NASA to test prototype Kilopower nuclear reactor

This is similar to the &quot;Stirling radioisotope generator&quot; [1] but it is an actual nuclear reactor (albeit a small one). Both systems are a response to the same fundamental problem, the dwindling supply of Plutonium-238 [2]. The Stirling radioisotope generator uses Pu-238 more efficiently than thermoelectric RTGs, and the nuclear reactor from the article dispenses with Pu-238 altogether.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Stirling_radioisotope_generator" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Stirling_radioisotope_generato...</a><p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Plutonium-238" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Plutonium-238</a>

This is a very cool technology, but frankly I have a hard time imagining that it will see much use. NASA sees public protests and scare mongering whenever it tries to fly an RTG, which is based in the radioactive decay of (usually) plutonium, and does not use a nuclear chain reaction. They did fly one on Mars Science Lab, because it was the only way to get enough power for the rover. But it takes a PR hit every time it does so. RTGs are therefore only used when no other technology will work.<p>It think it&#x27;s likely that the public relations nightmare NASA would have to go through to fly an actual reactor will be through the roof.

Okay, this is awesome. 10kW is a serious enough amount of energy to do some fun stuff. Things like rovers that move at km&#x2F;h rather than m&#x2F;h and all day operation. It also solves the &#x27;base load&#x27; problem on deep space missions which would like to use more power for radio communications.

Thermo-acoustic stirling engines have long been a niche product. Seems like a great environment for them to shine, and far better efficiency than RTG&#x27;s.

I thought one of the advantages of the normal RTG is that it is non-mechanical. I would think a mechanical engine has a lot higher fail rates?

More details in this german article: <a href="https:&#x2F;&#x2F;www.golem.de&#x2F;news&#x2F;kilopower-ein-kernreaktor-fuer-raumsonden-1712-131418.html" rel="nofollow">https:&#x2F;&#x2F;www.golem.de&#x2F;news&#x2F;kilopower-ein-kernreaktor-fuer-rau...</a><p>I&#x27;ll summarize some of the interesting points:<p>- The nuclear core (75kg of enriched uranium&#x2F;molybdenum [1]) is designed to not go critical, even if it accidentally falls into the sea and is surrounded by water (which is a good neutron reflector). It only starts when you surround it with a neutron reflector made of beryllium (an even better neutron reflector, mainly due to less absorbtion). Combined with the fact that the reactor only gets nasty when it&#x27;s been running for a while (and thus is already far away from earth) it is a lot safer than plutonium fueled RTGs.<p>- It would be very useful to reach far away destinations (like the orbit of Uranus, Neptun or Pluto) using ion drives, as they need to run for years and solar panels aren&#x27;t effective far away from the sun.<p>- While there have been other attempts at developing nuclear reactors for space, most of them didn&#x27;t go far. They could use an existing research reactor (Flattop [2]) for this project which already has all the required permissions to run, so a lot of paperwork could be saved for the Kilopower experiments.<p>- The Kilopower reactor is the first to use heatpipes instead of pumps for the heat transport and stirling engines for the energy generation. The first experiment was thus to show that the cyclic heat draw of the stirling engine would be safe, because usually nuclear reactors reach an equilibrium between heating up (and thus expanding slighty which slows down the reaction) and cooling down (which accelerates the reaction).<p>- Instead of the planned eight 125W Stirling engines, they&#x27;re currently using two 70W ones from the Advanced Stirling Converter Project [3]. The other ones will be simulated using simple heatsinks.<p>- Theoretically it could run for hundreds of years (after 500 years less than 1% of the uranium will be used), but the Stirling engines will break much sooner than that.<p>[1] <a href="http:&#x2F;&#x2F;www.iaea.org&#x2F;inis&#x2F;collection&#x2F;NCLCollectionStore&#x2F;_Public&#x2F;33&#x2F;034&#x2F;33034319.pdf" rel="nofollow">http:&#x2F;&#x2F;www.iaea.org&#x2F;inis&#x2F;collection&#x2F;NCLCollectionStore&#x2F;_Publ...</a><p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Flattop_(critical_assembly)" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Flattop_(critical_assembly)</a><p>[3] <a href="https:&#x2F;&#x2F;tec.grc.nasa.gov&#x2F;rps&#x2F;stirling-research-lab&#x2F;advanced-stirling-convertor&#x2F;" rel="nofollow">https:&#x2F;&#x2F;tec.grc.nasa.gov&#x2F;rps&#x2F;stirling-research-lab&#x2F;advanced-...</a>

My first thought was &quot;deep space mission&quot;. But because of moving parts involved, this is probably not the use-case.<p>So a bit OT, I was wondering if anyone has yet thought about the solution of still using solar panels for them, but to also use a mirror to focus more light in the direction of the probe or a laserbeam?<p>I mean, theoretical I don&#x27;t see why not, appart from being more expensive? Andd you could also offset the laser&#x2F;mirror cost, because you only need them later on ....<p>(but to be on the safer side, I still would add a RTG)

From <a href="https:&#x2F;&#x2F;ntrs.nasa.gov&#x2F;archive&#x2F;nasa&#x2F;casi.ntrs.nasa.gov&#x2F;20160012354.pdf" rel="nofollow">https:&#x2F;&#x2F;ntrs.nasa.gov&#x2F;archive&#x2F;nasa&#x2F;casi.ntrs.nasa.gov&#x2F;201600...</a><p>2-5 W &#x2F; kg.<p>Solar cells seem to be about 150 W&#x2F;kg.<p>This is relevant for outer system exploration (beyond Jupiter) or maybe for night power on planetary &#x2F; moon surfaces.

Anyone know the approximate size of that thing? Hard to tell from the picture.

I first read &#x27;NASA to test KILLpower nuclear reactor&#x27; and thought are they starting to use Space X naming conventions...

the cold of space and the heat of a nuclear reactor would be the perfect combination for a peltier reaction. not very good for a rover though.

put it in a car

Strap it to an EmDrive and head for the stars!