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The system that strips radioactive cesium out of Hanford’s most dangerous tank waste is running again, and federal officials say the six months it sat idle cost the cleanup more than time.
The Tank-Side Cesium Removal system, known at the site as TSCR, restarted operations on Sept. 15 after being paused since Feb. 25, according to the U.S. Department of Energy’s Office of Environmental Management and the American Nuclear Society. The unit sits near the Hanford Site’s tank farms outside Richland and feeds pretreated low-activity waste into the Waste Treatment and Immobilization Plant, the massive vitrification complex Hanford workers call the Vit Plant, where it gets turned into glass for disposal.
The reason for the pause was blunt: Tank AP-106, the receiving tank downstream of TSCR, filled up. DOE says the tank was holding roughly 1 million gallons of pretreated waste with nowhere further to send it, so the system had to stop until the Vit Plant’s Low-Activity Waste Facility could work through enough of the backlog to make room. Since vitrification at that facility began in October 2025, more than 240,000 gallons have moved out of AP-106 into the plant, DOE says. The current TSCR batch is expected to run through the rest of September and add roughly 230,000 more gallons of pretreated waste to the queue.
DOE and its tank-waste contractor, Hanford Tank Waste Operations and Closure, or H2C, used the framing on offer to most cleanup contractors: a shutdown as an opportunity. The agency says the six months were spent on maintenance, equipment upgrades, worker training, and construction of a new weather enclosure for the unit. “The restart underscores why Hanford is advancing a dual glass-plus-grout approach for appropriate treated waste streams,” said Mat Irwin, DOE’s assistant manager for tank waste operations, in a statement carried by the American Nuclear Society and the Center Square wire service. H2C president and program manager Ken Langdon said the broader effort marks progress “never done before” in reducing the volume of waste sitting in Hanford’s underground tanks.
What DOE’s statement does not say as plainly is what a six-month bottleneck means for the pace of the cleanup it is paid to run. The Defense Nuclear Facilities Safety Board, the independent federal body that oversees safety at Hanford and the nation’s other nuclear-weapons cleanup sites, has previously flagged that TSCR may not be able to feed the Vit Plant’s Low-Activity Waste Facility fast enough to keep that facility running at its intended rate — the opposite problem from the one that shut TSCR down in February, but evidence of the same underlying mismatch: retrieval and pretreatment at Hanford are currently outpacing the site’s ability to actually vitrify and dispose of what comes out of the tanks. One local official quoted in coverage of the restart put the cost of the pause in plain terms: “The biggest cost is a six-month delay in risk reduction,” said Destry Henderson, in remarks reported by the Center Square.
Hanford Challenge, the Seattle-based watchdog group that has tracked the site’s cleanup for two decades, has raised the same concern in its own reporting on the restart: that storage capacity constraints on both ends of the TSCR-to-Vit-Plant pipeline are becoming a structural problem, not a one-time glitch. Neither DOE’s public statement nor the contractor’s has addressed what happens if AP-106, or another tank in the chain, fills up again before the Low-Activity Waste Facility’s throughput catches up — a scenario the DNFSB’s own warnings suggest is plausible rather than remote.
The tanks at the center of this story are not an abstraction for Benton County. Hanford remediation remains one of the region’s largest employers, and every month TSCR sits offline is a month of contracted cleanup work not being billed, not being staffed, and not moving toward the legal deadlines the state of Washington and the federal government have fought over for years in federal court. DOE officials floated one possible fix in the same round of statements: a “dual glass-plus-grout” strategy that would let some treated waste streams be stabilized in grout rather than sent through the glass-melting vitrification process alone. Officials estimated that approach could save 12 years and $12 billion in cleanup costs — a projection from Hanford’s own program office, not an independently audited figure, and one Benton County has heard versions of before as the cleanup timeline has slipped across multiple administrations.
DOE has not said what happens to TSCR’s schedule if AP-106 or a successor tank fills again this fall, nor has it published a public timeline for when the Low-Activity Waste Facility is expected to reach full throughput. Hanford’s court-ordered cleanup framework requires regular public reporting on tank-waste progress; residents and the Hanford Advisory Board are due updates in the coming months that should show whether September’s restart holds or whether the region is looking at the same standstill again by spring.
Sources: U.S. Department of Energy, Office of Environmental Management, American Nuclear Society, Just The News / The Center Square.
