[KenB]

I understand the technology and the risks and would happily live right next to a nuclear power station in the U.K.

BUT i am not prepered to pay 3X the cost for the electricity it produces.

 

[Bornidentity]

It isn't just people objecting to nuclear that makes it expensive. Also, everything has to be done right, so if the welds are messed up or the concrete isn't right then you have to start over.

Flammanville had an issue because the reactor vessel casting process went wrong: all the carbon ended up at one end because they didn't mix it enough, and it was brittle on one end and floppy on the other.

Basically, you make one vessel every decade, most of the workers have retired or changed job in the meantime, and by the time you need to make the next one, everyone has forgotten how to do it.

Again, that’s foot dragging related! The whole point of an SMR is to stop them being bespoke mega projects. The parts are assembled in modules in factories that can be transported by standard HGV’s in a volume worth setting up assembly lines then put the parts together on site. The Rolls Royce SMR is designed to have a canopy built over the construction site so weather doesn’t interfere with the schedule. They aren’t trying to reinvent the wheel in terms of reactor technology but focusing on reducing construction costs.

 

[Bornidentity]

I understand the technology and the risks and would happily live right next to a nuclear power station in the U.K.

BUT i am not prepered to pay 3X the cost for the electricity it produces.

If you want to get away from Gas you’re going to pay more than 3x the cost of nuclear to have enough renewable energy to cover days when the Sun isn’t shining and the wind isn’t blowing in massive renewable overcapacity and battery storage. Most of the time if we had that much over capacity we’d be spending more on curtailment.

And again, the whole point of SMR’s is to make nuclear cheaper.

 

[KenB]

If you want to get away from Gas you’re going to pay more than 3x the cost of nuclear to have enough renewable energy to cover days when the Sun isn’t shining and the wind isn’t blowing in massive renewable overcapacity and battery storage. Most of the time if we had that much over capacity we’d be spending more on curtailment.

We are aiming for NET zero CO2 not zero gas. I have no problem with using some gas and NESO (aka Nat Grid) are aiming for 5% gas to cover the low RE periods. In the UK wind is already the largest producer of leccy and this will continue at a steady pace including the repowering of the old onshore wind farms and thereby double their capacity and remove their expensive leccy produced under the old ROCs system.

TOU tariffs will ensure that much of any excesses is soon mopped up. The biggest ones being EVs, HW, Hydro (2 big ones in the pipeline), batts, Refrigeration. Dont worry when there is cheap leccy about there will always be a consumer.
People seem to think that interconnectors are all about us importing but they are just as capable of exporting and do.

At the moment the price of leccy is controlled by the cost of gas but when that ceases to be the case the price of leccy will drop signicantly and it does occassionally when the gas plants have to bid uneconomic prices to to keep turning and warm.

 

[dashpool]

I don't have any particular problem with people researching and developing SMRs, but the main practical purpose of SMRs seems to be as an excuse for people who are opposed to renewables to do nothing right now to reduce power system emissions.

The main advantage of SMRs is that you don't need to put your money where your mouth is and build actually-existing nuclear with all of its difficulties. You can just blithely paint a picture of some miraculous future nuclear that is fast and clean and cheap...

SMRs also mostly seem to arise in combination with ridiculous strawmen about wind/solar dominated electricity systems (no, batteries will not be the only source of firming).

 

[mishad]

I just guided an answer and asked for its 'opinion' so as to optimise total annual energy using £100bn.

I suspect it guessed at a split between wind and nuclear because it came to the same split with and without maintenance drawn from the £100bn, but it is a starting point, and includes some data

…

Maintenance included;-
Updated Table (Including Maintenance):

Question	Nuclear	Wind
Installed cost (£/GW)	~£7 billion	~£3.25 billion
Annual maintenance cost (£/GW/year)	~£75 million	~£60 million
Total maintenance cost over 25 years (£/GW)	~£1.875 billion	~£1.5 billion
Total cost (installation + maintenance) over 25 years (£/GW)	~£8.875 billion	~£4.75 billion
Optimal spend from £100 billion (installation + maintenance)	£60 billion (6.76 GW)	£40 billion (8.42 GW)
Total annual kWh (for optimal spend)	~53.4 billion kWh	~29.5 billion kWh
Typical peak power output per day	6.76 GW	~8.42 GW
Lifetime (assumed)	25 years	25 years

Those figures show the price per generated kWh over the 25 years to be 4.5p/kWh for nuclear and 5.4p/kWh for wind, right?

On that basis why would the optimal split be 60:40? Why not 100% nuclear?

On those figures, for £100bn spent on nuclear you could build and maintain 11.27GW of capacity, and generate 89bn kWh pa - rather than the 82.9bn kWh for the 60:40 split.

Perhaps you need to ask deepseek to check its workings for the optimality of the split?

Or use a spreadsheet rather than an LLM!

 

[BornAgainEcoWarrior]

To be frank, that’s like a MacMaster video about electric cars.

Nuclear energy has been stuck in a world where people that don’t understand it or are irrationally / ignorantly against it have gotten the biggest microphone to scare people away from it.

I understand the technology and the risks and would happily live right next to a nuclear power station in the U.K.

It’s expensive because every time anyone tries to build one it gets objected to over and over and the safety cases keep moving on because everyone keeps objecting to it so the technology moves on and then it gets modified and the safety case changes and it’s objected to again and again. Then you have governments flip flopping because it drags on so long. Review after review.

Nuclear power is nowhere near as expensive in China because they just crack on with it. There is an EPR in china like Hinkley point C that took far less time and money to build.

https://en.m.wikipedia.org/wiki/Taishan_Nuclear_Power_Plant

I think you missed some context and information here. Much of what you say is true. But it’s not like other people’s ignorance or objections are the only reason nuclear is difficult or expensive.
And even in an authoritarian state which can railroad through whatever the government wants… and with the advantages of scale and experience… China has still yet to reach its target for nuclear for last decade. Yet they surpassed their targets for wind and solar by large margins.

Even in China with its authoritarian government, 30 year plan, scaled industry and experience from a consistent long term program, government secured finance… nuclear is still difficult and slow. Taking longer and proving more difficult than predicted. Yet wind and solar keep scaling and keeping adding vastly more power at decreasing cost.

 

[Bornidentity]

We are aiming for NET zero CO2 not zero gas. I have no problem with using some gas and NESO (aka Nat Grid) are aiming for 5% gas to cover the low RE periods. In the UK wind is already the largest producer of leccy and this will continue at a steady pace including the repowering of the old onshore wind farms and thereby double their capacity and remove their expensive leccy produced under the old ROCs system.

TOU tariffs will ensure that much of any excesses is soon mopped up. The biggest ones being EVs, HW, Hydro (2 big ones in the pipeline), batts, Refrigeration. Dont worry when there is cheap leccy about there will always be a consumer.
People seem to think that interconnectors are all about us importing but they are just as capable of exporting and do.

At the moment the price of leccy is controlled by the cost of gas but when that ceases to be the case the price of leccy will drop signicantly and it does occassionally when the gas plants have to bid uneconomic prices to to keep turning and warm.

That 5% from gas net zero target, includes building 24 GW of new nuclear power stations by 2050.

https://lordslibrary.parliament.uk/the-role-of-nuclear-in-the-uks-energy-supply/

If we don’t build that it’s going to have to come from something else reliable instead like gas. So the target won’t be met. If we have 24 GW of gas generation sat around doing nothing most of the time they will want a fortune per MWh when they do run in order to remain profitable.

I’m not saying it’s impossible to get to net zero without nuclear but it’s part of the current plan and if we do the usual foot dragging and can kicking it won’t be ready in time, the alternative won’t exist and we’ll still need plenty of gas power stations running on days like today.

I’m very pro renewables, but I think there is definitely a place for nuclear in our energy mix and we need to get on with it. We don’t need another 30 years of delaying tactics.

The Rolls Royce SMR seems like a good solution and it getting close to making it through GDA and being licensed. Hopefully it will win the government competition and they can start being built.

 

[Bornidentity]

I don't have any particular problem with people researching and developing SMRs, but the main practical purpose of SMRs seems to be as an excuse for people who are opposed to renewables to do nothing right now to reduce power system emissions.

The main advantage of SMRs is that you don't need to put your money where your mouth is and build actually-existing nuclear with all of its difficulties. You can just blithely paint a picture of some miraculous future nuclear that is fast and clean and cheap...

SMRs also mostly seem to arise in combination with ridiculous strawmen about wind/solar dominated electricity systems (no, batteries will not be the only source of firming).

Yes, there are some that see nuclear as an alternative and it could be.

I don’t but do think it should be part of the solution as is the current policy.

 

[donald]

Those figures show the price per generated kWh over the 25 years to be 4.5p/kWh for nuclear and 5.4p/kWh for wind, right?

On that basis why would the optimal split be 60:40? Why not 100% nuclear?

Deepseek's answer, and TBH, the reason I didn't question it is because it looks fine to me. I also repeat what I have said before, that by having as much renewable as nuclear, one can turn off the nuclear when there is plenty of renewable, thus reduce decommissioning, which I did not set as a metric because it wasn't important to hit zero CO2 by 2050 (decommissioning costs wouldn't be included in your frame of question).


"
If the cost of nuclear per kWh is less than wind power, from your table above, and I asked you to optimise for maximum kWh, which is it not 100% nuclear power?

Great question! The reason the optimization isn’t 100% nuclear—even though nuclear has a lower cost per kWh and a higher capacity factor—comes down to a few key factors:
1. Upfront Capital Constraints

• Nuclear power has a very high upfront cost (~£7 billion/GW for installation, plus ~£1.875 billion/GW for maintenance over 25 years).
• With a fixed budget of £100 billion, investing entirely in nuclear would allow for:
  £100 billion£8.875 billion/GW=11.27 GW of nuclear.£8.875billion/GW£100billion=11.27GW of nuclear.
• This would generate:
  11.27 GW×7.9 billion kWh/GW/year=89 billion kWh/year.11.27GW×7.9billion kWh/GW/year=89billion kWh/year.

2. Wind Power Adds Capacity Within the Budget

• Wind power has a lower upfront cost (~£3.25 billion/GW for installation, plus ~£1.5 billion/GW for maintenance over 25 years).
• By splitting the budget between nuclear and wind, we can install more total capacity:
  • Nuclear: 6.76 GW (from £60 billion).
  • Wind: 8.42 GW (from £40 billion).
• This generates:
  (6.76 GW×7.9 billion kWh/GW/year)+(8.42 GW×3.5 billion kWh/GW/year)=53.4+29.5=82.9 billion kWh/year.(6.76GW×7.9billion kWh/GW/year)+(8.42GW×3.5billion kWh/GW/year)=53.4+29.5=82.9billion kWh/year.
• While this is slightly less than the 89 billion kWh/year from 100% nuclear, it provides greater peak capacity (15.18 GW vs. 11.27 GW) and diversifies the energy mix, which is valuable for grid stability and resilience.

3. Diversification and Risk Mitigation

• Nuclear power is reliable but has risks: long construction times, regulatory hurdles, and public opposition.
• Wind power is faster to deploy and mitigates the risk of delays or cost overruns in nuclear projects.
• A mixed approach balances the strengths of both technologies.

4. Grid Stability and Intermittency

• Nuclear provides baseload power (constant output), but it cannot easily ramp up or down to match demand fluctuations.
• Wind power, while intermittent, can complement nuclear by providing flexibility during high-wind periods.
• Adding wind reduces the need for expensive energy storage or peaking plants to handle variability.

5. Cost of Variability

• While wind has a lower cost per kWh when the wind is blowing, its intermittency requires additional investments in grid infrastructure, storage, or backup power.
• Nuclear, with its high capacity factor, avoids these additional costs, making it more cost-effective in the long run.

Why Not 100% Nuclear?

• Budget constraints: With £100 billion, 100% nuclear would provide 89 billion kWh/year, but a mix of nuclear and wind provides 82.9 billion kWh/year while also delivering greater peak capacity and grid flexibility.
• Diversification: A mixed portfolio reduces risk and ensures a more resilient energy system.
• Deployment speed: Wind can be deployed faster, providing energy sooner while nuclear plants are under construction.

Final Thoughts:
If the sole goal is to maximize kWh/year without any other constraints (e.g., grid stability, diversification, or peak capacity), then 100% nuclear would indeed be the optimal choice. However, in real-world scenarios, other factors (like budget constraints, risk mitigation, and grid needs) make a mixed approach more practical and resilient.
"

 

[sidehaas]

I don't have any particular problem with people researching and developing SMRs, but the main practical purpose of SMRs seems to be as an excuse for people who are opposed to renewables to do nothing right now to reduce power system emissions.

The main advantage of SMRs is that you don't need to put your money where your mouth is and build actually-existing nuclear with all of its difficulties. You can just blithely paint a picture of some miraculous future nuclear that is fast and clean and cheap...

SMRs also mostly seem to arise in combination with ridiculous strawmen about wind/solar dominated electricity systems (no, batteries will not be the only source of firming).

I have literally never met any proponent of SMRs or anyone designing them (of many people) who said they were against renewables. They all want a mixed grid.

 

[dashpool]

I have literally never met any proponent of SMRs or anyone designing them (of many people) who said they were against renewables. They all want a mixed grid.

Pretty much every renewables-opposed ideologue I've ever encountered (mostly online, but occasionally IRL) pushes SMRs or Nuclear in general as a superior alternative to wind/solar. Been happening for decades now.

I'm sure most of the people actually practically working on the design of SMRs are more sensible, but the public discussion is dominated by "nuclear instead of unreliables" folk.

This is particularly bad in Australia where one wing of politics has embraced nuclear as a "solution", and when they get into power have started revoking permits for wind/solar farms. Of course,they don't have any real concrete plans to build nuclear in Australia (which has never had a power reactor, and has no regulatory framework except for a ban on nuclear power).

The Australian ones have gone full-SMR now, because the less it actually exists as an option, the more excuse they have for sitting on their hands and keeping the coal plants burning.

 

[BornAgainEcoWarrior]

Pretty much every renewables-opposed ideologue I've ever encountered (mostly online, but occasionally IRL) pushes SMRs or Nuclear in general as a superior alternative to wind/solar. Been happening for decades now.

I'm sure most of the people actually practically working on the design of SMRs are more sensible, but the public discussion is dominated by "nuclear instead of unreliables" folk.

This is particularly bad in Australia where one wing of politics has embraced nuclear as a "solution", and when they get into power have started revoking permits for wind/solar farms. Of course,they don't have any real concrete plans to build nuclear in Australia (which has never had a power reactor, and has no regulatory framework except for a ban on nuclear power).

The Australian ones have gone full-SMR now, because the less it actually exists as an option, the more excuse they have for sitting on their hands and keeping the coal plants burning.

I fear another terrible deal struck on our behalf pissing away money on pipe dreams. The government is great at spending money without getting much in return. Take the CCS funding for instance. £22bn spent which will come from electricity costs, raising prices for consumers. Based on false calculations.
If it ever makes money in its own right taxpayers will get none of the return. Zero.
We spent £22bn to build something to justify ongoing consumption of FF in order to make money for someone else at the taxpayers expense.

SMRs sounds like more of the same. We pay for the development, we pay to build it at alpha and beta. And in the event it’s an economic success with significant export and global installs… RR will make all the profits, while Uk consumers live with the costs and foibles of their alpha and beta design experiments added to our bills. Not that it seems particularly likely to be a winner in the context of the growing cost effectiveness of solar and batteries.

 

[mishad]

Deepseek's answer, and TBH, the reason I didn't question it …

This is the scariest bit of AI for me right now. Not AIs achieving sentience and triggering the AGI singularity.

No, it is people just taking the output of a stochastic word model at face value and not questioning it, simply because it “looks about right”.

TBH @donald you were quite low down on my list of people likely to be susceptible to that mistake.

Remember, folks, an LLM is just a big matrix of numbers, through which a particular set of “prompt” words is run, repeatedly, to generate a good guess as to the next word, and then that process is repeated with the generated word added, and so on until an answer is generated.

That one can get cromulent responses out of such a model with only a billion* or so numbers in it, which can be stored and evaluated in under 0.5GB of ram and just a few seconds of processing time is wildly impressive - but it should also be a clear indicator that such a model cannot possibly be able to analyse such a question properly let alone answer it reliably.


*commercial models are much bigger, of course, with hundreds of billions of parameters, but even the small models can generate stuff that looks kind right if you don’t know the subject matter well.

 

[donald]

This is the scariest bit of AI for me right now. Not AIs achieving sentience and triggering the AGI singularity.

No, it is people just taking the output of a stochastic word model at face value and not questioning it, simply because it “looks about right”.

TBH @donald you were quite low down on my list of people likely to be susceptible to that mistake.

No, not me.

You see, my request was for the largest total kWh and I had no reason to doubt it had done that optimisation. It clarifies in the calculation that the wind would come on-stream faster, so, even if the 'start point' was some moment in the future when nuclear was build, however you swing it the wind would already start pumping out kWh, and thus for the lifetime of the project, no matter when it starts, the wind will have 'credit' for the kWh it generates.

Nothwithstanding that word-engineering, I recognise what you are saying about the dangers of simply accepting some given output, but that's my line!!! That is what I keep telling others!

In this case, I already offered all the caveats needed;

Worth noting that I have not, anywhere, merely stated it speaks for me.

 

[KenB]

https://assets.publishing.service.gov.uk/media/5a8244b8ed915d74e6236aef/TEA_Projects_5-7_-_SMR_Cost_Reduction_Study.pdf

I dont see any cheap nuclear electricity in that, just more wasted money which may provide expensive leccy just as expensive as a big nuclear plant ie 3X that of RE.

 

[KenB]

LCOE (levelised cost of electricity) which gives every cost for building in 2030

CCGT £130/MWh
Off Wind £39
On Wind £36
Large solar £37
Nuclear £ 130 +

https://assets.publishing.service.gov.uk/media/6556027d046ed400148b99fe/electricity-generation-costs-2023.pdf

One could build twice as much RE as required, never use 1/2 and its still cheaper!! or just co-locate storage with the RE or just use all those EVs sitting around.

 

[donald]

LCOE (levelised cost of electricity) which gives every cost for building in 2030

CCGT £130/MWh
Off Wind £39
On Wind £36
Large solar £37
Nuclear £ 130 +

https://assets.publishing.service.gov.uk/media/6556027d046ed400148b99fe/electricity-generation-costs-2023.pdf

One could build twice as much RE as required, never use 1/2 and its still cheaper!! or just co-locate storage with the RE or just use all those EVs sitting around.

Those costs are a different answer to the question @mishad posed. The nuclear cost includes decommissioning, which would not form part of achieving zero carbon by 2050.

As the mice found with deepthought, you have to understand the question to understand the answer.

 

[BornAgainEcoWarrior]

https://assets.publishing.service.gov.uk/media/5a8244b8ed915d74e6236aef/TEA_Projects_5-7_-_SMR_Cost_Reduction_Study.pdf

I dont see any cheap nuclear electricity in that, just more wasted money which may provide expensive leccy just as expensive as a big nuclear plant ie 3X that of RE.

Hmmm
So have I got this right?… the expectations were that SMRs would initially cost 30% more (LCOE) than large nukes.
With a possibility to bring costs down after building 5GW worth… so double what we have today for nuclear capacity, but that’s only bringing price to the same as large nukes? And that only after we’ve built many.
That was in 2016, and there was at the time “substantial challenges” to show feasibility and deploy 1 by 2030. So while construction time is suggested as 3-4 years it is in fact a 14 year timeframe… So are we still on schedule to deploy 1 in 2030, or is that already pushed back?
And are we then expecting to pay for the electricity at erm(£92/MWh in 2014 = £130 now so plus 30%) … is that £170/MWh? Yikes.
And if we follow through and build 5GW of it all of it will cost >£130/MWh. Double Yikes.

 

[jgwozdzicki]

As Rei already said SMR/s generate more waste (although are designed to be buried as is rather than cracked open), they use highly enriched fuel, much higher than current commercial reactors so have a nuclear proliferation risk and are more expensive to build over bigger reactors which is why the industry moved to big reactors in the first place. Also @Bornidentity’s comments earlier that they’ll benefit from standardisation unlike their bigger cousins isn’t necessarily true. Most reactors that exist now are copies of a particular design, all the UKs reactors bar Sizewell are copies and even Sizewell was the first of a planned 20 I think it was (probably got that wrong). The thing is, the learning curve doesn’t always apply to every technology, oil extraction is a good example, we pump more now than at any other time but it hasnt made it cheaper. Nuclear also gets more complex and advanced with each design and therefore prevents this learning curve, making itself felt too. Even China, the biggest nuke builder have frozen inland nukes due to worry over lack of water and their SMR program has cost more than China anticipated and in a country that can basically build anything is struggling to reach its nuclear targets.

SMR’s are a distraction. Sure if tech bros want to pay for them to run their data centres then go ahead, but you pay for them, don’t go cap in hand to governments for subsidies and for them to be run by utilities so they can put the cost on our bills.