Annealing (metallurgy) brass can be cooled slowly in air, or quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. In this fashion, the metal is softened and prepared for further work—such as shaping, stamping, or forming. Annealing occurs by the diffusion of atoms within a solid material, so that the material progresses towards its equilibrium state. Heat increases the rate of diffusion by providing the energy needed to break bonds. The movement of atoms has the effect of redistributing and eradicating the dislocations in metals and (to a lesser extent) in ceramics. This
Liquid metal cooled reactor the only U.S. submarine to have a sodium-cooled nuclear power plant. It was commissioned in 1957, but it had leaks in its superheaters, which were bypassed. In order to standardize the reactors in the fleet, the submarine's sodium-cooled reactor was removed starting in 1958 and replaced with a pressurized water reactor. Liquid metal cooled reactors were studied by Pratt & Whitney for use in nuclear aircraft as part of the Aircraft Nuclear Propulsion program. The Sodium Reactor Experiment was an experimental sodium-cooled nuclear reactor sited in a section of the Santa Susana Field Laboratory then operated by the Atomics International