Japan's JT-60 Tokamak Sets New Plasma Record 209
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."
Re:How long (Score:5, Informative)
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.
Re:How long (Score:5, Informative)
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.
Comment removed (Score:2, Informative)
Re:How long (Score:5, Informative)
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.
fusion (Score:2, Informative)
ITER is designed to produce approximately 500 MW (500,000,000 watts) of fusion power sustained for up to 500 seconds (compared to JET's peak of 16 MW for less than a second). It is a significant amount of power for a fusion research project; a future fusion power plant would generate about 3000-4000 MW of thermal power. Although ITER will produce net power in the form of heat, the generated heat will not be used to generate any electricity.
http://en.wikipedia.org/wiki/Iter [wikipedia.org]
Re:How long (Score:5, Informative)
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.
Re:How long (Score:5, Informative)
Re:fusion - can you count neutrons? (Score:3, Informative)
The short of it is that fusion is rather dirty - just as bad if not worse than fission and the reason is because of all of those neutrons that are released.
Forget about OIL & GAS dropping in price for any length of time.
Saudi Aramco has announced as of April 2006 that Saudi Arabian oil production is now in terminal decline and this is taken over all the production the country can muster which includes some heavy oils that were frowned upon before. Ghawar in particular is suffering about 8% declines.
Kuwait announced in November of 2005 that they are in terminal decline as well as the Bergan field has gone over the top.
Of the top four this leaves the Pemex (Mexico) Canateral field dropping from about 2 million BOPD currently to under 1.6 before the end of 2007 and China's DaQing feild also dropping by about 6% per year.
The combined reduced production (read depletion) of these 4 fields alone cannot be replaced.
You can say that in Ireland they will _NEVER_ look at fission - and you are completely correct about the problems with wind and solar. However their other option will be to see if they can buy coal and failing that - they will have to start driving their cars less which might mean getting a horse - and figuring out how to superinsluate their houses which is also something that most people seem to be adverse to doing. And even if they do this I suspect they will be importing nuclear power. Perhaps it will be from France mind you via the tunnel.
Why is Tore Supra ignored here ? (Score:3, Informative)
As far as I can read, it seems rather impressive. Their record for plama duration is... 390s ! More information on the fusion-dedicated French CEA (Commissariat à l'Energie Atomique) site [www-fusion...que.cea.fr] (in English).
But the question is honest: what have achieved the Japanese? Is their plasma self-sustaining? Have they reached break-even point and maintained it during the whole 28.6 seconds?
Anyway, just give a look to the CEA site: from pictures to videos, plenty to discover there.
Re:Why is Tore Supra ignored here ? (Score:2, Informative)
Actual discharge duration for JT-60U (Score:2, Informative)
For God's sake!! (Score:5, Informative)
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.