Idaho Project Advances Cleanup With Expanded Treated Waste Storage

Idaho Cleanup Project construction of a second storage building increases the storage capacity at the Integrated Waste Treatment Unit to 84 total vaults for safely storing 1,344 canisters of treated sodium-bearing waste.

IDAHO FALLS, Idaho — Idaho Cleanup Project construction crews have completed a new 20,000-square-foot building, more than doubling the current storage capacity for waste treated at the Integrated Waste Treatment Unit (IWTU).

Since beginning radiological operations in April 2023, IWTU has converted more than 279,000 gallons of radioactive liquid sodium-bearing waste to a safer, granular solid using steam-reforming technology. Once in a dried form, the waste is transferred to stainless steel canisters and placed in concrete vaults. Vaults are then transported to two buildings for storage, including the new one recently built.

IWTU is on track to resume waste treatment operations this spring, following completion of scheduled maintenance. During this maintenance pause, IWTU engineers successfully replaced the granulated activated carbon beds, which remove mercury during radiological operations, and swapped out the process gas filter bundles. Gases from the facility's primary reaction vessel are filtered through 18 filter bundles comprised of 342 individual filters. They also conducted minor maintenance operations in the run-up to restart.

The new storage building adds space for an additional 48 vaults for a combined capacity of 84 concrete vaults consisting of 1,344 canisters. Treated sodium-bearing waste will be safely stored in the two buildings until a national geologic repository is available for permanent disposal.

The second storage building has the same stringent design features and operational requirements as the existing storage building. Constructed of structural steel and reinforced concrete, the new structure connects with the existing storage building by a breezeway.

Construction of the new storage building began in 2023 and was completed in early September last year at an estimated cost of $23 million. In December, the U.S. Department of Energy Office of Environmental Management received authorization from the Idaho Department of Environmental Quality to begin storing IWTU treated waste in the building.

Sodium-bearing liquid waste being treated at IWTU was generated during decontamination activities following historic spent nuclear fuel reprocessing runs, which ended at the Idaho Nuclear Technology and Engineering Center in 1992. More than 850,000 gallons of liquid waste from those operations were transferred to three underground stainless steel storage tanks.

Treatment of the liquid waste is required by the Site Treatment Plan, which requires 15% of the liquid waste to be treated per year based on a three-year running average. Once the three tanks are emptied, they and an unused spare tank will be washed, grouted and closed under federal regulations. The site of the underground tanks will then be capped and closed under the U.S. Resource Conservation and Recovery Act.

-Contributor: Erik Simpson