USS Seawolf SSN 575

• Second Nuclear Submarine: USS Seawolf (SSN-575) was the second nuclear-powered submarine ever built, following USS Nautilus (SSN-571). • Experimental Power Plant: Unlike Nautilus's pressurized water reactor, Seawolf was initially fitted with a sodium-cooled nuclear reactor, which was experimental and unique in the U.S. Navy. • Reactor Replacement: Due to operational challenges and safety concerns, Seawolf’s sodium-cooled reactor was replaced with a more conventional pressurized water reactor in 1958-1960. • Longest Submerged Voyage: In 1957, Seawolf set a record by remaining submerged for 60 days, demonstrating the endurance advantages of nuclear power. • Presidential Visit: President Dwight D. Eisenhower became the first sitting U.S. President to submerge aboard a submarine when he visited Seawolf in 1957. • Advanced Sonar Testing: Seawolf was used as a test platform for new sonar systems, playing a key role in advancing U.S. Navy underwater detection capabilities during the Cold War. • Arctic Operations: Seawolf participated in early under-ice operations, exploring the feasibility of nuclear submarines operating in the Arctic Ocean. • Silent Running: The submarine was one of the first to experiment with quieting measures to reduce noise and improve stealth. • Unique Crew Experience: Due to the sodium-cooled reactor, early Seawolf crew members underwent special training and procedures not required on other submarines of the era. • Decommissioning and Disposal: USS Seawolf was decommissioned in 1987 after 30 years of service, and its reactor compartment was disposed of at the Hanford Site in Washington.