The parties to the Tri-Party Agreement on cleanup at the Hanford Site this week proposed new milestones for dealing with cesium and strontium capsules and bulk sodium at the Department of Energy facility in Washington state.
A new proposed milestone would require any facilities needed to prepare the waste be available by the end of 2047. Currently the Tri-Party Agreement requires the milestone for the new or modified facilities to be set by the end of this fiscal year.
The Tri-Party Agreement is a legally binding document negotiated by the Department of Energy and its Hanford regulators — the Washington state Department of Ecology and the U.S. Environmental Protection Agency. It has been frequently updated since it was signed by the three parties in 1989 to set the schedules and priorities for environmental remediation at the former plutonium production complex.
The most controversial milestone may be a new deadline of August 2025 to repackage and relocate the cesium and strontium capsules, now stored under 13 feet of water, to interim dry storage on an outdoor pad in central Hanford.
Discussions have been underway for months among the Tri-Party Agreement agencies. Oregon sent a letter in January, as it was privy to discussions, saying 2025 would not work for it. It has not commented yet on the tentative agreement made public this week.
The cesium and strontium in the 1,936 capsules were removed from Hanford waste storage tanks from 1974 to 1985 to alleviate the buildup of heat in the tanks. The capsules are now held in wet storage.
The Energy Department has been considering moving the capsules to dry storage for more than a decade, with stakeholders weighing in with concerns that the existing storage pool was extending beyond its design life.
In 2014, the DOE Office of Inspector General told Hanford officials the capsules should be moved to dry storage as soon as possible because their storage pool in the Waste Encapsulation and Storage Facility is at risk in a severe earthquake. The water not only shields workers from radiation, but provides cooling for the cesium and strontium. If the pool loses water, the capsules could heat up and breach. The state of Oregon, among others, has also raised concerns that radiation has deteriorated the concrete walls of the pool.
“Needless to say, we were quite disappointed to see a proposed interim milestone in which the transfer of the cesium and strontium capsules to a new interim safe storage facility would not be completed until Aug. 31, 2025,” said Ken Niles, assistant director for nuclear safety for the Oregon Department of Energy, in a Jan. 24 letter to the Tri-Party Agreement agencies. “That is more than seven and a half years from now and more than 12 years since we raised our concerns to DOE and its regulators.”
There are no apparent technical reasons to delay the move to dry storage, Niles said. Some of the dry storage technology is already available from the commercial nuclear plant industry rather than having to be custom-made for Hanford. Unlike a burial ground, there are not unknown hazards, he said. The Energy Department has extensive experience handling the capsules, which were loaned out for industrial use and research until one sprang a leak in 1990. The Washington state Department of Ecology said DOE asked for the 2025 date based on its expectation of the funding available from 2020 to 2025.
The milestone changes also would require bulk sodium with radioactive contaminants to be addressed. Much of it remains from the liquid sodium-cooled Fast Flux Test Facility, a research reactor no longer operated at Hanford. Smaller quantities were shipped to Hanford in the 1960s and 1970s from other nuclear projects and are now stored at the site. Sodium is stored in Building 402 at the Sodium Storage Facility.
By the end of 2026, DOE would need to submit a conceptual design to the Department of Ecology for a facility or other capability to convert bulk sodium into aqueous sodium hydroxide to be ready by the proposed 2047 deadline. The Energy Department plans to use the aqueous sodium hydroxide in operations at the Pretreatment Facility at the Hanford Waste Treatment Plant. It would neutralize acids and dissolve certain metals. Because converting the bulk sodium will substantially increase its quantity, DOE wants to store it until closer to the planned 2033 start of operation of the Pretreatment Facility.
The proposed changes also include the removal of a requirement to create a plan for any facilities needed to prepare for the disposal of the 300 Area Special Case Waste. The waste has been moved to 200 Area storage and disposal facilities, making its management no longer necessary under the current milestone, according to the tentative agreement. The waste, left from cleaning out 300 Area buildings, initially had an undetermined disposal path because of high levels of radioactivity and difficulties in characterization, classification, and packaging.
The changes also include five target milestones, which are not legally binding, to keep the bulk sodium and cesium and strontium capsules on track to meet the three key proposed milestones, which would be legal requirements for DOE.
A public comment period is open until July 6. Submit comments to [email protected]. No public meeting is planned, but one will be considered if there is enough interest.
