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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 ins
by trentlott 9y ago
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.
- dnautics 9y agopolyproplene tubing lets helium pass through, which is why helium is used as a sparging gas in high performance liquid chromatography.
- eesmith 9y agoThis 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 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".
- Natsu 9y agoCan 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.
- Iv 9y agoOh, 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!
- tylerhou 9y agoImpact can also cause damage, afaik.
- marcosdumay 9y agoAFAIK, 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.
- iaw 9y agoMy 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.