The Department of Energy expects it will be early 2023 before an Amentum-led contractor starts pretreating its third batch of low-level radioactive tank waste at the Hanford Site in Washington state.
An ongoing planned outage could take a few more months, a DOE spokesperson said by email Wednesday. That is longer than the agency’s characterization in August, when it said the outage at the Tank Side Cesium Removal (TSCR) project should wrap up in weeks.
The DOE and tank farms prime Washington River Protection Solutions are also planning a briefing by early January to answer Defense Nuclear Facilities Safety Board questions about work practices at TSCR.
TSCR is a vital link in the Direct Feed Low Activity Waste program to turn low-level radioactive tank waste into glass at the Waste Treatment and Immobilization Plant by the end of 2023. TSCR removes solids and cesium from tank waste prior to vitrification.
In an Oct. 6 letter from Defense Nuclear Facilities Safety Board Chair Joyce Connery to Secretary of Energy Jennifer Granholm, the board “requests a briefing within 90 days of receipt of this letter” on safety issues at TSCR. Ninety days from Oct. 6 is Jan. 4, 2023.
The board is an independent safety watchdog charged by congress with providing outside analysis and recommendations to DOE about defense nuclear facilities.
The contractor continues to update safety documents and make upgrades to equipment at the TSCR project since the second batch run ended in late July, a DOE spokesperson said by email Wednesday.
The board’s concern over the pretreatment system dates to an October 2021 contractor readiness assessment. DNFSB staff watched the contractor remove an ion-exchange column from TSCR and replace it with a new one: a chore that must be done every few months.
DNFSB staff said there was damage to the “threaded connections” or couplers used to connect the ion exchange columns to the system, according to Connery’s letter. The DNFSB staff concluded the contractor’s evaluation and repairs don’t meet requirements of the American Society of Mechanical Engineers for nuclear quality assurance, according to the letter.
A lot has changed since then, according to the DOE spokesperson. New transfer hoses on the system were installed during the first planned outage in the spring. More cameras were installed to improve visibility inside the treatment system.
Also, a few components used to connect the ion exchange columns to the system were redesigned, the spokesperson said. Additionally, a faulty valve indicator was replaced to avoid getting a false reading on whether a valve is open.
The contractor is also working on improved procedures for disconnecting ion exchange columns once they become loaded with cesium, the spokesperson said. Part of this effort includes gleaning critical information from workers on how to improve radiological safety when switching out the ion exchange columns.
The Defense Nuclear Facilities Safety Board sought a detailed briefing on what’s being done to minimize damage to threaded ChemJoint connections that attach the columns to TSCR. As early as November 2021, the board has voice concerns that parts of the system might be prone to leaks due to friction between metal surfaces that could result in damaged threads and compromised connections over time.
Washington River Protection Solutions and DOE rely too much on “skill of the craft” to ensure the connections have adequate thread to hold together in the event of a flammable gas explosion, the safety board said in its letter this month to DOE.
Operation of the TSCR system will start back up when the contractor team, the equipment, and the revised procedures are ready, according to the DOE spokesperson.
The TSCR project, which uses similar technology to a system at the DOE’s Savannah River Site in South Carolina, employs ion exchange columns to filter out undissolved solids and radioactive cesium from liquid waste before sending the stream to the Waste Treatment and Immobilization Plant to be solidified into glass.
So far, TSCR has pretreated 380,000 gallons of waste during two batch runs. The first occurred between January and March and pretreated 198,000 gallons while the second one from June to July handled 182,000 gallons according to DOE.
The agency’s goal is to have a million gallons of pretreated tank waste ready to run through the Direct Feed Low Activity Waste Facility at the Waste Treatment and Immobilization Plant, for conversion into glass, starting by the end of 2023. Because of delays attributed to the COVID-19 pandemic, an amended federal court order allows DOE to bump the startup of the plant until early 2024.
The Hanford Site has about 56 million gallons of radioactive waste left over from decades of plutonium production for the U.S. military complex.
