The
S2W reactor was a naval nuclear reactor developed by Westinghouse Electric Corporation for use in the United States Navy's nuclear-powered submarines. The reactor's designation, S2W, stands for "Submarine platform," "second-generation core design," and "Westinghouse," the contractor responsible for its development. It was a pressurized water reactor (PWR) initially installed aboard the '
USS Seawolf
(SSN-575)', the second nuclear-powered submarine launched by the U.S. Navy in 1955. The S2W reactor was originally designed as a sodium-cooled system, but operational difficulties with this cooling method led to its later conversion to a conventional pressurized water reactor. This design provided substantial improvements in submerged endurance and speed over conventional diesel-electric submarines, marking a pivotal advancement in naval propulsion. The S2W reactor, though eventually phased out, was significant in the early stages of nuclear submarine technology and helped shape the U.S. Navy's future reactor designs, which ultimately favored the reliability and operational ease of pressurized water reactors. This
nuclear reactor is the shipboard equivalent of the
prototype S1W reactor, with minor design changes, that was installed on . As installed in
Nautilus it generated . It was originally designated STR.
USS Nautilus (SSN-571) USS Nautilus (SSN-571) was powered by the Submarine Thermal Reactor (STR), later redesignated the S2W reactor, a
pressurized water reactor produced for the US Navy by
Westinghouse Electric Corporation.
Bettis Atomic Power Laboratory, operated by Westinghouse, developed the basic reactor plant design used in
Nautilus after being given the assignment on 31 December 1947 to design a nuclear power plant for a submarine. After
Nautilus was
decommissioned, the reactor equipment was removed. The submarine is now moored and displayed as a
museum ship at the
Naval Submarine Base New London in
Groton, Connecticut. == Variant ==