The Department of Energy’s Office of Environmental Management said that crews at the Idaho National Laboratory site are making “significant progress” decommissioning the Submarine 1st Generation Westinghouse (S1W) reactor, the prototype pressurized water reactor that supported the development of the USS Nautilus, the world’s first operational nuclear-powered submarine.

The Department of Energy’s Office of Environmental Management (EM) announced on February 10 that it is set to deactivate and demolish the prototype for the reactor used for the USS Nautilus, the world’s first operational nuclear-powered submarine and the first submarine to complete a submerged transit of the North Pole.