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What's the "meltdown" equivalent of fusion? What is the worst thing that could happen given unlikely sequence of failures? Is it possible it would go from contr
by umvi 7y ago
What's the "meltdown" equivalent of fusion? What is the worst thing that could happen given unlikely sequence of failures? Is it possible it would go from controlled fusion to uncontrolled fusion?
- chubs 7y agoThe main problem being tackled is trying to get fusion to remain 'alight' - i think if any of the containment systems fail, it simply extinguishes immediately. Not a physicist, though :)
- WalkingMedium 7y agoThere isn't enough fuel in the reactor to create something even close to a meltdown.
- DennisP 7y agoIt's hard to get fusion to happen at all. If something goes wrong, it just means fusion stops happening.
- petschge 7y agoThe energy content in a fusion reactor (even at the 3 GW output scale) is only a few mega joules, or in other words a few sticks of dynamite. Enough to damage the wall. Maybe enough to break the vacuum vessel. At that point the air would stop any further fusion. You might release radioactive tritium, but nothing else that should be felt outside the building. For comparison: The total inventory of tritium would be about 500g, about 50 times the amount of tritium released by fukushima, but the other radioactive isotopes that got released there (caesium, iodine, tellurium) that are much more problematic biologically would be missing.
- radicalbyte 7y agoOnce containment fails the energy which is within the reactor escapes and the reaction stops. Fusion only occurs at these insane pressures/temperatures which won't be maintained if containment fails. I wouldn't want to be in the building when it fails. If it uses Tritium then that's going be an environmental hazard (it's radioactive and will get everywhere). To be honest it's all conjecture right now because we don't have a viable reactor design and failure modes will depend what exactly we build.
- CodeWriter23 7y agoHalf life of Tritum is about 12.5 years, much more favorable than elements used in fission reactions.
- radicalbyte 7y agoTrue, but on the other side if it gets into the water system in any significant quantities then that's going to a bad for local residents. However I can't see that happening. You'd have to have the tanks of it very close to the reactor. That's something you'd obviously not do. There's probably a greater risk transporting the stuff (road accidents) or in bad maintenance of the tanks or human error (emptying the tanks by accident).
- amluto 7y agoIt seems to me that one could avoid storing any tritium as a liquid. Tritium gas is light will generally tend to rise. Insoluble tritium salts will be less likely to enter the ground water. Although... an inexpensive risk mitigation would be to wrap any tritiated water tanks with sodium polyacrylate. Imagine a giant diaper. Leaks would be absorbed.
- DennisP 7y agoIt wouldn't hurt you a bit if containment failed while you're in the building. The fusion plasma is held at very high temperature but there's very little of it. It's only ever at high pressure in inertial fusion, which doesn't actually contain the plasma at all except for a tiny fraction of a second before it explodes by design.
- deleted 7y ago[deleted]
- K0SM0S 7y agoBasically, none that we need to be concerned with. The general idea is this: when you fuse elements, you produce heavier elements; if you wanted to fuse these new elements into even heavier ones, you'd need to input much more energy — thus it can be said in layman terms that the products of fusion are 'toxic' to the fusion itself, i.e. the more you do it the less likely it is to go on, until if finally stops (like in real-world stars). For instance, the Helium produced by the Sun is making it harder to sustain the Hydrogen fusion, which will stop before all Hydrogen is depleted. In addition, the radioactive elements produced by fusion are much lesser than fusion, by orders of magnitude, so it's pretty much 'clean' in that regard for all intents and purposes (50 years of fission probably produced much worse than 1,000 years of fusion would). And the fuel is available in pretty much limitless quantity — in fact, it would probably make a space industry, starting with mining hydrogen isotopes for fusion, profitable from day 1. It's basically the closest thing we have to God's tech, and there's not much else in theoretical physics that comes close in terms of benefits in our real-world context. Fusion would essentially hand over the galaxy to us with little to no chance of failure, given enough time. If we can pull it off, that is. Which remains to be seen, there's nothing new or groundbreaking in this article.
- deleted 7y ago[deleted]
- vbezhenar 7y agoWorst thing is an (non-nuclear) explosion releasing some radioactive matter with small contamination. From my understanding it's similar to conventional power plant explosion and contamination is negligible (nothing like fukushima disaster). It's not possible to get uncontrolled fusion, at least for reactor designs we are considering now. It requires star scale to have uncontrolled fusion.
- buboard 7y agoFusion to higher molecular weight atoms releases energy until it turns to Iron. I don't think it is possible to have energies for fusion beyond helium however.
- Svoka 7y agoI would say "none" but just containment failing is not equivalent of meltdown. If left to own devices, fusion would stop. You can get some kind of explosion/fire, since you know, high energies are involved, but it would be simple thermal explosion. There are still issues, like most fusion reactions produce neutrons, which are not great by themselves, and basically most dangerous type of radiation. They can make regular matter radioactive. But we are far from that stage when this is a problem.