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Japan's JT-60 Tokamak Sets New Plasma Record
Dipster writes "The Japan Atomic Energy Agency has announced that its JT-60 Tokamak has almost doubled the previous record for sustained plasma production, which is now sits at 28.6 seconds. It is believed that once 400 seconds can be achieved, a sustained nuclear fusion reaction will be possible. While 28.6 seconds is a long way from 400, it raises hopes for what will be possible from the ITER reactor, expected to be finished in 2016."
"Also, if we do get large scale fusion, is it really going to be cleaner and safer than modern fission plants?"
No meltdown risk...
No long-lived waste products...
No dangerous fuels...
Likely no immediate danger of weapon proliferation...
And you have to ask if it's safer?
Just so we're clear, fission power is reasonably safe already (provided the reactors are well designed and maintained, and provided that the waste is reproccessed). All of the dangers of a fission plant are outlined above, and they're not that bad when compared with the alternatives. Fusion has none of those dangers; the nuclear reaction ceases if the reactor vessel loses confinement, the major waste product is helium-4 (which is commercially useful and chemically inert), reactor irradiation is minimal, and can be limited further by careful choice of building materials, the fuels are safe to handle, and there's no way to make a bomb out of the reactor technology that we know of yet.
That's not to say there are absolutly no problems. Even with careful material selection, the reactor vessel will become slighly radioactive over it's lifetime. But safer and cleaner than fission? Yes, and by an order of magnitude at that.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
And I'm not just being flippant, though the answer has been 50 years for the last 30 years or more.
ITER isn't going to be operational until 2016 at the earliest, and it's an experimental reactor not expected to be a net energy producer. Based on operational experience with ITER and IFMIF (for which construction has not even started), another experimental reactor will be designed and constructed with the goal of net energy production. Perhaps that might be operational by 2035. And if it works well enough, it's *remotely* possible that a commercial reactor could be designed and constructed, and be operational by 2055.
When all is said and done, fusion recactors are expected to produce *slightly* less expensive electricity than fission.
The big win with fusion will require a major theoretical breakthrough rather than simply carrying the current plans to their logical conclusion.
In general it's reasonable to expect that they'll be cleaner and safer. There is no possibility of a runaway chain reaction; the reactor only contains enough fuel at any given time to operate for a fraction of a second, vs. months or years for a fission reactor. If the fusion reaction containment fails, the reaction quickly stops, without serious damage to the reactor and without any abnormal leakage of radioactive material. A fusion reactor can't "melt down".A fusion reactor will produce a greater quantity of radioactive waste (crumbling radioactive shielding and structural materials after years of exposure to high neutron flux), but fortunately the waste will have a very short half-life so it won't be dangerous for too many decades, and will thus be easier to store. No need to worry about safety over geological time scales, or about whether our descendents will be able to read warning signs printed in 21st century languages.
It it worth noting that the progress made in fusion research has been HUGE throughout the past 3-4 decades and while the next step is more difficult than the last we aew still making steady progress. JT-60 HAS attained a confinement quality in the deuterium-deuterium shots it has taken which are VERY good, so good that if they were done with deuterium-tritium mix they would firmly place JT-60 in the breakeven parameter space very near the ignition regime (they have not "gone DT" due to pain in the ass handling issues with the radioactive tritium). There is also always hope for a shocking surprise breakthrough too (but don't hold your breath). For example, 10 or so years ago, it was though there was no way you could get around having to build immensely expensive multi-hundred beam multi-MEGAjoule laser systems in order to make inertial confinement fusion work. Then along comes a cute little trick called Chirped pulse amplification and suddenly you can start talking about petawatt lasers being used to reduce the overall cost of the machine by 10 fold (fast ignition fusion schemes! That's why science is so great, there is always hope something better is just around the corner waiting to be discovered.
- "Hear that?! The percolations are imminent! Cease your ingress!"
As a bachelor degree student in physics in the 70's and early 80's, fusion research was on of the 'hot' topics. The tokamak was the predominant fusion plant, but other fusion reactors were being investigated. In those days we measured sustained reaction times in milliseconds. Obviously I haven't been keeping up, 'cuz 28 seconds sounds like a lifetime to me now.
-- There are 10 kinds of people in the world, those who understand binary and those who don't.
Everytime I read any Fusion based posts it really allows me to see how ignorant a LOT of people are. Some seem pretty close, but get caught out as being bulls-hitters somewhere in their post
K, I am doing a PhD in Fusion in one of the best fusion plasma groups in the world. I would be happy to answer any questions.
Not having a go at any random posts, but just a few mistakes I didn't see get checked. 1. Yes Fusion is safe, very safe, super safe. Safe!! You can ask me why, but no-one ever seems to pay attention, or even understand.
2. Fusion weapons have been around since at least the 1960's! Hydrogen bombs. Kinda like 50 years too late to be scared about that one.
3. Would you like to know why fusion isn't here yet? It's very difficult! It's not an oil conspiracy!! The people in fusion are academics and believe me when I say they don't generally give a crap about money. They are smart people concerned with the environment.
4. Why is it difficult? You can't switch JET or MAST on for too long because of Ohmic heating. It basically implies that super conducting (very $$$!) coils are needed to get around this problem. ITER will be one of the first reactors to have all superconducting coils.
6. Anything else? Yes, actually. We are literally making it up as we go along. How many people know exactly what a plasma is? I mean what defines it? It's Debeye length? Collisionless? Quasi-neutrality? What do any of these terms mean? If you don't know you probably aren't qualified to talk on fusion. Plasma physics is relatively to the rest of science an incredibly new and young field and it is extremely varied.
There's lots and lots going on in fusion. I apologise for the lack of links but i'm typing quickly and don't have time. Suffice to say, everyone in the fusion community is very enthusiastic about it. It is getting more and more (international) money all the time. The Chinese and Japanese are involved, not to mention India and the most of the West.
On an interesting side note. The thing that mainly held fusion back was
can you guess?
AMERICA!! Constantly pulling in and out of the project. However, now that the Indians are involved the funding is about 110% of what is required. So if the yanks pull out again then they will fall behind because no-one else cares anymore and we'll have enough money to, and we will, continue.