While most of the grounds were released as safe, a cask storage facility remained under NRC supervision. 533 spent fuel assemblies weighing approximately each are still on-site. They are contained in dry casks made of 21 inches of reinforced concrete, surrounding a -inch-thick steel liner, with each cask weighing 100 tons. The sixteen casks sit on a 3-foot-thick concrete pad. These will be located at the site until the U.S. Department of Energy completes a permanent storage facility for spent nuclear reactor fuel and the spent fuel stored at Rowe can be transferred to such a future federal facility. The time frame for removal of spent fuel from the Yankee Rowe site is unknown.