The Department of Energy expects to begin transferring cesium and strontium capsules from underwater storage at the Hanford Site in Washington state to dry storage in 2022. The latest step toward that goal has been identifying a proposed location at Hanford for dry storage and completing a conceptual design of a new concrete pad storage area.
The 1,335 cesium capsules and 601 strontium capsules now are stored under 13 feet of water at the Waste Encapsulation and Storage Facility (WESF) adjoining the B Plant processing facility in central Hanford. The capsules are estimated to contain about one-third of the radioactivity at the former plutonium production site. The underwater storage protects workers from radioactivity and helps keep the capsules cool.
The Energy Department has considered moving the capsules to dry storage for more than a decade. But it took a 2014 report by the DOE Inspector General’s Office to push the project forward. The IG said the capsules should be moved as soon as possible because of the potential for damage to the storage pool in a severe earthquake. A loss of water could cause the capsules to overheat and breach.
The dry storage area is planned for the 200 East Area, southwest of WESF. The Energy Department said the site is more than 6.5 miles from the Columbia River and more than 500 feet from wetlands, a natural area preserve, and a bald eagle protection area. Construction is expected to start in 2019 and wrap up in 2020. DOE has not released a cost estimate for the project.
The capsules will be packaged in stainless-steel sleeves, which will be inserted in additional stainless-steel containers. Those will go into steel-lined, reinforced concrete casks for storage standing upright on the outdoor pad. The cask will provide radiation shielding, and heat will be dispersed with passive airflow starting at inlet vents and rising through the interior space between the vertical concrete cask and steel liner. The storage system is similar to that used to store spent commercial nuclear fuel around the nation.
The cesium and strontium were removed from Hanford’s underground waste tanks in the 1970s to reduce the temperature of the radioactive and chemical waste in storage.
The planned outdoor dry storage is a temporary measure until the capsules can be disposed of permanently, likely in a deep geological repository. They had been candidates for disposal in a deep borehole until DOE dropped plans for a test borehole this spring.
