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Nuclear Reactor for Mars Outpost Could Be Ready to Fly by 2022 (space.com)
36 points by chr1 67 days ago | hide | past | web | favorite | 23 comments




From what I've seen nuclear is clearly the best option at first. Once there are enough people you could get an industrial infrastructure capable of making batteries and solar PV on Mars, negating the transport cost factor.


My next question would be, if we have a reactor we can bring there, do we have an atmospheric or other type of processor that the reactor could power to convert martian air into something closer to earth air?


We can get methane and oxygen from the martian atmosphere.

https://en.wikipedia.org/wiki/Sabatier_reaction#Manufacturin...

This can be elaborated to produce plastic feedstocks. However, for making an earthlike atmosphere, we'd need to import nitrogen.

For more, check out The Case for Mars by Robert Zubrin.


Sabatier reaction?

CO2 + H20 (mined) -> CH4 (rocket fuel, and a good greenhouse gas if vented) + O2 (rocket fuel, and a breathing gas if you vent the CH4)

But one nuclear reactor isn't going to have much effect. And the bigger problem with mars atmosphere is quantity (there is nearly none) not quality.

Greenhouse gasses are good because they will warm up the planet, which will release more gasses, which increases the quantity of atmosphere (not to mention bringing mars closer to a temperature we can survive in).


Even if you could generate Earth air on Mars, how would you get Mars to hold on to it?


Domes? More practically: We already know that martian soil can be made into bricks. So we could build thick masonry arch tunnels in trenches, then cover them over with soil. This would provide radiation shielding, and the weight could then counteract internal pressurization. Such tunnels could be made airtight by using impermeable plastics, or by using frozen water, which would be literally rock hard at martian temperatures.


Mars doesn't lose atmosphere fast enough to matter on the timescale of the expected lifetime of the human species as a whole.


Science fiction plot: We figure out that the signs of water on Mars are actually evidence of past alien terraforming. (Xenoforming?)


It's such a shame that nuclear research stopped in 80s.... What are we waiting for to fund nuclear powered cargos? I've always dreamt of nuclear powered cars but believed that nuclear reactors were necessarily too big.

This experimental reactor from NASA + DOE is far smaller than fossil motors! (not accounting the cooling part) What could be the expected price of kilo reactors? Why would they cost? Fuel cost nothing. Autonomous. Very small so few material costs. Can it be created at scale (fordism-like) ? Can anybody on internet estimate an optimistic yet realistic cost? Could this revolutionize electric cars?


Making things small is actually not that big a challenge in nuclear. The challenge are safety, cost, and proliferation. There are a lot of reasons this shouldn't be produced at scale.

- at 10 kW, it produces power for about 5 American homes. You'd need 60 M of these for the US.

- Proliferation. Kilopower uses high enriched fuel (92%). This is bomb material from the get go. They could probably build a lower enrichment core. But they haven't. shame. In any case, if there were lots of these cores around, it would lower the barrier to access and process spent nuclear fuel.

- This is for space and NASA. Not the right type of innovation for terrestrial and mass produced. They went small, high performance. We need safe and low cost.

- It's a heat pipe cooled reactor and heat pipes have the worst heat transfer characteristics (compared to water, gas, molten salts) and will have a new set of accident scenarios like what happens if a heat pipe bursts and you get a sodium fire.

- You don't really want nuclear systems to be too small or mobile mobile devices or to travel much. You want to build em and know they're not going to move. You don't want to give the reactor more kinetic energy that it can use to break itself apart and release fission products. During a launch to space, this isn't so big a problem because the reactor has not yet been turned on and contains no fission products, so failed launch is not so bad.


Nuclear reactors in cars are a bad idea. Even if they can be built small and never needed refueling, cars get destroyed in all imaginable ways all the time, so the nuclear pollution would need to be expected to be released often. Also, we don't have a solution for the contaminated waste that millions of nuclear powered cars would produce.

We can satisfy our power needs from renewable sources with existing technology to competitive prices.


such predictable answers... The same schema repeat over and over. Let me be clear, what you say is mostly not wrong, but misleading. Your comment understate the importance, the necessity of quantification.

"never needed refueling" Wouldn't that be fascinating?

"cars get destroyed in all imaginable ways all the time" Right. "so the nuclear pollution would need to be expected to be released often" Yes BUT can we have a little bit of intellectual riguor and admit that we must quantify how much dangerous that would be. Let's keep in mind that a nuclear car having an accident != a new chernobyl. Being at most a kilowatt reactor make it order of magnitude less radioactive. I Guess (wishful thinking maybe) that the radiations would be far less dangerous and more local than is explosion and fire from current car crashs. But I want a nuclear expert to show me a calculus that would show if the dangerosity is negligible or higher (how much) than current crashs. The thing is, such experts will not read this thread and even if there were a scientific consensus on whether it's probably safer, democracy would be order of magnitudes too dumb / ignorant to vote for it. BTW the numbers of death due to C02 emissions should be taken into account too.

"we don't have a solution for the contaminated waste that millions of nuclear powered cars would produce." How do you know that? There's 0 funding to experiment solutions in the first place. But I expect it to be trivial. Current wastes are trivially contained in safe places. They do not need maintenance. Do you know how much a nuclear reactor produce waste per year? I did, I don't remember the exact number, but it was like a few kilos at most. So for a micro reactor in a car it should be a few grams at most. Which should be recuperated at the end of life of the car (if not negligible).

I've not even talked about nuclear advances such as reusing the wastes or provably safe reactors which necessarily auto shutdown by design. This already exists, but democratize very slowly due to lack of funding because of irrational politics driven by hysterical people fear (did you know that nuclear was both cleaner than solar AND safer (yes solar killed more people statistically).

"We can satisfy our power needs from renewable sources with existing technology to competitive prices." Wishfull thinking? Firstly solar does not scales well, is not autosuffisant, it fascinatingly less efficient than nuclear (did you remark that solar is indirectly catching the output of a nuclear (fusion) energy AKA the sun?) But the fact is, electric cars are a lie. They will drive no pun intended a penury in Lithium which is necessary for efficient batteries which will be dramatic. Nuclear cars would not need batteries or only small batteries.

Thanks for reading.


You don't need a nuclear expert, just around a high school physics class understanding of what's going on.

From https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/r...

> High-level wastes are hazardous because they produce fatal radiation doses during short periods of direct exposure. For example, 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly exceeds 10,000 rem/hour – far greater than the fatal whole-body dose for humans of about 500 rem received all at once.

And that's for fuel that's been run in commercial reactors, which is commonly only 5% enriched. The NASA reactor uses 90% enriched fuel.

Once that thing is turned on it will become deadly for centuries. Any breach of containment during a car crash would be instantly lethal for a considerable distance. Using a robot to extract the core from the wreck and place it in new containment would be a very non trivial task taking days if not weeks.

The idea of putting a kilopower reactor in a car is a total non starter, and not because people lack 'rationality' or aren't as smart as you think you are.


""never needed refueling" Wouldn't that be fascinating?" The act of refueling is not a problem in ICE cars. It's arguably their greatest advantage (only?) over electric ones.

" I Guess (wishful thinking maybe) that the radiations would be far less dangerous and more local than is explosion and fire from current car crashs."

And you'd be guessing wrong. A breach in the containment would be catastrophic for the whole neighborhood, if not city, for decades.

" The thing is, such experts will not read this thread " Actually nuclear experts do, sometimes, show up.

" But I want a nuclear expert to show me a calculus that would show if the dangerosity is negligible or higher (how much) than current crashs."

Buy Lamarsh's book. It has all the calculus you want. Amazon has it for less than $40. I myself have a copy in my basement and it's a good book.

" reusing the wastes or provably safe reactors which necessarily auto shutdown by design"

I don't know much about breeders ("reusing" waste reactors), but I doubt you could contain the neutrons of fast reactor.

No design is "provably" safe (this isn't 10 LOC run through Coq). The industry uses the term "inherently" safe or, better, "passively" safe. It typically refers to the reactor power naturally tending to zero if the safety mechanisms fail. If you crash into cement barrier, though, all bets are off.

""we don't have a solution for the contaminated [...] But I expect it to be trivial" and you'd be wrong. Waste management is the number one problem of the industry.

"but it was like a few kilos at most" Actually it's in the tons, you're confusing waste with mass that no longer exists as it became energy. 1Kg is the amount of mass that became energy through E=mc^2 (try it: 1GWe reactor @ 0.3% thermal efficiency running for 365243600 s = 1.05E17 Ws = m * c^2 -> m = 1 Kg)

But that's only about 0.1% of the total mass of fuel and waste... therefore tons!

" So for a micro reactor in a car it should be a few grams at most" It doesn't scale linearly.

"This already exists, but democratize very slowly due to lack of funding because of irrational politics driven by hysterical people fear "

A patronizing attitude towards people's fears mixed with general ignorance on the subject doesn't bode well.


Okay, so I'm not an expert, but hopefully a B.S. in nuclear engineering is enough qualification to answer some of the questions posed.

1st point; obviously the fantastic thing about nuclear power is the high energy density of the fuel, that's what makes it so attractive in the first place. However, a reactor sized for cars would definitely need some sort of refueling, at that size you'd already be very hard pressed to reach criticality with geometry and mass constraints. Something so small would be impacted quite a bit from burnup and fuel poisoning.

2nd point; the name of the game for nuclear is to contain radiological releases. While we accept other forms of pollution quite readily, there isn't really any amount of radiation discharge that the public is willing accept. Call it "too dumb" if you want, but the reality is that any risk of nuclear contamination is poorly received, just look at the public backlash pretty much any commercial reactor faces. This is despite the fact that coal-fired power plants release more nuclear contamination than nuclear plants. Millions of vehicles susceptible to high-impact collisions? That's a non-starter. There'd be no way to guarantee that radiation wouldn't be released to the environment, and I'd go as far as to say it'd be inevitable. Like you said, this wouldn't be another chernobyl, but we'd still be dealing with ridiculous amounts of activity. Your guess of it being less dangerous and local than current crashes is completely wrong. Any involved in the crash? Dosed strong enough to get acute radiation poisoning in minutes. First responders? Same deal. And then the winds/rain would scatter much of that contamination to the surrounding environment, where it would linger at dangerous levels for thousands of years. We're not even talking about the long-term problem of iodine or cesium, exposed nuclear fuel would give enough of an alpha dose to kill anyone near it.

3rd point; the waste solution is so tricky I don't even want to get into it. For all intents and purposes however, right now only one country in the world has a long-term waste storage facility, and it's Finland. Even if experts could agree that deep-geological storage is the best option, such an option is politically impossible for most countries. On-site storage is far from "trivial," and the dry cask storage employed by the US requires a pretty significant amount of engineering and monitoring. As for reusing fuel, it's not as easy as throwing spent fuel in a new reactor and calling it a day. It requires a pretty significant amount of politically contentious infrastructure and reprocessing, of which only a few countries (France, Japan I believe) have.

I'm a huge proponent of nuclear power, but if I'm being completely honest, making the case for it is getting harder and harder, even when only considering the technological aspect. There's lots of new and exciting designs, but I wouldn't bet on them to make a huge impact in the global energy makeup moving forward. Even for large scale energy generation, nuclear is heavily burdened by cost and political opposition. The idea of fission technology being usable as a fuel source for personal transport vehicles is laughable at most.


> not accounting the cooling part

...but the cooling part is critical. These are RTGs which basically just use the heat generated by the nuclear material to generate electricity through thermocouples which rely on the difference between the hot (plutonium) side and the cold radiator side. Without sufficient cooling the power output will be much lower because the temperature difference will be lower.


Yes and no.

The Kilopower design is not an RTG (Radioisotope Thermoelectric Generator). Those rely on the decay of a heavy element like plutonium to generate heat, which then generates electric power using a thermocouple.

Kilopower is making an actual fission reactor, which generates heat from the chain reaction of fissile atoms splitting each other. Another difference is that their design will utilize a linear-actuating sterling engine to convert the heat to electricity.

That being said, you're correct. The management of thermal flux and particularly discharging waste heat is hugely important to keeping this design working and efficient.


It's not 100% clear these are that different from RTGs it sounds like they just use Stirling engines instead of thermocouples to do the heat -> electricity conversion which is more efficient than the old style but seem largely the same otherwise.


Again, this reactor design is different from an RTG, precisely because it is a reactor. RTGs like those used in the Cassini mission rely on radioactive decay to generate heat. They have a significantly smaller power output, on the scale of watts. In Cassini's case, PuO2 fuel was used, and the primary decay mode was alpha decay. These designs are great for long-term, low power missions.

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

Kilopower will utilize highly-enriched uranium fuel to power a fission reactor. This means that the atoms in the fuel will be sustaining a chain reaction of fissioning, releasing neutrons, causing more atoms to fission, and on and on. This is what generates heat in reactor systems. This design will prove usable for shorter, higher energy demand missions.

https://www.nasa.gov/directorates/spacetech/kilopower

An RTG is essentially a lump of fuel which sits and decays, generating heat. Kilopower's reactor would be an actual reactor, needing to manage reactivity, burnup, and maintain criticality. They are vastly different systems. For someone not in the field I can see how there'd be some confusion but please be less speculative on topics of which you're less familiar.


Nuclear electric cars would be extremely dangerous. You need to crash-proof the reactor and utilise a direct capture instead of thermo-electrics.


> What are we waiting for to fund nuclear powered cargos?

China to scare us with a temporary technological lead.


> It's such a shame that nuclear research stopped in 80s

Did it?




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