SP-100 (Space reactor Prototype [1]) 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. [2]
A reactor was developed with heat pipes transporting the heat to thermoelectric generators. It was cooled with lithium. [3] The project never advanced to flight hardware and was terminated in 1994. [4]
The SP-100 program objective was to develop the technologies needed for a broad range of space missions requiring a high power-to-weight ratio with nominal 100 kWe power output. The program began in 1982 and was terminated by Congress in 1994. A high temperature (1350 K) refractory alloy heat transport system with thermoelectric power conversion was designed, uranium nitride fuel was fabricated and irradiated to 6% burnup, and significant amounts of hardware and electronics were successfully tested.