The cocoon will protect the building while radioactivity in the deactivated reactor core decays over the next several decades, making it safe and easier to complete disposition.
This is the seventh of Hanford's nine reactors cocooned. The 100 K Area is the last reactor area in Hanford's Columbia River corridor where cleanup is still progressing.
Part of that process includes debris removal and stabilization at K West Basin. DOE is currently processing and segregating highly radioactive debris, such as contaminated equipment and tools, in the K West Reactor fuel storage basin.
Separating the material allows workers to safely remove water and eventually demolish the basin, reducing risk to the nearby Columbia River.
In August 2023, DOE completed demolition of the K West Reactor Annex, marking another key step toward completing cleanup at the former plutonium production reactor.
Understanding preparations taking place at K West helps show the significance of work underway at the former K East reactor. K West is scheduled for interim safe storage, or cocooning, in 2027.
The project includes draining and removing the reactor's spent fuel basin where the sludge was stored, then placing the reactor building in interim safe storage.
DOE is also preparing to remove some of Hanford's most hazardous legacy waste. The Waste Encapsulation and Storage Facility (WESF) provides safe, compliant underwater storage for 1,936 highly radioactive capsules containing cesium and strontium.
DOE is committed to safely storing the capsules until they can be removed for both interim and final placement. While the capsules are currently in a safe configuration, the WESF is an aging facility. DOE is constructing a mock-up facility for training, constructing the Capsule Storage Area, fabricating capsule transfer equipment and modifying the WESF to install equipment to facilitate capsule transfer to safer interim dry storage, allowing for eventual deactivation of the WESF.
View the Waste Encapsulation and Storage Facility Fact Sheet.