UK backs Rolls-Royce project to build a nuclear reactor on the moon

Re:UK backs Rolls-Royce project to build a nuclear reactor o... by credit_guy on Saturday March 18, 2023 @09:57PM (#35215212)

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.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by krasin on Saturday March 18, 2023 @10:20PM (#35215349)

Heat 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-lun...

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by m4rtink on Saturday March 18, 2023 @10:30PM (#35215411)

Interesting!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.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by krasin on Saturday March 18, 2023 @10:40PM (#35215449)

Under 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

2. https://en.wikipedia.org/wiki/List_of_thermal_conductivities

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by sanp on Saturday March 18, 2023 @11:34PM (#35215769)

Nice Chernobyl reference!

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by krasin on Sunday March 19, 2023 @12:06AM (#35215936)

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by mongol on Sunday March 19, 2023 @12:57AM (#35216177)

https://youtu.be/ocBVLMHK6c8

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by krasin on Sunday March 19, 2023 @01:25AM (#35216304)

Thanks! I now get the reference, although it was completely accidental. I should watch the movie, I guess.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by sph on Sunday March 19, 2023 @04:21AM (#35217049)

It is a miniseries and it is excellent and gripping from start to end.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by iancmceachern on Saturday March 18, 2023 @11:04PM (#35215593)

Your 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.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by deepsun on Sunday March 19, 2023 @03:10AM (#35216747)

Sunlit 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.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by iancmceachern on Sunday March 19, 2023 @11:23AM (#35219873)

Radiation doesn't need a temperature gradient anyway

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by FridayoLeary on Saturday March 18, 2023 @11:18PM (#35215696)

I don't know if that will cool the reactor enough to prevent a meltdown.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by krasin on Sunday March 19, 2023 @03:35PM (#35222671)

A gigawatt-class reactor? - not a chance

A 10kW reactor - easily; almost no engineering will be required, but it's also not enough for anything useful.

I suppose the future of Moon energy will be in a megawatt-class reactors, which are still possible to cool like that, but provide enough heat+energy to be useful for colonies.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by djmips on Saturday March 18, 2023 @10:26PM (#35215391)

Other liquid coolants could be used and recirculated.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by jliptzin on Sunday March 19, 2023 @12:20AM (#35215995)

I 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.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by psychphysic on Sunday March 19, 2023 @12:26AM (#35216021)

My 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

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by blitzar on Monday March 20, 2023 @05:27AM (#35229126)

The pew pew of space lasers are just to heat up the enemy ship and then they blow up of their own accord

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by retrac on Sunday March 19, 2023 @12:58AM (#35216180)

A 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

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!

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by pomian on Sunday March 19, 2023 @01:13AM (#35216253)

A fun fiction novel by John Sanford, Saturn Run, presents a neat solution for the problem of heat dissipation, in space. Fun read.

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Re:UK backs Rolls-Royce project to build a nuclear reactor o... by double2helix on Sunday March 19, 2023 @01:19AM (#35216279)

Yea I loved that book, and not even a huge fan of sci-fi.

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