NASA funds nuclear power systems for possible use on the moon

[Admin]

Three companies will demonstrate their potential to power lunar infrastructure using nuclear fission systems, under new joint NASA contracts announced on Tuesday (June 21).

NASA funds nuclear power systems for possible use on the moon : Read more

 

[Unclear Engineer]

I am wondering what that "artists conception" of a nuclear reactor on the moon is based on.

https://cdn.mos.cms.futurecdn.net/B6ftA9CSzp8d2THkiWzfcM-1024-80.jpg.webp

It doesn't look like it has any radiation shielding for astronauts who would be around it, and that umbrella gizmo on top looks like a meteoroid catcher to me, so I hope it isn't some sort of cooling fin that needs fluid to flow through it. Looking at its shadow, it certainly does not look like it is intended to be a sun shade.

Anybody know what this umbrella thing is supposed to do?

 

[billslugg]

The umbrella feature is designed to radiate waste heat into outer space. The electricity generation is by Zeeman effect, basically a bunch of thermocouples. They need a temperature differential to generate electricity.
There is no need for shielding as the astronauts would be far away as it was generating power. It could be hidden behind a boulder or put down inside a crater. When not operating it would be emitting no dangerous levels of radiation.

 

[Unclear Engineer]

OK, if the thermal radiator does not involve flow of liquid or gas coolant that could leak when it hit by a micrometeoroid. But, that "umbrella handle" looks mighty thin for a solid state conductor to take much energy to that large "umbrella" radiator. What is the proposed power level of that reactor?

However, it is not correct to say that a fission reactor does not emit dangerous levels of radiation when it is shut down (fission chain reaction stopped). The fission products are highly radioactive, emitting several percent of the full power of the reactor at the moment of shutdown, and decaying away with a sum of many vastly different half-lives so that it decays very rapidly at first, but emits radiation for thousands of years. Putting an unshielded fission reactor on the lunar surface would create a no-go zone around it for the foreseeable future. Maybe putting it in a bore hole would make it suitable for a lunar outpost site, provided nobody goes over and looks into the hole for too long. Or, they might put a shadow shield on the top to cover just the area of the bore hole opening.

 

[billslugg]

Yes, once operated it would emit dangerous radiation basically forever. My comment was related to the transportation to the Moon and its set up. Once operated there would be a permanent, large no-go zone.
Yes, the pipes look a bit thin, but this an artist's conception not a scientist's.
Yes, it would be susceptible to meteors.

 

[Unclear Engineer]

I think if I were designing it, I would make the design suitable for burying in a hole, with a radiator that was positioned in such a way that it could be repaired without being directly in the beam of radiation coming out of that hole, or at least put a shield in the hole mouth. When the fissionable fuel was exhausted, I would want to bury the dead core in such a way that it would not leave much of a no-go area, so that a new reactor could be installed and hooked up in the future in roughly the same area.

So, this would be like simply burying the radioactive waste and reactor together when it is past its useful life. Assuming no water or atmosphere to cause metal corrosion and eventual release of radioactive materials (as would happen here on Earth), that might be a solution for radioactive waste on our moon.

But, I do wonder about the unintended consequences. For example, if we intentionally locate the moon base where there is water frozen in the rocks, and we then put a radioactive heat source in those rocks, will there really be no corrosion in the very long term? If we are wrong about that, could we end up contaminating the very thing we went there to use?

(We need some analytical risk thinking for ventures like this.)