Abstract: A thermoelectric power system particularly adaptable for use in outer space in which a nuclear reactor heats a working fluid, which in turn supplies heat to a plurality of thermoelectric generators spaced about a ring-shaped support. A first heat pipe is employed to couple heat between the hot fluid and hot junction of the thermoelectric element of each generator, and a second heat pipe couples heat away from the cold junction of each thermoelectric element. Each of the second heat pipes are elongated flexible units adapted to be folded upon launch of the system of a space vehicle and thereafter extended in space to provide a substantial area of radiation of heat to be discharged.