[Arodex]

>i feel like available space, time to complete construction

All of these favor again bigger reactors.

>considering the length of time and sheer number of people, companies, and governments considering/investing in SMR tech it seems unlikely to be a mania.

All of the Swiss energy companies are asking to be bailed out in advance of the investment in nuclear.

[Jolter]

Sweden recently did the same: in order for companies to agree to make new reactors, the government had to promise them a price floor for the electricity they produce. The price floor suggested is more than twice the current price on the spot market. That means that, for the lifetime of those reactors, Swedish taxpayers will be subsidizing production of nuclear power. I thought the idea was that they would be profitable? What happened to the political right’s love of the free market? When politicians go fixing prices with this kind of ”advance bailout”, it just makes it look like they are trying to get a nice retirement job in the nuclear power sector…

[mpweiher]

The biggest risk for nuclear is the government.

That's why the government has to indemnify the companies against those risks.

Spot market prices are not total system costs.

[Jolter]

You’re right, the total system costs include a lot of things, including disposal of spent fuel. Which is apparently so expensive, nuclear can’t compete with renewables fairly.

[mpweiher]

That's not true. Disposal of spent fuel was always included in the price of electricity (for example in Germany, but many/most others as well) and is negligible in cost.

Finland just built a spent-fuel repository for ~ € 1 billion. For the entire country. Just the single EPR at Olkiluoto 3 will produce electricity worth €100 billion over its lifetime if you assume a price of 10 cents/kWh.

So at 10 cents, it would be 1% of the price of electricity if Olkiluoto 3 had to finance the whole thing by itself.

[Jolter]

What part isn’t true? That disposal of fuel is part of the total systems cost? Or that the new nuclear can’t compete without subsidies? I think both are evident truths.

[mpweiher]

The part I explained: disposal is, unlike your claim, not a significant part of total cost of nuclear power.

Therefore, even assuming for a second your counterfactual that nuclear power isn't cost-competitive, it wouldn't be due to the disposal costs.

Of course it's also not true that nuclear isn't cost competitive. It absolutely is.

[Scroll_Swe]

Base load generation.

Yes, we have hydro.

Wind is way too unpredictable, solar is too.

So, we can only have 2 powers to provide base load in Sweden.

https://www.svk.se/om-kraftsystemet/kontrollrummet/

[crote]

Nuclear base load is a lie.

The aforementioned subsidies aren't just for the electricity it produces, it is also for the electricity it could produce. The nuclear plant has a right to sell electricity to the grid at a certain price. Market price too low? The government pays the difference. No demand? The government buys the unused production capacity.

In practice this means that during periods of excess you are shutting down dirt-cheap solar and wind just so you can run a heavily-subsidized nuclear power plant. Nuclear doesn't pick up the gaps left by solar and wind, solar and wind pick up the gaps left by nuclear!

[mpweiher]

Giving priority to non-reliable producers is insane.

[Arodex]

With batteries, not only is renewable more reliable, it is also much easier to maintain grid stability.

[Scroll_Swe]

Okay so we turn off all nuclear like Germany?

Now what?

[Jolter]

Straw man.

[john_strinlai]

>All of these favor again bigger reactors.

how does having less available space favor a bigger reactor?

and how is constructing a bigger reactor faster than constructing a smaller one?

[bryanlarsen]

There are two ways of achieving economies of scale: making things bigger or making more of them.

For small quantities, the former is usually more effective -- making things bigger lets you make fewer of them, reducing costs.

For large quantities, a factory can enable insane economies of scale.

SMR proponents are talking about building dozens of reactors. That fits very firmly in the "small quantity" column where economies of scale almost always favor building things bigger.

[Arodex]

If you need 500 MW, you build one 500 MW reactor, not five 100 MW reactors. They will take more space.

As for speed, a 100 MW reactor is not commissioned in 1/5 of the time a 500 MW reactor is.

[Jolter]

I think the promise of SMR is that the 1/5th reactor can be built in 1/2 the time. And you build five of them in parallell. And you have your power sources gradually online over about the same time as one ”big bang” build would take.

I don’t think it’s going to work out that way, but that’s how it’s being sold.

[cauch]

Even like that, it is not clear-cut. 1/5 in 1/2 the time is still 2.5 shorter per worker, and building in parallel require multiplying expert builders, which is not easy (as it takes time to acquire the expertise and you don't want to learn a trade to build one project and have nothing to do next).

But, yes, I get it is how it is sold. Just that even sold like that, people with common sense should say "wait a minute, that's obviously not that simple".

[cauch]

Just a guess (I'm not the previous user), but I guess you need to look at the space _per GWh_?

If a big nuclear reactor takes 10x more space but has 20x more capacity, then it means not having much space favors the big nuclear reactor rather than building 10 small ones that will take twice more space.

(and same for the time)

[john_strinlai]

its probably my fault for not making myself clear. i mean when the available space is constrained to a specific amount of space that cannot be exceeded.

just picking random numbers:

i have 1 square mile available. a big reactor takes 4 square miles. i cannot fit a big reactor, despite the bigger reactor being more efficient.

[cauch]

well, I don't think that there is a real problem of "1 square mile is available but not 4 square miles" (this is a different sentence than "there is not enough space"). Especially as small reactor also need to be placed very specifically. So even then, it is still possible that the advantage is for big nuclear plant, as they are still more compact per GWh.

[john_strinlai]

>"1 square mile is available but not 4 square miles" (this is a different sentence than "there is not enough space").

how are these different? one is an example, one is general, but they communicate the exact same point. if you have something that requires 4 sq. miles, you cannot fit it into a place that is 1 sq. mile in size because there is not enough space to fit it.

>as they are still more compact per GWh.

i am really struggling here... if i cannot fit something large, whether the large thing is "more compact per GWh" does not matter. i only have so much physical space to work with. if its too big, its too big.

for a more easily visualized example, you cannot fit a reactor from three mile island into a submarine. efficiency doesnt come into the equation, because physical space constraints get in the way first.

[cauch]

> how are these different?

Well, if you have 1000 places of 1 square mile and 0 space of 4 square miles, the available space is 1000 square miles. If you have 100 places of 4 square miles, the available space is 400 square miles.

You cannot say that the first sentence means the same thing that the second sentence, and you cannot say that "there is not enough space" is only something you can say in the first-sentence situation and not in the second-sentence situation.

Maybe what you meant to say is not "there is not enough space", but "there is plenty of small space but not a lot of large space" (which I doubt is true in the real world: space occupancy is usually regrouped in dense areas, leaving non-dense areas).

> if i cannot fit something large ... i only have so much physical space to work with

First, the idea that, for a domestic power plant, you only have limited space, seems very unrealistic. The real world is not a submarine or a 7/11: you want your power plant at the periphery of cities, not squeezed between 2 buildings in the middle. There is only disadvantage of doing so: you cannot distribute high power lines from the middle of the city safely, you probably need facilities to deal with the fuel, probably need water for cooling, probably need a security perimeter as you have around any typical factory, the cost of the square meter is more expensive, ...

But secondly, you need the power plant to produce some power. If your country needs X GWh, and you need either 1 large power plant of 4 square miles or 10 SMR of 1 square mile and you just have few places where you can put a power plant, the "the unit itself is more compact" does not matter . I only have so much physical space to work with. If the surface needed to get X GWh using SMR is too big, it's too big.

> you cannot fit a reactor from three mile island into a submarine

Yep. Similarly, you cannot fit a SMR in a bicycle. But how is that relevant? In real life, domestic power plant do not have the constraints of being in thigh places (on the opposite, it is better for a power plant to be in regions that also happen to not have thigh places).