A helium-resistant material could finally usher in the age of nuclear fusion | Hacker News Reader

A helium-resistant material could finally usher in the age of nuclear fusion

sciencealert.com

94 pointsphr4ts26 comments

Perhaps more specifically, alpha radiation resistant. Alpha radiation is helium nuclei.

Right. Chemically, most things are helium-resistant. It's a noble element.

It's apparently just that someone came up with a way to allow the gas that forms inside the metal to escape by allowing nanocomposite phases to link up as He is generated.

Oh, your sentence explained to me something I had never understood. Alpha radiation is harmful because the helium nucleus acquires an electronic, becomes helium that tries to escape? I always thought it was just the impact of the particle that caused damage but now I understand better, thanks!

AFAIK, alpha radiation is not a big problem at all. But if it's that bad, you can put a layer of paper sheets (or metal film, or whatever) on the inside of the reactor to absorb it.

Again AFAIK, all the issues are caused by neutron radiation.

My understanding aligns with yours. These are probably highly energetic Alpha particles that embed in metals but I always thought they were of little concern compared to the problems of decay due to neutron bombardment.

Impact can also cause damage, afaik.

Can you confirm if I'm understanding the paper properly?

My read on this is that they've found a way to use layers in the material to make the Helium from alpha particles form little tubes on their way through the metal to escape, rather than building up into little balls that cause blisters and weaken the metal.

polyproplene tubing lets helium pass through, which is why helium is used as a sparging gas in high performance liquid chromatography.

This new material is not "alpha radiation resistant", so I don't think that's the right way to describe this article.

I think the term "resistant" in "helium-resistant" is too ambiguous. Helium is inert, meaning it rarely reacts with anything (only a few helium compounds are known). But some things are permeable to helium, including low density solids like polyproplene.

Here's the start of the paper at http://advances.sciencemag.org/content/3/11/eaao2710.full (Thanks to mtgx for the pointer):

"Metals do not absorb helium (He) from the environment. Large quantities of He may nevertheless be introduced into metals by nuclear reactions that produce α particles (He nuclei) (1, 2). Because it is insoluble in metals, any He forced into solution this way rapidly precipitates out into nanometer-scale “bubbles” (3). These bubbles nucleate as small He/vacancy clusters and remain approximately equiaxed as they grow into micrometer-sized voids (4–6). When they impinge on free surfaces, He-filled voids form blisters that release the He trapped inside them as they burst apart (7, 8)."

"We show that confinement within nanoscale layers markedly alters the life cycle of He precipitates. Rather than expanding continuously while remaining equiaxed, He precipitates confined within nanolayers spontaneously coalescence into elongated, He-filled channels."

I had to look up "equiaxed": "Having axes of approximately the same dimensions".

I find it very hard to believe in anything published originally by Futurism... can someone with more background on the topic comment if it's trustworthy stuff?

Original paper here:

http://advances.sciencemag.org/content/3/11/eaao2710.full

No idea about futurism, but someone that speaking about nuclear fusion writes something like this is not worth of any consideration:

Not only does the fusion process expose reactors to extreme pressure and temperatures

Seriously? Extreme pressures in a tokamak? What am I missing?

Yes, that surprised me too. Are there any fusion designs without high vacuum?

But on the other hand, magnetic stresses in full-scale systems would be huge, right? And one could consider that to be pressure. In that it reflects confinement of the plasma. Or it could be an incoherent edit.

Several years ago I got a tour of MIT's Alcator C-Mod, which had the strongest magnetic fields of any tokamak in the world. A grad student showed us a metal tie, about a meter long and several inches thick. He said they'd calculated that two of them could hold down the Space Shuttle when it was trying to launch.

Holding the C-Mod together at full power required 38 of them.

Technically a high vacuum is an extreme pressure, just a negative extreme.

Sure, but isn't 1 atmosphere pretty small?

> Seriously? Extreme pressures in a tokamak? What am I missing?

Maybe they're including stellarators, and other possible variations -- as the article didn't specify tokamaks.

Even if true, and feasible, this does noting for spalling from fast neutrons, and half a dozen major bottlenecks with no daylight in sight. Helium impregnation is hardly the major hurdle, at least, not compared to atomic spalling, the breeder blanket, diverter design, magnetic containment, etc...

Sounds like you're focusing on the tokamak approach to nuclear fusion. There are fusion approaches that avoid some of those hurdles.

Some, but not all, especially not the issue of fast neutrons turning whatever your make your reactor out of, into crumbly crap. Now, I know that some people are placing bets on forms of aneutronic fusion, but realistic forms still produce enough neutrons to ruin metal, that's just not their primary means of transmitting energy. Worse, they require temperatures/pressures far in excess of what's realistic any time soon, except possibly for very brief bursts in the lab.

> "I know that some people are placing bets on forms of aneutronic fusion, but realistic forms still produce enough neutrons to ruin metal"

What makes aneutronic fusion unrealistic?

https://lppfusion.com/lppfusion-publishes-world-record-fusio...

"Hydrogen-boron fuel, also called pB11, is an ideal fuel, producing no neutrons, and no radioactive waste. Its energy can be converted directly into electricity, potentially greatly reducing energy costs below that from any existing source. Both hydrogen and boron are abundantly available. But the fuel needs extremely high ion energy—temperature—to burn. The new results demonstrate that FF-1 has achieved the energies needed to burn pB11 fuel."

The problem is funding. Lack of funding makes it unrealistic.

There are these small teams and they amass a lot of very specific knowledge about a certain, very particular type of fusion, and ... then they fizzle out financially. Or just burn out psychologically.

Or not. I might be too pessimistic.

And eventually we'll figure it out.

There are incremental gains every year. ITER is "growing" every day: https://www.youtube.com/channel/UCZzwQDDag5eP4Rs-2d4nX5g

But the fuel needs extremely high ion energy—temperature—to burn.

That’s the killer caveat.

The line that follows indicates why this may no longer be a problem (for the FF-1 at least):

"The new results demonstrate that FF-1 has achieved the energies needed to burn pB11 fuel."

Worse, they require temperatures/pressures far in excess of what's realistic any time soon, except possibly for very brief bursts in the lab.

Are you familiar with the dense plasma focus approach to fusion (which is what the device I linked to is using)? It's built around brief bursts of plasma. Maintenance of a stable plasma is not required.

Reply on news.ycombinator.com