4 ms·

Watch Robert Whyte's presentation. https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4 The basic problems have all been sol

Watch Robert Whyte's presentation. https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4 The basic problems have all been solved, the science has been solved too. Tokamaks have already made net fusion power. The only difference between JET, which already succeeded, and ARC, is using Magnets with 2.6x the field strength. The B^4 power scaling, gives you about 50x the power, so ARC will generate 500 MW of power whereas JET (remember, already proven engineering), generated 10MW. So without a doubt, this is just an engineering problem at this point. A prototype device that didn't have to be maintained, could be built exactly like any other Tokamak, just with REBCO magnets, and you'd have the required fusion power. To get the required electric power, and add in maintenance, you need to at the FliBe liquid blanket, replacable toroid sections, and a heat exchanger, but again, these are known engineering problems with known solutions, akin to knowing that landing a rocket is possible, but figuring out the grid fins, heat shield, landing legs, and guidance software. Fusion devices on a small scale have been proving the plasma physics since the 90s. We don't have fusion yet simply because of people being conservative and sticking with traditional "known to work" magnets, which is why ITER is a huge, hulking monstrosity. As Dr Whyte says, cost scales by R, R can be reduced by a factor of 10 from ITER simply by using different magnets, so ARC will produce the same power as ITER, but significantly smaller and cheaper. The basic papers have been peer reviewed by Nature, and the science and engineering have been found solid, and thus, the economic arguments as well. Ergo, this is exactly like the SpaceX scenario vs ULA and NASA (e.g. SLS). Small allows fast iteration, fast innovation. ITER's going to spend $20 billion and 20+ years of development just to turn around a realize that the follow on to ITER will need to use HTS magnets and a smaller design.

DrNuke 6y ago
It was mainly an engineering issue: materials, manufacturing and assembling. It is too big to fail right now, and most issues have been solved. It never was as simple as webinars from scientists would make it. The funniest joke within nuclear eng insiders is the marvels of paper reactors pretty always make real reactors just seem glorified boilers.
- cromwellian 6y ago
  ITER's too big the fail. But again, the parameters were known. The magnets give you the field strength, the field strength tells you the radius, the radius^3 gives you the cost, and also, some measure of the construction time. This is one of the great things about Elon Musk -- he looks at things from first principles. When it looked like he needed 1000 Gigafactories to reach his goal, he went back to the drawing board on decades of battery manufacturing, to come up with the Terafactory. When carbon composite rockets looked to be too hard to manufacture, and have too many other detriments, despite the clear wins in strength-to-weight, he dropped it and went with stainless steel. I'm pretty sure if he was staring at the basic Tokamak equations, he would have long again saw the economic and time dependence on R, and the massive benefits to improving B, and that would have driven him to look for alternatives. Too many researchers engage in sunk cost / dollar auctions, doubling down on obvious wrong approaches, because they've already spent so much. This is also why DeepMind won CASP again, because rather than try to iteratively improve their 2018 result, they dropped it as a dead end and restarted with a completely new approach, even though the 2018 approach was also a revolutionary breakthrough. What I'm getting at is, being able to let go of your previous projects if they are stalling, with huge cost over runs, and a mediocre future return, is a value we should seek in fusion research, and elsewhere.
  - DrNuke 6y ago
    Ok but ITER was much more than engineering: soft diplomacy, supranational bureaucracy, manufacturing modernisation. Musk comes from a different era and a different environment but, again, launching rockets successfully, with humans in them safely going and coming back, was achieved well before him. Stable nuclear fusion is still unclaimed as a milestone, even if sustainable nuclear fusion might well come from different, smaller approaches the likes we are seeing from United Kingdom and South Korea.
  - pfdietz 6y ago
    Going back to first principles is how you conclude DT fusion is a dead end. And this has been known for decades. http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trouble-With-Fusion_MIT_Tech_Review_1983.pdf http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trou... (That prescient article has stood the test of time, except that advanced fuels were mostly ruled out also.)
pfdietz 6y ago
> The basic problems have all been solved The basic problems of power density and complexity have not been solved. Putative REBCO magnets do not solve these problems. Yes, these are engineering problems, but engineering problems are perfectly capable of being fatal. After all, fission has faced only engineering problems since 1942, and yet still has failed.
- rkangel 6y ago
  You could make an argument that Fission has succeeded on a technical front (large amounts of electricity are being generated for multiple countries at this precise moment), and that most of its problems are social.
  - pfdietz 6y ago
    No, the primary problem of fission is economic, not social. That's why it's been a global failure. It simply has not been able to compete with the alternatives. And this is why fusion is such a boondoggle. It's similar to fission, only even more complex and expensive. It's like the opposite of Keep It Simple, Stupid.
    - cromwellian 6y ago
      No, Pressured Water Reactors (LPWRs) are large, expensive, dangerous, etc. Molten Salt Reactors, especially Thorium Molten Salt Reactors (e.g. LFTR) are much much smaller and passively safe. What you're missing is that cost scales with volume. If you use a technology that allows you to reduce your reactor size by a linear factor of 2, you reduce its reduce volume and cost by a factor of 8. Likewise, while ITER is uber expensive like large PWRs, ARC is 10 times smaller, and a factor of 30 times or more cheaper. It's also not as complex as some fission reactors, the most complex elements being the HTS magnets and the blanket. This is the problem with ITER and PWRs, they have convinced the public that nuclear energy is inherently dangerous and expensive and impossible to make substantially safer, cleaner, and cheaper, but that is false. You should look up at the history of LPWRs vs MSRs from the guy who invented them. There's a documentary on the Oak Ridge Molten Salt Reactor experiment. He himself thought LPWRs were too dangerous requiring ginormous size and shielding, but the US government and cronies, preferred LPWRs, and so MSRs were abandoned, despite successful trials.
thinkcontext 6y ago
> Tokamaks have already made net fusion power. Nope. The record for Q is .67 set by JET in 1997. The whole justification for ITER is that it would be able to do Q > 1. Why do you think that net power has been achieved? https://en.wikipedia.org/wiki/Fusion_energy_gain_factor https://en.wikipedia.org/wiki/Fusion_energy_gain_factor

DrNuke 6y ago

It was mainly an engineering issue: materials, manufacturing and assembling. It is too big to fail right now, and most issues have been solved. It never was as simple as webinars from scientists would make it. The funniest joke within nuclear eng insiders is the marvels of paper reactors pretty always make real reactors just seem glorified boilers.

cromwellian 6y ago
ITER's too big the fail. But again, the parameters were known. The magnets give you the field strength, the field strength tells you the radius, the radius^3 gives you the cost, and also, some measure of the construction time. This is one of the great things about Elon Musk -- he looks at things from first principles. When it looked like he needed 1000 Gigafactories to reach his goal, he went back to the drawing board on decades of battery manufacturing, to come up with the Terafactory. When carbon composite rockets looked to be too hard to manufacture, and have too many other detriments, despite the clear wins in strength-to-weight, he dropped it and went with stainless steel. I'm pretty sure if he was staring at the basic Tokamak equations, he would have long again saw the economic and time dependence on R, and the massive benefits to improving B, and that would have driven him to look for alternatives. Too many researchers engage in sunk cost / dollar auctions, doubling down on obvious wrong approaches, because they've already spent so much. This is also why DeepMind won CASP again, because rather than try to iteratively improve their 2018 result, they dropped it as a dead end and restarted with a completely new approach, even though the 2018 approach was also a revolutionary breakthrough. What I'm getting at is, being able to let go of your previous projects if they are stalling, with huge cost over runs, and a mediocre future return, is a value we should seek in fusion research, and elsewhere.
- DrNuke 6y ago
  Ok but ITER was much more than engineering: soft diplomacy, supranational bureaucracy, manufacturing modernisation. Musk comes from a different era and a different environment but, again, launching rockets successfully, with humans in them safely going and coming back, was achieved well before him. Stable nuclear fusion is still unclaimed as a milestone, even if sustainable nuclear fusion might well come from different, smaller approaches the likes we are seeing from United Kingdom and South Korea.
- pfdietz 6y ago
  Going back to first principles is how you conclude DT fusion is a dead end. And this has been known for decades. http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trouble-With-Fusion_MIT_Tech_Review_1983.pdf http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trou... (That prescient article has stood the test of time, except that advanced fuels were mostly ruled out also.)

pfdietz 6y ago

> The basic problems have all been solved The basic problems of power density and complexity have not been solved. Putative REBCO magnets do not solve these problems. Yes, these are engineering problems, but engineering problems are perfectly capable of being fatal. After all, fission has faced only engineering problems since 1942, and yet still has failed.

rkangel 6y ago
You could make an argument that Fission has succeeded on a technical front (large amounts of electricity are being generated for multiple countries at this precise moment), and that most of its problems are social.
- pfdietz 6y ago
  No, the primary problem of fission is economic, not social. That's why it's been a global failure. It simply has not been able to compete with the alternatives. And this is why fusion is such a boondoggle. It's similar to fission, only even more complex and expensive. It's like the opposite of Keep It Simple, Stupid.
  - cromwellian 6y ago
    No, Pressured Water Reactors (LPWRs) are large, expensive, dangerous, etc. Molten Salt Reactors, especially Thorium Molten Salt Reactors (e.g. LFTR) are much much smaller and passively safe. What you're missing is that cost scales with volume. If you use a technology that allows you to reduce your reactor size by a linear factor of 2, you reduce its reduce volume and cost by a factor of 8. Likewise, while ITER is uber expensive like large PWRs, ARC is 10 times smaller, and a factor of 30 times or more cheaper. It's also not as complex as some fission reactors, the most complex elements being the HTS magnets and the blanket. This is the problem with ITER and PWRs, they have convinced the public that nuclear energy is inherently dangerous and expensive and impossible to make substantially safer, cleaner, and cheaper, but that is false. You should look up at the history of LPWRs vs MSRs from the guy who invented them. There's a documentary on the Oak Ridge Molten Salt Reactor experiment. He himself thought LPWRs were too dangerous requiring ginormous size and shielding, but the US government and cronies, preferred LPWRs, and so MSRs were abandoned, despite successful trials.

thinkcontext 6y ago

> Tokamaks have already made net fusion power. Nope. The record for Q is .67 set by JET in 1997. The whole justification for ITER is that it would be able to do Q > 1. Why do you think that net power has been achieved? https://en.wikipedia.org/wiki/Fusion_energy_gain_factor https://en.wikipedia.org/wiki/Fusion_energy_gain_factor