5 ms·

I'm amazed that the industry is still propagating the mistake made in the early nuclear age of using PWR and solid fuel. The more I read about nuclear the more

I'm amazed that the industry is still propagating the mistake made in the early nuclear age of using PWR and solid fuel. The more I read about nuclear the more convinced I become that SMRs for next gen plants are safest and most efficient using the Thorium-U233 fuel cycle and employing molten salt to transfer heat. It's automatically safe since if a runaway reaction takes place the fuel will drain into a tank and reactions will stop. This happens if no action is taken so all the humans at the plant and all the machinery could be incapacitated and a meltdown automatically stops. It uses a cheaper fuel of which we have a virtually endless supply of and enrichment is not needed as it is with U238-U235. There's less waste as well and it's less problematic waste (decaying in hundreds of years instead of millions). Operationally it's easier to load up fuel and wastes are easier to remove. Is it just "this is how we always do these things" or is there something else going on here?

pentae 7y ago
I also went down that rabbithole and I'm also convinced, but I'm not aware of any Thorium reactors currently in operation. Not being a proven technology would certainly be a business risk to consider though Thorium would be an easier pill to swallow politically and socially once the population is aware of the safety benefits.
- Beltiras 7y ago
  It was proven to work back in the 60's. With way worse material tech than we have today. The reinvigoration of Thorium research happened when that design was declassified and shared with some NASA folks. EDIT: wrong decade
pjc50 7y ago
Plumbing is a problem for hot radioactive molten salt. It's one of the few things that will erode ordinary stainless steel.
- Beltiras 7y ago
  I haven't researched those issues but apparently it could be done with stone age tech (1960's) compared to the material sciences we have today.
  - mechhacker 7y ago
    Yes they ran the molten salt reactor. However, running one and being able to make a cost effective reactor is completely different. Especially when water is already a very well known and very well understood heat transfer medium.
    - Beltiras 7y ago
      And we understand it to be rather dangerous in failure modes. TMI, Chernobyl and Fukushima all revolved around failure modes with water. The failure mode in Thorium is stopping the reactor. Will take a month or more to restart the reaction.
- 0x4863A0 7y ago
  Agreed that is a significant gating factor, but the situation is not impossible. Several paths are laid out for moving forward in a 2018 report by a couple of ANL scientists. The report is quite readable, even if you know little about materials science. [1] https://art.inl.gov/ART%20Document%20Library/High%20Temperature%20Materials/45171%20Status%20of%20Metallic%20Structural.pdf https://art.inl.gov/ART%20Document%20Library/High%20Temperat...
- mortivore 7y ago
  That seems like a pretty major issue. No wonder it hasn't gone forward. Are there any alternatives proposed?
- kerkeslager 7y ago
  Does titanium hold up to radioactive molten salt? There are a bunch of places I've found where the difficulty (and therefore cost) of working with titanium is really holding humanity back. If we could find cheaper techniques for working with titanium it would revolutionize a lot of industries, as it's plentiful, light, strong, non-reactive, and melts at high temperatures. But the same attributes that make it hold up under the stresses of use, make it very hard to shape.
DrNuke 7y ago
> Is it just "this is how we always do these things" or is there something else going on here? That tech is known, well designed, approved and extensively proven through many thousand years manwork experience worldwide. It’s also the most affordable in liberalized markets. Going smaller & modular is the real novelty in the industry, for grid-agnostic coupling and decoupling. FYI: I have been consulting and designing innovative or exotic NPPs for years and I am now pretty confident I will not live long enough to see any one of them built and working, maybe not even at the demonstrator stage... but this side of the story might come good for another post ehehe.
- Beltiras 7y ago
  I'm just a layman with enthusiastic interest. Can I ask you about one thing in this pipeline of decision making since you are in the field? Refueling is easier to do in MSRs and nigh takes away an embarrassing long downtime while the solid fuel is loaded. Why is that not a first concern (less downtime means more energy from roughly same capital expenditure)? Safety is critical. It also costs a lot. With MSRs you need less land and can place the plant closer to the point of use (frozen plug to drain tank makes it so that any runaway is contained without intervention). It's even been suggested that for high-thermal uses like steel plants you could get better efficiency by using a thermal plant instead of making electricity for at least a twofold gain in power use. Is there anything inherently wrong with that idea? Is the dialysis design as solid as it looks like on paper? Are there operational problems with it that the advocates are not talking about? I have so many questions.....
  - DrNuke 7y ago
    Good to have interested laymen, really, so thanks! The fundamental point is (in my very humble opinion, mind) you may still have a business case for nuclear in 2020 but no feasible return on investment against non-nuclear sources for decades-long experiments that, all in all, are aimed at marginal improvements in the grand scheme of things and the enormous hassle proponents have to face. It is fusion or nothing, apart of a couple of Gen IV that are advanced enough already, for the next 20-30 years or such in the West (China or Russia might be more ambitious, but they are not liberal or neoliberal democracies, so they can play a different game to some extent)... until all the PWRs still operating worldwide must be put down for obsolescence. For a layman computer science comparison, think of the still up-and-running fortran legacy in some sectors (banks?) you won’t really really want to drop if not really forced to... because it works, you need no fix, you do not expect any unheard catastrophic incident or accident anymore.
MuffinFlavored 7y ago
> It uses a cheaper fuel of which we have a virtually endless supply of Which fuel is that? Thorium-U233?
jason0597 7y ago
Someone made an excellent post on reddit a while back on why Thorium reactors will never become a reality, it's a really good read: https://old.reddit.com/r/europe/comments/9unimr/dutch_satirical_news_show_on_why_we_need_to_break/e95mvb7/?context=3 https://old.reddit.com/r/europe/comments/9unimr/dutch_satiri...
- Lutzb 7y ago
  Thank you, this was very informative. It seems a lot of thorium reactor proponents never discuss those issues or are not aware of them.
Accujack 7y ago
The PWR tech was chosen by the US government originally because using that type of reactor supported weapons production. Many countries still want it for that reason. Newer types aren't used yet in the US because the incredible over-regulation of existing reactors due to the fear involved has made them very un-economical to build and very difficult to get new designs approved... if there's no money in something, corporations won't do it.

pentae 7y ago

I also went down that rabbithole and I'm also convinced, but I'm not aware of any Thorium reactors currently in operation. Not being a proven technology would certainly be a business risk to consider though Thorium would be an easier pill to swallow politically and socially once the population is aware of the safety benefits.

Beltiras 7y ago
It was proven to work back in the 60's. With way worse material tech than we have today. The reinvigoration of Thorium research happened when that design was declassified and shared with some NASA folks. EDIT: wrong decade

pjc50 7y ago

Plumbing is a problem for hot radioactive molten salt. It's one of the few things that will erode ordinary stainless steel.

Beltiras 7y ago
I haven't researched those issues but apparently it could be done with stone age tech (1960's) compared to the material sciences we have today.
- mechhacker 7y ago
  Yes they ran the molten salt reactor. However, running one and being able to make a cost effective reactor is completely different. Especially when water is already a very well known and very well understood heat transfer medium.
  - Beltiras 7y ago
    And we understand it to be rather dangerous in failure modes. TMI, Chernobyl and Fukushima all revolved around failure modes with water. The failure mode in Thorium is stopping the reactor. Will take a month or more to restart the reaction.
0x4863A0 7y ago
Agreed that is a significant gating factor, but the situation is not impossible. Several paths are laid out for moving forward in a 2018 report by a couple of ANL scientists. The report is quite readable, even if you know little about materials science. [1] https://art.inl.gov/ART%20Document%20Library/High%20Temperature%20Materials/45171%20Status%20of%20Metallic%20Structural.pdf https://art.inl.gov/ART%20Document%20Library/High%20Temperat...
mortivore 7y ago
That seems like a pretty major issue. No wonder it hasn't gone forward. Are there any alternatives proposed?
kerkeslager 7y ago
Does titanium hold up to radioactive molten salt? There are a bunch of places I've found where the difficulty (and therefore cost) of working with titanium is really holding humanity back. If we could find cheaper techniques for working with titanium it would revolutionize a lot of industries, as it's plentiful, light, strong, non-reactive, and melts at high temperatures. But the same attributes that make it hold up under the stresses of use, make it very hard to shape.

DrNuke 7y ago

> Is it just "this is how we always do these things" or is there something else going on here? That tech is known, well designed, approved and extensively proven through many thousand years manwork experience worldwide. It’s also the most affordable in liberalized markets. Going smaller & modular is the real novelty in the industry, for grid-agnostic coupling and decoupling. FYI: I have been consulting and designing innovative or exotic NPPs for years and I am now pretty confident I will not live long enough to see any one of them built and working, maybe not even at the demonstrator stage... but this side of the story might come good for another post ehehe.

Beltiras 7y ago
I'm just a layman with enthusiastic interest. Can I ask you about one thing in this pipeline of decision making since you are in the field? Refueling is easier to do in MSRs and nigh takes away an embarrassing long downtime while the solid fuel is loaded. Why is that not a first concern (less downtime means more energy from roughly same capital expenditure)? Safety is critical. It also costs a lot. With MSRs you need less land and can place the plant closer to the point of use (frozen plug to drain tank makes it so that any runaway is contained without intervention). It's even been suggested that for high-thermal uses like steel plants you could get better efficiency by using a thermal plant instead of making electricity for at least a twofold gain in power use. Is there anything inherently wrong with that idea? Is the dialysis design as solid as it looks like on paper? Are there operational problems with it that the advocates are not talking about? I have so many questions.....
- DrNuke 7y ago
  Good to have interested laymen, really, so thanks! The fundamental point is (in my very humble opinion, mind) you may still have a business case for nuclear in 2020 but no feasible return on investment against non-nuclear sources for decades-long experiments that, all in all, are aimed at marginal improvements in the grand scheme of things and the enormous hassle proponents have to face. It is fusion or nothing, apart of a couple of Gen IV that are advanced enough already, for the next 20-30 years or such in the West (China or Russia might be more ambitious, but they are not liberal or neoliberal democracies, so they can play a different game to some extent)... until all the PWRs still operating worldwide must be put down for obsolescence. For a layman computer science comparison, think of the still up-and-running fortran legacy in some sectors (banks?) you won’t really really want to drop if not really forced to... because it works, you need no fix, you do not expect any unheard catastrophic incident or accident anymore.

MuffinFlavored 7y ago

> It uses a cheaper fuel of which we have a virtually endless supply of Which fuel is that? Thorium-U233?

jason0597 7y ago

Someone made an excellent post on reddit a while back on why Thorium reactors will never become a reality, it's a really good read: https://old.reddit.com/r/europe/comments/9unimr/dutch_satirical_news_show_on_why_we_need_to_break/e95mvb7/?context=3 https://old.reddit.com/r/europe/comments/9unimr/dutch_satiri...

Lutzb 7y ago
Thank you, this was very informative. It seems a lot of thorium reactor proponents never discuss those issues or are not aware of them.

Accujack 7y ago

The PWR tech was chosen by the US government originally because using that type of reactor supported weapons production. Many countries still want it for that reason. Newer types aren't used yet in the US because the incredible over-regulation of existing reactors due to the fear involved has made them very un-economical to build and very difficult to get new designs approved... if there's no money in something, corporations won't do it.