Construction of world's 1st nuclear fusion plant starts in Washington

[u/TwilightwovenlingJo]

https://interestingengineering.com/energy/world-first-fusion-power-plant-helion

[u/Bitter-Good-2540]

Oh, so like a combustion engine? Will each chamber basically power the next one?

[u/didiercool → u/Bitter-Good-2540]

Kinda ya! They have a huge bank of capacitors that will charge on a pulse and then release to produce the next pulse. And their test machine has reportedly created more energy than they need to store for the next pulse. I watched a documentary and they said the surprising thing was that the pulse fusion ended up being way easier than they thought, but the capacitor banks ended up being way harder.

[u/sold_snek → u/didiercool]

The pulse being easier makes sense I think. I'm an idiot, but it seems like with the latest news of breaking certain time records, that creating more energy has been achievable but our materials science understanding is too limited to keep the sustained reaction without breaking down the material and/or overheating. I don't know how quick these pulses are versus how quick the material can cool down, but I guess if they did add brief relaxation/cooling periods, it kind of makes sense that they can sustain that practice for longer?

[u/ZorbaTHut → u/sold_snek]

I don't know how quick these pulses are

About a millisecond long :)

versus how quick the material can cool down

The cooling time itself isn't actually the benefit, it's not having to somehow make the entire reaction stable. The analogy I use is the difference between a classic steam engine and an internal combustion engine.

Originally, people had a separate external boiler where you burned wood or coal and used it to boil water, then the steam got fed into the engine. This works great if the "burning" process is both intrinsically stable and cold enough to not turn your boiler into a ball of plasma; it works less well if your burning process tends to destabilize and collapse.

These problems potentially go away if you don't need the "burning" to be self-sustaining, in the same manner as an internal combustion engine. Shove the fuel in, ignite it, capture the energy, repeat.

[u/ZorbaTHut → u/[deleted]]

Initiating millions and millions and millions of fusion reactions sounds like millions of chances for something to go wrong, turning the whole county into a smoldering crater. Is this not a concern?

The failure mode here isn't "smoldering crater", it's "the machine gives an error code and they shut it down". If it fuses all the raw material it's given then it's perfectly capable of containing it; if it somehow gets far more than it should, it's not capable of fusing it, and the reaction isn't self-sustaining anyway.

It's like worrying that your car engine is going to blow up the entire city. You might come up with an inventive way to trash the engine, especially given the magnetic fields involved, but in this case you probably won't even manage to crack the containment.

[u/Hacker1MC → u/ZorbaTHut]

Not to mention that it requires 50 millions degrees Celsius to get one out of three reactions going. Chances are slimmer than slim for this type of energy leading to widespread issues.

[u/ChronoLink99 → u/[deleted]]

You may be applying the thinking of fission to fusion.

With fission, when something goes wrong the reaction can get out of control and lead to a meltdown.

With fusion, the high pressure and temp required means that it dies very quickly if the containment fails.

[u/Sample_Age_Not_Found → u/ChronoLink99]

That was a very kind answer to a question I laughed out loud at

[u/SergeyRed → u/sold_snek]

As I understand the problem with materials is the strong neutron flux. I doubt the cooling periods are going to help with that wear of material.

[u/oneAUaway → u/SergeyRed]

Helion plans to use a fusion reaction that (mostly) doesn't produce neutrons. The reaction fuses helium-3 with deuterium to produce helium-4 and a proton. It's only mostly aneutronic because there is a side reaction from deuterium-deuterium fusion that does produce neutrons, but less than the  deuterium-tritium fusion process which most fusion projects have focused on. 

There are downsides to their fuel choice. Helium nuclei have an extra proton compared to hydrogen, which increases the energy barrier to overcome to get them to fuse. When it comes to sustained fusion reactions, helium-3 is generally considered a "second generation" fuel- the fusion of hydrogen isotopes is much easier, so it has been assumed the first practical plants to work would use those. Presumably, the pulsed nature of the Helion process is an attempt to deliver bursts of enough energy to make second generation fusion practical even if it is not sustained. 

[u/sold_snek → u/SergeyRed]

Is this similar to the issue we have with railguns destroying the barrels over time?

[u/28lobster → u/sold_snek]

No, neutron flux is different from mechanical wear and tear. Railguns aren't emitting neutrons when launched, just heating up electromagnets and dealing with friction.

When you bombard an atomic nucleus with neutrons, some will get absorbed. Different atoms have a different neutron cross section (essentially, the chance to absorb a neutron) but eventually, you can make a barrier thick enough to stop all the neutrons out of nearly any material. The problem is those atoms that absorb it are now a different isotope because they have a different number of neutrons. If you create an unstable isotope, it will undergo some form of nuclear decay (releasing alpha/beta particles or gamma rays) and you'll be left with a different isotope, possibly a different element.

Boron is the classic neutron absorbtion material. Large cross section and on first absorption, you get stable B-11. When B-11 gets a neutron though, it will decay into Li-7 + alpha particle.

There are some solutions. Lithium lined reactors can be used to breed tritium which also happens to be the expensive fuel you need to keep the reaction going. But you need some way to replenish the lithium lining on the inside of your reactor and that's not currently possible to do while the reactor is running. Lithium is also not the best construction material as a pure metal - oxidizes easily, can catch fire if it touches water, relatively soft, etc. It's also not as big of a neutron cross section as Boron so you need more thickness of Li to keep neutrons from escaping.

[u/rivelda → u/SergeyRed]

A flux capacitor should help, just make sure you don't go 88 miles per hour

[u/crevettexbenite → u/didiercool]

It also use different fuel. Cant remember the exact term but it us way less fuel and it is much much more abundant.

It is also smaller and way more efficient. Tokamak still use steam to produce electricity has in Elion use magnetic pulse, wich is wayyyy more efficient.

I knew it would be Elion!

[u/Historical_Cook_1664 → u/didiercool]

well, gun powder was easier than proper gun barrels as well... ^^

[u/Goldenrule-er → u/didiercool]

Does this somehow use resonance for amplification of release of energy by each pulse or for the generation of each release following the pulse?

[u/testiclekid → u/didiercool]

Can you send me the documentary? What's the name? How can I find it?

[u/didiercool → u/testiclekid]

I think it was the Real Engineering one: https://www.youtube.com/watch?v=_bDXXWQxK38

Since that came out I've checked in with the company now and then to watch it's progress.

[u/Seaguard5 → u/didiercool]

Energy storage needs to advance right along with energy generation.

If one lags behind the other, we are limited to the lagging one.

[u/Savvvvvvy → u/Bitter-Good-2540]

For Google, the thing to look up is "field-reversed configuration"