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| Tags: energy, fusion, iter, limitless, produce |
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Good . Now we can dismantle all the wind mills , oil
platforms. With fusion energy water can be turned into fuel by mixing it with carbon dioxide. excerpt guardian.co.uk Iter began life in 1985, at a summit in Geneva between Ronald Reagan and Mikhail Gorbachev. They called for scientists to prove that fusion was a scientifically and economically viable way of producing electricity. Europe and Japan soon joined Russia and the US as partners in the project. Eighteen years on, and countless designs, experiments and tests later, the project now also involves China, Canada and South Korea, and the plan is to build a huge ó4.5bn (£3bn), 17m high reactor by the end of the decade. Where the reactor will be built remains up for grabs. The shortlist will be composed of three sites: Rokkasho in Japan, Clarington in Canada and either Cadarache in France or Vandellos in Spain (the EU wants to submit one of these sites to avoid splitting the final vote later this year). The competition is being fought fiercely - aside from the kudos of having the world's largest fusion reactor on their doorstep, the winning site will get an economic boost from more than a thousand (highly-paid) scientists and support staff who will eventually live and work there. In the end the decision may be made for political, rather than scientific, reasons. Rumours abound that, thanks to recent events, the US wants Europe to put forward the Spanish rather than the French site as its candidate. Whatever politics get in the way, though, they will just be a temporary distraction from the burgeoning new era for the scientists. Already, they are being asked to address the issues related to generating large amounts of power, rather than the basic aspects of whether or not their designs will work in the first place, according to David Ward, a fusion physicist at Culham. "We've never had to do that before," he says. Llewelyn-Smith says that there's never been a better time for believing that fusion will work. "There's been terrific progress not least because of Jet, and technology has moved on," he says. "Fusion's time has come." How fusion works At the heart of each star swim countless billions of hydrogen nuclei (single protons). They fuse to form helium nuclei (two protons and two neutrons), plus energy. This doesn't happen easily, however. Despite the immense gravitational pressure and temperature at the core of every star, it takes millions of years to fuse two nuclei together, such is the repulsive force between two protons. On Earth, generating energy using a reaction that takes so long would be next to useless. So, instead of hydrogen, physicists fuse two of its isotopes - deuterium and tritium. The nuclei of these heavier elements can be made to fuse more easily. Deuterium is abundant in sea water. Tritium is harder to come by and has to be made inside a fusion reactor. Even so, we have enough resources to last several million years. The fuel is placed inside a torus (a donut-shaped chamber) at the centre of the machine and heated to create plasma at 100m C. The deuterium and tritium fuse to form helium, energy and spare neutrons (which are absorbed by a lithium shield around the torus). When the neutrons hit the metal, more tritium is produced, and this is fed back into the torus. As well as virtually limitless fuel, physicists say fusion itself produces no dangerous waste products. There are secondary reactions, however, that produce radioactive materials. But these have short half-lives and become safe in a few hundred years, as opposed to the thousands of years with fission waste. |
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#2
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"habshi" wrote in message ... Good . Now we can dismantle all the wind mills , oil platforms. With fusion energy water can be turned into fuel by mixing it with carbon dioxide. excerpt guardian.co.uk Iter began life in 1985, at a summit in Geneva between Ronald Reagan and Mikhail Gorbachev. They called for scientists to prove that fusion was a scientifically and economically viable way of producing electricity. Europe and Japan soon joined Russia and the US as partners in the project. Eighteen years on, and countless designs, experiments and tests later, the project now also involves China, Canada and South Korea, and the plan is to build a huge ó4.5bn (£3bn), 17m high reactor by the end of the decade. Where the reactor will be built remains up for grabs. The shortlist will be composed of three sites: Rokkasho in Japan, Clarington in Canada and either Cadarache in France or Vandellos in Spain (the EU wants to submit one of these sites to avoid splitting the final vote later this year). The competition is being fought fiercely - aside from the kudos of having the world's largest fusion reactor on their doorstep, the winning site will get an economic boost from more than a thousand (highly-paid) scientists and support staff who will eventually live and work there. In the end the decision may be made for political, rather than scientific, reasons. Rumours abound that, thanks to recent events, the US wants Europe to put forward the Spanish rather than the French site as its candidate. Whatever politics get in the way, though, they will just be a temporary distraction from the burgeoning new era for the scientists. Already, they are being asked to address the issues related to generating large amounts of power, rather than the basic aspects of whether or not their designs will work in the first place, according to David Ward, a fusion physicist at Culham. "We've never had to do that before," he says. Llewelyn-Smith says that there's never been a better time for believing that fusion will work. "There's been terrific progress not least because of Jet, and technology has moved on," he says. "Fusion's time has come." How fusion works At the heart of each star swim countless billions of hydrogen nuclei (single protons). They fuse to form helium nuclei (two protons and two neutrons), plus energy. This doesn't happen easily, however. Despite the immense gravitational pressure and temperature at the core of every star, it takes millions of years to fuse two nuclei together, such is the repulsive force between two protons. On Earth, generating energy using a reaction that takes so long would be next to useless. So, instead of hydrogen, physicists fuse two of its isotopes - deuterium and tritium. The nuclei of these heavier elements can be made to fuse more easily. Deuterium is abundant in sea water. Tritium is harder to come by and has to be made inside a fusion reactor. Even so, we have enough resources to last several million years. The fuel is placed inside a torus (a donut-shaped chamber) at the centre of the machine and heated to create plasma at 100m C. The deuterium and tritium fuse to form helium, energy and spare neutrons (which are absorbed by a lithium shield around the torus). When the neutrons hit the metal, more tritium is produced, and this is fed back into the torus. As well as virtually limitless fuel, physicists say fusion itself produces no dangerous waste products. There are secondary reactions, however, that produce radioactive materials. But these have short half-lives and become safe in a few hundred years, as opposed to the thousands of years with fission waste. Yeah don't get your hopes up. Read the World Nuclear Association's info regarding fusion: http://www.world-nuclear.org/info/inf66.htm Under the section "Assessing fusion power" you can start to get some idea how totally infeasible fusion really will likely be. They are likely to release a bunch of highly radioactive tritium in standard operation. Also very serious is they blow themselves to smithereens if they loose superconductivity (which must be kept at cryogenic temps while in operation). A reactor costing $4.5 billion isn't something you want blowing itself up the first time something goes wrong (not to mention releasing a bunch of radioactives in the process). Besides that a $4.5 billion + + + reactor could never produce economical electricity compared to basic nuclear fission. Check the economics of nuclear power at the world nuclear association as well: http://www.world-nuclear.org/info/inf02.htm While nuclear power is quite competive with fossil fuels, we notice more than half the cost is the capital investment of the plant, and only a very tiny fraction is the fuel. Fission nuclear plants today cost somewhere between ~$1-1.6 billion for 1 GW electric capacity. If it were even possible to practically build a fusion plant, it would surely cost well more than $1.3 billion per gigawatt of capacity. As such, even if the fuel was totally free (which by no means is it free) it wouldn't be possible to compete with fossil fuels or nuclear fission. What we really desparately need to be doing instead is building fully bug worked out fission breeder reactors (of both U238--Pu239 and Th232--U233 flavors) and spallation sub-critical reactors/nuclear waste incinerators. That is where the real future lies, not this non-sense fusion baloney. Expecting fusion to play any practical role in the anywhere near forseeable future is about as foolish as believing renewable energy sources could ever contribute more than ~30% of our electricity needs. Neither is gonna happen in anywhere but fantasy land. |
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True, large amounts of Tritium will be generated with long term use, not to
mention the likely short lifetime of the reactor chamber (it will have to be changed, robotically, every few years cos of the large neutron flux from the fusion reaction). But these are problems specific to the DT reaction. Of course, the neutrons could be mopped by using the reaction Li-6 + n -- He-3 + H-3, but this is unlikely to capture all the neutrons (i'm not sure what the cross section is for this reaction). A much more promising reaction is D + He-3, which is aneutronic, and thus completely elimates all problems with radioactive waste. This probably wont make it into the first generation of reactors, though. Besides, Tritium only has a half life of 12.3 years, considerably less than that for Uranium. It is thus much more easily handled. The benefits of commercial fusion *far* outweigh the potentially solvable problems listed below. Ziggi [SNIP] Yeah don't get your hopes up. Read the World Nuclear Association's info regarding fusion: http://www.world-nuclear.org/info/inf66.htm Under the section "Assessing fusion power" you can start to get some idea how totally infeasible fusion really will likely be. They are likely to release a bunch of highly radioactive tritium in standard operation. Also very serious is they blow themselves to smithereens if they loose superconductivity (which must be kept at cryogenic temps while in operation). A reactor costing $4.5 billion isn't something you want blowing itself up the first time something goes wrong (not to mention releasing a bunch of radioactives in the process). Besides that a $4.5 billion + + + reactor could never produce economical electricity compared to basic nuclear fission. Check the economics of nuclear power at the world nuclear association as well: http://www.world-nuclear.org/info/inf02.htm While nuclear power is quite competive with fossil fuels, we notice more than half the cost is the capital investment of the plant, and only a very tiny fraction is the fuel. Fission nuclear plants today cost somewhere between ~$1-1.6 billion for 1 GW electric capacity. If it were even possible to practically build a fusion plant, it would surely cost well more than $1.3 billion per gigawatt of capacity. As such, even if the fuel was totally free (which by no means is it free) it wouldn't be possible to compete with fossil fuels or nuclear fission. What we really desparately need to be doing instead is building fully bug worked out fission breeder reactors (of both U238--Pu239 and Th232--U233 flavors) and spallation sub-critical reactors/nuclear waste incinerators. That is where the real future lies, not this non-sense fusion baloney. Expecting fusion to play any practical role in the anywhere near forseeable future is about as foolish as believing renewable energy sources could ever contribute more than ~30% of our electricity needs. Neither is gonna happen in anywhere but fantasy land. |
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