FIELD: nuclear power systems for space engineering. SUBSTANCE: power plant has thermionic conversion power reactor with core functioning as heat source and direct heat-to- electricity converter, as well as reactor cooling system in the form of circulating loop with radiating cooler, pumping unit, and coolant pipelines. Newly introduced additional heat-to- electricity converter is mounted beyond thermionic reactor core and has delivery pipeline connected to pipeline section running between thermionic reactor and radiating cooler, discharge pipeline connected to pipeline section between radiating cooler and pumping unit, additional system for releasing heat not converted in thermodynamic cycle of additional converter, and device that functions to convey coolant flow from thermionic reactor to additional converter. Thermoelectric or thermionic converter, motor-generator set built around Rankine-, Brayton-, or Stirling-cycle steam or gas machines, and regenerative electrochemical generator may be used as additional converter. Power plant can be used to convey space vehicles including information ones to stationary and, primarily, geostationary orbit to feed space vehicles for long period of 10 to 15 year. EFFECT: improved service life at low power requirement. 5 cl, 2 dwg
