The Department of Energy’s long-awaited Integrated Waste Treatment Unit at the Idaho National Laboratory could start operating in mid-fall, perhaps October, a Fluor Idaho executive told the online Waste Management Symposia Monday.

The facility is now in the final weeks of an extended maintenance period that will precede a 50-day test run and eventual approval from the state and federal governments to start hot commissioning, Fluor Idaho President Fred Hughes and Joel Case, an assistant manager in DOE’s Idaho field office, said.

That commissioning should start this fall will initially use a mixture of 10% radioactive waste and 90% simulant before advancing to a 50/50 mix, the officials said.

That’s another delay in a long line of them for the Integrated Waste Treatment Unit (IWTU), which was supposed to begin solidifying some 900,000 gallons of sodium-bearing waste nearly 10 years ago. Back in October, a DOE spokesperson said IWTU might begin radioactive operations in June.

Hughes said work on IWTU slowed during 2020 due to the COVID-19 pandemic as the tight quarters at the project made it tough to maintain physical distance between construction workers. Some crews suffered significant productivity losses when key people were quarantined, he added.

Fluor Idaho and DOE coped with this by reducing the amount of concurrent work taking place in adjacent areas as well as using company-wide testing to identify employees who may have had COVID-19 but were not showing symptoms. The contractor also installed robots to vacuum and wipe certain canisters and surfaces inside the IWTU.

Designed to convert about 900,000 gallons of sodium-bearing waste into a more stable form for disposal, the first-of-a kind IWTU was largely constructed in 2012 by former contractor CH2M-WG Idaho. However, the unit never worked as designed, the Government Accountability Office reported in September 2019. Current contractor Fluor Idaho has re-engineered much of the plant and, since 2012, the cost estimate for the project has grown from $570 million to more than $1 billion.

Startup of IWTU is deemed one of DOE’s Priority No. 2 projects scheduled for 2021, according to the list published by the cleanup office Monday. The office’s No. 1 priority projects are finishing construction of three projects — the Tank Side Cesium Removal System at the Hanford Site in Washington state; the Saltstone Disposal Unit No. 7 at the Savannah River Project in South Carolina and the Salt Reduction Building on the surface of the Waste Isolation Pilot Plant in New Mexico.