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You can't wave away the remaining challenges of a molten salt reactor. It is a legitimately difficult materials science problem to operate a liquid salt pump lo

You can't wave away the remaining challenges of a molten salt reactor. It is a legitimately difficult materials science problem to operate a liquid salt pump loop operating at ~1000K and under high neutron flux. It's also not a super-great explanation that a major accident will just cause the salt to flow into the holding tank. What if the holding tank is full of water? Why would it be full of water? I don't know but the planet is absolutely filthy with water and "the basement is unexpectedly full of water" has happened to almost every building humans have ever built. These are supposed to be installed _entirely_ underground, enhancing the danger of water intrusion. Finally there is still the challenge of continuous processing of the liquid fuel, to remove ash, add fissile materials, and separate gases. Nobody knows how to do this. Nobody has explained what to do with all the radioactive krypton etc.

nickik 7y ago
I don't wave anything away. My point is there are not fundamental challenges. Its a large expensive engineering project, but you don't need any miracles. We built a working molten salt reactor with 9m and 30 people and they built it in 4 years and then operated it for 10-15 years in the 60-70s. Not Magic. > It is a legitimately difficult materials science problem to operate a liquid salt pump loop operating at ~1000K and under high neutron flux. Depending on your reactor design your not actual pumping fuel salt itself at all. Both leading contenders use a pool type system and not LFTR type system where you have to do substantial pumping, specially not of the fuel salt. Neither system in fact pumps fuel salt that is in neutron flux at all. Have you actually looked at the real world proposed reactors we are talking about? > It's also not a super-great explanation that a major accident will just cause the salt to flow into the holding tank. What if the holding tank is full of water? Why would it be full of water? I don't know but the planet is absolutely filthy with water and "the basement is unexpectedly full of water" has happened to almost every building humans have ever built. These are supposed to be installed _entirely_ underground, enhancing the danger of water intrusion. In the case of IMSR, there is 1 meter nuclear grade concrete then a thick wall of steel, then a meter of a secondary cooling salt buffer, then another thick wall of steel, then the primary reactor vessel that is another massive steel cylinder. There are no opening anywhere except from the top. That whole thing is in a hole that is topped of heavy steel protection on top and that is in building that is safe from aircraft attack. Even if you would have contact of water with the fuel salt the water would be in contact with the top layer of the fuel salt (far less surface area then fuel tubes), that would would freeze the top layer into a solid layer and shortly after the whole reactor would essentially be one block of salt in a metal concrete box. These reactors are also not depended on water cooling at all, meaning you can build them in the desert or wherever, you don't need to be close to water in any way shape or form. Also you don't just build these anywhere, there is a citing process that looks at these like that. Next, there is the point that in liquid salt actually does not produce many of the same hazards as fuel pellets. There are gases inside of the solid fuel pellets that get released. In a molten salt reactor the cesium and iodine are not gases, but rather they are bound in the fuel and will not get released in gas form. This is one of the primary reasons molten salts were proposed int he first place. So even if you flood the building and a meteor somehow made a hole in the building and reactor containment, and then you would flood it with water that would somehow show up. And all you would achieve with this is a gigantic pool heater, as a solid block of salt sits in the bottom of a hole and produces some steam (without being a system under pressure) that didn't contain the primary dangerous gases we talk about in the 'nuclear cloud'. The amount of highly improbable events you have to chain to even achieve any danger outside of the nuclear regulated zone borders on comical. And even then its not even close to what we saw happen in Japan. > Finally there is still the challenge of continuous processing of the liquid fuel, to remove ash, add fissile materials, and separate gases. Nobody knows how to do this. Nobody has explained what to do with all the radioactive krypton etc. You don't actually need continuous processing and neither company that proposes to build Molten Salt reactors are proposing that. So again, have you actually looked at the real world proposed reactors we are talking about? You seem to think all Molten Salt reactors are LFTRs.
- amluto 7y ago
  Wikipedia reports that Beryllium salts (fluoride and chloride at least) are quite soluble in water and are fairly toxic. Do the leading designs use these salts or do they use something else that is insoluble?
  - nickik 7y ago
    Neither of the company wants to work with Beryllium. The reason being that its a incredibly limited resources (only one supplier) and the kinds of salts you would have to work with would have go threw a whole lot of analysis first. There is a talk by one of the people who worked on the original salt used in the reactor experiment you can find. Beryllium has excellent properties but unless you are building a breeder are not really that essential. The primary concern for the companies working on this right now is commercialization, not peak performance. They are fine with loses and inefficiency. You have to prove to the regulator that these salts will not be outside of the reactor boundary that takes care of both the radiation and the toxic aspect.
    - amluto 7y ago
      What companies are you talking about?
      - nickik 7y ago
        The furthest along is Terrestrial Energy, they already passed the first step in the Canadian review process. Moltex Energy is still in the first stage of Canadian review process, as they had to relocate from Britain to Canada. Because the British regulatory system is not really active. There is also Flibe Energy and they actually want to use lithium fluoride (LiF) and beryllium fluoride (BeF2) salt (hence the name). But that is a much longer term project and they are not anywhere close to commercialiastion. They are also working in the US Regulatory system that is not close to being ready to even start a serious commercionalisation process right now. They are also not targeting commercial energy as their primary market. There is also ThorCon power I don't know as much about them and they are not engadged in any Western effort for commercialisation as far as I know. There used to be Transatomic Power, but the never wanted to use beryllium fluoride either and have open sourced their reactor design.
bassman9000 7y ago
It is a legitimately difficult materials science problem to operate a liquid salt pump loop operating at ~1000K and under high neutron flux. And so it's containing the fusion plasma, yet billions are poured into material research. And hastelloy N is already invented.
- nickik 7y ago
  Hastelloy N will not be used by any of the companies building commercial reactor. Hastelloy N would have to go threw a whole lot of regulation to allowed to use in modern reactor. The data gathered on its properties would not be sufficient for a modern regulator, and such a qualification would take way to long. Also, there is not really a supplier for commercial Hastelloy N. Their focus is on using 'regular' nuclear grade materials that have already been approved. This is THE single most important focus of those reactor design. In the choice of containment, reactor type, salt solution and so on, they all picked sub-optimal things in order to make it threw the regulator and have a existing supply chain.
bassman9000 7y ago
Nobody has explained what to do with all the radioactive krypton etc. But they have. There's dozens of youtube videos on MSR.

nickik 7y ago

I don't wave anything away. My point is there are not fundamental challenges. Its a large expensive engineering project, but you don't need any miracles. We built a working molten salt reactor with 9m and 30 people and they built it in 4 years and then operated it for 10-15 years in the 60-70s. Not Magic. > It is a legitimately difficult materials science problem to operate a liquid salt pump loop operating at ~1000K and under high neutron flux. Depending on your reactor design your not actual pumping fuel salt itself at all. Both leading contenders use a pool type system and not LFTR type system where you have to do substantial pumping, specially not of the fuel salt. Neither system in fact pumps fuel salt that is in neutron flux at all. Have you actually looked at the real world proposed reactors we are talking about? > It's also not a super-great explanation that a major accident will just cause the salt to flow into the holding tank. What if the holding tank is full of water? Why would it be full of water? I don't know but the planet is absolutely filthy with water and "the basement is unexpectedly full of water" has happened to almost every building humans have ever built. These are supposed to be installed _entirely_ underground, enhancing the danger of water intrusion. In the case of IMSR, there is 1 meter nuclear grade concrete then a thick wall of steel, then a meter of a secondary cooling salt buffer, then another thick wall of steel, then the primary reactor vessel that is another massive steel cylinder. There are no opening anywhere except from the top. That whole thing is in a hole that is topped of heavy steel protection on top and that is in building that is safe from aircraft attack. Even if you would have contact of water with the fuel salt the water would be in contact with the top layer of the fuel salt (far less surface area then fuel tubes), that would would freeze the top layer into a solid layer and shortly after the whole reactor would essentially be one block of salt in a metal concrete box. These reactors are also not depended on water cooling at all, meaning you can build them in the desert or wherever, you don't need to be close to water in any way shape or form. Also you don't just build these anywhere, there is a citing process that looks at these like that. Next, there is the point that in liquid salt actually does not produce many of the same hazards as fuel pellets. There are gases inside of the solid fuel pellets that get released. In a molten salt reactor the cesium and iodine are not gases, but rather they are bound in the fuel and will not get released in gas form. This is one of the primary reasons molten salts were proposed int he first place. So even if you flood the building and a meteor somehow made a hole in the building and reactor containment, and then you would flood it with water that would somehow show up. And all you would achieve with this is a gigantic pool heater, as a solid block of salt sits in the bottom of a hole and produces some steam (without being a system under pressure) that didn't contain the primary dangerous gases we talk about in the 'nuclear cloud'. The amount of highly improbable events you have to chain to even achieve any danger outside of the nuclear regulated zone borders on comical. And even then its not even close to what we saw happen in Japan. > Finally there is still the challenge of continuous processing of the liquid fuel, to remove ash, add fissile materials, and separate gases. Nobody knows how to do this. Nobody has explained what to do with all the radioactive krypton etc. You don't actually need continuous processing and neither company that proposes to build Molten Salt reactors are proposing that. So again, have you actually looked at the real world proposed reactors we are talking about? You seem to think all Molten Salt reactors are LFTRs.

amluto 7y ago
Wikipedia reports that Beryllium salts (fluoride and chloride at least) are quite soluble in water and are fairly toxic. Do the leading designs use these salts or do they use something else that is insoluble?
- nickik 7y ago
  Neither of the company wants to work with Beryllium. The reason being that its a incredibly limited resources (only one supplier) and the kinds of salts you would have to work with would have go threw a whole lot of analysis first. There is a talk by one of the people who worked on the original salt used in the reactor experiment you can find. Beryllium has excellent properties but unless you are building a breeder are not really that essential. The primary concern for the companies working on this right now is commercialization, not peak performance. They are fine with loses and inefficiency. You have to prove to the regulator that these salts will not be outside of the reactor boundary that takes care of both the radiation and the toxic aspect.
  - amluto 7y ago
    What companies are you talking about?
    - nickik 7y ago
      The furthest along is Terrestrial Energy, they already passed the first step in the Canadian review process. Moltex Energy is still in the first stage of Canadian review process, as they had to relocate from Britain to Canada. Because the British regulatory system is not really active. There is also Flibe Energy and they actually want to use lithium fluoride (LiF) and beryllium fluoride (BeF2) salt (hence the name). But that is a much longer term project and they are not anywhere close to commercialiastion. They are also working in the US Regulatory system that is not close to being ready to even start a serious commercionalisation process right now. They are also not targeting commercial energy as their primary market. There is also ThorCon power I don't know as much about them and they are not engadged in any Western effort for commercialisation as far as I know. There used to be Transatomic Power, but the never wanted to use beryllium fluoride either and have open sourced their reactor design.

bassman9000 7y ago

It is a legitimately difficult materials science problem to operate a liquid salt pump loop operating at ~1000K and under high neutron flux. And so it's containing the fusion plasma, yet billions are poured into material research. And hastelloy N is already invented.

nickik 7y ago
Hastelloy N will not be used by any of the companies building commercial reactor. Hastelloy N would have to go threw a whole lot of regulation to allowed to use in modern reactor. The data gathered on its properties would not be sufficient for a modern regulator, and such a qualification would take way to long. Also, there is not really a supplier for commercial Hastelloy N. Their focus is on using 'regular' nuclear grade materials that have already been approved. This is THE single most important focus of those reactor design. In the choice of containment, reactor type, salt solution and so on, they all picked sub-optimal things in order to make it threw the regulator and have a existing supply chain.

bassman9000 7y ago

Nobody has explained what to do with all the radioactive krypton etc. But they have. There's dozens of youtube videos on MSR.