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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."
Let's see, 400 seconds - 28.6 seconds .... works out to about 50 years. Still.
Never shake hands with a man you meet in a fertility clinic.
"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.
"...it raises hopes for what will be possible from the ITER reactor, expected to be finished in 2016."
Look at that, it'll be completed in exactly 10 years. Finally, this time 10 years means 10 years.
If you are about to mod me down, keep in mind that this post was most likely sarcastic.
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.
Was I the only one who thought that it was for a 60-inch plasma screen?
"Sure there's porn and piracy on the Web but there's probably a downside too."
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".
Unfortunately, like most reactors, it will collapse into a pile of rubble after exactly 50 years. Which is why I prefer to use hydroelectric power...
Oh, wait, we were talking about Sim City, right?
-:sigma.SB
WARN
THERE IS ANOTHER SYSTEM
reactor irradiation is minimal
Now I freely admit that things may have changed in the 7 or so years since I quit my Phd in plasma physics, but back then that simply wasn't true. One of the major byrpoducts of a fusion reaction is (was) a pretty steady flux of neutrons. Being neutral, the only way to contain it is to absorb it. This shielding will become radioactive, and will need to be replaced periodically. It is inevitable that eventually, the entire reactor will have been damaged to the point of having to be replaced; it will all also be radioactive.
Now it's true that the half-life of the irradiated components is much, much shorter than that of the waste products of fission, and (imnho) fusion is absolutely the way to go long-term for nuclear power. However, I really don't think it's true to say "reactor irradiation is minimal".
Like I said though, it's been some time since I last really looked at this, so it's possible that progress has been made. It's also not impossible that I'm mis-remembering things (or simply misinterpreting your meaning), of course.
It's official. Most of you are morons.
When comparing to a fission based reactor, perhaps my use of the word "minimal" was a tad skewed.
Remember that the object of comparison here has the same issue with neutron irradiation (ie, even ignoring waste products, a fission reactor core will become irradiated over time, as will the coolant in the heat exchangers). In addition to the neutron problem, which applies to both fission/fusion, you've also got to consider direct radioactive contamination from the fuel/waste. At least with a fusion reactor we can eliminate (or reduce) the risk of elements like strontium-90, since we get the option of choosing what radioactives we want left over at the end of the plant's life when we build it.
But I cede the point that, objectively, the degree of radioactivity in the core of a decomisioned plant would not be "minimal" by human standards.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
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.
The actual research itself is relatively unpredictable, I understand that. But when I read that completion of the ITER (the way I see it a relatively straightforward job, I assume the blueprints are already completed) is still 10 years away, I wonder how much time could be shaved off that estimate, as well as the ~2050 estimate, if (a lot) more money were put into fusion research.
If nuclear fusion has the potential to provide a clean, efficient, lasting energy source, and thereby eventually solve the energy crises, it would seem to me that investing a far larger amount of money than is being put into it today would be a very good investment if that could mean nuclear fusion can be used a few years earlier. I think ITER's cost is estimated at about EUR 10 billion, which is a lot of money, but in the grand scheme of things (I think the world GDP is somewhere around 50 trillion) it's tiny. And seeing the large potential for creating armed conflict there is in energy shortages even these days, I'd say getting fusion sooner rather than later may very well be a real matter of life and death.
However, when I hear discussions on the energy crises, the efficiency of solar/wind/water power, whether more nuclear fission reactors should be built, fusion isn't even mentioned, let alone considered by politicians for larger investments. Is it simply because it's so far away, and that for the most of us, only our descendants would benefit from those investments?
Once again this is a serious question, I'm no expert in any of this so I honestly don't know.
"There is no perpetual motion energy source."
Perhaps, but when your fuel source is the most abundant substance in the universe, there's "close enough for engineering purposes."
"Where is the balancing "bad" for fusion energy?"
You seem to be confusing thermodynamics with kharma.
Also, Tore Supra has achieved discharge durations in excess of 200 seconds since 2002 and has more recently had shots in excess of 360 seconds (6 minutes). Of course Tore Supra has a significant advantage over most other tokamaks in that it has superconducting toroidal field coils, giving it a steady state toroidal magnetic field. My experience in working with these machines is that on most of them the toroidal magnetic fields seriously handicap their performance due to the massive power requirements of generating a typically > 1 T magnetic field. This brings in the requirement for expensive and bulky power supplies and energy storage devices such as large capacitor banks and flywheel generators. The Joint European Torus has two 3750 MJ flywheel generators that can supply as much as 800 MW (400 MW each) of peak power which are used for the toroidal and poloidal magnetic field coils. The magnetic field coils on JET consume more than half of the power required to run the machine. The remaining power is drawn directly from the grid. Using superconducting magnetic coils greatly reduces the power required to run a tokamak and extends the time over which the discharge can last. Tore Supra has a goal of, I believe 1000 second discharges, which is similar to what ITER will be aiming for.
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.