3 ms·

I thought the real problem with Thorium is that salt eventually corrodes just about everything, which makes building a reactor that uses molten radioactive salt

by ohazi 8y ago

I thought the real problem with Thorium is that salt eventually corrodes just about everything, which makes building a reactor that uses molten radioactive salt a bit of a sketchy long-term proposition.

baybal2 8y ago
How big it is of a problem? Sodium alloys do the same, if not worse, but industry had metallurgy solutions to deal with it for last 50 years.
- ohazi 8y ago
  My understanding of the situation is that corrosion is the main issue holding back Thorium reactor design. Molten sodium is used in the coolant loop of some fast reactors, but it doesn't develop any long-lived radioactive byproducts, so it (and the various parts and fittings that it inevitably corrodes) can be disposed of relatively easily. They don't really have solutions to keep it contained, it eventually eats through everything. You just have to keep it from contacting water and exploding.
  - nickik 8y ago
    Corrosion is by far not the main issue holding back Thorium reactors. In fact in the MSR experiment they did a lot of work on corrosion and they considered it very solvable. Re-qualifying that material would be tricky and costly, but there are companies doing it. For the MSR style modern 2 fluid reactor your main problem is the chemical plant that needs to live in the reactor itself. Secondly Thorium has absolutely no regularly support, and given the way nuclear regulation works its basically impossible to get a new fuel and type of reactor to market. There is Thorium fuel for LWR coming to the market very slowly, but the advantages of that are very limited.
  - angry_octet 8y ago
    I thought the combination: - hot corrosive sodium - heat exchanged with water for steam turbine - water+sodium = boom was always going to be problematic.
nickik 8y ago
The primary problem for a Breeder is actually that it corrodes the graphite. We have the metals that are corrosion resistant for long enough. The primary problem with the metal is actually just qualifying that it is actually the case. The material they used in the original Molten Salt Experiment was great at resistance but re-qualifying this (or anything) to modern standards is incredibly difficult. The 'Stable Salt Reactor' for Moltex actually have a solution where they use a slightly different salt that they can put some metal into and the chemistry works out that it will corrode that metal first and the piping is fine. I however primary believe that for the last 40 years, regulatory approve and path to market were the primary issues. In the molten salt reactor experiment they solved many of these problems in relatively short time with a tiny team of people. Because of regulations you basically can not develop a test reactor, and all of the nuclear companies basically design directly to production because it would be way to expensive to build a test reactor. Building a tiny research reactor would be an option, but those are limited to sizes that are to small to actually validate your design.
- danmaz74 8y ago
  > The material they used in the original Molten Salt Experiment was great at resistance but re-qualifying this (or anything) to modern standards is incredibly difficult. Care to elaborate? Looks like a very interesting problem.
  - nickik 8y ago
    I am not very knowledge about nuclear material qualification, I can just tell you what I have heard. The material they developed for the MSR was called Hastelloy N and showed a lot of promise. Sadly, because its primary benefit was working with salts, it was not further developed and the use it saw does not qualify it for use in a modern nuclear reactor. Therefore you have to do a complete re-qualification of the material under advanced neutron flux. Nuclear regulations are so incredibly strict that doing that alone would probably blow most development timelines. [1] https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment#Structural_alloy_Hastelloy-N https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment...
tim333 8y ago
I think the real problem with Thorium from a practical point of view is cost effectiveness. Having to develop a bunch of new technology and reprocess red hot fuel is probably going to work out considerably more expensive just building a conventional reactor which itself is looking like being more expensive than renewables.

by ohazi 8y ago

baybal2 8y ago

How big it is of a problem? Sodium alloys do the same, if not worse, but industry had metallurgy solutions to deal with it for last 50 years.

ohazi 8y ago
My understanding of the situation is that corrosion is the main issue holding back Thorium reactor design. Molten sodium is used in the coolant loop of some fast reactors, but it doesn't develop any long-lived radioactive byproducts, so it (and the various parts and fittings that it inevitably corrodes) can be disposed of relatively easily. They don't really have solutions to keep it contained, it eventually eats through everything. You just have to keep it from contacting water and exploding.
- nickik 8y ago
  Corrosion is by far not the main issue holding back Thorium reactors. In fact in the MSR experiment they did a lot of work on corrosion and they considered it very solvable. Re-qualifying that material would be tricky and costly, but there are companies doing it. For the MSR style modern 2 fluid reactor your main problem is the chemical plant that needs to live in the reactor itself. Secondly Thorium has absolutely no regularly support, and given the way nuclear regulation works its basically impossible to get a new fuel and type of reactor to market. There is Thorium fuel for LWR coming to the market very slowly, but the advantages of that are very limited.
- angry_octet 8y ago
  I thought the combination: - hot corrosive sodium - heat exchanged with water for steam turbine - water+sodium = boom was always going to be problematic.

nickik 8y ago

The primary problem for a Breeder is actually that it corrodes the graphite. We have the metals that are corrosion resistant for long enough. The primary problem with the metal is actually just qualifying that it is actually the case. The material they used in the original Molten Salt Experiment was great at resistance but re-qualifying this (or anything) to modern standards is incredibly difficult. The 'Stable Salt Reactor' for Moltex actually have a solution where they use a slightly different salt that they can put some metal into and the chemistry works out that it will corrode that metal first and the piping is fine. I however primary believe that for the last 40 years, regulatory approve and path to market were the primary issues. In the molten salt reactor experiment they solved many of these problems in relatively short time with a tiny team of people. Because of regulations you basically can not develop a test reactor, and all of the nuclear companies basically design directly to production because it would be way to expensive to build a test reactor. Building a tiny research reactor would be an option, but those are limited to sizes that are to small to actually validate your design.

danmaz74 8y ago
> The material they used in the original Molten Salt Experiment was great at resistance but re-qualifying this (or anything) to modern standards is incredibly difficult. Care to elaborate? Looks like a very interesting problem.
- nickik 8y ago
  I am not very knowledge about nuclear material qualification, I can just tell you what I have heard. The material they developed for the MSR was called Hastelloy N and showed a lot of promise. Sadly, because its primary benefit was working with salts, it was not further developed and the use it saw does not qualify it for use in a modern nuclear reactor. Therefore you have to do a complete re-qualification of the material under advanced neutron flux. Nuclear regulations are so incredibly strict that doing that alone would probably blow most development timelines. [1] https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment#Structural_alloy_Hastelloy-N https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment...

tim333 8y ago

I think the real problem with Thorium from a practical point of view is cost effectiveness. Having to develop a bunch of new technology and reprocess red hot fuel is probably going to work out considerably more expensive just building a conventional reactor which itself is looking like being more expensive than renewables.