessel needed for efficient waste treatment.
“Haynes 556 is extremely challenging to weld,” Fluor Idaho Project Manager Scott Shurtliff said of the alloy. “It’s a material that’s widely unknown to most other welders in the world.”
A carbon steel DMR mockup allowed the workers to practice their tasks before entering the vessel’s confined space. Welders brought ½-inch-thick curved plates into the 48-inch vessel through a tight 18-inch manway, or portal. They tacked the plates into place before following up with subsequent welds.
“Getting the individual pieces to fit into the out-of-round vessel was one of our biggest challenges,” said welder Ben Hobley. “Some of those cone sections took us over two days to get their shape right before we could start welding on them.”
Noting the uncomfortable working conditions, Hobley said much of the welding required him to bend down to weld at the level of his ankles and knees.
“It was difficult to make things ergonomically comfortable,” he said. “Welding out of position for days on end can be exhausting, but we know how important this project is and we are proud to be a part of it.”
Welder Tyson Pincock echoed Hobley’s comments.
“This was a mentally and physically challenging project considering we had to work in such a tight space,” Pincock said. “We always take pride in our work, but this required the most meticulous attention to detail. We had to be very strategic in how we applied each weld.”
Shurtliff praised the crew headed by lead pipefitter Eric Lewis.
“I was very impressed with everyone,” he said. “They’ve been a very good team.”
Fluor Idaho Program Manager Fred Hughes said the welders and pipefitters completed their work safely and ahead of schedule.
“I want to thank them for their get-it-done attitude as well as their professionalism during the entire effort. They are clearly leaders in their fields.” Hughes said.
All welds will be inspected before the next IWTU demonstration planned for March. Following treatment of a simulant demonstrating proper operation of the facility, crews will inspect the DMR and welds to ensure the facility is ready for operations.
The IWTU will use a fluidized bed steam-reforming process to treat the remaining 900,000 gallons of liquid radioactive waste from the Idaho Site’s underground tank farm. The beads in the DMR are kept in a fluidized state with the help of superheated gases. Liquid waste enters the fluidized bed, coating the beads like the formation of pearls. The waste product is transferred to stainless steel canisters and ultimately concrete vaults.