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GlockAF t1_j7h1oob wrote

Post below asks “why nuclear all of a sudden? Partly because the technically well-informed have finally (inevitably )!come to the correct conclusion that there is no route to a decarbonized economy without nuclear power. Renewables are great, renewables are the future, but nuclear power absolutely is going to be part of the solution.

As far as their connection to space travel, nothing else can match the energy density of nuclear power. There’s just no getting around it, if we limit ourselves to chemical fuel the rest of the solar system is essentially off-limits to anything biological


certain_people t1_j7h8mtw wrote


[deleted] t1_j7hdf0z wrote

Left solar and wind off the chart


certain_people t1_j7hdwzq wrote

Not left off so much as can't be shown. What's the energy density of wind?


[deleted] t1_j7hg3vn wrote

They measured it in joules/kg. Solar is infinite. Wind I'm not so sure.


certain_people t1_j7hgogl wrote

It's just not the right way to compare nuclear with solar and wind. And you can't put wind or sunlight in a fuel tank.


[deleted] t1_j7hh9tb wrote

Seems reasonable to me? Light is zero kg, so infinite energy per kg. I can't put uranium in my fuel tank either. Just not practical for the everyday person.


moral_luck t1_j7hxh0p wrote

Nuclear reactors use light as the energy for power.

Coal generators use light as the energy for power.

Natural gas generators use light as the energy for power.

Geothermal generators use light as the energy for power.

Light is the way energy is transferred from one atom or molecule to another atom or molecule.

Heat is light.

For example:

Coal is burned, the chemical reaction creates lots of photons. Those photons get absorbed by water molecules. The water molecules become excited. Excited water molecules move faster. Faster moving water molecules have more kinetic energy. Steam is the result. High velocity steam spins a turbine. The turbine spins a magnetic field inside an coil. This produces electricity.

Energy density is really a measure of the number and energy of the photons generated by a certain fuel. Light is not the fuel (hint: fusion).


[deleted] t1_j7i6i75 wrote

Fusion is what happens on the sun

Not what we do on earth


moral_luck t1_j7hwh78 wrote

Solar power is neither infinite in energy density, total amount of energy or duration of energy.

Not sure what you mean by "Solar is infinite."


[deleted] t1_j7hwnqn wrote

How many megajoules per kg is it?


moral_luck t1_j7i2c65 wrote

Einstein's most famous equation (E=mc^(2)) limits energy density of any fuel to 9 x 10^(10) MJ/kg

And that would be an antimatter reactor. Physics means no fuel can have infinite density.


[deleted] t1_j7i5cy1 wrote

Light. Zero mass. Lots of energy.


SowingSalt t1_j7jjchk wrote

Therefore in the ratio mJ/kg, light is undefined and cannot be on the chart; which was the original point.


moral_luck t1_j7hz7ym wrote

Solar energy is hydrogen fusion, deuterium–tritium fusion is about 338,000,000 MJ/kg.

But we don't have the technology to create miniature suns in our rockets.

BTW, U-235 fission has an energy density of about 144,000,000 MJ/kg.


Another source puts the energy density of the sun's core around 6.43 x 10^(8) MJ/kg, or 643,000,000 MJ/kg.

The second source is titled The Source of Solar Energy.


[deleted] t1_j7i5md1 wrote

That's fusion reactors not solar energy on the surface of the earth


moral_luck t1_j7i7uhl wrote

Where does the solar energy on the surface of the earth come from?


Taxus_Calyx t1_j7hxzqa wrote

"Wind powered travel to Mars." M'kay.


John-the-cool-guy t1_j7i9xfp wrote

What about solar winds? And a sail to catch them? Feels like I've heard about this someplace.


TheGacAttack t1_j7ku5zo wrote

Some of us have got this idea..... we want to land a craft. Deploy solar sails. It'll have a great, big canopy! Solar winds will be caught by the mylar sails....



[deleted] t1_j7i6mr4 wrote

That's not the sick burn you think it is


moral_luck t1_j7icz4b wrote

It was 3rd degree.

I get the feeling you'd rather "win" an "argument" than be correct. Your whole premise is born of ignorance, but it's easier for some to remain ignorant than to recognize they are wrong.

Heat has infinite energy density, so we should just burn coal for rockets. <- your logic at work.


SexyOldHobo t1_j7hnhem wrote

I personally have my suspicions that the anti-nuclear “movement” is ultimately funded by fossil fuel interests gaslighting as environmentalists


urmomaisjabbathehutt t1_j7il3dj wrote

im pretty sure that fossil fuel like to use propaganda greenwash themselves

and also have my suspicion that they may want use pro nuclear propaganda an industry they have been coexisting and competing with for the last seven decades in order to delay the energy transition because they cannot compete and control the disruptive changes that renewables caused in the market

i also have the suspicion that they may be using pro nuclear propaganda to blame any renewable supporter as pro fossil fuel 😌

i also am aware that a pro nuclear bot was found doing his rounds at reddit and also that there are plenty of pronuclear comments dressed as facts not being so also i realized that often pro nuclear energy coments apprear in threads that are not discusing such

Incidently this thread was about nuclear PROPULSION yet here are the church of the fissiontology in force proselitizing

i rather back read about nuclear propulsion which is something i find interesting


VitaminPb t1_j7hc25b wrote

German Greens would disagree (wrongly and stupidly) with you.


HerburtThePervert t1_j7haa6d wrote

I have a feeling that fusion power will radically change humanity’s way of life sometime this century. All the benefits of nuclear, without the waste and lower risk. Hopefully even something more radical will come along.


standarduser2 t1_j7j21e3 wrote

Nuclear for space travel is probably the best option we currently have.

For land based power, that is absolutely not true.


GlockAF t1_j7jxqpr wrote

The US used ~4000 terawatt hours in 2021, about 900 of that (~20%) renewable.

Barring the discovery and miraculously quick deployment of a resource-effective & cheap energy storage technology, we are still gonna need a quick spooling backup of some sort.

Unless you have a plan to cut energy use by 80%


Leather-Mundane t1_j7hxx75 wrote

Renewable sources can likely support about 40 percent of future energy demands.


urmomaisjabbathehutt t1_j7ha0w3 wrote

I don't see a reason to think that there is no rute to decarbonizing without nuclear power, i don't see any reason to think that as the "inevitable " or "correct" conclusion

I see many reasons why nuclear in space can be useful and desirable at least till we have fusion which we don't have

i don't see the need to proselitize the use of nuclear fission as energy on the ground in an thread about the use of nuclear propulsion in space


toothpastetitties t1_j7huhzs wrote

Because there is no way to decarbonise without nuclear energy doing the “heavy lifting”- keep in mind this is only for energy purposes. This does nothing for the other uses of hydrocarbons.

Renewables are not a viable solution to providing consistent clean energy- as abundant as wind, flowing water, and photons are, the machinery used to convert to electricity don’t produce enough, long enough, or consistently enough. Nuclear energy provides energy at any time of day, any load, any external environmental factor. Doesn’t give a shit. And with people mass buying electric cars, on top of consuming electricity as normal, our infrastructure is in for one hell of a ride.

I don’t get why this is such a hard concept for the Reddit hive mind to understand. You can’t power a country exclusively on solar panels and windmills. We need nuclear energy. It’s a no brainer. The longer we argue the longer the transition is delayed.


simcoder t1_j7hd243 wrote

Nuclear is not a silver bullet either monetarily or carbon wise. It's an option. But one with a number of VERY significant downsides and quite dependent on govt indemnification/socialism.


Orion2033 t1_j7hgfrt wrote

I don’t see socialism as an issue since Lockheed, NASA, ESA, and JPL are the main stars. Rolls Royce is a contractor. Well so are Boeing and Lockheed for thatvmatter


simcoder t1_j7hgxf9 wrote

It's just that privatizing profits and socializing the costs kind of thing that's somewhat intrinsic to the nuclear equation.


Orion2033 t1_j7hi2jg wrote

I think it more of an old boys club like Standard Oil before the govt broke the monopoly


simcoder t1_j7hielo wrote

Nuclear power is indemnified by the govt beyond a certain amount. Without that indemnity, it wouldn't be economically viable.


CarlJH t1_j7igsko wrote

So is the interstate highway system, which kills a lot more people than nuclear reactors ever have.


Orion2033 t1_j7hilnc wrote

Yes but many countries can now supply it or is that a dumb thing to say?


simcoder t1_j7hj23g wrote

I guess the point is that it's a form of socialism for the nuclear energy industry.


moral_luck t1_j7jd60o wrote

>privatizing profits and socializing the costs

How is this different than oil or coal? Or heavy industry?

Pollution is socialized cost with privatized profits. Mining coal destroys environments. Burning coal causes asthma.

Seems nuclear would reduce socialized costs.


simcoder t1_j7jgig7 wrote

I would have thought that would have been obvious to a nuclear expert.


moral_luck t1_j7jhxxf wrote

Not sure what you mean, but I think that falls into the field of economics. Or public health.


simcoder t1_j7ji15r wrote

Do you understand how the indemnities work?


moral_luck t1_j7jijcp wrote

Are you implying that I am the economist/lawyer/nuclear physicist or you are?


moral_luck t1_j7jib08 wrote


That sounds like law. Not sure what you're getting at with the nuclear expert comment.

Or where you're going with this in general. But do you think kids growing up around coal generators that get asthma get a big pay out from the companies? IF they did I don't think coal plants would exist.


simcoder t1_j7jijee wrote

Well it's kind of critical to the original argument. Not sure we can go any further if you don't understand them.


moral_luck t1_j7jiu8t wrote

no results

So you are a lawyer, nuclear physicist, public health expert, and economist.


simcoder t1_j7jj0s9 wrote

Ok then.

Well it's kind of important to understand how the indemnities work to get the original point of privatizing profit and socializing costs.

I agree that sort of thing happens a lot. I guess with nuclear it's just a matter of the scales involved.


moral_luck t1_j7jjcv0 wrote

>I guess with nuclear it's just a matter of the scales involved.

Exactly my point. Coal is much worse for people than nuclear, even when accounting for MWh/year life lost. So many more people are affected by coal than nuclear.

It's like comparing car accidents to air accidents. Car accidents cause more deaths in total and per mile traveled, but people freak out about air accidents because there are more deaths per accident.

Or where you trying to imply that mining and heavy industry actually pay out all the indemnities they should, but nuclear plants don't? Politics kind of makes that improbable.

Still don't understand the "nuclear expert" comment. Are you referring to yourself as the "nuclear expert" or to me?


simcoder t1_j7jjg2e wrote

You should really look up how the indemnities work to have a fuller understanding of what you're advocating. It's worth your time.


moral_luck t1_j7jjmii wrote

So you're a lawyer?

I'm very confused about your point. If you are a lawyer I'd think you'd be better about making your point.


simcoder t1_j7jjo3r wrote

It should be crystal clear by this point I would have thought?


moral_luck t1_j7jjslu wrote

Your point? Crystal clear? If mud is crystal.

You've done little to further your point. Or to counter my claims that fossil fuels have more social costs than nuclear.


simcoder t1_j7jjwpw wrote

It's just that you're probably going to struggle understanding the "privatizing profits and socializing costs" angle if you don't know what indemnities are and how they function in the nuclear power equation.


moral_luck t1_j7jkbag wrote

Oh. So you've taken steps to make your point clearer? Crystal clear? Like hematite?

Or you've countered my claims that coal plants cause asthma, but haven't been held responsible for them?

If you're a lawyer, you're not very good at supporting your point.


simcoder t1_j7jkf9p wrote

I'm just saying that if you want to understand what I meant by privatizing profits and socializing costs you have to understand what indemnities are and how they work in the nuclear power industry


moral_luck t1_j7jkowd wrote

If you really wanted me to understand your POV on indemnities and socializing costs and privatizing profits were, you'd have done so by now.

But you haven't. Because you know I'm right.


simcoder t1_j7jku28 wrote

You don't seem to be very trusting of my opinion. And that's perfectly fine.

That's why I suggested you do your own research so you're not having to depend on my own personal take on the subject.


moral_luck t1_j7jl00c wrote

You haven't had an opinion in the last 5 responses.

Socialized costs is much greater than indemnities.


simcoder t1_j7jl3kg wrote

That's because you refuse to educate yourself on the subject so we can begin an actual debate on the subject of indemnities and how they affect the cost structure of nuclear power.


moral_luck t1_j7jld3q wrote

Yes, the person who has posted references is the person who refuses to do research or educate themselves.


simcoder t1_j7jlhlt wrote

Well. I gotta say. After all this, it still sounds like you don't understand what they are. And it's really not hard at all to find out what they are and how they work.


moral_luck t1_j7jlv3d wrote

You do realize that CO2 emission is a socialized cost, right? Socialized costs are bigger than what's in a contract.

I'm beginning to think you have no idea what indemnities are. You keep typing the word, but haven't given any evidence you know how they work.


simcoder t1_j7jm003 wrote

OK then. Well it was good chatting with you. Definitely check those things out if you want to consider yourself an informed nuclear advocate.


moral_luck t1_j7jmh8v wrote

Are you the nuclear expert you were talking about earlier?


simcoder t1_j7jmnlh wrote

Expert is kind of a relative term. I do know how the indemnities work in the nuclear industry.


moral_luck t1_j7jnkkq wrote

So if you have specific knowledge of an industry insider, why would you assume that everyone would have access to that same knowledge?

Does that also give you knowledge of indemnities in the coal industry? How about plastic? Are you aware of the concept of externalized cost (basically interchangeable with socialized costs)?

Externalized costs exist in all forms of industry. Even groceries. Are you suggesting that only those things specifically mentioned in an indemnity is the entire social cost of a thing? And nuclear is the worst alternative, in terms of externalized costs, per MWh among electrical generation methods?


simcoder t1_j7jnn5r wrote

I'm not an industry insider. Google and wiki are just about all you need to get the high level gist.


moral_luck t1_j7jnp1j wrote

Ah, I got ya. That is why you kept talking in circles.


simcoder t1_j7jnwd7 wrote

LOL. OK. Well at least I'm not the one making a fool of themselves by not knowing what they are talking about.

Good chat!


moral_luck t1_j7jo0fd wrote

I think you proved you didn't know what you are talking about.

Which is why you avoided talking about it.


simcoder t1_j7jplpb wrote


Well, anywho, look up those indemnities so next time you'll know what you're talking about. Should make for a much more interesting conversation.


moral_luck t1_j7jqn6g wrote

You've made it very clear you have no idea what indemnities actually are. Or how they work.

You've also made it clear you don't understand that indemnities are not connected to the total socialized cost. How much did "x" corporation contribute to the polluted water of Flint, MI?

Sure, they have indemnities. Even if we legally could and wanted to, we still can't calculate the total cost. We know the total costs is insane, but don't know how many years of lost productive labor was lost due to health issues. Nor can we assign a specific amount of to each corporation, even if indemnities allowed it.

But you're not a lawyer. You just pretend to be one on the internet.

Why don't you explain it to me in your own words? Surely you can ELI5.


simcoder t1_j7jqppb wrote

How can you even make a judgement when you don't even know what they are? No wonder you're a fan of nuclear!


moral_luck t1_j7jrcpq wrote

Well, you still have your chance to prove you know what you are talking about.

Tell me how indemnities are the total final socialized cost of thing.


simcoder t1_j7jrhq7 wrote

I already said why you should find out yourself and you just plowed on with not wanting to know or educate yourself for many many posts.

So why should I do your homework for you?


moral_luck t1_j7jrnv0 wrote

You have no fucking clue, do you? You are completely clueless. You read an article about indemnities in the nuclear industry, and now you have no idea how to explain it at all. You can't actually understand what you read. And you surely wouldn't be able to explain it or connect it to a conversation about socialized costs.

You've proved all this.


simcoder t1_j7jrw8a wrote

So tell me why the indemnities aren't socializing the costs and privatizing the profit?


moral_luck t1_j7jsali wrote

I never said they weren't. I said they are nearly irrelevant when calculating the TRUE socialized cost.

Even if we could sue a coal company from co2 emissions because our crops died from a heat wave, we couldn't. Even if there are no indemnities. It would be hard to prove that that specific plant contributed to that specific heat wave. But it's still a socialized cost, indemnity or not.

You learned a big word and think it's a conversation. You're such a big boy!


simcoder t1_j7jsfqv wrote

How can you say the cost of a cleanup or evacuating a Tokyo or New York is irrelevant?

Those are entirely relevant and were you to include them in the cost structure it would make nuclear power far too expensive to be competitive.


moral_luck t1_j7jslwz wrote

You realize a EULA contain indemnities? Or even being on reddit?


simcoder t1_j7jspuo wrote

It's sounds like you're still kind of struggling to understand the concept WRT nuclear power. Again, i don't think you'll accept my opinion on the matter so I suggest you really try to understand how they work in the nuclear power cost equation and then we can have a more fruitful discussion on the matter.


moral_luck t1_j7jt7rn wrote

Three mile island cost about $1 billion from 1979 to 1991. Or about $3 billion in today's money.

How much cost has coal externalized in the last 40 years?


moral_luck t1_j7jszcb wrote

Quick question. What do you think the total externalized cost of Fukushima was? I have an estimate ~$100billion. Sound like a lot, right?

Coal industry externalizes an estimated $50 billion/year.


simcoder t1_j7jt8v2 wrote

I'm no fan of coal and I'm a huge, huge fan of clean air regulations and things like carbon/pollution taxes. So, to that extent, I'm in favor of acknowledging the true price of coal as well.

But, once you shut the coal plant down, the vast majority of the long term impact shuts down as well. Not so much with nukes. That stuff hangs around for a very long time and you have to manage it all along the way.

That's why the industry requires such extreme indemnities.


moral_luck t1_j7jtvfj wrote

>the vast majority of the long term impact shuts down as well

Source? because I can find one that contradicts this.


simcoder t1_j7ju8f2 wrote

Let me ask you this.

If we had to evacuate or abandon a major city because of a nuclear power plant accident, would you still think that nuclear power was worth it?


moral_luck t1_j7jv00i wrote

You're asking airplanes vs cars here. And we know the answer to that, airplanes are vastly safer.

To answer your question directly. It depends. Basically what would the frequency of occurrence be and what are the alternatives?

With the information we have, yes, it is worth the risk. Why?

Nuclear is a better alternative in terms of externalized economic and health costs than what it would replace (it won't replace solar, wind or hyrdo).

Do you think we should continue to mine and burn coal while we transition to an entirely solar/hydro future? You really think coal is better than nuclear? Or do you think natural gas is better than either of them?

I am assuming you realize that an entirely solar/hyrdo/geothermal/wind electrical grid is not currently feasible. I am also assuming you also realize that is what we will and need to transition into completely in a few generations.

So the real question is, what is best gap filler for the next 50 to 100 years?


simcoder t1_j7jv7xn wrote

Oh I'm not saying we should get rid of nuclear. And I think that nuclear is precisely that, a gap filler till we have something better.

But I also think the risk of having to abandon or evacuate a major city is enough to push nuclear over the edge to a "currently necessary 'evil'" as opposed to some techno silver bullet.

Plus managing the spent fuel for the next 10,000 years or so. That's going to hit your bottom line pretty hard without a govt stepping in and pushing that onto future generations to pay for.


moral_luck t1_j7jvweg wrote

Great! so we're on the same page! Very few people who currently advocate for nuclear thinks it's the end all of electrical generation.

I think it's pretty clear to most people that we should be harnessing the huge fusion reactor in the middle of our solar system for the future use. Currently our issue is energy storage, i.e. batteries. Those will also have externalized costs.

Storage is obviously a long term issue. We have built a seed vault so it's not entirely outside our capability to handle.

But long story short, nuclear is a better option than coal ESPECIALLY when considering externalized costs.


simcoder t1_j7jw6dj wrote

>But long story short, nuclear is a better option than coal ESPECIALLY when considering externalized costs.

I would say they are both bad in unique ways.

However low the risk, abandoning a major city is unimaginably bad. The spent fuel management will soak up money that could be spent on better options for 10,000 years or so after we've transitioned to something else.

And the carbon benefit is not a slam dunk. Particularly when you consider those externalized costs.


moral_luck t1_j7jso9c wrote

Now you wanna talk.

How about the cost of the healthcare of all the children who get asthma? What about compensation for their years of lost labor? Coal can't compete if that were the case.


moral_luck t1_j7jsgva wrote

Start reading about coal and health outcomes associated with childhood in certain radii of burning plants.

Or how water is polluted and diverted from agriculture.

Socialized costs are not exclusive to the nuclear industry (or indemnities).


GlockAF t1_j7hyoy5 wrote

Ah…the “s-word” rears its ugly, stupid head yet again


simcoder t1_j7hyvq9 wrote

Privatizing profit and socializing cost and hiding true costs are an ugly thing indeed and something that nuke power is entirely dependent upon.


GlockAF t1_j7i17cv wrote

So take the profit margin out of it. Nuclear power should be run entirely by the government/military


simcoder t1_j7i1p76 wrote

Even if you could somehow do that, if you include the true total lifetime cost, it'd require huge subsidies to remain competitive.


GlockAF t1_j7jvxxc wrote

Still the best, and currently ONLY zero-carbon solution for the non-renewable fraction needed


simcoder t1_j7jwbjx wrote

It's only zero carbon if you forget to include all the carbon in the lifecycle etc.


GlockAF t1_j7l8qmg wrote

Compared to the current 80% / 3000 terawatts we get from burning oil, gas, & coal it is. ESPECIALLY if we start utilizing the vast energy resources stored in “spent” reactor fuel


simcoder t1_j7lc39w wrote

Yeah but it's not zero and not insignificant.


Mother-Wasabi-3088 t1_j7hms9q wrote

Nuclear power will never be safe and it's unnecessary. We can easily power the entire world with solar.


Disastrous_Elk_6375 t1_j7hvc22 wrote

> Nuclear power will never be safe

Mmmhhmm. We've had extremely safe, sufficiently compact and mobile nuclear power since the 50s. We know they're safe because navy personnel on nuclear subs / ships have lived long healthy lives. In fact, the commander of the first US nuclear sub (commissioned in 1954) went on to also command the first nuclear ship. He got to live 94 years!


SwerdnaJack t1_j7hou5n wrote

But the sheer weight of solar panels on a rocket make it unusable.


GlockAF t1_j7hzltp wrote

False, at current energy use levels.

Potentially possible, if we have massive crash-course investment in transmission, infrastructure and a corresponding (and profoundly improbable) society-wide massive decrease in the average per-capita energy consumption of western countries.

In other words, not possible


[deleted] t1_j7h7z5x wrote

This article is an absolute mess:

"Rolls-Royce Holdings is getting into the nuclear reactor business"

RR have been in the nuclear reactor business since the late 50s and their first home grown reactor went critical in 1965.

"Rolls-Royce Holdings announced in 2021 its intent to develop nuclear reactor technology, having obtained $600 million in public and private funding to develop its business"

That money was for small modular reactors (SMRs), small terrestrial power stations completely unrelated to microreactors.


jamiecarl09 t1_j7hivff wrote

Do you think once the company has SMR's, they aren't going to dump more money into R&D for microreactors?

With the amount of talk around mining asteroids, if RR developed a spacefairing propulsion system they'd explode in market value.


[deleted] t1_j7hvidk wrote



thuanjinkee t1_j7ikvqi wrote

Hmm sell them as sealed units and you might have a safe product there. There's some progress on thermophotovoltaic cells (like solar cells except they operate in the IR spectrum) that could make a solid state no-moving-parts RTG about 20x to 40x more efficient than the old voyager RTGs.


ShadyRedditInvestor t1_j7iq4tn wrote

Efficiency isn't really the thing...the actual plutonium oxide pellet they use for RTG's only gives off a total of about 40-60 watts. Doesn't matter how good your collection is, they'll only run the equivalent of a single 60w incandescent bulb assuming absolutely perfect conversion.

Even if you had theoretically perfect insulation, you're just going to make the the alpha decay happen faster.


thuanjinkee t1_j7j7hjg wrote

One pellet is 60w, but you use more than one pellet.


ShadyRedditInvestor t1_j7j7vmj wrote

ah yes, exactly what we want, a proliferation of millions of orphan sources of enriched uranium. Small scale nuclear is probably the way forward, but RTG's in grandma's basement aren't it, chief.


Shrike99 t1_j7mj99t wrote

It's still extremely inefficient. 100kg worth of plutonium pellets in some RTGs will produce about 50 kilowatts of thermal power. 100kg of plutonium in an SMR on the other hand could easily provide 500 megawatts of thermal power.

The average US household has an average power draw of about 1.3 kilowatts, so assuming 100% conversion efficiency in the above cases, the RTGs could power about 38 houses while the SMR could power about 38,500 houses.

Given how expensive plutonium is, that thousand-fold difference makes RTGs a complete non-starter. And in practice an SMR would actually use uranium which is much cheaper, making things even worse.


e36freak92 t1_j7im7vz wrote

Rtgs don't put out much .energy though. Fine to run some spacecraft instruments. A house? Maybe not so much


[deleted] t1_j7htp2z wrote

RR SMRs is a separate company to RR now (majority owned by RR still), so SMRs and microreactors will be developed concurrently and independently.

Either way, if they wait until SMRs hit the big time to dump money into microreactors it will be far too late and Westinghouse (eVinci) or someone else will have already dominated the market.

The space propulsion side is really nothing to do with RR and I don't think they are developing it as there is no expertise for that. They are simply providing new reactors, as they have done for 60 years.


ProjectDv2 t1_j7jrldg wrote

I don't think a company known for designing engines for automotive, marine, and aeronautic applications deciding to develop engines for interplanetary applications is nearly as farfetched as you believe it to be.


[deleted] t1_j7jsv1e wrote

Not farfetched at all, just it isn't happening at present. If they start hiring space propulsion experts tomorrow then it wouldn't shock me, but they don't have any today.

The RR microreactor will power someone else's nuclear propulsion tech.


JPhonical t1_j7myxvo wrote

>The space propulsion side is really nothing to do with RR

RR is currently studying nuclear propulsion for the UK Space Agency:


[deleted] t1_j7oi8h5 wrote

The study is "nuclear power for space exploration", it touched on propulsion but that was the extent of the effort.


JPhonical t1_j8cir2n wrote

Here's an article with a quote from Jake Thompson, Head of Innovation Products and Services at RR, " We’re working on nuclear thermal propulsion; really efficient, fast transport for space travel."


wowsosquare t1_j7iljzw wrote

Did it say how these planned nuclear engines would actually work?

Could someone explain how it's supposed to work?



Automatic_Llama t1_j7h707r wrote

Gonna make urban combat with super mutants and radscorpions way more dangerous though


VitaminPb t1_j7hc7ax wrote

On the other hand, much better than current reality tv. And on the third hand, more mutations!


moral_luck t1_j7hy8f5 wrote

Does anyone know what the total mass of the exhaust* (momentum generator) would be in a nuclear rocket versus a chemical one?

And what would that exhaust* be?

*I'm not sure what the correct term is, maybe propellant?


Backlit_keys t1_j7iungd wrote

The propellant mass of nuclear thermal rockets would vary based on the fuel chosen (ideally, hydrogen) and the specific mission requirements but generally an equivalent NTR will have twice the efficiency of a chemical rocket. So twice your delta-v for the same propellant and mission payload.


littlebitsofspider t1_j7j6g2y wrote

Isp is the term you want, it's a measure of fuel efficiency for generated thrust. For example, Ultra Safe Nuclear generated a reference design for NASA for a small, 25MWth NTR with an Isp of 900 seconds. Traditional chemical rockets (like the Raptor engines from SpaceX) are ~325-360 seconds depending on altitude.


Decronym t1_j7hivg8 wrote

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

|Fewer Letters|More Letters| |-------|---------|---| |ESA|European Space Agency| |ICBM|Intercontinental Ballistic Missile| |Isp|Specific impulse (as explained by Scott Manley on YouTube)| | |Internet Service Provider| |JPL|Jet Propulsion Lab, California| |MON|Mixed Oxides of Nitrogen| |NTR|Nuclear Thermal Rocket| |RTG|Radioisotope Thermoelectric Generator|

|Jargon|Definition| |-------|---------|---| |Raptor|Methane-fueled rocket engine under development by SpaceX|

^(8 acronyms in this thread; )^(the most compressed thread commented on today)^( has 10 acronyms.)
^([Thread #8521 for this sub, first seen 6th Feb 2023, 21:02]) ^[FAQ] ^([Full list]) ^[Contact] ^([Source code])


PirateQueenOfAshes t1_j7hj62m wrote

Rolls-royce. Good so that means I'll never be able to afford that


vilius_m_lt t1_j7hxsi6 wrote

I mean they make jet engines for airliners. You can fly one without having to affording the whole plane..


1infinitefruitloop t1_j7i6lk9 wrote

What a mess of an article. I’ve said it before and I’ll say it again. Gizmodo is a far cry from the days of paying $5000 for the iPhone 4.


Mementose t1_j7h7xzm wrote

What are the Vegas odds for the first manned Mars landing being done in a Rolls?


Affectionate-Yak5280 t1_j7hdjwh wrote

If you're going to Mars you want Rolls Royce Engines, looks way better on the brochure.

Plus less cancer.

So to answer your question, 50%.


John-the-cool-guy t1_j7i9nx7 wrote

The Nostromo in the original Alien movie had Rolls Royce engines. Not sure if they were nuclear.


PtrWalnuts t1_j7iem0o wrote

Hey Rolls-Royce. You need another "R"

You know Rolls-Royce Reactor.

Rolls-Royce and only Rolls-Royce is allowed to use this idea gratis.


homerfraun t1_j7i8mti wrote

I wonder if the space crafts will have complementary luxury umbrellas that astronauts can pop out of the doors.


zoinkability t1_j7inbiv wrote

The article leaves out how exactly the energy would be used to propel the spacecraft. It does not seem like it will be “throw the bomb out the back” type nuclear propulsion. Perhaps the idea is to use the energy to power an ion drive of some kind?


UnadvertisedAndroid t1_j7gznde wrote

Why are our attitudes towards rocketing nuclear material into the stratosphere and beyond all of the sudden changing from "absolutely not" to "this is fine"?


VitaminPb t1_j7h0r4n wrote

The anti-nuclear groups are losing funding thanks to the collapse of the Soviet Union and Russia is a big part of it. Also, the anti-nuclear groups were largely ignorant and manipulated baby boomers who are dying off.


urmomaisjabbathehutt t1_j7hc44g wrote

the "anti nuclear groups" don't matter to to investors and money makers the same that those against fossil fuels didn't matter, the soviet union never was anti nuclear either

as per nuclear propulsion goes the soviets developed and lauched several and if this didn't go further was due to the policies for the use of nuclears in space driven by national security agreements between the world powers not because any "anti nuclear groups"

the only thing that matters to investors are returns to their investment the less riskier and the quicker the better and on that nuclears never competed with oil neverminnd with renewables

this thread is about nuclear propulsion


dittybopper_05H t1_j7hixec wrote

>the soviet union never was anti nuclear either

The Soviet Union was never anti-nuclear for itself.

However, the anti-nuclear movement in the West was at least encouraged, if not partially funded, by the USSR, especially when it came to nuclear weapons. But it also spilled into nuclear power generation.


Miserable-Deal-5703 t1_j7h8upm wrote

Why Uranium based though... My very limited knowledge on these things thought that Thorium reactors were the safer option?


cjameshuff t1_j7hflsk wrote

There's already ~4 billion metric tons of uranium in seawater. Dissolving the entire reactor and dumping it into the ocean would have no measurable effect. RTGs are actually more dangerous, as they require isotopes with high enough levels of radioactivity to generate useful amounts of heat, and those materials are at their highest levels of activity the moment they are can't just delay turning them on until after they've safely launched.

Thorium is just another possible fission fuel. It's often proposed to be used in a molten salt reactor, but molten salt reactors are not all thorium reactors and thorium reactors are not all molten salt reactors. There's no shortage of safe uranium reactor designs, it's just been impossible to get them implemented because of the anti-nuclear groups.


[deleted] t1_j7h7kkd wrote

TRISO fuel among other safety advances mean that dangers due to a failed launch are massively limited compared to a few decades ago.


[deleted] t1_j7hik2j wrote

Space is already radioactive. The vehicles using nuclear propulsion will be outside of the atmosphere and shouldn't make an impact on radiation levels on earth. It was frowned upon because it was seen as putting nuclear weapons in Space, but that's different now. We could all easily kill each other with ICBM's so putting a nuclear ship in Space isn't the treat it was in the 70's, plus we can put more mass into space now, so things like shielding are less costly.


Leather-Mundane t1_j7hyswa wrote

The fact that there has never been a accident with a payload containing fissile material.