Will SpaceX use NASA Kilopower Nuclear Reactors?

[Ludus]

I'm quite confident that solar power will be the single largest source of electrical energy for humanity in the future. It will be combined with other things, of course, such as hydro power, geothermal, and I actually think nuclear is not a terrible option, so long as you're not located in a place that's susceptible to natural disasters. That, also I think, defies common sense. So long as there are not huge earthquakes or weather systems that have names coming at you, then I think nuclear can be a sensible option. There are much safer and better ways of generating nuclear energy - I'm talking fission here - than existed in the past when nuclear reactors first came out. At some point in the future it would be nice to make fusion work, of course. That'd be quite good, but in the mean time I think indirect fusion, being solar power, is a good thing to do. That's what Solar City is doing, it's really trying to improve the economics of solar power, and they're doing a great job. I don't run the company, so the credit really goes to the two key guys who run that company. They're doing a great job of really accelerating the good option of solar power in the United States, and hopefully they'll come to the UK as well.

From: http://shitelonsays.com/transcript/elon-musk-the-future-of-energy-and-transport-2012-11-14

[lamontagne]

There is that quote of Shotwell about ''trying to lay hands on nuclear material''
And there was some L2 information about nuclear reactors for SpaceX.
And there is a quote of Mueller saying that eventually nuclear will be superior to chemical.
And the excellent quote above :-)

But one think is certain, nuclear will not be quick.  Not today, not in this age.  We might regret this, we might think it makes no sense, but if you want to build soon, you will go solar.  BFR is fuel rich architecture, mass efficiency is not the most important thing.

I expect Mars will be one of the best possible clients for small nuclear.  Eventually.

You can't cool a 'real' reactor without circulating a fluid through it.  And then cool the fluid in a heat exchanger. Heat exchangers with soil are large, as soil is not very conductive.  You need to experiment.  You don't need to experiment (as much) with solar.  I think the choice is simple.

Tesla may not know this, but most important designs, at the conceptual level, are made by small teams, with little money to spend.  The big design machine, the detailed engineering, comes latter.  After the dream is set, and the money is found.

[Ludus]

Mars settlement may help change popular attitudes toward nuclear. It would be a case of people who very much want a nuclear reactor in their backyard, who have no other interest than their own survival. It would be politically different if it’s demand pull from heroic people already on Mars. I know I’d be a lot more comfortable living on Mars with reactors (preferably both Megawatt and Kilowatt) than without.

[CuddlyRocket]

A well made, high pressure Helium, Stirling engine is a good choice for the application...

I get the impression that SpaceX has a bit of a downer on high pressure Helium!

[Eric Hedman]

A well made, high pressure Helium, Stirling engine is a good choice for the application...

I get the impression that SpaceX has a bit of a downer on high pressure Helium!

That's probably only when it's inside another cryogenic tank.

[john smith 19]

In order to make large quantities of propellant to meet the planned ISRU they need a settlement site with a lot of available water as well as a lot of power. Water to cool a reactor shouldn’t be an issue since they need it anyway prepped to feed into the ISRU plant. Whether it’s pure or like permafrost that’s what they have to design the process around, so they have some incentive to pick a site where it’s easier.

Depends on how much data SX have to decide a site.

There are a lot of Small Modular Reactor designs in development that might be suitable too.

No, there are a lot of Powerpoints for Small Modular Reactor designs.

The number that have got actual hardware built is much smaller.

The number that have actual hardware built in the US smaller still.

Not that the little 10k plants won’t be useful too.

I think people underestimate how useful a steady supply of heat 24/7/365 can be on Mars. Such a unit can be melting through a glacier at night while continuing to charge batteries for high rate processing during the day. In fact it would allow more batteries to be carried.

I’d think with large amounts of Methane and LOX stored they’d have some use for Methane Fuel Cells. The waste heat would come in handy and the fairly pure CO2 could feed back into ISRU. Reactors would be better for cranking out LOX and Methane 24/7 than Solar.

Methane FC's do sound like a good backup plan. But we know Musk is not a fan of "Fool cells" and I'm not sure how developed MFC's are.

[AncientU]

If you want to use methlox as your back-up/emergency power source, just install gas turbines.  They are compact for power delivered, low maintenance in long idle condition, and can quickly start and pick up load.

Discussion of nuclear is base load related... this is the long pole for expanding beyond the outpost stage on Mars or the Moon.  Wonder if the Moon could be a 'proving ground' for 10KW Kilopower or space versions of naval nuclear reactors.  A research-sized reactor modeled after that on the Navy's NR-1 deep submersible (MW scale) could be developed quickly by the USG...

[john smith 19]

Are they making it for anyone or any planned mission?  The concept was pushed 10-15 years ago, but not sure anyone stepped up with the killer app or claimed it as a solution to their problem.

That's why I said it's granular. At the bottom end (the actual hardware that's being tested right now) is AFAIK at the 1Kw level. So it's in drop in replacement territory for an RTG (but able to be throttled up or down depending on flight phase, or even inert until it reaches its target).

As I said it's already moved the Mars DRM 5.0 baseline to these units from the single, custom built reactor they were planning to use.

Lastly there is IIRC a road map up to 1MW IOW a 1:1000 range in power outputs with the same basic design.

And let me repeat. It's not a Powerpoint. It's actual hardware being tested now.

I'd be very interested in any other system that's got to that stage so far.

[john smith 19]

I talked with a SpaceX representative a few weeks ago about this given that I am a nuclear engineer.

They have essentially no realistic concept of how to refuel on Mars.

WRT to the thread title do you mean "refueling" as in refueling the BFS to get home or refueling nuclear reactors?

Looking at other physically and economically impossible concepts like the hyper-loop and BRF Earth to Earth, I have no doubt that they just dont care.

Checking Wikipedia's entry on Musk

https://en.wikipedia.org/wiki/Elon_Musk
we find

Musk transferred to the University of Pennsylvania, where in May 1997 he received a Bachelor of Science degree in physics from its College of Arts and Sciences, and a Bachelor of Science degree in economics from its Wharton School of Business

But you reckon his ideas are both physically impossible and uneconomic, making him incompetent to practice the both the subjects he graduated in?

Edit: I also asked them about a CO rocket engine, given that it could be extracted easily from the air without water mining, I was given the answer that this was rejected by Elon's trade studies. So yeah, the god doesnt like it, so it wont be done.

Possibly because O2/CO gives substantially lower Isp but (more importantly) there is no long term settlement without a large supple of water.

if you can't find a reasonably accessible large water supply there's no point in going to begin with. 

[EDIT BTW for maximum Isp using Mars atmospheric the Reaction Engines "Project Troy" team looked at the little known "Cyanogen" combination. Very potent, but burns hotter than H2 and very toxic. OTOH needs no water, so could be made anywhere on the surface with a suitable power source.  ]

[KelvinZero]

I did a google of Elon Musk's quote about "Nuking Mars" and found some cool details I hadn't met before.
http://mashable.com/2015/10/02/elon-musk-nuke-mars-two-suns/#_Q_aY4aeEPq0

I expect this is just a brainstorm he had, but he certainly is not anti nuclear when it comes to Mars. In the short term I don't expect him to do much more than verify that success is still an option with solar though. Anything that distracts too much from BFR commercial success around earth would be a mistake IMO.

[lamontagne]

If you want to use methlox as your back-up/emergency power source, just install gas turbines.  They are compact for power delivered, low maintenance in long idle condition, and can quickly start and pick up load.

Discussion of nuclear is base load related... this is the long pole for expanding beyond the outpost stage on Mars or the Moon.  Wonder if the Moon could be a 'proving ground' for 10KW Kilopower or space versions of naval nuclear reactors.  A research-sized reactor modeled after that on the Navy's NR-1 deep submersible (MW scale) could be developed quickly by the USG...

Is nuclear really needed if you have a hydrogen/oxygen back up system?  The big fusion reactor in the sky is so reliable...
What is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun,  but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?

[lamontagne]

I think nuclear is just one thing too many for Spacex at this time.

They need to develop so much stuff, in so many fields, that anything they can do without is a gain.

The question should really be: What can Spacex do without and still achieve its goal?

[meekGee]

The question is - can you have a realistic MWatt solar solution that is compatible with the task at hand.

Those tunnel machines, the ground vehicles, the fuel for return trips - it's a lot of Watts.

By "reallistic" I mean that it is a fraction of the total upmass plan, and can be installed by a fraction of the crew, using power production that already exists.

[RoboGoofers]

The question should really be: What can Spacex do without and still achieve its goal?

What about beamed solar? Sure there are a lot of issues with it and it's never been done before but at least it doesn't require getting hands on a reliable Mars-rated reactor.

Oh and I'm a nuclear engineer too and also talked to SpaceX recently. /s
(Come on, Tesla, if you want to be believed you could at least give some personal details to back up your credentials. I also question why they would reach out to you professionally when you are so ill-informed and opinionated, unless by "SX representative" you mean "tour guide". In addition, I doubt that anyone at SpaceX would discuss their Mars plans with just a random nuclear engineer, but if what you say is really true it at least confirms that SpaceX is interested in nuclear on Mars.)

[john smith 19]

Is nuclear really needed if you have a hydrogen/oxygen back up system?  The big fusion reactor in the sky is so reliable...

Not when it's blanketed by a dust storm that cuts off 75% of your daytime sunlight and lasts for months, which can, and does happen, on Mars. IOW to handle such an event you'd need 4x to maybe 5x the baseline load to maintain power levels. That ignores how you're going to grow food in months long twilight as well, as artificial light multiples power needs about 6x IIRC.

What is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun,  but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?

Poor, if you have to liquefy or pressurize the H2, which you do if you want to store reasonable amounts. Basically LH2 or GH2 uses 3-4x the energy used to make it, and by extension 3-4x the energy you can recover from it. 

When you factor that energy into the process it makes a fairly poor way to move energy, let alone store and release it cyclically.

[M.E.T.]

Is nuclear really needed if you have a hydrogen/oxygen back up system?  The big fusion reactor in the sky is so reliable...

Not when it's blanketed by a dust storm that cuts off 75% of your daytime sunlight and lasts for months, which can, and does happen, on Mars. IOW to handle such an event you'd need 4x to maybe 5x the baseline load to maintain power levels. That ignores how you're going to grow food in months long twilight as well, as artificial light multiples power needs about 6x IIRC.

What is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun,  but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?

Poor, if you have to liquefy or pressurize the H2, which you do if you want to store reasonable amounts. Basically LH2 or GH2 uses 3-4x the energy used to make it, and by extension 3-4x the energy you can recover from it. 

When you factor that energy into the process it makes a fairly poor way to move energy, let alone store and release it cyclically.

How about space based solar power to counter the threat of Martian dust storms - which seems very alarming based on your description. If they don't have nuclear power for the first decade or so, it seems a months long dust storm could wipe out the entire colony by cutting off its power source.

So would SpaceX feasibly be able to build orbital solar farms in geostationary orbit above a colony, and beam the power down through a dust storm?

[Jcc]

Is nuclear really needed if you have a hydrogen/oxygen back up system?  The big fusion reactor in the sky is so reliable...

Not when it's blanketed by a dust storm that cuts off 75% of your daytime sunlight and lasts for months, which can, and does happen, on Mars. IOW to handle such an event you'd need 4x to maybe 5x the baseline load to maintain power levels. That ignores how you're going to grow food in months long twilight as well, as artificial light multiples power needs about 6x IIRC.

What is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun,  but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?

Poor, if you have to liquefy or pressurize the H2, which you do if you want to store reasonable amounts. Basically LH2 or GH2 uses 3-4x the energy used to make it, and by extension 3-4x the energy you can recover from it. 

When you factor that energy into the process it makes a fairly poor way to move energy, let alone store and release it cyclically.

The best way to store energy on Mars is to make methane and oxygen, since they will need large quantities of that for rocket fuel and oxygen to breath. Eventually other industrial processes that use a lot of energy, make more of those products when excess energy is available. So if you have a continuous nuclear source plus variable solar, increase fuel production when the sun shines. Batteries will help, building up a stock of energy intensive essential commodities is better from an efficiency standpoint.

[RoboGoofers]

So Elon is not a fan of space based solar, apparently, though his comments on it relate to Earth.

NSF topic on spaced based solar on Mars:
http://forum.nasaspaceflight.com/index.php?topic=39583.0

[john smith 19]

The best way to store energy on Mars is to make methane and oxygen, since they will need large quantities of that for rocket fuel and oxygen to breath. Eventually other industrial processes that use a lot of energy, make more of those products when excess energy is available. So if you have a continuous nuclear source plus variable solar, increase fuel production when the sun shines. Batteries will help, building up a stock of energy intensive essential commodities is better from an efficiency standpoint.

And best of all you have some very large tanks available to store it in from the day you land. 

[WindnWar]

Basically need a much smaller version of these SMR designs that Nuscale is working on, with a higher enriched fuel to be able to last longer between refuelling. The weight they list seems wrong though as you can't transport a 700 ton item by truck. 70 tons seems more realistic. 50 megawatts of electric power and 160 megawatts of thermal power would be quite useful.

http://www.nuscalepower.com/our-technology/technology-overview