2. Why Pressurized Water?

The Navy’s need for extended use submarine power drove the initial research into nuclear reactor development. This effort produced two land-based prototypes, followed by operating reactors in Navy subs. The two designs included the PWR of the Nautilus and the Sodium cooled reactor of the Seawolf. The US Navy opted for the PWR design for general use after seeing the difficulties in working with sodium and the relatively strong operating performance of the Nautilus and its land-based prototype. The Nuclear Navy provided an enormous impetus to the development of the PWR type. Rickover used a parallel path development program to ensure that the Navy achieved a nuclear, air-independent propulsion system that would revolutionize submarine technology. By investigating both the PWR and sodium cooled reactor, Rickover managed to create an organization that produced the nuclear powered Nautilus in the 10-year period from the end of the war until the submarine’s launch in 1955. In the end PWR became the dominant, and indeed sole propulsion system adopted by the Navy. The corrosion problems associated with the sodium coolant led to it falling into disuse. Following the Navy success, the Atomic Energy Commission attempted to “seed” commercial nuclear power plant development in the US. This development program used additional commercial entities to design cores, enlist utility partners, and offer alternate reactor design concepts. The end result of this decade-long development effort was numerous sites with one of a kind reactors that had significant design or operating flaws. In the end, it was the Navy’s preferred design type, the PWR that became the design for nearly two third of the commercial operating reactors in the US.