A new legally binding deadline requires cesium and strontium capsules at the Hanford Site in Washington state to be moved to dry storage by August 2025, though some key stakeholders argued the work should done sooner.
The Department of Energy and its regulators, the U.S. Environmental Protection Agency and the Washington state Department of Ecology, announced the new milestone to the Tri-Party Agreement on Oct. 4.
Hanford keeps 1,936 capsules under 13 feet of water in a concrete pool at the Waste Encapsulation and Storage Facility at the center of the site. The 22-inch-long capsules hold cesium and strontium removed from Hanford’s underground waste storage tanks from 1974 to 1985 to help control the buildup of heat in the containers. The capsules account for about one-third of the radioactivity remaining at the 586-square-mile former plutonium production complex.
The Energy Department has considered moving the capsules to dry storage for at least a decade, with a 2014 report from its Inspector General’s Office helping push the project forward. The report said the capsules should be moved as soon as possible given the potential for damage to the storage pool in a severe earthquake. A loss of water could cause the capsules to overheat and breach, releasing radiation.
Stakeholders commenting before the new milestone was finalized echoed those concerns. A total of five comments were submitted. The Tri-Party Agreement agencies responded to comments in the final approval package for the new milestone, saying funding is the issue even though they agree with the need “for concerted action” to move the capsules to dry storage.
The Energy Department asked Congress for an additional $10 million for the dry storage project in fiscal 2019, but it was not included in the final Hanford-funding appropriations bill signed into law last month. If Congress provides funding beyond what DOE requests for compliance with legal requirements for fiscal 2020, the Tri-Party Agreement agencies would consider accelerating the transfer to dry storage, they said in response to comments.
The Oregon Department of Energy raised concerns as early as 2013 that the concrete walls of the pool now holding the radioactive capsules might have suffered a loss of structural integrity due to high radiation exposure. “We recognize that budget limitations are likely the main reason for the delay and acknowledge that there are many competing priorities,” said Ken Niles, the Oregon Department of Energy nuclear safety administrator, in a submitted comment. “We simply believe this should be one of the highest spending priorities at Hanford and again encourage the Tri-Parties to elevate this project so that this risk is alleviated well before 2025.”
Richland, Wash., Mayor Bob Thompson, representing the Hanford Communities Governing Board, said in a public comment that the “capsules pose a serious risk to the health and safety of our region. … With concrete weakened by radiation, stresses from an earthquake could lead to direct failure of the walls or bottom of the basin, causing water to drain from the pool.” Hanford Communities is a coalition of Hanford area-local governments.
Tri-City Development Council leaders said in a public comment that there is a low probability of an event that would drain the pool holding the capsules of water. But such an event would present a substantial risk to Hanford workers, the public, and the environment, they said: “Considering these risks, and that there are relatively few technological challenges associated with the project, we believe every effort should be made to place the capsules into more secure dry storage as soon as possible.”
Plans for dry storage call for the capsules to be packaged in a stainless-steel sleeve, which will be inserted into another stainless-steel container. That will go into a steel-lined, reinforced concrete cask for storage upright on an outdoor pad. The cask will provide radiation shielding, and heat will be dispersed with passive air flow starting at inlet vents and rising through the interior space between the vertical concrete cask and steel liner. The storage approach is similar to that used to store spent commercial nuclear fuel around the nation.
The planned outdoor dry storage is a temporary measure until the capsules can be disposed of permanently. Under a separate Tri-Party Agreement milestone set late last month, facilities would be ready by 2047 to process the cesium and strontium for final disposition. That date is intended to ensure a plan is in place while Hanford’s Waste Treatment Plant is still operating. One option would be to remove the radioactive contents from the capsules and vitrify the material at the plant. Alternately, the capsules could be sent directly to a national deep geological repository for high-level waste. The capsules had been candidates for disposal in a deep borehole until DOE dropped plans for a test borehole in spring 2017.
