Delivering 4GW in a single project would certainly set it apart. Perhaps the sweet spot for nuclear is not the traditional 1GW level.

Although that would create a very large single point of failure that would need peakers/batteries/pumped hydro to backup on failure.

An interesting project would be to stick a 5GW reactor in the middle of the North Sea and run export cables to all the surrounding countries. Build near an old oil well for hydrogen storage and include a thermal hydrogen generator.

Yes, a 4GW reactor is certainly not for any country to build for above reasons (shut down a double digit of your generation every time you refuel.) Even moderately industrialised countries will think twice, but it is indeed very logical for top 10 economies.

The biggest problem will be building a containment building this big.

A dilemma it is. Containment building can't do anything about reactor explosion. Either steam explosion from Chernobil like event, or hydrogen explosion is not survivable by containment building of any reactor in service.

And containment building for a reactor this big will be even less useful.

This means abandoning them, and going for Chernobil like no containment building construction.

>hydrogen explosion is not survivable by containment building of any reactor in service

Or you can simply include specialized hydrogen burners like in the modern VVER reactors, which have complied with the post-Fukushima requirements even before the event has happened. Also a Chernobyl-like event is simply impossible on PWR reactors.

> simply impossible on PWR reactors.

Easily possible. I'll give you a few scenarios I came up within just minutes.

Loss of coolant -> drop in reactivity -> overheat of core -> core melts, and falls into puddle of remaining water at the bottom of the reactor -> instant reactivity boost -> boom

Loss of coolant -> drop in reactivity -> overheat of core -> coolant comes back -> water spayed onto hot fuel -> steam flash -> steam-cladding reaction -> boom

I can reply to you with only one thing: please, learn more about modern reactor designs and their safety systems, don't embarrass yourself. Also learn why the Chernobyl event was so nasty and why its impact is significantly bigger compared to Fukushima (hint: graphite moderation).

Now, do us a favour, and tell us how that is not possible.

You are embarrassing yourself here with lack of manners, and constant attacks. Behave yourself.

It's unproductive to discuss such matters with a total layman who didn't bother to do even a basic research, but ok, I will play along.

Let's start from the simplest thing: a Chernobyl-like event is impossible on PWR because they do not use graphite moderators. Simple, right? I could've finished on this, but let me educated you a bit more. Modern reactors have the following safety systems in place (it's not a full list):

- Hydrogen burners (recombiners) mentioned in my previous comment, which significantly reduce amount of hydrogen inside containment.

- Systems for fast automatic Boron injection.

- Heat sink systems designed to work without electricity.

- Passive cooling systems, which are significantly more reliable than the isolation condenser used on Fukushima-1.

- A way of supplying additional coolant externally.

- Core catchers which lead corium from the containment building.

If you know Russian you can read for example this paper [0] from Gidropress (Rosatom subsidiary) to learn more about how modern nuclear reactors handle severe accidents associated with a total loss of electricity. It's about older VVER-1000 reactors, which are a bit less advanced than the newer VVER-1200 and TOI designs, but it should be a good starting point.

[0]: http://www.gidropress.podolsk.ru/files/proceedings/mntk2019/...

> It's unproductive to discuss such matters with a total layman who didn't bother to do even a basic research, but ok, I will play along.

I will play along too. It will be very surprising to me if you are an actual industry insider.

You have not addressed the loss of coolant.

> Let's start from the simplest thing: a Chernobyl-like event is impossible on PWR because they do not use graphite moderators. Simple, right? I could've finished on this, but let me educated you a bit more. Modern reactors have the following safety systems in place (it's not a full list):

Power excursion is very well possible on PWRs during rapid coolant/pressure loss, especially with very fresh, or very old fuel.

Positive scram is possible on PWRs too under condition when rods/poison rapidly reduce coolant temperatures.

Boron injection will not work if your coolant went supercritical.

Catalytic hydrogen recombiners can help with gradual hydrogen release, but would be of no use if you are hit with sudden release.

Passive heat sinks will not do anything if you reactor already lost big part of its coolant. Etc, etc.

What do you do with this power if solar and wind are cheaper? I.e. in a free market, what if buyers prefer wind and solar energy? Do you dump the energy at a loss, go bankrupt leaving investors and banks to write off the cost?

Why would anyone take that risk?

Is there anyone willing to build such a powerplant at fixed cost? (i.e. after x billion euro you either get the plant or your money back)

Obviously, the situation will change if hit the wall with wind and solar. But there are no reliable predictions if or when we would hit a wall.

> What do you do with this power if solar and wind are cheaper?

> Do you dump the energy at a loss

Yes, if you dump energy at loss is still not a total loss, and you still make money if you above water longer than you aren't.

The point of making the reactor that powerful is exactly to get more profit even at super low rates.

That seems unlikely. If, for example, you run at a loss 50% for the time, then you need to have extra expensive rates during the other 50% of the time. Based on typical construction costs of nuclear power plants, those high rates are extremely attractive for competition from wind and solar. Which will reduce the amount of power that can be sold at premium rates, which requires even higher rates to compensate, etc.

Basically, in a free market, nuclear power is competing with power from batteries, hydrogen, and other ways of storing electricity.

This is an extremely unattractive market for nuclear.

No, the solution is building multiple sub 100 MW (NuScale Power and others) and a few sub 500 MW SMRs for major cities (think post VVER 440 designs and Rolls Royce SMRs). Gen VI+ has passive safety requirements that would render a multi GW plant too big and too expensive. Think huge tanks of water, double containment, passive circulation, gravitational safety features and minimal disruption of fisheries and habitats. We need smaller and more modular NPPs with reactor vessels built on an assembly line and QCed, good safety guarantees, minimal staff, minimal operational costs and the ability to regulate the energy output in a wider range.

Building smaller reactors in not as solution to nuclear's cost for many reasons I wrote above.

Economics of small reactors is unsound. A cult like group pushing "small modular reactors" pushes a very likely deliberately miscalculated pricing estimates for them.

Some of the designs seem to have high civil engineering costs. Digging big holes is not exactly a cheap thing to do.

>Nuclear will always be many times more expensive than equivalent power hydrocarbon powerplant.

No, you're behind the times. You're thinking of present nuclear plant technology, and in that you're correct.

Newer plant designs solve most of the issues with construction and management cost, nuclear proliferation, and even reduce the waste that must be stored.

Arguing for greater use of the 1960s technology that's presently in power plants is silly, and no one is really advocating that.

Google "small modular reactors" and read up.

Please tell me how can you make reactor vessels cheaper by making 2 smaller vessels instead of 1 bigger one on current reactor scales. Their math is plainly wrong.

The "small modular reactor" community is a bit of a cult.

Be extra wary of everything they say.

The SMR community does have a lot of hype, but the general idea seems fairly sound. Instead of building huge reactors on site, as basically big one off projects. Instead, mass produce a bunch of smaller modular reactors at a factory. That doesn't seem much different than a modular home vs a custom home to me, with the modular home being way cheaper. But we will see if it actually works.

But for me the biggest issue is, if fighting climate change is so important, why wouldn't we try everything possible? Why do so many people insist on only renewables?

I think as you do. People are not going to settle for "Well we can keep solar up for up to a few hours when the blizzard comes and reduces radiation levels by 70% with our new battery bank". That's not going to cut it when the blizzard lasts for week. That will never get off the ground.

You have smaller logistics costs for smaller reactor, yes... But you don't have reduction in marginal logistics cost per unit of energy produced.

While reactor vessels themselves are most expensive single piece in the nuclear power station, they are not going to save much on them by making them smaller, and they would not get any cheaper from mass manufacturing.

I don't know, the idea that mass manufacturing wouldn't lower the price of something seems kinda ridiculous, you have any examples of a product where mass manufacturing didn't lower the price?

If you said something like "mass manufacturing wont make them cheap enough to be economical", that seems believable, but I'm not sure how you can blanket declare it wont make them any cheaper.

> idea that mass manufacturing wouldn't lower the price of something seems kinda ridiculous

The "something" to be manufactured isn't nuclear power plants.

If we made a few 5 MW plants at a certain price but then decided to scale that up and produce huge amounts of 5 MW plants then we could obviously produce those plants at a significantly lower per-unit cost. Everyone agrees. But our goal with electricity isn't to make plants, it's to make watt-hours of electricity.

So what is cheaper? Manufacturing, setting up, operating, and securing 1000 5 MW plants or one 5 GW plant? It seems like the 5 GW one might be cheaper.

>The "something" to be manufactured isn't nuclear power plants.

Wrong, actually. Whenever multiple nuclear plants for submarines in a given class are manufactured, the fact that multiples are being built does lower the cost, although most of that is just from having a complete design to use rather than any kind of mass production. Navy reactors aren't really SMRs since they're also old technology, but they're a good example of how much easier/cheaper/greener it is to build small reactors instead of large ones.

> It seems like the 5 GW one might be cheaper.

Small modular reactors typically run up to 300MW in size. There are very few applications for a 5GW reactor. Besides, the costs of the small reactors in terms of time, money, operating expense, security and other things are so much less than for the large plants that the math really doesn't work anyway, even for your extreme example of 1000 5MW reactors.

> So what is cheaper? Manufacturing, setting up, operating, and securing 1000 5 MW plants or one 5 GW plant? It seems like the 5 GW one might be cheaper.

It's not 1000 5MW plants vs 1 5GW plant, each SMR plant would have dozens of smaller cores. Most of the plans I see are in the 300MW - 1100MW range.

> Everyone agrees. But our goal with electricity isn't to make plants, it's to make watt-hours of electricity.

If the goal is to create carbon free electricity then making as many carbon free power plants is exactly how you'd get more watt-hours.

This has been my argument for a long time. Standardize on one of the designs that makes "going critical" is impossible and is "good enough" as power generation and let mass production do its thing. I believe that a lot people who are into "green energy" are also anti-capitalists and think that terms like mass-production are dirty words and tend to ignore history.

I do not think this is fair. Cost of fossil fuels is largely undervalued: most of the cost (wars and pollution) is not taken into account.