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Progress toward fusion energy gain as measured against the Lawson criteria

fusionenergybase.com

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Re: Progress toward fusion energy gain as measured against the Lawson criteria

#141

Post by worik »

UltraSane wrote: post #139
worik wrote: post #138

Earlier quoted context omitted.

The vast majority of nuclear waste needs to be stored only hundreds of years. But there is still plenty that needs to be stored for hundreds of millennium There is no answer to that, and no amount of arguing by analogy, argumentum ad hominem nor wishful thinking can make that go away It is a very good thing we do not need nuclear power

"But there is still plenty that needs to be stored for hundreds of millennium" Stop repeating this lie. We absolutely need Nuclear. It is the only way to eliminate CO2 emissions from electricity production completely.

> Stop repeating this lie.

It is not a lie

https://en.m.wikipedia.org/wiki/Long-lived_fission_product

Wishful thinking on your part

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#142

Post by boxed »

DennisP wrote: post #120
boxed wrote: post #91

Earlier quoted context omitted.

From what I understood, laser fusion needs laser efficiencies not just 40x better than what NIF uses, but like 3 or 4 orders of magnitude more efficient than the state of the art. Seems like a non-starter.

NIF's lasers are 0.5% efficient. Equivalent modern lasers are 20% efficient. Both of these sources have both numbers: https://physicsworld.com/a/national-ignition-facilitys-ignit... https://pubs.aip.org/physicstoday/Online/31501/The-commercia...

80% energy loss on the way in would make the entire thing unworkable immediately. That's my point.

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#143

Post by DennisP »

boxed wrote: post #142
DennisP wrote: post #120

Earlier quoted context omitted.

NIF's lasers are 0.5% efficient. Equivalent modern lasers are 20% efficient. Both of these sources have both numbers: https://physicsworld.com/a/national-ignition-facilitys-ignit... https://pubs.aip.org/physicstoday/Online/31501/The-commercia...

80% energy loss on the way in would make the entire thing unworkable immediately. That's my point.

Not at all. If you have that, plus 30% efficiency in a turbine, but you've got a 35X gain from fusion, then overall you have .2 * .3 * 50 = 2.1X overall gain.

NIF's latest shot is 2 MJ in, 7 MJ out[1], for a 3.5X fusion gain. So they've got an order of magnitude to go before getting to modestly practical levels. NIF seems to scale much better than linear with respect to the laser power, so an order of magnitude better gain is probably not a big change to the device.

(This does neglect energy loss in the hohlraum, so it assumes that direct drive laser fusion will get similar results. There are several projects working on that. Based on another comment here[2], the main reason for the hohlraum was that it made the experiment more relevant to weapons.)

[1] https://physicsworld.com/a/fusion-industry-meets-in-london-t...

[2] https://news.ycombinator.com/item?id=43935891

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#144

Post by DennisP »

pfdietz wrote: post #140
DennisP wrote: post #121

Earlier quoted context omitted.

Commercial REBCO tape is an entirely sufficient superconductor for tokamaks. At this point the limiting factor for the magnetic field is the structural strength of the reactor. Tokamak output scales with the square of size and the fourth power of magnetic field strength, and using REBCO, the CFS ARC design should get practical power output from a reactor much smaller than ITER.

Much smaller than ITER, but ITER is so huge a reactor could be much smaller and still be too big to be practical.

About the size of JET. It's definitely practical in the sense that we can build it and it's likely to produce overall net power. Whether it will be competitive is another issue, and for that I agree with you that other designs, like Helion, have a better shot.

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#145

Post by actinium226 »

worik wrote: post #79
actinium226 wrote: post #75

Earlier quoted context omitted.

Just curious, what makes you oppose new fission plants? Do you think existing ones should be closed before their scheduled end-of-life?

I will bite. There are any problems with fission that are all related to the extraordinary danger of handling the fuel, byproducts, and the sites themselves. The cost of them is huge, some people are hoping that modularity will help with construction, but it is still astonishingly expensive. The problems of handling the fuel has been solved, in theory and practise. Except when commerce is involved. When the money peo…

What exactly is the danger though? I'm imagining that another Chernobyl-level reactor breach is unlikely (not least since the other 3 reactors at Chernobyl of the same type kept running until 2000, and several more reactors of the same type are still operating today in various post Soviet countries). And while reactivity release is unfortunate, the effects tend to be localized (excepting Chernobyl), and let's not pretend that other modalities have 0 environment impact or risk factors.

If fact more people die from falling off wind turbines during maintenance than have died from nuclear accidents on a per-TWh basis [1].

And there were greater health effects in Fukushima due to panic and unnecessary evacuation than from radiation [2].

Again I agree radioactivity = bad, but I think it needs to be put in context.

And as for the disposal of nuclear waste, yes it's a problem for thousands of years, but we don't need a thousand year solution, it's not like we're leaving the planet. One possible outcome there is that eventually we develop cheap enough neutron sources that we can bombard the waste with neutrons until the various atoms capture enough neutrons to become stable isotopes. Considering the technological progress over the last 300 years, maybe in another 300 such a feat will be economically feasible.

[1] https://ourworldindata.org/safest-sources-of-energy

[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8208296/

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#146

Post by Calwestjobs »

Calwestjobs wrote: post #115
PaulDavisThe1st wrote: post #64

Earlier quoted context omitted.

I am no fan of fission (I strongly oppose new fission plants). But one problem with solar+storage is that the cost of the storage component increases roughly linearly with the desired storage duration. That's not true of a fueled power plant (fission or fossil).

this is manipulative coal power plant needs to have 100 or so rail cars worth of material brought every single day. so you are simplifying too much. every person doing anything with power generation should put into spreadsheet, what quantities of material is needed to provide power capacity for entire grid. and you need people, infrastructure to bring, prepare, load that material. which adds COST OF LOCKING PEOPLE, l…

https://www.youtube.com/watch?v=iT72tMMBxVg

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#147

Post by pfdietz »

DennisP wrote: post #144
pfdietz wrote: post #140

Earlier quoted context omitted.

Much smaller than ITER, but ITER is so huge a reactor could be much smaller and still be too big to be practical.

About the size of JET. It's definitely practical in the sense that we can build it and it's likely to produce overall net power. Whether it will be competitive is another issue, and for that I agree with you that other designs, like Helion, have a better shot.

That's not a definition of "practical" that I would use. "Possible", perhaps, but practical implies effectiveness and suitability, and without competitiveness that isn't there.

Re: Progress toward fusion energy gain as measured against the Lawson criteria

#148

Post by UltraSane »

worik wrote: post #141
UltraSane wrote: post #139

Earlier quoted context omitted.

"But there is still plenty that needs to be stored for hundreds of millennium" Stop repeating this lie. We absolutely need Nuclear. It is the only way to eliminate CO2 emissions from electricity production completely.

> Stop repeating this lie. It is not a lie https://en.m.wikipedia.org/wiki/Long-lived_fission_product Wishful thinking on your part

The longest lived fission products are actually the LEAST radioactive. This inverse relationship exists because of the fundamental relationship between half-life and radioactivity. The longer a radioisotope's half-life, the lower its specific activity (radioactivity per unit mass)

You are like a firefighter who opposes using water (nuclear energy) to extinguish fires (reduce CO2 emissions) because people might drown.

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