KRUSTY - not the clown

Source: U.S. tests nuclear power system to sustain astronauts on Mars | Reuters

Initial tests in Nevada on a compact nuclear power system designed to sustain a long-duration NASA human mission on the inhospitable surface of Mars have been successful and a full-power run is scheduled for March, officials said on Thursday.​

Source: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170002010.pdf

Abstract— The development of NASA’s Kilopower fission reactor is taking large strides toward flight development with several successful tests completed during its technology demonstration trials. The Kilopower reactors are designed to provide 1-10 kW of electrical power to a spacecraft or lander, which could be used for additional science instruments, the ability to power electric propulsion systems, or support human exploration on another planet. Power rich nuclear missions have been excluded from NASA mission proposals because of the lack of radioisotope fuel and the absence of a flight qualified fission system. NASA has partnered with the Department of Energy’s National Nuclear Security Administration to develop the Kilopower reactor using existing facilities and infrastructure and determine if the reactor design is suitable for flight development. The three- year Kilopower project started in 2015 with a challenging goal of building and testing a full-scale flight-prototypic nuclear reactor by the end of 2017. . . . ​

The architecture is a U-235 core that is launched, non-critical. Then a beryllium oxide reflector cylinder around the core moves into position to enable fission. The heat then goes to a pair of Sterling engines with heat-pipe connected radiators. The claim is it is a self regulating system that failure of a Sterling engine or radiator(s) would end the fission reaction. But this isn't well explained, yet.

There have been similar claims, some tested, of other reactors, molten salt reactors being one. The thermal expansion would expand the fission material to a low enough density to stop the reaction. There would still be highly radioactive by-products that continue to generate heat. Still the power generated is very attractive as the distance from the sun increases.

One interesting approach is to power an ion or similar electric propulsion to achieve greater speeds. This I like.

Bob Wilson

 

Nothing much on the nuclear part (d*mn it) but when I worked for a NASA contractor, I remember reading a report of a 'gas bearing' Sterling engine that due to lack of seal frictions was supposed to have a long, maintenance, service life. Being within a yard of an unshielded fission reaction and in space, this makes a lot of sense.

Source: Advanced Stirling Convertor | Thermal Energy Conversion

Bob Wilson