SP-100 (Space reactor PrototypeAcronyms: SP-100 means Space reactor prototype) was a U.S. research program for nuclear fission reactors usable as small fission power systems for spacecraft. It was started in 1983 by NASA, the US Department of Energy and other agencies.SP-100, the US Space Nuclear Reactor Power Program, Technical information report. Available at Energy Citations Database
A reactor was developed with heat pipes transporting the heat to thermoelectric generators which would generate 100 kilowatts of electric power, thus the name SP-100. It was cooled with lithium. The project never advanced to flight hardware and was terminated in 1994.
See also Systems Nuclear Auxiliary Power Program and SNAP-10A, that flew in 1965 Safe Affordable Fission Engine, a later project Kilopower, a later small space reactor
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