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MIT-designed project achieves major advance toward fusion energy

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Re: MIT-designed project achieves major advance toward fusion energy

#51

Post by LeegleechN »

zetalyrae wrote: post #49
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

It's just an absolutely giant construction project. The mass and volume of the construction goes as the cube of the major radius of the reactor. Back of the envelope, SPARC is (6/1.5)^3 = 64 times smaller than ITER. The construction budget for SPARC is ~$500M, so ITER being tens of billions is in line.

Re: MIT-designed project achieves major advance toward fusion energy

#52

Post by jvanderbot »

zetalyrae wrote: post #49
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

Margin?

Akin's law of spacecraft #29 "To get an accurate estimate of final program requirements, multiply the initial time estimates by pi, and slide the decimal point on the cost estimates one place to the right."

Re: MIT-designed project achieves major advance toward fusion energy

#53

Post by drdeca »

MauranKilom wrote: post #44
JackFr wrote: post #23

Earlier quoted context omitted.

Ah yes, and how much money? The answer always seems to be “More”.

Please consult this graphic from 1976 if you are actually interested in the answer. https://i.imgur.com/3vYLQmm.png

Could you clarify how to read this chart? The y axis is, funding given different plans? Or.. I got the impression that this is meant to depict a relationship between when practical fusion would be developed and how much funding it receives, but I don’t see how to get that from the chart.

Also, not sure why imgur has that image marked as adult content.

Re: MIT-designed project achieves major advance toward fusion energy

#54

Post by dfdx »

zetalyrae wrote: post #49
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

Anecdotally, ITER was the largest of few options for a fusion researcher to run their experiment in a new tokamak. Everybody wanted to put their work into it, and as more features were added, the more funding it sucked up, leaving less money for other experiments, leading to more people wanting to put their experiment into ITER. Here's a presentation [0] that goes over why SPARC, being so much smaller and simpler than ITER could be more likely to succeed.

[0] https://library.psfc.mit.edu/catalog/online_pubs/iap/iap2016...

This quote from the presentation summarizes it well:

“The more money that's involved, the less risk people want to take. The less risk people want to take, the more they put into their designs, to make sure their subsystem is super-reliable. The more things they put in, the more expensive the project gets. The more expensive it gets, the more instruments the scientists want to add, because the cost is getting so high that they're afraid there won't be another opportunity later on- they figure this is the last train out of town. So little by little, the spacecraft becomes gilded. And you have these bad dreams about a spacecraft so bulky and so heavy it won't get off the ground- never mind the overblown cost.”

“That boils down to the higher the cost, the more you want to protect your investment, so the more money you put into lowering your risk. It becomes a vicious cycle.” - Rob Manning, Chief spacecraft engineer, JPL

Re: MIT-designed project achieves major advance toward fusion energy

#55

Post by danans »

rnhmjoj wrote: post #50
anonuser123456 wrote: post #17

Earlier quoted context omitted.

> What's the catch this time? This is D-T fusion. Which means you have to have T. Which currently comes from fission reactor and has a half life of 15 years. So the plan is to use a molten salt blanket with Be to breed T. But Be isn’t scalable for consumption, so maybe lead eventually. That’s probably do-able, it just slows down the rate new reactors can come online since Pb is not as good a neutron multiplier. Once…

> But are they surmountable AND cheaper than existing nuclear or other energy sources? DT fusion solves the two biggest arguments that are always raised by nuclear energy opponents: storage of nuclear waste (it doesn't produce high-level waste) and safety (it's not perfect but it can't explode). I wouldn't call it a "meh", even if it comes off as much more expensive than fission.

> I wouldn't call it a "meh", even if it comes off as much more expensive than fission.

It's not competing with fission, though. It's competing with renewables + storage + load shifting + efficiency. Compared to those, it might indeed be "meh".

Re: MIT-designed project achieves major advance toward fusion energy

#56

Post by bigyikes »

LeegleechN wrote: post #51
zetalyrae wrote: post #49

Earlier quoted context omitted.

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

It's just an absolutely giant construction project. The mass and volume of the construction goes as the cube of the major radius of the reactor. Back of the envelope, SPARC is (6/1.5)^3 = 64 times smaller than ITER. The construction budget for SPARC is ~$500M, so ITER being tens of billions is in line.

How do projects like LIGO ever get completed? I’m probably totally naive here, but I thought LIGO is physically larger and has many difficult constraints. The LHC comes to mind as well, and that absolutely dwarfs ITER in physical size. What’s the difference? Dealing with heat output? Superconductors are really hard maybe?

Re: MIT-designed project achieves major advance toward fusion energy

#57

Post by sbierwagen »

zetalyrae wrote: post #49
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

Here's a render of the completed reactor: https://www.iter.org/doc/all/content/com/gallery/media/7%20-... Note human for size.

It's all completely bespoke scientific equipment hand made for this project only. The cryostat will be the largest stainless steel vacuum vessel ever made-- all welded by hand.

After welding, a substantial number of in-vessel components have to be installed by threading them through access ports, which is also quite a task: https://www.youtube.com/watch?v=pt70mO2nQac

Re: MIT-designed project achieves major advance toward fusion energy

#58

Post by speed_spread »

rnhmjoj wrote: post #50
anonuser123456 wrote: post #17

Earlier quoted context omitted.

> What's the catch this time? This is D-T fusion. Which means you have to have T. Which currently comes from fission reactor and has a half life of 15 years. So the plan is to use a molten salt blanket with Be to breed T. But Be isn’t scalable for consumption, so maybe lead eventually. That’s probably do-able, it just slows down the rate new reactors can come online since Pb is not as good a neutron multiplier. Once…

> But are they surmountable AND cheaper than existing nuclear or other energy sources? DT fusion solves the two biggest arguments that are always raised by nuclear energy opponents: storage of nuclear waste (it doesn't produce high-level waste) and safety (it's not perfect but it can't explode). I wouldn't call it a "meh", even if it comes off as much more expensive than fission.

It sounds like the T production chain might itself be quite messy. Molten isotopes salt and lead? How much of that stuff would you need? What do you do with when it goes bad? It may not go boom Chernobyl-style, but it's still far from the birds-in-the-sky deuterium-from-the-sea fusion dream.

Re: MIT-designed project achieves major advance toward fusion energy

#60

Post by sbierwagen »

bigyikes wrote: post #56
LeegleechN wrote: post #51

Earlier quoted context omitted.

It's just an absolutely giant construction project. The mass and volume of the construction goes as the cube of the major radius of the reactor. Back of the envelope, SPARC is (6/1.5)^3 = 64 times smaller than ITER. The construction budget for SPARC is ~$500M, so ITER being tens of billions is in line.

How do projects like LIGO ever get completed? I’m probably totally naive here, but I thought LIGO is physically larger and has many difficult constraints. The LHC comes to mind as well, and that absolutely dwarfs ITER in physical size. What’s the difference? Dealing with heat output? Superconductors are really hard maybe?

LIGO did take decades to construct, like the LHC. According to LIGO's wikipedia article, it was the most expensive project ever funded by the NSF in 1994.
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