Idaho’s IWTU surpasses tank waste treatment goal

As of last week, crews with Department of Energy cleanup contractor Idaho Environmental Coalition (IEC) processed more than 142,000 gallons of radioactive sodium-bearing tank waste at Idaho's Integrated Waste Treatment Unit (IWTU) this year.

The amount of treated waste exceeds the DOE's Office of Environmental Management goal of treating 100,000 cumulative gallons in the calendar year, as stated in its 2024 mission and priorities.

According to DOE-EM, in all, the facility has treated more than 210,000 gallons since the start of operations in 2023, which represents about 23 percent of the total 900,000 gallons of liquid waste stored in three underground tanks at the Idaho National Laboratory Site.

Restart of operations: IEC restarted radiological operations at the IWTU, which uses steam-reforming technology to convert the radioactive liquid waste to a granular solid for safe storage, in late August following the completion of two maintenance campaigns.

During that campaign, engineers replaced the IWTU's granulated activated carbon beds, which remove mercury during the sodium-bearing waste treatment process. Crews also replaced process gas filter bundles and conducted minor maintenance operations. Gases from the facility's primary reaction vessel are filtered through 18 filter bundles composed of 342 individual filters.

According to reports by the Defense Nuclear Facilities Board, the facility was shut down early in the year when it was discovered that material was bypassing the process gas filter during operations.

In thanking his crew, IEC program manager Dan Coyne said, "Everyone from the operators, engineers, to support staff have been committed to this project from the beginning." "This benchmark represents the first of many to follow."

The waste: The sodium-bearing waste treated by the IWTU is a byproduct of decontamination and rinse campaigns associated with historic spent nuclear fuel reprocessing runs at the center. The treated, solidified waste is transferred to stainless steel canisters and placed in concrete vaults for on-site storage.

Sodium-bearing waste treatment is expected to take three to seven years to complete, accounting for outages to conduct regular maintenance on the facility, according to DOE-EM.