7 ms·

Does it even need to be a metal? (Since the pressure is so low strength requirements are lower)... How about ceramic or glass (or quartz), or something else non

Does it even need to be a metal? (Since the pressure is so low strength requirements are lower)... How about ceramic or glass (or quartz), or something else non-metal?

kenned3 4y ago
non-metals have their own problems and glass tends to have some really weird properties. I would think a major one would be their failure mode. Metals flex and expand before they eventually fail. Glass/ceramic is fine until suddenly it isn't and has a total failure. Think of a window being hit. If it were metal it would probably deform but if it is glass it shatters. Next would be joining them on-site. If needed, metal piping can be bent and welded in-place. what do you do with a glass pipe that needs a join? what do you do if there is a small variation in the plans and the pipe needs an adjustment? I think there are a host of reasons why glass is not used for pipes.
- Turbots 4y ago
  what about glass pipes encased in said metals :-)
  - deleted 4y ago
    [deleted]
  - HPsquared 4y ago
    Glass-lined vessels and pipes are already used in the chemical industry so it's a somewhat proven technology. Not sure if it's suited to the chemistry and temperatures (and radiation) of a molten salt reactor, but it seems like an interesting technology.
- systemvoltage 4y ago
  Composites? Such as the stuff used in Aviation?
  - deleted 4y ago
    [deleted]
  - PaulHoule 4y ago
    Most of those contain plastics which are usually not good for high temperatures but also have long chain molecules which get broken by neutrons and other particles and cannot heal defects the way metals can.
- mulmen 4y ago
  Glass is already basically welded, or maybe it's more like brazing. But an oxyacetylene torch can be used to work with glass just as well as to cut or weld metal. Metals also have weird properties. Like tempering and hardening based on temperature. In an industrial setting you need expert welders with deep knowledge of the materials or a weld is going to fail and ruin your day. So it doesn't seem like a huge leap to me actually, assuming ceramics or glass actually have desirable properties.
  - werdnapk 4y ago
    Doesn't glass.... melt?
    - onlyrealcuzzo 4y ago
      At 3100 F. Salt melts at 1474 F.
      - eitland 4y ago
        1704C 801C (or 1978K 1074K)
    - mulmen 4y ago
      So does metal. Welding is just melting two parts together.
      - baq 4y ago
        https://en.wikipedia.org/wiki/Cold_welding https://en.wikipedia.org/wiki/Cold_welding
        mulmen 4y ago
        https://en.m.wikipedia.org/wiki/Welding https://en.m.wikipedia.org/wiki/Welding What point are you trying to make here?
ortusdux 4y ago
It doesn't, but any material used needs to withstand 4 extremes - high temperatures (650-850 C), corrosion (dissolves uranium), very high neutron flux, and US govt. regulation. Graphite is the current favorite non-metal option. It is already widely used in traditional reactors, so it is approved, and its interaction with radiation is well understood. On the other hand, its interaction with radiation and molten salt is not as well understood, but hopefully this test reactor and others like it will solve that. One of my favorite solutions seals the reactor in with a crane and 8 graphite containment vessels. The best estimate of the lifespan of structural graphite in this environment is ~7 years, so the plan would be to monitor the system and move the reactor to a new vessel as needed. The goal is 50 year life-span for these reactors. Anyway, there is research into alternate materials, but to really test them you need to expose them to both molten salts and radiation. And if they pass, you need to get government approval. The last material to get govt approval was Hastelloy N, and I heard the process was a slog.
- chris_wot 4y ago
  Ah yes, the most extreme thing one withstands is U.S. regulation.
  - Retric 4y ago
    Nothing requires this research to to be carried out in the US specifically beyond funding being available here. It’s really the inherent difficulties which is holding back progress.
    - panick21_ 4y ago
      My understanding is that you are not allowed to build a research reactor that is bigger then a university reactor but isn't a full scale energy producing reactor. My understanding is that for such a reactor you would need the full operating license just as a grid connected PWR. And since in the US its essentially impossible to get a license for anything but a PWR, that isn't rally possible. Technology independent regulatory framework is one of the main reasons Canada has so many reactor startup, even those that started in other countries. https://nuclearsafety.gc.ca/eng/reactors/power-plants/pre-licensing-vendor-design-review/ https://nuclearsafety.gc.ca/eng/reactors/power-plants/pre-li...

Does it even need to be a metal? (Since the pressure is so low strength requirements are lower)... How about ceramic or glass (or quartz), or something else non-metal?

kenned3 4y ago

non-metals have their own problems and glass tends to have some really weird properties. I would think a major one would be their failure mode. Metals flex and expand before they eventually fail. Glass/ceramic is fine until suddenly it isn't and has a total failure. Think of a window being hit. If it were metal it would probably deform but if it is glass it shatters. Next would be joining them on-site. If needed, metal piping can be bent and welded in-place. what do you do with a glass pipe that needs a join? what do you do if there is a small variation in the plans and the pipe needs an adjustment? I think there are a host of reasons why glass is not used for pipes.

Turbots 4y ago
what about glass pipes encased in said metals :-)
- deleted 4y ago
  [deleted]
- HPsquared 4y ago
  Glass-lined vessels and pipes are already used in the chemical industry so it's a somewhat proven technology. Not sure if it's suited to the chemistry and temperatures (and radiation) of a molten salt reactor, but it seems like an interesting technology.
systemvoltage 4y ago
Composites? Such as the stuff used in Aviation?
- deleted 4y ago
  [deleted]
- PaulHoule 4y ago
  Most of those contain plastics which are usually not good for high temperatures but also have long chain molecules which get broken by neutrons and other particles and cannot heal defects the way metals can.
mulmen 4y ago
Glass is already basically welded, or maybe it's more like brazing. But an oxyacetylene torch can be used to work with glass just as well as to cut or weld metal. Metals also have weird properties. Like tempering and hardening based on temperature. In an industrial setting you need expert welders with deep knowledge of the materials or a weld is going to fail and ruin your day. So it doesn't seem like a huge leap to me actually, assuming ceramics or glass actually have desirable properties.
- werdnapk 4y ago
  Doesn't glass.... melt?
  - onlyrealcuzzo 4y ago
    At 3100 F. Salt melts at 1474 F.
    - eitland 4y ago
      1704C 801C (or 1978K 1074K)
  - mulmen 4y ago
    So does metal. Welding is just melting two parts together.
    - baq 4y ago
      https://en.wikipedia.org/wiki/Cold_welding https://en.wikipedia.org/wiki/Cold_welding
      - mulmen 4y ago
        https://en.m.wikipedia.org/wiki/Welding https://en.m.wikipedia.org/wiki/Welding What point are you trying to make here?

ortusdux 4y ago

It doesn't, but any material used needs to withstand 4 extremes - high temperatures (650-850 C), corrosion (dissolves uranium), very high neutron flux, and US govt. regulation. Graphite is the current favorite non-metal option. It is already widely used in traditional reactors, so it is approved, and its interaction with radiation is well understood. On the other hand, its interaction with radiation and molten salt is not as well understood, but hopefully this test reactor and others like it will solve that. One of my favorite solutions seals the reactor in with a crane and 8 graphite containment vessels. The best estimate of the lifespan of structural graphite in this environment is ~7 years, so the plan would be to monitor the system and move the reactor to a new vessel as needed. The goal is 50 year life-span for these reactors. Anyway, there is research into alternate materials, but to really test them you need to expose them to both molten salts and radiation. And if they pass, you need to get government approval. The last material to get govt approval was Hastelloy N, and I heard the process was a slog.

chris_wot 4y ago
Ah yes, the most extreme thing one withstands is U.S. regulation.
- Retric 4y ago
  Nothing requires this research to to be carried out in the US specifically beyond funding being available here. It’s really the inherent difficulties which is holding back progress.
  - panick21_ 4y ago
    My understanding is that you are not allowed to build a research reactor that is bigger then a university reactor but isn't a full scale energy producing reactor. My understanding is that for such a reactor you would need the full operating license just as a grid connected PWR. And since in the US its essentially impossible to get a license for anything but a PWR, that isn't rally possible. Technology independent regulatory framework is one of the main reasons Canada has so many reactor startup, even those that started in other countries. https://nuclearsafety.gc.ca/eng/reactors/power-plants/pre-licensing-vendor-design-review/ https://nuclearsafety.gc.ca/eng/reactors/power-plants/pre-li...