Safe affordable fission engine

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SAFE-30 small experimental reactor

Safe affordable fission engine (SAFE) are NASA's small experimental nuclear fission reactors for electricity production in space. Most known is the SAFE-400 reactor producing 400 kW thermal power, giving 100 kW of electricity using a Brayton cycle closed-cycle gas turbine. The fuel is 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 is called a heatpipe power system.[1][2] The reactor is about 50 centimetres (20 in) tall, 30 centimetres (12 in) across and weighs 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 reactor called SAFE-30 was made first.[4]

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

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

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. Retrieved February 23, 2009.[dead link]
  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.