New poppy seed-sized fuel pellets could power nuclear reactors on the moon

Oct 30, 2021
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TO BE CLEAR, this is a fission reactor, not a fusion reactor, as the article claims.

No doubt we will one day utilize fusion reactors for our future energy needs but we are still decades away from that being a reality (both practical and actual).

Still, Rolls-Royce is doing some pretty amazing work with just modest funding, scaling this down to something that's on a practical scale to launch and operate on the Moon and other planetary bodies, as well as large strides in efficiency - converting the resulting reactionary heat into useable energy.
 
The article is very misleading in that it seems to imply that only one tiny particle makes a reactor. That is not correct - it takes a lot of these particles mixed into something like a stack of graphite blocks, or perhaps loose inside a pebble bed, to support a nuclear fission chain reaction.

These fuel particles are not a new concept. The Fort St.Vrain nuclear power reactor in the U.S. was built and operated with these fuel particles. (see https://en.wikipedia.org/wiki/Fort_Saint_Vrain_Nuclear_Power_Plant ) Gulf General Atomic designed it, The fuel TRISO particles are contained in graphite blocks that have cooling holes through them, and are stacked inside a containment vessel that is filled with helium for collant. The hot helium is circulated through steam generators to make the steam to run turbines to turn generators to make electric power.

The recent work really only explores changes to the materials used in the fuel particles to make them even more resilient to high temperatures.

The attractive attributes of these particles is that they can operate at much higher temperatures than metallic fuel elements, so they can produce much more efficient nuclear reactors (~40% thermal efficiency). Although they do not leak fission products, but they do not capture the ionizing radiation emitted by the fission process or the radioactive decay of the fission products. So shielding is required if personnel will ever be in the vicinity once the reactor has been run at power, even when it is subsequently shut down.

These fuel pellets are designed to not be recycled, so they would be disposed in geologic repositories here on Earth for ground based nuclear power plants. The ceramic outer layers of these pellets are designed to not degrade like metallic fuel rods degrade, so they would not be leaking radioactive contaminants into the environment even after being buried in a nuclear waste repository that failed and was flooded with water some time in the distant future.

For space colonies, these types of reactors make good sense. They are efficient and can be made relatively light in weight. They do not require a lot of maintenance.
 

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