Naval Reactors (NR) is an umbrella term for the U.S. government office that has comprehensive responsibility for safe and reliable operation of the United States Navy's nuclear propulsion program. A single entity, it has authority and reporting responsibilities within both the Department of the Navy (NAVSEA, Chief of Naval Operations) and the Department of Energy (National Nuclear Security Administration).
Program responsibilities are delineated in Presidential Executive Order 12344 of February 1, 1982, and prescribed by Public Laws 98-525 of October 19, 1984 (42 USC 7158), and 106-65 of October 5, 1999 (50 USC 2406).
Soon after his U.S. Navy service during World War II, Captain (later Admiral) Hyman G. Rickover became an early advocate of nuclear marine propulsion. Assigned to the Bureau of Ships in September 1947, Rickover received training in nuclear power at Oak Ridge, Tennessee, and worked with the Bureau to explore the possibility of nuclear ship propulsion. In February 1949 he received an assignment to the Division of Reactor Development, United States Atomic Energy Commission and then assumed control of the Navy's effort as Director of the Naval Reactors Branch in the Bureau of Ships.
The office was originally a joint activity of the U.S. Atomic Energy Commission (AEC) and the U.S. Navy's Bureau of Ships. When the AEC was abolished, Naval Reactors became a joint effort of the Navy and the Energy Research and Development Administration, which partly replaced the AEC. In 1977, ERDA was combined with the Federal Energy Administration to form the U.S. Department of Energy. On the Navy side of the organization, the Bureau of Ships has transitioned since the 1950s to become the Naval Sea Systems Command (NAVSEA), within which NR is Code 08, usually abbreviated NAVSEA 08 or SEA 08.