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Scientists in Germany successfully created a very short burst of nuclear fusion using the Wendelstein 7-X stellarator. Although still far from commercial production, this is a promising start for clean and safe energy.
Following nine years of construction and testing, researchers at the Max Planck Institute for Plasma Physics in Greifswald injected a tiny amount of hydrogen into a doughnut-shaped device — then zapped it with the equivalent of 6,000 microwave ovens. The resulting super-hot gas, known as plasma, lasted just a fraction of a second before cooling down again, long enough for scientists to confidently declare the start of their experiment a success.
"Everything went well today," said Robert Wolf, a senior scientist involved with the project. "With a system as complex as this you have to make sure everything works perfectly and there's always a risk." Among the difficulties is how to cool the complex arrangement of magnets required to keep the plasma floating inside the device, Wolf said. Scientists looked closely at the hiccups experienced during the start-up of the Large Hadron Collider in Switzerland more than five years ago to avoid similar mistakes, he said.
[...] Known as the Wendelstein 7-X stellarator, or W7-X, the 400-million-euro ($435 million) device was first fired up in December using helium, which is easier to heat. Helium also has the advantage of "cleaning" any minute dirt particles left behind during the construction of the device. Over the coming years the device, which isn't designed to produce energy itself, will slowly increase the temperature and duration of the plasma with the goal of keeping it stable for 30 minutes, Wolf said. "If we manage 2025, that's good. Earlier is even better," he said.
(Score: 0) by Anonymous Coward on Friday February 05 2016, @11:39PM
To add to this, once they achieve energy generation the possible explosion would likely be less than however much energy they are generating. With fission the reaction can get out of control because it is like rolling a boulder down a hill and we control it by putting on the brakes. Fusion will require constant energy input to keep the process going, we have to push the boulder constantly, so a failure will shut the process down and only the energy output at that exact moment will possibly damage anything.
Also, the lack of nuclear radiation is a big deal. Fission splits atoms open and neutrons go flying out, fusion squishes atoms together and much less gets shot out.
TLDR: no meltdown risk, less explosive energy (depending on reactor size), less to no nuclear radiation.
(Score: 2) by Runaway1956 on Friday February 05 2016, @11:45PM
To refine your own analogy, breaking matter apart is like rolling that boulder downhill. Putting matter together is like rolling that same boulder uphill. So, they are building the Sisyphus Reactor.
https://www.nyu.edu/classes/keefer/hell/camus.html [nyu.edu]
(Score: 2) by Immerman on Sunday February 07 2016, @04:13PM
Actually, no. Iron (Fe56) is sort of the minimum-energy nucleus, with the highest known nucleon binding energy. Any time you break or combine nuclei to get things closer to iron, you are "rolling downhill" and get energy out. Both fusion and fission take nuclei at the extremes of mass, light or heavy, and turn them into more mid-range, low-energy nuclei plus energy. The more massive elements are created by novas and supernovas releasing such ridiculous quantities of concentrated energy that the midrange elements to fuse together despite it being an energy loss. Essentially, fission is the release supernova energy that's been neatly stored away in the nuclei for billions of years.
The big difference in reactors is that squishing nuclei together takes much higher input energy than breaking them apart, so it's sort of like pole-vaulting downhill instead of just rolling. If you don't jump first, you just end up leaning against the barrier.
(Score: 1) by WalksOnDirt on Friday February 05 2016, @11:52PM
According to Wikipedia, 80% [wikipedia.org] of the energy of a D-T reaction is released as neutrons. I'm not sure of what the number is for fission, but it can't be much worse.
I still welcome any progress they can make, but frankly I think advanced fission reactors are a better bet.
(Score: 0) by Anonymous Coward on Saturday February 06 2016, @01:45AM
The "T" in D-T is for tritium, which is radioactive and is made in fission reactors.
(Score: 2) by Immerman on Sunday February 07 2016, @04:25PM
I forget the exact numbers, but I think D-T fusion releases something like 2-3x more neutrons per watt than typical fission reactions. Of course, you can potentially do something useful with those neutrons such as using a shielding material that fissions into more tritium under bombardment, such as in the Lockheed Martin design. Or if you can just keep them from reacting with anything for a moment they'll rapidly decay into a relatively harmless proton and electron.
The big factor for "clean and safe" with fusion is that you don't get the highly radioactive fission byproducts, but unless you're doing something clever you end up with even more low-grade neutron-activated waste. At least early on. Once we master the easy target of D-T fusion we can then attempt more challenging aneutronic fusion such as proton-Boron, which only produces free neutrons from side reactions.
(Score: 0) by Anonymous Coward on Saturday February 06 2016, @12:41PM
The neutron radiation as such is not the big problem with fission. The problem is that those neutrons are exactly what triggers the fission, so an uncontrolled fission produces more neutrons, which produces even more uncontrolled fission (the so-called chain reaction). This doesn't happen with fusion.
Other than that, the problem with nuclear reactors is the fission products, which are highly radioactive (much more so than the original uranium!), and of course get blown into the environment if the reactor explodes. Nuclear fusion generates Helium, which is stable.
What happens in both fusion and fission reactors is that neutrons activate the materials of the containment. But that's only weak radioactivity, and is the least of the problems with fission reactors. With fusion reactors, it's the only radioactivity (other than the neutrons themselves) which is produced.
Also note that neutrons have a half-life of about 20 minutes, and decay into protons. In other words, shortly after a neutron is emitted, it already decays, and all that is left is ordinary hydrogen. So there's no way you'll find them a day later irradiating some area hundreds of kilometers away.