Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space heat rejection systems. These heat pipes would be incorporated into a large radiator for waste heat rejection from a space nuclear power source. Current fabrication technology limits the heat pipes to straight lengths, although different cross‐sections can be fabricated. A radiator analytical model was developed and used to examine the effects of fin pipe cross‐section and fin material on radiator mass. Carbon‐Carbon, Compglas, and beryllia fins were examined. The overall radiator mass was only slightly affected by the choice of material, however, the carbon‐carbon design required fewer fin heat pipes. Radiators with carbon‐glass composite (Compglas) fins had a slightly higher mass, but may still be attractive based on the other properties of Compglas, including resistance to atomic oxygen, and the ability to be fabricated into thin sheets. Square Nb/Alumina tubes have already been fabricated, while rectangular niobium composite tube is under development. These tubes will be bonded to carbon‐carbon or Compglas fins, and fabricated into sodium heat pipes.
