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Rolls-Royce plans mini nuclear reactors by 2029

bbc.co.uk

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Re: Rolls-Royce plans mini nuclear reactors by 2029

#181

Post by renaudg »

cygx wrote: post #142
belorn wrote: post #103

Earlier quoted context omitted.

Renewables are not a replacement for existing nuclear power unless you either add fossil fuels or batteries to the mix. Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels, with fossil fuels burning when renewables are not producing. Batteries, usually reverse hydro power, is an interesting future technology. Some argue it is significant more developed than fu…

Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels Which countries? Germany for example isn't - yet. We're still in a place where we can reduce usage of both fossil fuels and nuclear, though that won't last unless we figure out effective means of energy storage.

Germany absolutely is relying on coal and (Russian) gas to afford its ideological decision to prematurely sunset nuclear plants, at the worst possible time in history : just as climate change becomes an emergency.

The cold hard truth is that it's impossible to operate a grid with solar & wind energy alone, unless and until a hypothetical battery storage breakthrough lands in the next decades.

I've just checked the realtime figures and as I write this, German electricity is 5 times more carbon intensive than in France (72% nuclear) : https://www.electricitymap.org/

Re: Rolls-Royce plans mini nuclear reactors by 2029

#182

Post by epistasis »

roenxi wrote: post #75
hannob wrote: post #48

Earlier quoted context omitted.

I'm always baffled by such statements. Can you explain in which way solar is not a "near-infinite source of energy"? I mean... there are without doubt technical challenges and all that (but arguably less technical challenges than to do the same with nuclear), but there really is no relevant limit to the deployment of solar cells if you include things like large-scale installations in the desert.

The solar panels do have to be fabricated. That probably doesn't have the same scaling potential as nuclear given how much power/m2 nuclear can reach. Also, at a guess the energy in solar panels drop with the square of distance to the sun. It is unlikely to be a good choice for interstellar travel if 'advance[ing] as a species' heads in the more fantastic directions.

If we are getting to the point where W/m2 is an important win for nuclear, we are going to start to have serious problems with the rejected heat.

A fundamental limitation of thermal steam engines is that they can only ever be 50% efficient, and you have to dump that waste heat in order to maintain power.

Already, heat mitigation systems for some existing nuclear plants are starting to fail during heat waves as the climate warms. And these are expensive systems: at Diablo Canyon in California, it's cheaper to replace an entire, functioning reactor with renewables than it is to simply build a new cooling system.

Which is all to say that nuclear won't scale tremendously well unless we 1) figure out fusion, and 2) figure out direct conversion of energy to electricity rather than using steam turbines to mechanically drive a generator.

For the ultimate goal that many people have for nuclear, as a power source when not on earth, these sorts of advancements are also likely also necessary. Cooling in space is not a trivial matter.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#183

Post by samatman »

throw0101a wrote: post #145
vidarh wrote: post #126

Earlier quoted context omitted.

We could grind nuclear waste from current nuclear plants into fine powder and intentionally blow it into the atmosphere and still cause fewer deaths than coal, as well as cause the release of less radioactive material, as the coal industry causes huge amounts of uranium dust to be released in the air. So as it stands, if we look at the real world instead of some hypothetical future, we continue to depend on types of…

> We could grind nuclear waste from current nuclear plants into fine powder and intentionally blow it into the atmosphere and still cause fewer deaths than coal, as well as cause the release of less radioactive material, as the coal industry causes huge amounts of uranium dust to be released in the air. How does the math work on this? It seems... hyperbolic.

There exists coal with more fissile energy, in the form of heavy isotopes such as thorium and uranium, than it has chemical energy, in the form of carbon-carbon bonds.

This is then burned in power plants, releasing the radioactive material into the atmosphere, and leaching it into groundwater from exposed piles of fly ash.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#184

Post by duckymcduckface »

chrisco255 wrote: post #154
posix_me_less wrote: post #84

Earlier quoted context omitted.

Loss of power during distribution is not a problem that needs solving, power losses due to transmission in conventional grid are mere 5%. [1] https://en.wikipedia.org/wiki/Electric_power_transmission#Lo... Considering how costly and inflexible all superconductors are, I don't see why they would help.

Those losses are on a per 100 mile basis. 2-5% per 100 miles of line (not as the crow flies mind you). Superconductors would make a huge difference if they could build a room temperature superconductor.

The 5% is quoted further in the article for overall grid waste. The per mile basis is purely there to compare why higher voltages for the Samer power lead to less waste.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#185

Post by Nasrudith »

ed_balls wrote: post #139
koheripbal wrote: post #117

Earlier quoted context omitted.

The best economies of scale comes from building many LARGE reactors - not small ones.

I'm not sure how do you mean. You get economy of scale by saving in costs gained by an increased level of production. It's cheaper to create 100 widgets for 100 small reactors in 10 locations, then for 10 large reactors.

The efficency also scales with size in this case - separate from the per unit production scale.

It is still cheaper and more efficient to have a 1.2 GW diesel power plant instead of a warehouse of thousands of back up generators wired together.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#186

Post by vidarh »

throw0101a wrote: post #145
vidarh wrote: post #126

Earlier quoted context omitted.

We could grind nuclear waste from current nuclear plants into fine powder and intentionally blow it into the atmosphere and still cause fewer deaths than coal, as well as cause the release of less radioactive material, as the coal industry causes huge amounts of uranium dust to be released in the air. So as it stands, if we look at the real world instead of some hypothetical future, we continue to depend on types of…

> We could grind nuclear waste from current nuclear plants into fine powder and intentionally blow it into the atmosphere and still cause fewer deaths than coal, as well as cause the release of less radioactive material, as the coal industry causes huge amounts of uranium dust to be released in the air. How does the math work on this? It seems... hyperbolic.

Look up fly ash. Orders of magnitude more fly ash is produced than waste from nuclear plants, and it contains high concentrations of uranium and thorium.

While plants in e.g the US now captures most of it, huge quantities are still released into the air especially in countries with lower environmental standards.

But even places where it doesn't get released that just means having to deal with far more radioactive waste than nuclear plants produces.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#187

Post by akiselev »

kerkeslager wrote: post #179
pjc50 wrote: post #143

Earlier quoted context omitted.

Plumbing is a problem for hot radioactive molten salt. It's one of the few things that will erode ordinary stainless steel.

Does titanium hold up to radioactive molten salt? There are a bunch of places I've found where the difficulty (and therefore cost) of working with titanium is really holding humanity back. If we could find cheaper techniques for working with titanium it would revolutionize a lot of industries, as it's plentiful, light, strong, non-reactive, and melts at high temperatures. But the same attributes that make it hold up…

A radioactive fluoride salt might just be one of the most corrosive substances on the planet. Titanium might hold up a little longer but not by much.

Any material that can resist the corrosion will be bombarded by neutrons until it is transmuted into another material that can't, even with "slow" neutrons.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#188

Post by Symmetry »

the8472 wrote: post #88
dmos62 wrote: post #54

Earlier quoted context omitted.

> we want to advance as a species I'm somewhat weary of people talking of civilization progress as if its definition is obvious and universal.

As far as humans are concerned overall progress has been linked to climbing up fractions of the kardashev scale since fire was invented. And even before fire, organisms could only become more complex as the energy available to them increased. You can't run a hummingbird or mammalian brains on photosynthesis directly, it's just not energy-dense enough.

even before fire, organisms could only become more complex as the energy available to them increased

Heck, look at how the complexity of life increased as soon as mitochondria were invented, going from genomes measured in millions of base pairs for bacteria to billions for amoebas once cells were no longer caught in the square/cube trap of respirating over the cell wall.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#189

Post by renaudg »

belorn wrote: post #175
cygx wrote: post #142

Earlier quoted context omitted.

Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels Which countries? Germany for example isn't - yet. We're still in a place where we can reduce usage of both fossil fuels and nuclear, though that won't last unless we figure out effective means of energy storage.

As an example, Sweden. People will use fossil fueled energy when the choice is between people freezing in their home or burning fossil fuels. Sweden rely on a mix between hydro and nuclear, but it is not feasible to extend hydro beyond current capacity. The nuclear plants however is getting older, and politically people want to shut them down. Something has to produce the energy, and during the winter it is imported…

German anti-nuclear activists like to tout the percentage figure of renewables in the country, but that's not the right metric to look at : the coal+gas baseline is so bad in terms of CO2 emissions, that even in ideal conditions when wind production is 70%, German electricity's carbon intensity is still way higher than in France, Sweden or Iceland (

Coal causes 35.000 premature deaths in Europe every year, and 7 of the 10 most polluting industry sites on the continent are German lignite power plants.

The hypocrisy and constant lecturing from Die Grüne needs to stop.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#190

Post by renaudg »

Brometheus wrote: post #171
belorn wrote: post #103

Earlier quoted context omitted.

Renewables are not a replacement for existing nuclear power unless you either add fossil fuels or batteries to the mix. Countries which currently are replacing nuclear power do so with a combination of renewables and fossil fuels, with fossil fuels burning when renewables are not producing. Batteries, usually reverse hydro power, is an interesting future technology. Some argue it is significant more developed than fu…

For nuclear you still need to have peaker plants. ALso nuclear is really expensive.

Pretty sure it's actually cheapest per kWh
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