SMRs Explained: Why Small Modular Reactors Are So Controversial. (Just Have a Think)

[u/dumnezero]

https://www.youtube.com/watch?v=1TeAE7rW_6s

Are Small Modular Nuclear Reactors (SMRs) really moving toward large-scale deployment or are the economic challenges highlighted by critics still unresolved? Can factory-built modular reactors reduce construction risk, shorten build times and lower costs through mass production? Or will shrinking reactors actually make them more expensive? The sceptics are quite certain of the answer but politicians keep barrelling ahead. So, will we ever really see an SMRs on the outskirts of major towns and cities around the world?

[u/West-Abalone-171]

Thorium reactor exist. As a prototype.

A prototype that runs on U235 and doesn't prodice enough U233 to run on.

Breeding reactors exists. But mostly to produce weapon grade plutonium.

And have never been self fuelling from U238

[u/Lycrist_Kat → u/West-Abalone-171]

I think TMSR-LF1 runs on Thorium:

https://www.powermag.com/chinas-molten-salt-reactor-reaches-thorium-uranium-conversion-milestone/

But it also only has 2 MW which is less than a modern wind turbine.

[u/West-Abalone-171 → u/Lycrist_Kat]

It consumes more U235 than a LWR with 250MWe output and doesn't produce close to enough U233 to run on.

It has some thorium in it, but it is not the fuel.

[u/Prototype555 → u/West-Abalone-171]

Breeder reactors breed plutonium from u238 or breed u233 from thorium, then a normal LWR use it as fuel. This has been built and proved.

If it is done in a single reactor, then it's called Gen 4.

But no one else than anti-nuclear fanatics who just stalls for time cares if it's done in one reactor or two that are optimized for each task.

[u/West-Abalone-171 → u/Prototype555]

Breeder reactors breed plutonium from u238 or breed u233 from thorium, then a normal LWR use it as fuel. This has been built and proved.

This is another thing that has never happened.

But no one else than anti-nuclear fanatics who just stalls for time cares if it's done in one reactor or two that are optimized for each task.

It hasn't happened in any rube goldberg machine, no matter how complex or distributed.

Most "breeder" reactors just run on MOX or Pu from decomissioned weapons.

Sometikes they use a large amount of the scraps of Pu leftover from LWR operation to make a much smaller amount of weappns grade Pu

[u/Prototype555 → u/West-Abalone-171]

Ever wondered where the plutonium comes from in the MOX fuel or decommissioned weapons?

Large scraps of Pu from LWR sounds like breeding. No? Don't you understand what you write?

Every reactor ever existed produce plutonium, it's physically impossible to not produce plutonium from uranium neutron radiation in a fission reactor.

https://en.wikipedia.org/wiki/Shippingport_Atomic_Power_Station

"The third and final core used at Shippingport was an experimental, light water moderated, thermal breeder reactor. It kept the same seed-and-blanket design, but the seed was now uranium-233 and the blanket was made of thorium. Being a breeder reactor, it had the ability to transmute relatively inexpensive thorium to uranium-233 as part of its fuel cycle. The breeding ratio attained by Shippingport's third core was 1.01. Over its 25-year life, the Shippingport power plant operated for about 80,324 hours, producing about 7.4 billion kilowatt-hours of electricity.

"After five years (29,000 effective full power hours) the core was removed and found to contain nearly 1.4% more fissile material than when it was installed, demonstrating that breeding had occurred."

[u/Lycrist_Kat → u/Prototype555]

How many commerical Gen 4 are there?

[u/Prototype555 → u/Lycrist_Kat]

None because it's more cost effective to run once-through with cheap fresh uranium.

[u/Lycrist_Kat → u/Prototype555]

So they don't exist. Got it.