Workers from the Central Plateau Clean-up Company (CPC Co), contracted by the US Department of Energy (DOE) Environmental Management (EM) Office, have constructed a protective enclosure, or cocoon, over the former K East Reactor building at the Hanford Site near Richland, Washington. The cocoon is designed to protect the reactor building while the radioactivity in the deactivated reactor core decays over the next several decades, making it safer to complete disposition of the reactor in the future.

Just over a year after breaking ground, the workers completed construction of the cocoon around the seventh of nine former plutonium production reactors at the site. The K East Reactor operated from 1955 to 1971. The nearby K West Reactor will be the eighth. The ninth, the B Reactor, has been preserved as the world’s first full-scale plutonium production reactor and is part of the Manhattan Project National Historical Park. Hanford’s other six reactors were cocooned between 1998 and 2012.

DOE said on 26 October that this EM 2022 priority, completed ahead of schedule and under budget, marks a significant accomplishment in EM's risk-reduction clean-up mission along the Columbia River. It was one of EM’s key construction priorities for 2022. The huge steel structure is more than 120 feet tall and 150 feet wide. The interim safe storage structure will protect the K East Reactor building while the radioactivity in the deactivated reactor core decays over the next several decades, making it safer to complete disposition of the reactor in the future.

“Our One Hanford team continues to deliver taxpayer value by safely completing projects that reduce risks to our workforce, our community, the Columbia River and the environment of the Pacific Northwest,” said Brian Stickney, deputy director, EM Office of River Protection and Richland Operations Office. “With this achievement and the exceptional accomplishments over the last few years, I am very optimistic about the Hanford Site’s future.”

Earlier this year, crews finished backfilling and compacting the area around the former reactor with approximately 34,000 cubic yards of sand and gravel to level the site before pouring a 6-foot-thick concrete foundation to support construction of the cocoon. The first steel columns for the enclosure were placed in mid-May with construction of the frame and installation of metal sheeting on the walls and roof continuing through the summer.

The cocoon’s design allows for routine inspections of the reactor every five years. During this check-up, radiation technicians will confirm that no contamination is leaving the sealed reactor core, and that nothing is entering the building from the outside. Additional safety features include new lighting between the structure and the reactor building, as well as upgraded lighting inside the building.

“I’m very proud of our team’s performance on this complex project,” said John Eschenberg, CPC Co president. “So many different skillsets were needed to successfully complete this work. From laborers to trades and crafts to the support of the Department and our regulators, it was a true collaborative effort, and we did it all with a spotless safety record.”

Image: The cocoon over the former K East Reactor building at the Hanford Site (courtesy of DOE-EM)