S1W reactor

The S1W reactor was the first prototype naval reactor used by the United States Navy to prove that the technology could be used for electricity generation and propulsion on submarines.

The designation of "S1W" stands for

• S = Submarine platform
• 1 = First generation core designed by the contractor
• W = Westinghouse was the contracted designer

and is a later Navy designation. During the plant's early years the project name was "Submarine Thermal Reactor" (STR)

The land-based nuclear reactor was built at the National Reactor Testing Station, later called Idaho National Engineering Laboratory near Arco, Idaho.^[1] The plant was the prototype for the power system of USS Nautilus (SSN-571), the world's first nuclear-powered submarine, which used the improved S2W reactor. The specific location within the vast Idaho National Laboratory where the S1W prototype was located was the Naval Reactors Facility.