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ITER: World's largest nuclear fusion project begins assembly

bbc.co.uk

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Re: ITER: World's largest nuclear fusion project begins assembly

#441

Post by pezezin »

the8472 wrote: post #169
eximius wrote: post #73

It is hard for me to conceive of the steps required in these projects that add up to years - just in assembly. Is it due to precision requirements being difficult to achieve? Supply chain delays for custom parts? Lots of experimental runs that require dis-assembly and tuning?

One part of it is that it's a research project. The other part is the bureaucracy of international cooperation and the pieces being built all over the world according to a huge centrally managed specification. It's not like SpaceX that starts with a small design and then builds incrementally larger versions to have something to show in the meantime. It's from 0 to finished product.

I'm currently working for IFMIF (sister project of ITER), and I know some people who work or worked for ITER, and yes, the bureaucracy is an absolute nightmare. Coordinating so many countries with so many different working cultures is really difficult.

On the other hand, we DO build incrementally larger versions. The machine is built and tested in stages, it would be impossible to build such complex machines in just one go.

Re: ITER: World's largest nuclear fusion project begins assembly

#442

Post by osn9363739 »

Scarblac wrote: post #336
elihu wrote: post #161

Earlier quoted context omitted.

Most people live in cities where land is very expensive, but rural land is cheap. So, it makes sense to do large-scale solar projects that aren't near cities at ground level, and put solar panels on roofs in cities and towns where the power is being used on-site and land is expensive. If people are putting installing solar panels at ground level in expensive urban settings, then yeah I think that's pretty weird. (It…

In my country (the Netherlands), there are a lot of huge distribution centers, large warehouses with flat roofs. But instead of putting solar on the roofs of those, rural land is used, and we don't have so much of that. It's a shame.

Hopefully more shared use becomes a thing. Stick the panels a bit higher, space them out a bit more. No reason why you can't have a mix of livestock and solar panels on one piece of land. Raises the price a bit for now, but everyone wins I guess?

Re: ITER: World's largest nuclear fusion project begins assembly

#443

Post by lmm »

korantu wrote: post #431
lmm wrote: post #373

Earlier quoted context omitted.

You're talking about fission? I think we should push it as far as it will go. At the same time I think there is some legitimacy to the waste and disaster concerns (even if mostly overblown) and so fusion offers enough potential advantages to still be worth pursuing.

I am all for pursuing fusion, for pushing borders of our knowledge. At the same time, concerns are way overblown about fission. You know, it is regulated to 1/10000 amount of radioactive increase that is known to ever cause harm. This is causes the designs to be order of magnitude more expensive then they could be. For example, for BWR, fukushima, there is no graphite inside, and reaction is going on only when water…

> To look at it this way, most dangerous nuclear plant is the one that does not get built, as it will be for significant part will be replaced with something burining dinosurs.

Entirely true. But unfortunately there are a lot of nuclear plants not getting built at the moment. Tragic as it is, developing working fusion is probably an easier way to change that than political persuasion.

Re: ITER: World's largest nuclear fusion project begins assembly

#444

Post by nicoburns »

mytailorisrich wrote: post #415
nicoburns wrote: post #400

Earlier quoted context omitted.

That depends on how quickly you think the storage problem can be solved. If it can be solved in 10 years then it makes little sense to build more nuclear (fission) capacity, because it will be obsolete by the time it is built.

Storage is only part of the problem, though a big one. The area that needs to be covered with solar panels and windmills is another one.

> The area that needs to be covered with solar panels and windmills is another one.

I don't really see that as a huge problem. There's loads of free area for solar panels on rooftops. Sure, it's more expensive to build solar there. But that's not even an engineering problem, it's simply a matter of allocating funds to it. And most of the cost is labour. Which is arguably a bit of a bonus in a world where we're constantly worrying about there not being enough jobs.

Re: ITER: World's largest nuclear fusion project begins assembly

#445

Post by willis936 »

blazekp wrote: post #358
usui wrote: post #7

I am going to need some help on this one as my knowledge on physics is limited: What makes scientists believe that the solution to nuclear fusion power is only a matter of scale? I desperately want nuclear fusion to work because nuclear power is the only realistic way to solve the looming energy crisis of the 21st century while still maintaining the same standard of living for everyone. It's also 500% more important…

> What makes scientists believe that the solution to nuclear fusion power is only a matter of scale? I guess there are too many physicists who can lobby well and their income depends on it. I don't expect any results after the many attempts (as opposed to fission, which had almost immediate results).

In case anyone read this comment and wanted the real answer: empirically derived scaling laws from a series of machines increasing in size. The last/largest is JET.

http://fusionwiki.ciemat.es/wiki/Scaling_law

Re: ITER: World's largest nuclear fusion project begins assembly

#446

Post by pfdietz »

lambdatronics wrote: post #436
pfdietz wrote: post #262

Looking at stories like this, you need to realize how far out of the running this technology is. The power density of ITER (gross fusion power of the reactor divided by the volume of the reactor, not just the volume of the plasma) is 50 kW/m^3. This is horribly low, about 1/400th the power density of a PWR reactor vessel. The power/$ is also horribly bad. The cost is going to have to come down by two orders of magnit…

Solar was 2 orders of magnitude out of the running around 1975 -- and now it's at grid parity. So maybe fusion is 45 years away? :P You're right that the cost is going to have to come down, and the power density up, before fusion can compete. High-field superconductors are one obvious route, and using plasma configurations that make better use of the magnetic fields are another. Either one of those approaches could d…

That approach doesn't work, because reactor power density becomes limited by wall loading (neutron and/or thermal), regardless of how good the plasma physics is.

It's the square cube law. At a given wall loading limit the volumetric power density is inversely proportional to the linear dimensions. And a DT fusion reactor must be meters across, due to the fixed cross section of the neutrons with wall materials. In contrast, fission fuel rods are 1 cm in diameter and are closely spaced, so the available surface area for heat transfer is much higher (neutrons in fission are also much less of a problem, since they carry a much smaller fraction of the energy output and are of much lower energy, on average.)

(I think the only hope for DT fusion is something like LINUS, where the entire first wall is thick flowing liquid lithium.)

> I think there's been an element of that in the way the federal program has been run, but claiming it's the only reason to pursue fusion is not defensible.

What is the other reason? I cannot find any other plausible justification. This is particularly true now that fission is out of the running. Fusion used to be justified by "it won't be too much more expensive than fission, but it's safer and won't run out of uranium." That argument is now pointless.

Re: ITER: World's largest nuclear fusion project begins assembly

#447

Post by willis936 »

zionpi wrote: post #276

“We hope to see first plasma in five years. That will only be a short plasma - lasting a few milliseconds” this is a quote from original article.I was wondering why `few milliseconds` can make such a huge impact?What does this `few milliseconds` plasma mean?

In MCF machines plasmas are made by heating gas through RF (gyrotrons) or momentum (NBI). Both gyrotrons and NBI are very expensive, complicated, high power machines with big subsystems that go into them. Bringing on all of the heaters and diagnostics take time. Wall conditioning takes time. The first plasma is before most of the necessary systems are up. It’s a demonstration that the machine is built.

Re: ITER: World's largest nuclear fusion project begins assembly

#448

Post by willis936 »

The_rationalist wrote: post #305
lambdatronics wrote: post #261

Earlier quoted context omitted.

Tokamak-style reactors like ITER rely on a rapidly-changing magnetic field to induce an electric current in the plasma, for stability of the plasma. The magnet that provides this rapidly-changing field (the 'central solenoid') can't keep increasing in field strength indefinitely -- so there's a time limit to the life of the plasma. There are other ways to supplement the current in the plasma, which can help extend th…

But this is beyond ridiculous, so many years of R&D for 8 minutes of sustained acticivty activity? That sound like a joke

That’s like saying “spending $30,000 for a license plate holder sounds like a joke”. This machine is being built for the information needed to make real reactors. Empirically derived scaling laws, confinement physics, and divertor physics all greatly benefit from having their regimes pushed past where they have been. It’s a science machine.

Re: ITER: World's largest nuclear fusion project begins assembly

#449

Post by akvadrako »

cwhiz wrote: post #128
dantillberg wrote: post #100

Earlier quoted context omitted.

You could imagine building a globe-spanning power distribution network. Solar panels on one side of the planet could provide power at night on the other side of the planet.

If we could transmit power across vast distances like that then we wouldn't even need to bother with solar. We could build a thousand nuclear power plants in the middle of nowhere. Unfortunately, power transmission suffers from line losses. Even a few hundred miles requires several hundred thousand volts to avoid losses. Maybe that's an easier problem to solve than fusion.

China has built a 1100 kV line for 12 GW with losses of only 1.5% per 1000 km.

source: http://en.people.cn/n3/2018/0622/c90000-9474097.html

Re: ITER: World's largest nuclear fusion project begins assembly

#450

Post by the8472 »

pezezin wrote: post #441
the8472 wrote: post #169

Earlier quoted context omitted.

One part of it is that it's a research project. The other part is the bureaucracy of international cooperation and the pieces being built all over the world according to a huge centrally managed specification. It's not like SpaceX that starts with a small design and then builds incrementally larger versions to have something to show in the meantime. It's from 0 to finished product.

I'm currently working for IFMIF (sister project of ITER), and I know some people who work or worked for ITER, and yes, the bureaucracy is an absolute nightmare. Coordinating so many countries with so many different working cultures is really difficult. On the other hand, we DO build incrementally larger versions. The machine is built and tested in stages, it would be impossible to build such complex machines in just…

> On the other hand, we DO build incrementally larger versions.

You're referring to JET? Does ITER benefit from production facilities that were used for it?

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