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ITER is not the route to an economical fusion reactor. The supporters have even stopped promoting it as such. It is now a research reactor. We may find out some

ITER is not the route to an economical fusion reactor. The supporters have even stopped promoting it as such. It is now a research reactor. We may find out some novel information on how plasma behaves in a certain regime, but this data is not likely to be useful in building a future reactor. The amount of resources that have been diverted from fundamental fusion research to be spent pouring cement and building magnets is a tragedy. We should have a thousand $3 million dollar or a hundred $30 million dollar experimental reactors, not this monstrosity.

pas 8y ago
Scale is everything for fusion (plasma). ITER is very important, as it represents the current most likely way. (Hence the name.) That said, it's big, design by committee, slow, meticulous, etc. It's not a fail fast market-driven experiment. Also, most of the money is spent on the fundamentals, planning, developing operational knowhow, basic material science and plasma vessel engineering. All in all, it could be better, but at least ITER is actually being built. MIT's ARC is still somewhere between "secured funding for a scaled down prototype" and actually will build something. Though it's great news, that they got funding (from Eni, an Italian energy company).
- nickik 8y ago
  Scale is not everything. There are types of fusion that would not build such huge monstrosities. We should look at a broader range of ways to do fusion and then finance the ones most likely to work. As you said, most of the money on ITAR is hardly directly related to fusion. A few companies get lots of money to do research to hit very specific performance that are specific to ITAR. The problem is this does not really build a broad range of companies that work in fusion. It was simply to early to engaged in such a huge project especially because the technologies are evolving so fast outside of the project and some parts of the design are already not up to date 20 years before it will really be ready.
- Tuna-Fish 8y ago
  > Scale is everything for fusion (plasma). No. Q is everything in fusion. Scale is one way to improve Q in a Tokamak. The problem with improving Q by increasing scale is that it makes the reactors uneconomical. A reactor the size of ITER cannot ever be economically viable, even was capable of producing massive amounts of electricity. Luckily, scaling up is not the only way to increase Q. The better way is to use more powerful magnetic fields. Put more eloquently than I can: https://www.youtube.com/watch?v=L0KuAx1COEk&t=43m47s https://www.youtube.com/watch?v=L0KuAx1COEk&t=43m47s
  - infogulch 8y ago
    Wow that's a really great talk, thanks for sharing!
  - pfdietz 8y ago
    Unfortunately, even with higher magnetic fields, DT fusion is unlikely to ever be practical. That's because the power density of the reactors is inherently limited by wall loading and minimum size considerations from neutron cross sections. Look at the numbers. The power density of a PWR fission reactor core is 100 MW/m^3. If you consider the volume of the primary reactor vessel instead, it's 20 MW/m^3. The power density of ITER is 0.05 MW/m^3 (counting gross fusion power). Even if you just include the volume of the plasma, it's 0.6 MW/m^3. What about higher field concepts like MIT's ARC reactor? If you look at the paper on arxiv where details are given, the power density is 0.5 MW/m^3 -- 40 times worse than a PWR. The low power density is devastating to the economic case for fusion. Magnetic fusion reactors will be complex, expensive things, with superconducting magnets, complex cooling systems, breeding blankets, heating and control systems. They will be much more expensive per unit mass or volume than a simple PWR reactor vessel. And much of that complex system will need to be periodically replaced due to neutron damage. If the power density is 40x worse they cannot possibly compete. Yes, (SP)ARC is better than ITER. But ITER is so horribly bad that a reactor can be an order of magnitude better and still not have any real chance of competing.
    - tim333 8y ago
      Well, from a 2016 article on ARC they say cost 4 to 5 billion USD, output to the grid 200MW, which is not competitive with existing reactors but that would be the first one producing power built, the designs may improve. (https://www.computerworld.com/article/3028113/sustainable-it/mit-takes-a-page-from-tony-stark-edges-closer-to-an-arc-fusion-reactor.html https://www.computerworld.com/article/3028113/sustainable-it...)
azernik 8y ago
The research I've seen planned isn't about plasma physics - it's about material properties, lithium blanket designs, and lots of other finicky engineering details that will be necessary for actual practical reactors of different designs.
- AlanSE 8y ago
  While those are all important, I thought that the main research goal of Iter was to understand the stability of the plasma for sustained net-energy operation. Aren't there still some remaining open questions about operating a D-T tokomak reactor to produce energy, like, does the plasma begin to rip itself apart after 1ms, okay, how about 10 seconds, how about 500 seconds, and so-on. I accept that I'm talking based on extremely vaguely remembered statements from many years ago... After all, if the goal was really these ancillary things you mention, many of them could be studied in other environments.

pas 8y ago

Scale is everything for fusion (plasma). ITER is very important, as it represents the current most likely way. (Hence the name.) That said, it's big, design by committee, slow, meticulous, etc. It's not a fail fast market-driven experiment. Also, most of the money is spent on the fundamentals, planning, developing operational knowhow, basic material science and plasma vessel engineering. All in all, it could be better, but at least ITER is actually being built. MIT's ARC is still somewhere between "secured funding for a scaled down prototype" and actually will build something. Though it's great news, that they got funding (from Eni, an Italian energy company).

nickik 8y ago
Scale is not everything. There are types of fusion that would not build such huge monstrosities. We should look at a broader range of ways to do fusion and then finance the ones most likely to work. As you said, most of the money on ITAR is hardly directly related to fusion. A few companies get lots of money to do research to hit very specific performance that are specific to ITAR. The problem is this does not really build a broad range of companies that work in fusion. It was simply to early to engaged in such a huge project especially because the technologies are evolving so fast outside of the project and some parts of the design are already not up to date 20 years before it will really be ready.
Tuna-Fish 8y ago
> Scale is everything for fusion (plasma). No. Q is everything in fusion. Scale is one way to improve Q in a Tokamak. The problem with improving Q by increasing scale is that it makes the reactors uneconomical. A reactor the size of ITER cannot ever be economically viable, even was capable of producing massive amounts of electricity. Luckily, scaling up is not the only way to increase Q. The better way is to use more powerful magnetic fields. Put more eloquently than I can: https://www.youtube.com/watch?v=L0KuAx1COEk&t=43m47s https://www.youtube.com/watch?v=L0KuAx1COEk&t=43m47s
- infogulch 8y ago
  Wow that's a really great talk, thanks for sharing!
- pfdietz 8y ago
  Unfortunately, even with higher magnetic fields, DT fusion is unlikely to ever be practical. That's because the power density of the reactors is inherently limited by wall loading and minimum size considerations from neutron cross sections. Look at the numbers. The power density of a PWR fission reactor core is 100 MW/m^3. If you consider the volume of the primary reactor vessel instead, it's 20 MW/m^3. The power density of ITER is 0.05 MW/m^3 (counting gross fusion power). Even if you just include the volume of the plasma, it's 0.6 MW/m^3. What about higher field concepts like MIT's ARC reactor? If you look at the paper on arxiv where details are given, the power density is 0.5 MW/m^3 -- 40 times worse than a PWR. The low power density is devastating to the economic case for fusion. Magnetic fusion reactors will be complex, expensive things, with superconducting magnets, complex cooling systems, breeding blankets, heating and control systems. They will be much more expensive per unit mass or volume than a simple PWR reactor vessel. And much of that complex system will need to be periodically replaced due to neutron damage. If the power density is 40x worse they cannot possibly compete. Yes, (SP)ARC is better than ITER. But ITER is so horribly bad that a reactor can be an order of magnitude better and still not have any real chance of competing.
  - tim333 8y ago
    Well, from a 2016 article on ARC they say cost 4 to 5 billion USD, output to the grid 200MW, which is not competitive with existing reactors but that would be the first one producing power built, the designs may improve. (https://www.computerworld.com/article/3028113/sustainable-it/mit-takes-a-page-from-tony-stark-edges-closer-to-an-arc-fusion-reactor.html https://www.computerworld.com/article/3028113/sustainable-it...)

azernik 8y ago

The research I've seen planned isn't about plasma physics - it's about material properties, lithium blanket designs, and lots of other finicky engineering details that will be necessary for actual practical reactors of different designs.

AlanSE 8y ago
While those are all important, I thought that the main research goal of Iter was to understand the stability of the plasma for sustained net-energy operation. Aren't there still some remaining open questions about operating a D-T tokomak reactor to produce energy, like, does the plasma begin to rip itself apart after 1ms, okay, how about 10 seconds, how about 500 seconds, and so-on. I accept that I'm talking based on extremely vaguely remembered statements from many years ago... After all, if the goal was really these ancillary things you mention, many of them could be studied in other environments.