Safe affordable fission engine

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SAFE-30 small experimental reactor

Safe affordable fission engine (SAFE) were NASA's small experimental nuclear fission reactors for electricity production in space. Most known was the SAFE-400 reactor concept intended to produce 400 kW thermal and 100 kW electrical using a Brayton cycle closed-cycle gas turbine. The fuel was uranium nitride in a core of 381 pins clad with rhenium. Three fuel pins surround a molybdenumsodium heatpipe that transports the heat to a heatpipe-gas heat exchanger. This was called a heatpipe power system.[1][2] The reactor was about 50 centimetres (20 in) tall, 30 centimetres (12 in) across and weighed about 512 kilograms (1,129 lb). It was developed at the Los Alamos National Laboratory and the Marshall Space Flight Center under the lead of Dave Poston.[3] A smaller test reactor called SAFE-30 was first built.[4]

The working fluid used in the reactor was a helium–xenon gas mixture.[5]

The project was funded with discretionary money in the lab's budget and done mostly outside the researchers' normal work.[6]

As of 2019, this project appears to have been superseded by Kilopower.[citation needed]

See also[edit]


  1. ^ David I., Poston; Richard J. Kapernick; Ray M. Guffee (2002). "Design and analysis of the SAFE-400 space fission reactor". In ohamed S. El-Genk and Mary J. Bragg (ed.). Space Technology and Applications International Forum – STAIF 2002. 608. AIP. pp. 578–588. doi:10.1063/1.1449775.
  2. ^ Blanchard, James P. (2003). "Stretching the Boundaries of Nuclear Technology". Eighth Annual Symposium on Frontiers of Engineering: Reports on Leading-Edge Engineering from the 2002 NAE Symposium on Frontiers of Engineering. National Academies Press. p. 84. ISBN 0309087325. Retrieved July 2, 2014.
  3. ^ Poonawala, Qurratulain (July 24, 2004). "Nuclear adventure: the next evolutionary step in space exploration". Dawn Sci-tech World. Archived from the original on January 21, 2013. Retrieved February 23, 2009.
  4. ^ Poston, David; et al. (2001). "The Safe Affordable Fission Engine (SAFE) Test Series" (PDF). NASA/JPL/MSFC/UAH 12th Annual Advanced Space Propulsion Workshop April 3–5, 2001. Archived from the original (PDF) on October 22, 2004. Retrieved February 23, 2009.
  5. ^ Harty, R.B. (1994). "Application of Brayton Cycle Technology to Space Power". IEEE Aerospace and Electronic Systems Magazine. 9 (1): 28–32. doi:10.1109/62.257140.
  6. ^ Spotts, Peter N. (February 28, 2002). "NASA eyes nuclear rockets to reach deep space". The Christian Science Monitor. Retrieved February 24, 2009.