Nuclear submarine

When the S1W pressurized water reactor achieved criticality at Idaho's Naval Reactors Facility in March 1953, it marked the convergence of four streams: Manhattan Project uranium stockpiles and nuclear expertise, wartime advances in pressure vessel metallurgy, submarine warfare lessons from the Battle of the Atlantic, and one relentlessly focused naval officer—Hyman Rickover.

The Manhattan Project created the essential substrate: enriched uranium production at Oak Ridge, reactor physics understanding, engineers who knew how to control fission. But nuclear knowledge alone wasn't enough. Pressure vessels had to contain water at 2,250 psi and 325°C. Reactors needed extreme power density, requiring highly enriched uranium (93%, weapons-grade).

WWII demonstrated that diesel-electric submarines, forced to surface to recharge, were vulnerable. The Battle of the Atlantic proved detection meant death. A true submarine—never needing to surface—would alter naval warfare fundamentally.

Rickover succeeded by eliminating organizational friction. He simultaneously held positions at the Bureau of Ships and AEC, giving unprecedented authority. By December 1948, Westinghouse received the contract for USS Nautilus' S2W reactor. When GE's sodium-cooled reactor for USS Seawolf developed persistent leaks, Rickover abandoned it. Nautilus' pressurized water reactor worked—standardize on PWR.

USS Nautilus launched January 21, 1954, commissioned September 30, 1954. On January 17, 1955, Commander Wilkinson sent: "Underway on nuclear power." The reactor required no oxygen for combustion—submarines could remain submerged for months, limited only by food supplies. Nautilus maintained 20-25 knots submerged indefinitely.

On August 3, 1958, after 96 hours submerged and 2,940 km under Arctic ice, Nautilus crossed the North Pole—"Nautilus 90 North." Impossible for surface ships. Impossible for diesel submarines.

By 2025, the US operates 66 nuclear submarines, Russia 30, China 12. Six nations total operate them. All US naval reactors are pressurized water type, and over 300 civilian PWRs descended from Rickover's standardization.