csua.org/u/7fi -> science.slashdot.org/science/04/05/24/1333202.shtml?tid=134
This new plant creates plasma, which is akin to creating a star on Earth. Interesting to note that 1kg of fusion fuel would produce the same amount of energy as 10,000,000kg of fossil fuels."
org/) I think perhaps you don't grasp the fundamentals of what a magnetically confided burning plasma reactor really means. While a reactor of this sort aims at providing net power production via nuclear fusion, you have to be aware that a significant amount of energy is used to create the magnetic fields, and other auxillory control mechanisms like nuetral particle beams and radio/microwave power used in controlling the plasma to get the very precise conditions under which net power can be achieved. Unlike fission, you aren't trying to control a run-away process by slowing it down. you are doing everything you can think of to produce the very specific conditions that maximize the amount of nuclear reactions. And if the plasma conditions change or your control system fails, plasma performance quickly degrades on its own because of naturally occuring instabilities in the magnetohydrodynamics that govern bulk plasma behavior. Nothing like a world ending 'meltdown' can happen, a magnetically confided plasma has so many different ways to dissipate energy. The trick has always been and always will be to get enough nuclear reactions out of this plasmas to make it worth while to build them as an energy source, becuase running them invovles using lots of energy just to create the plasmas conditions at all.
Thursday February 19, @10:48PM) Another way of stating what you have said is that plasma fusion requires intervention to sustain the reaction, whereas the current generation of fission based power plants require intervention to restrain the reaction. The difficulty in sustaining fusion is due to the fact that it is so hard to sustain the conditions under which it will occur. The implications for safety are obvious: current generation fission designs require all kinds of redundant safety systems to prevent an ongoing and very dirty accident. Such systems would not be needed in a fusion reactor, becuase the least hiccup, such as weakening of magnetic containment or the leaking of tiny amounts of contaminants into the reactor would cause the reaction to collapse. There is no possibility of anything like the reactor catching fire driven by the heat of a runaway reaction. That said, I'm skeptical we're going to see practical fusion in my lifetime, because it is so difficult to sustain, although you can always hope. A more promising technology would be a stable fission designs, that would require intervention to maintain fission, or which would only output heat at a limited rate.
Wednesday March 10, @02:38AM) Actually, you have it backwards on fission. the difference is the following: Fusion reactions occur at an energetic peak. Basically, for fusion, we're trying to balance a ball on top of a hill. If we lose our balance, the ball rolls down the hill and the energy production ceases. If we lose our balance, the reaction can shoot up a wall and then you get meltdown. notes on this: fission reactors can be designed to be negative coefficient, such that an increase in output leads to a cycle that will decrease output, but the reaction itself is still positive coefficient.
cc/garrett/) There are some fission designs that require active intervention to remain active, and have been in active production in Germany and South Africa. My understanding is that these designs have been ignored in the US due to the costs to get approval from the Nuclear Regulatory Commision are too high.
com/) Except: 1: Fossil fuels aren't necessarily fossil. It's possible that oil is produced in a way that doesn't involve life. Abiogenic theory might turn out to be correct after all. Remember how in the 1960s everyone believed "the oil is going to run out in forty years"? I agree that the anti-nuclear lobby can be mischevious, but that's one of the aspects of lobbies. They have totally bought into nuclear power and they still can't come up with a good pop song or a decent car.
Keeping the plasma hot enough for fusion to be possible is only part of the picture; You not only have to keep the ionized plasma confined (and no, a material "containment vessel" similar to what's used in fission reactors doesn't work; you need something nonmaterial, such as strong magnetic fields), you also need that confinement to be within a very small volume for reaction rates to be sufficiently high (for any kinetic "collision"-ish process, reaction rates are proportional to the square of the density). Heat is necessary for the nuclei to be moving fast enough for fusion to take place; but heat is also the enemy of keeping the plasma at high density.
org/) Let me point you to the sun as an an example of what it takes to keep fusion conditions viable over long timescales without extra energy input. Thats a hell of a lot of mass to produce the gravitational energy to keep a burning plasma self-confined, not to mention the large scale bulk motion of the solar plasma that is still not completely understood that allows the sun to create its own magnetic field via a dynamo effect. Regardless of what the open scientific questions about how our sun and other stars operate, few if any competent researchers will argue that a self-sustaining magneticially confined plasma is something that can be created on earth, simply because of the scales invovled to produce a dynamo. getting to the much higher pressure/temperature conditions required to produce a self-sustaining magneticlly confided plasma will require stellar mass.
org/) I don't think that was the question the poster asked at all. Its a very complicated process to turn the nuclear energy released in a plasma back into electricity, and requires a metric buttload of human effort. The point at which this happens is called break-even, there is a handy dandy ratio called Q=power-out/power-in that gets used to describe the reactor power. the reactor produces just enough energy via nuclear reactions to make up for the energy needed to be spent by humans to power the reactor. Of course what goes into defining Q is sort of dependant on who you talk to. The efficiency of turning the energy released in the nuclear reactions into electricity is a matter of debate. turning fast moving energetic nuclear particles into steam is something we aren't really good at doing. The point at which a plasma is self-sustaining is Q=infinity and is called ignition. Plasmas that ignite, don't need external power sources to continue their fusion processes. They go about their business all by themselves if given a supply of fuel. Production reactor designs aim between something like Q=5 to Q=20. At first glance a higher Q value would seem to be a better thing. Q isn't just a measure of how much net power your are getting out, but its also a measure of how much control you have over the plasma itself by external means. It could very well be the case that the most economical reactors long term are ones that can be better controlled at Q=5 than higher performing Q=20 reactors.
com/) Please don't paint all environmentalists with one big brush! However, that said, bring on the nuclear power plants (provided we can properly secure them from whoever may want to crash a small plane into them... Nuclear power is much cleaner than coal power, and the waste, while icky, isn't produced in huge quantities. Some environmentalists will agree with me, some will disagree. That'd be like me saying that most republicans are christian conservatives who want to turn the United States into a Christian version of Iran.
com/) I'm looking forward to fusion for a number of reasons. Yes, I'm sure there will be unforseen problems - odds are, some radioactivity will be a problem, and then you're going to want failsafe's out the ass so you don't get a "Chernobl on steriods" effect. But this is the kind of thing that governments should be pouring tons of research into. For every politician that bitches about the Middle East and oil funding some nasty stuff ( from Iran putting a $25 million bounty on Rushdie to the US govern...
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