Preparations for a 50-day test-run of a crucial liquid-waste treatment system at the Department of Energy’s Idaho site were cut short Christmas Eve because someone installed an open/closed indicator on the unit’s plumbing backwards, according to the site.
The Integrated Waste Treatment Unit (IWTU), designed to solidify some 850,000 gallons of sodium-bearing, radioactive waste leftover from reprocessing spent nuclear fuel, shut down automatically on Dec. 24 after a failsafe system detected that operating pressures briefly exceeded safe limits when a simulant liquid — a non-radioactive stand-in for the waste — pumped through the unit.
The apparent cause, personnel discovered on Dec. 26, was that someone had installed a valve-position indicator backwards, meaning that some valves were actually wide open when operators thought they were closed tight. The day of the discovery, the unit shut down again, the site wrote in a report on the incident.
But, on Dec. 27, “IWTU began processing simulant” and continued until Jan. 6, when it shut down once more because a vendor said “that it would be unable to deliver the required quantities of nitrogen, which is needed for IWTU’s operations,” a spokesperson for the Department of Energy’s Office of Environmental Management (EM) said Wednesday.
From Dec. 27 to Jan. 6, IWTU processed some 19,000 gallons of simulant “into a stable, granular form,” the EM spokesperson said Wednesday. “We anticipate resuming the confirmatory run soon.”
As of late Thursday, a spokesperson for the Idaho Department of Environmental Quality, the state regulator for cleanup at Idaho, said the state agency had not received a firm ITWU restart date from DOE.
On Friday morning, a DOE spokesperson said via email that the agency and its cleanup contractor, the Idaho Environmental Coalition, are working to provide supplemental drivers with the vendor and industry to better ensure uninterrupted deliveries of nitrogen gas to IWTU.
During its planned 50-day test run, IWTU will use its steam-reforming technology to extract solids from the simulant liquid, demonstrating its ability to prepare the site’s leftover, sodium-bearing, fuel-reprocessing waste for permanent disposal. It is the only facility in the Environmental Management complex, operating or planned, that uses the technology to solidify liquid waste.
All told, it might take IWTU between three and seven years to solidify all 850,000 gallons of waste ticketed for treatment, a DOE official said last fall.
The test run is a major milestone for the novel IWTU, which is now nearing operation after years of delays, tinkering by multiple DOE contractors and cost growth that has swelled the project’s bill to more than $1 billion. The facility was largely finished in 2012, but, until recently, did not work as intended.
Last year the state gave DOE until September 2022 to successfully fill the first canisters of granular waste at IWTU. The deadline was previously June 2021. Completing processing of the first 100 sodium-bearing waste containers at IWTU is listed as one of the Environmental Management office’s key priorities for 2022.
