[JohnCClarke]

I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme. This is shortsighted because (1) for electricity renewables are cheaper than nuclear, and (2) large naval vessels are enormously vulnerable to drones.

Ukraine's success against Russia's Black Sea fleet proves this for surface vessels. Similarly, it is easy to imagine a swarm of small underwater drones detecting, tracking and trailing nuclear submarines.

The UK government's is more focussed on providing juicy contracts to large corporations than realistic preparations for the future.

[Closi]

> This is shortsighted because [...] electricity renewables are cheaper than nuclear

This is an oversimplification - Renewables are cheaper than nuclear, but they are also less reliable than nuclear in the sense that when the wind stops blowing, power stops being generated. Also if you include the cost of energy storage to survive a week or two without substantial wind, suddenly it's not the cheaper anymore.

A mixed nuclear + renewables grid would reduce the total cost because nuclear can provide a stable base load which isn't affected by seasonality. Modern plants can also ramp up/down to some extent to balance the overall system.

That's why you need an energy mix rather than just putting all your eggs in a single source.

[adrianN]

Either you build enough nuclear to cover 95% of peak demand and essentially only run it a few weeks a year (because most of the time you have plenty of renewable supply) for terrible ROI or you need storage and peaker plants anyway. Nuclear energy is mostly interesting for cross subsidizing a military nuclear program by keeping relevant skills in domestic supply.

[hdgvhicv]

What good is a “base load” when the problem is peak demand. You’re saying nuclear gets to take the easy stuff and another industry can worry about peaker plants.

I suspect you need far ledd in peaker capacity - both GW and GWh - with a 100% wind than 100% nuclear if you spend the same amount on wind and nuclear.

[Melatonic]

For civilian use I believe this has proven unnecessary (assuming mix of wind, solar, etc) plus battery and other storage

Still seems like a worthwhile pursuit though

[DoctorOetker]

nuclear energy still causes a lot of prompt heating

other forms of renewables could generate electricity while cooling the planet.

a super chimney (perhaps suspended with balloons) piercing the tropopause and carrying either air in open or closed loop fashion, or a "refrigerant" (not necessarily a harmful one, could just be moist air, or any other medium of thermal exchange, like a gravity assisted heat siphon) in a closed loop could generate power while cooling the planet, it would also be base load given the large temperature difference between surface level and tropopause (which persists day and night, summer and winter). Obviously this can also be used to desalinate sea water by freeze desalination.

as soon as such technology takes off and multiple blocs make use of such technology, they will probably even get into arguments about how long or what fraction of the time each nation state is allowed to generate power this way (arguing it was our Western excessive CO2 consumption to which we have to thank this excess heat availability, and India countering that we should take into account their proper share of excess CO2 due to the underground coal mines that have been burning uncontrollably for decades on end, etc...) to the point of nation states attacking each others superchimneys.

[TheOtherHobbes]

If you invest in battery and storage tech you'll get reliable storage long before the first "baseload nukes" start contributing to the grid.

Storage tech has been criminally underfunded and under-researched. There are many, many options. But because of poor investment decisions and lobbying from the usual suspects the tech is around twenty years behind where it could be.

[_n_b_]

> I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme

It absolutely isn’t. There is very little crossover between the RR SMR (which is 470 MWe, not really an ‘SMR’ by IAEA definition) and a submarine reactor core. Sub cores are smaller and optimised for different conditions. They’re vastly different tech. The teams at RR working on these are totally distinct with no crossover.

RR just got £9B for sub NSSS work. They don’t need a back door subsidy when they have a big cheque coming right through the front door!

If anything, UK govt is prioritising domestic technology, whether or not that’s the best from a purely economic point of view.

[ViewTrick1002]

It is all about having the workforce able to deliver on the military ambitions.

This has been well known for a while, and western governments have started to say the quiet part out loud to justify the insanely large handouts required to build civillian nucleaar power.

https://theconversation.com/military-interests-are-pushing-n...

[throw0101a]

> I suspect that the push for civilian SMRs is a disguised subsidy for the naval reactor programme.

Ontario, Canada is building a bunch of BWRX-300 SMRs and don't really have a desire for a naval reactor programme:

* https://www.cbc.ca/news/canada/toronto/carney-ford-announce-...

* https://www.opg.com/projects-services/projects/nuclear/smr/d...

* https://www.gevernova.com/news/press-releases/ge-vernova-hit...

Canada is currently looking at new submarines, and the final two candidates are both SSKs (and not nuclear SSNs):

* https://www.defensenews.com/naval/2025/08/28/canada-shortlis...

* https://www.canada.ca/en/public-services-procurement/news/20...

As an Ontario resident I wish they chose to build more CANDUs (which, AIUI, they are planning to do as well) rather than SMRs: our grid is in more need of 'bulk power', and SMRs are better suited to small grids (like the Canadian Maritimes) or small sites (like in Poland: replacing previous smaller scale coal plants).

[mr_toad]

> Similarly, it is easy to imagine a swarm of small underwater drones detecting, tracking and trailing nuclear submarines.

Those are called torpedoes.

[Retric]

It’s way cheaper to build a drone that doesn’t need to travel quickly or carry huge amount high explosives.

[AnonymousPlanet]

People often underestimate the amount of storage you need for renewables. Depending on the geographic location you might be looking at tens of TWh. The cost for renewables then suddenly becomes much higher.

I recommend everyone who is using the cost argument to actually do the math on this first. It might be an eye opening experience. It certainly was for me.

[mqus]

Could you share your numbers as well? According to [1], the UK currently needs about 300TWh per year. Lets say we go entirely solar+wind+battery(whatever that means) and assume that battery has to bridge a gap of at most 7 days (meaning no wind and no solar at all during this time, which is at most a few days at a time). This adds up to 300/365*7= 5,8TWh of max capacity. Lets take it safe, round up and say we need 10TWh (which is already not "tens of TWH", but "ten"). [2] Says that grid-scale batteries come at around 350$ per kWh right now. kWh -> TWh is factor 1 billion (10^9), meaning if we want to build 10TWh of storage, it will cost 3,5 Trillion Dollars. Impressive number indeed. But there are multiple asterisks here.

1. This calculation takes into account that there is no exchange with mainland europe and no gas power plants or other sources of power (e.g. hydro or hydro storage). This sharply reduces the need for batteries. 2. Battery costs will fall in the next decades, compared to nuclear, which will take a long time (if ever) until costs will fall.

[1] https://www.statista.com/statistics/322874/electricity-consu... [2] https://docs.nrel.gov/docs/fy25osti/93281.pdf

[crote]

The problem is that the math is often done using faulty assumptions, such as expecting to rely solely on batteries to store enough energy to last several months.

In practice there are never long periods with and zero wind and zero solar and zero import capacity. Place the right price on electricity during peak demand, and suddenly the market is more than happy to install an overcapacity of wind & solar. Gigawatt-capacity cables to neighboring countries? Already being built!

A country like the UK needs an average electricity input of 45GW. It is totally fine to serve that with 60GW of wind operating at 25% capacity, 60GW of solar operating at 25% capacity, and 15GW of import operating at 100% capacity.

[osn9363739]

Can you share the math?

[wbl]

Ukraine's success proves that you need to actually have people guarding ships against intrusion. This is not a new lesson ever since the Raid on the Medway.

[greedo]

It's dangerous to extrapolate much from the performance of the Russian Navy in the Black Sea. While Ukraine has had remarkable success in almost completely shutting down Russian naval activity in the Black Sea, it's not all due to the superiority of drones. Russian incompetence, both in naval strategy as well as operations is endemic, and the fate of the Moskva and other systems isn't indicative of a widespread vulnerability of surface vessels to drone systems. The Moskva was sunk with cruise missiles, primarily ones developed from Soviet era missiles (Kh-35). Much has been written about the materiel state of the Moskva, as well as operational decisions/inadequacies that lead to its demise.

Surface drones work well when air cover is limited/restricted. Tracking them via radar is difficult due to surface noise, but it can be done. Countering them isn't an impossible task either, it, like other threats are handled systematically. The Russians have a relatively slow OODA loop, and Ukraine has been very successful in leveraging their superiority.

Is the threat a universal one or limited to the UKR/Russian conflict? A little of both. We've seen where an unprepared ship can be easily damaged by a small boat laden with explosives (USS Cole). We've seen the Ukrainians shut down Russian activity in the Black Sea, even going so far as to down unwitting aircraft that didn't respect the threat. But militaries adapt, especially to proven threats. Witness how the West responded to the sinking of the Eilat in 1973. It developed countermeasures and weapon systems for the threat of cruise missiles, while simultaneously developing their own cruise missiles (Harpoon/Exocet/Otomat/Penguin).

Will undersea drones prove as concerning? I doubt small swarms of UUVs will proliferate like we've seen with FPV drones. Flying through the air is much much easier than operating in water. Propulsion, C2, and targeting is quite difficult underwater compared to UAVs. Both range and payload are a challenge, so I don't believe that a swarm of "small underwater drones" will be able to detect the quietest ships in the ocean any time soon, much less track and trail something that can travel at speeds above 40kts with ease.

Now will large UUVs have a role in future naval combat? Undoubtedly.

[ReptileMan]

Russia's naval prowess have always been a joke so you can't make too many conclusions.

[Melatonic]

It would also provide a steady source of tritium for upkeeping nuclear weapons

[DoctorOetker]

This: nuclear energy is a subsidy for nuclear weapons.

[FridayoLeary]

As for point one they are much less reliable because they are intermittent. I'm skeptical of how much cheaper renewables are. I haven't noticed energy prices declining recently. Correct me if i'm misinformed. I'm slightly confused by point 2. What are you saying, because soviet technology is getting sunk a lot we should stop bothering with having a navy?

Either way you are giving way to much credit to the power of the UK military industrial complex.

[zoul]

Solar power is very cheap and still getting cheaper:

https://www.statista.com/chart/35117/levelized-cost-of-energ...

[dan-robertson]

The Royal Navy only uses nuclear power for submarines, at least for now (unlike USN which uses it for big aircraft carriers)

[lazzurs]

Making the two new UK aircraft carriers dependent on natural gas has to be one of the worst military procurement decisions of the modern era.

[0x000xca0xfe]

Renewables are cheap but storage isn't.

[Retric]

Storage is cheaper than peaking power which is why it’s common to add huge battery bank to solar power plants. It’s simply more profitable to add storage.

Net result renewables currently save you money until ~80% annual electricity supply. At which point adding more batteries and generation to cover overnight demand is cheaper than adding nuclear to the mix. In such a mix, Nuclear saves a little per kWh overnight and cost way more per kWh during the day, net result it’s more expensive as baseload. But, operating nuclear only at night drives up per kWh costs above storage.

Due to plant lifespans, new nuclear is already a poor investment which is why it’s rare, which then drives up construction costs. It’s a viscus cycle which ultimately dooms nuclear without massive subsidies which become hard to justify.

[epistasis]

In 2025 storage is cheap too, it's just that there's no need for it until you already have a large amount of renewables.

2025 is the year that storage is really being deployed in a serious manner in the US, more than 18GW most likely:

https://www.eia.gov/todayinenergy/detail.php?id=65964

You can see on the map at the bottom of this page that almost all the batteries are in areas that already have high amounts of renewables:

https://www.eia.gov/todayinenergy/detail.php?id=64586

And the prevalence of batteries in Texas means that they must be cost effective, because all grid assets in Texas are from private investors risking their own capital, and there is zero incentive for batteries except for their profit generative capacity.

[detritus]

...just quite yet.

[OJFord]

> electricity renewables are cheaper than nuclear

Are they still if you include storage, vs. nuclear's continuous generation?

[hdgvhicv]

Continue generation is great if you have continues demand. The U.K. does not have that (especially if you include heating and travel which is currently mainly provided by gas)