4 ms·
There's a problem with nuclear power on the Moon. How do you get rid of the heat? Here on Earth, we just use water, of which we have plenty. But on Moon water i
by credit_guy 4y ago
There's a problem with nuclear power on the Moon. How do you get rid of the heat? Here on Earth, we just use water, of which we have plenty. But on Moon water is extremely scarce. It would make the sci-fi novel Dune look like an oasis. When we'll have some type of an economy on the Moon, it's very likely that water will be more expensive than gold. One thing is absolutely certain: we will not be able to afford to vaporize water and let the steam vent. So, any nuclear reactor on the Moon will need to have some complex array of pipes where steam is circulated through some radiators, then condensed and recirculated. Or, who knows, maybe we'll do this cooling with liquid metals. Among the more abundant metals on the Moon, tin could be a good candidate; there was an experimental reactor at the Oak Ridge National Lab in the 60's that used liquid tin as a coolant.
- krasin 4y agoHeat will be an asset, not a problem: the Moon sub-surface temperature is around -20C ([1]), which means there's an easy way to dissipate power. And if we have any humans living on the moon, that heat will very much be appreciated around all livable areas. https://space.stackexchange.com/questions/19906/constant-lunar-sub-surface-temperature https://space.stackexchange.com/questions/19906/constant-lun...
- m4rtink 4y agoInteresting!l, havent ever thought about that! What is the heat conductivity though ? If it is low, you might have to sink too many heat transfer channels, not to mention with possibly ending up with a hot "bubble" that would no longer provide a temperature gradient.
- krasin 4y agoUnder the layer of regolith, Moon crust is mostly basalt ([1]), which has about 1.6 W/mK thermal conductivity ([2]). Not great, not terrible. We all know how cold it is to stand on a stone floor - unlike wood or plastics, it keeps sucking that heat off. 1. https://en.wikipedia.org/wiki/Internal_structure_of_the_Moon https://en.wikipedia.org/wiki/Internal_structure_of_the_Moon 2. https://en.wikipedia.org/wiki/List_of_thermal_conductivities https://en.wikipedia.org/wiki/List_of_thermal_conductivities
- sanp 4y agoNice Chernobyl reference!
- iancmceachern 4y agoYour forgetting about radiation. You don't need to conduct it all away, there are 3 modes of heat transfer, conduction, convection and radiation. In this case it's the radiation they'd rely on.
- deepsun 4y agoSunlit surface of the Moon can reach 127 C. Don't know what type of reactor they choose, but it obviously won't work for boiling type of reactors. UPDATE: I forgot about not-water coolants. Molten salt or liquid metal reactors can work at 500 C, so would radiate anyway, right.
- iancmceachern 4y agoRadiation doesn't need a temperature gradient anyway
- FridayoLeary 4y agoI don't know if that will cool the reactor enough to prevent a meltdown.
- krasin 4y agoCooling a gigawatt-class reactor like that? - not a chance A 10kW reactor - easily; a very limited amount of engineering to design a heat distribution system will be required, but 10kW is also not enough for anything useful. I suppose the future of Moon energy will be in megawatt-class reactors, which are still possible to cool like that, but provide enough heat+energy to be useful for colonies.
- djmips 4y agoOther liquid coolants could be used and recirculated.
- jliptzin 4y agoI feel like it would be easier to build underwater cities via a network of watertight buildings than colonize the moon. At least with underwater cities we can essentially have flying cars (personal submarines), no adverse weather, plus cool creatures to watch swimming around outside your window.
- psychphysic 4y agoMy mind was blown when I first heard that heat dissipation would likely be the key shaping factor in space battles. I think this was the video https://youtu.be/9Xs3mGhQGxM https://youtu.be/9Xs3mGhQGxM
- blitzar 4y agoThe pew pew of space lasers are just to heat up the enemy ship and then they blow up of their own accord
- retrac 4y agoA hot object will radiate heat as infrared. The hotter it is, the more heat it will radiate. So, a sufficiently large heatsink designed to exploit that, can cool even in a vacuum. (Theoretically, this could even be used for reactionless propulsion.) In the 70s and 80s, the USSR launched a whole series of radar satellites that were powered by several generations of nuclear reactors: https://en.m.wikipedia.org/wiki/RORSAT https://en.m.wikipedia.org/wiki/RORSAT Liquid metal coolant, as you suggested. Also, direct thermionic conversion to electricity -- no heat engine cycle. No control rods either -- control reflectors outside the core. Very different kind of nuclear engineering than is needed down here on Earth. No shielding!
- pomian 4y agoA fun fiction novel by John Sanford, Saturn Run, presents a neat solution for the problem of heat dissipation, in space. Fun read.
- double2helix 4y agoYea I loved that book, and not even a huge fan of sci-fi.