The S7G reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on warships. The S7G designation stands for:
This prototype design was a land-based nuclear reactor that did not use control rods. It was tested in the late 1970s and early 1980s at the Modifications and Additions to a Reactor Facility (MARF) plant located at the Knolls Atomic Power Laboratory's Kesselring Site in Ballston Spa, New York. It consisted of an experimental reactor core installed in a modified S5W reactor plant.