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The Trouble with Fusion (1983) [pdf]

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Re: The Trouble with Fusion (1983) [pdf]

#11

Post by willis936 »

pfdietz wrote: post #9
willis936 wrote: post #5

I’m still only a few pages in. I don’t have the chance to read it all right now, but I will revisit this tomorrow morning. Here are my early thoughts. Disclaimer: I am an advocate of fusion and am moving into the field (professional electrical engineering support of an academic project). We need to walk before we can run. D+T fusion is viable. Hull maintenance is a solvable problem. Economic studies come after we can…

> So why skip over D+T if we need to go through it anyway? Because much of what you'd end up doing to "do" D+T will be worthless for H+11B. Tokamaks, for example, are useless for H+11B.

Tokamaks may not even be viable for steady state D+T. The bootstrap current effect still needs to be explored further. Electrostatic confinement and inertial confinement are the only known viable options for p+B11. Electrostatic has serious issues related to conduction losses, but perhaps if they were large enough scaling laws may make them viable. It’s not well explored. Inertial confinement is getting a lot of funding and shows serious promise. However, inertial confinement is not a steady state design and its pulsed nature makes it difficult to make a power plant out of. No such engineering cliffs exist for tokamaks and stellarators. The performance just needs to keep marching towards success. Then the discussion of economics can begin in earnest.

Re: The Trouble with Fusion (1983) [pdf]

#12

Post by pfdietz »

willis936 wrote: post #11
pfdietz wrote: post #9

Earlier quoted context omitted.

> So why skip over D+T if we need to go through it anyway? Because much of what you'd end up doing to "do" D+T will be worthless for H+11B. Tokamaks, for example, are useless for H+11B.

Tokamaks may not even be viable for steady state D+T. The bootstrap current effect still needs to be explored further. Electrostatic confinement and inertial confinement are the only known viable options for p+B11. Electrostatic has serious issues related to conduction losses, but perhaps if they were large enough scaling laws may make them viable. It’s not well explored. Inertial confinement is getting a lot of fund…

Electrostatic confinement is not known to be viable for H-11B. Indeed, Rider showed it probably isn't viable.

For inertial confinement, I understand compression would have to reach densities of as much as 10^6 g/cc for H-11B to be viable.

Re: The Trouble with Fusion (1983) [pdf]

#13

Post by willis936 »

willis936 wrote: post #5

I’m still only a few pages in. I don’t have the chance to read it all right now, but I will revisit this tomorrow morning. Here are my early thoughts. Disclaimer: I am an advocate of fusion and am moving into the field (professional electrical engineering support of an academic project). We need to walk before we can run. D+T fusion is viable. Hull maintenance is a solvable problem. Economic studies come after we can…

So I’m a few pages further and I fear I will not be finishing this paper. I am surprised it was published and is still referenced. Where are the citations? Where is the analysis? You can’t just say “fusion reactors need to be ten times bigger than fission reactors”. It’s frankly embarrassing to MIT that they would allow egregious, unfounded claims to be published. Peer review exists to shred such unsupported statements.

Re: The Trouble with Fusion (1983) [pdf]

#14

Post by bsder »

pfdietz wrote: post #10
bsder wrote: post #8

We know what the issue is--fusion never got a useful amount of funding. Now, it is entirely possible that even given an enormous amount of funding--fusion might still not work. However, engineers with lots of money are remarkably clever and effective beasts (see: radio, semiconductors, plastics, steel). Fusion has been funded at "Fusion Never" levels for almost 40 years while we subsidize every other significant ener…

No, that's not what the issue is. That's an effect, not a cause. The cause is that fusion turned out to be less promising than had been thought, and that led to budgets being tight. Lidsky's devastating critique was part of that (tokamaks not being as good as early hopes implied was another.)

> The cause is that fusion turned out to be less promising than had been thought

So did a whole lot of chemical rocketry. Instead of whining about it--we spent a lot of money on engineering, we made the Saturn V, and we went to the moon anyway.

The issue is that fusion only has one end point--providing energy. Researching chemical rocketry made better weapons--so we funded the snot out of it. The DOE spent billions on the Unconventional Gas Research Programs and lined a lot of pockets.

Funding isn't guaranteed to make progress, but lack of funding practically guarantees lack of progress.

Re: The Trouble with Fusion (1983) [pdf]

#15

Post by ncmncm »

There has never been any serious expectation of getting usable power from fusion. All the reactor designs worked on in mainstream research would destroy themselves in a short time by high-energy neutron flux.

Fusion research is, instead, a jobs program for high-neutron flux physicists, to provide a pool to draw on for weapons work.

There are interesting commercial projects for designs that do not suffer from high neutron flux, such as those pursuing pB reactions. I read of another where neutrons are emitted in a place some distance from where the expensive machine parts are.

You can tell if a fusion process is serious by whether they have an answer to the neutron problem. Tokamak doesn't.

Re: The Trouble with Fusion (1983) [pdf]

#16

Post by pfdietz »

bsder wrote: post #14
pfdietz wrote: post #10

Earlier quoted context omitted.

No, that's not what the issue is. That's an effect, not a cause. The cause is that fusion turned out to be less promising than had been thought, and that led to budgets being tight. Lidsky's devastating critique was part of that (tokamaks not being as good as early hopes implied was another.)

> The cause is that fusion turned out to be less promising than had been thought So did a whole lot of chemical rocketry. Instead of whining about it--we spent a lot of money on engineering, we made the Saturn V, and we went to the moon anyway. The issue is that fusion only has one end point--providing energy. Researching chemical rocketry made better weapons--so we funded the snot out of it. The DOE spent billions o…

Not a good analogy. Chemical rockets are the only real way to get to space. So if you make them better, even incrementally, you have a win. It also helped that launchers were very far away from fundamental economic limits on their performance. Expendable launchers, unlike power plants, are expended.

But fusion is competing against a plethora of other approaches to production of energy that actually work, and are being used, and are arguably superior.

Fusion also uses components that are mature due to their use in these other approaches. DT fusion, which Lidsky is addressing, will produce its energy as heat. This heat has to be turned into power using turbines and generators, a mature technology. And it's a mature technology that's a major part of the cost of coal and nuclear power plants, and is a big reason why those power plants are no longer competitive.

(This echoes an argument from the mid 20th century, when it was pointed out that fission power would, at best, be only slightly less expensive than power from coal, due to all the common elements the power plants shared. And it turned out nuclear fission was more expensive than that, as one could not do the nuclear parts too cheaply. DT fusion reactors promise to be much larger and more complex than fission reactors, for the fundamental reasons Lidsky and others gave, so one can reasonably expect their economics to fail even more.)

(This is also why the focus on thorium and SMRs to try to keep fission alive is probably hopeless.)

("Those who cannot remember the past are condemned to repeat it")

The complaint about funding is a red herring. It has the presumption that if funding had been available, fusion had a real chance of succeeding. But as Lidsky points out, it didn't have a real chance of succeeding. Even if the program had produced a reactor, no one would have wanted it.

Re: The Trouble with Fusion (1983) [pdf]

#17

Post by credit_guy »

ncmncm wrote: post #15

There has never been any serious expectation of getting usable power from fusion. All the reactor designs worked on in mainstream research would destroy themselves in a short time by high-energy neutron flux. Fusion research is, instead, a jobs program for high-neutron flux physicists, to provide a pool to draw on for weapons work. There are interesting commercial projects for designs that do not suffer from high neu…

High neutron flux is useful not only for weapons but for civilian purposes too, for example for "burning" nuclear waste, or for fusion-fission hybrid reactors. I wonder why the Department of Energy does not invest more in this area.

Re: The Trouble with Fusion (1983) [pdf]

#18

Post by pfdietz »

willis936 wrote: post #13
willis936 wrote: post #5

I’m still only a few pages in. I don’t have the chance to read it all right now, but I will revisit this tomorrow morning. Here are my early thoughts. Disclaimer: I am an advocate of fusion and am moving into the field (professional electrical engineering support of an academic project). We need to walk before we can run. D+T fusion is viable. Hull maintenance is a solvable problem. Economic studies come after we can…

So I’m a few pages further and I fear I will not be finishing this paper. I am surprised it was published and is still referenced. Where are the citations? Where is the analysis? You can’t just say “fusion reactors need to be ten times bigger than fission reactors”. It’s frankly embarrassing to MIT that they would allow egregious, unfounded claims to be published. Peer review exists to shred such unsupported statemen…

This was a semi-popular article. You can find more technical analyses in the literature.

The specific points made in the article have stood the test of time. Lidsky said the power density of a DT fusion reactor would be at least an order of magnitude worse than that of a fission reactor. And if you look at existing reactors and concepts, this is true. Compare to a commercial PWR, in which (thermal power)/(volume of reactor vessel) is about 20 MW/m^3. An order of magnitude worse than that would be 2 MW/m^3. The (thermal power)/(reactor volume) for ITER is about 0.05 MW/m^3. For ARC and Lockheed's concepts, about 0.5 MW/m^3.

Your outrage should not be directed at this article (although such outrage is sadly understandable, if this article is telling you things you don't want to hear.) Instead, it should be directed at the fusion community as a whole, which has downplayed these critiques and glad-handed the issues raised while marching confidently into a dead end.

Re: The Trouble with Fusion (1983) [pdf]

#19

Post by pfdietz »

ncmncm wrote: post #15

There has never been any serious expectation of getting usable power from fusion. All the reactor designs worked on in mainstream research would destroy themselves in a short time by high-energy neutron flux. Fusion research is, instead, a jobs program for high-neutron flux physicists, to provide a pool to draw on for weapons work. There are interesting commercial projects for designs that do not suffer from high neu…

You are referring to TAE's design. The people behind that were told 20+ years ago the concept would not work.

https://www.researchgate.net/profile/Wallace_Manheimer/publi...

http://w3fusion.ph.utexas.edu/ifs/ifsreports/919_wong.pdf

Re: The Trouble with Fusion (1983) [pdf]

#20

Post by pfdietz »

credit_guy wrote: post #17
ncmncm wrote: post #15

There has never been any serious expectation of getting usable power from fusion. All the reactor designs worked on in mainstream research would destroy themselves in a short time by high-energy neutron flux. Fusion research is, instead, a jobs program for high-neutron flux physicists, to provide a pool to draw on for weapons work. There are interesting commercial projects for designs that do not suffer from high neu…

High neutron flux is useful not only for weapons but for civilian purposes too, for example for "burning" nuclear waste, or for fusion-fission hybrid reactors. I wonder why the Department of Energy does not invest more in this area.

Fusion-fission hybrids combine the worst features of both. There is no user "pull" for the concept. If you want power with fission, just build a fission reactor; that's going to be simpler, cheaper, and altogether more sensible. If you want to dispose of waste, just seal it in dry casks and wait a century or three before deciding what to do with it. That will also be much simpler and (due to nonzero interest rates) cheaper.
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