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New Advances Bring Fusion Closer to Reality
An anonymous reader writes "The Christian Science Monitor reports on new advances in nuclear fusion research. For years we've been waiting for the technical breakthroughs that would make cost-effective fusion energy a reality. Are we getting close, or are the problems insurmountable?"
I think you mis-spelled "Duke Nukem Forever".
I object to the insinuation that we are the ones splitting the nuclei of the radioactive elements
Well, fine. But you can say that by refining the uranium, and bringing sub-critical amounts of together in a pile, or supercritical amount together in a bomb, we are utilising the nucleus's innate tendency to split, and to thereby trigger a chain reaction in nearby uranium nuclei, in order to generate a self-sustaining level of radioactivity that would not have otherwise occured.
You could also say when making tea that we are not the ones boiling water, we are merely allowing electricity to flow through a restisting metal rod, which generates heat which when transfered to the water causes a rise in temperatre to boiling point that would not have otherwise occured. But that would be very, very pedantic.
My Karma: ran over your Dogma
StrawberryFrog
Is this an Ask Slashdot?
If so then my answer is yes! I mean no! err..What was the question again?
IANANE (I am not a nuclear engineer) but if I read that article correctly then it seems some of the many problems have theoretical solutions. In other words, it worked in the simulation. We need to get this thing built and do real tests before we can even think about being "close" to having fusion plants.
They can't even decide where to build it! Why can't I vote to spend my (US) tax money on putting one of these over here. Even as a test bed it will give the contry it's in some home field advantage.
You can use my back yard if you want! Don't listen to my whiney neighbors, they don't know what's good for them!
I don't think, Therefore I'm not.
Nuclear Fusion is about 8 minutes away, and will always be*
* At least until the sun finishes its main phase
"Nuclear Fusion has always been 15 years away, and always will be"
This glib statement seriously underestimates the achievements in this area in the past few years. We have gone from doubts as to whether controlled fusion could ever be achieved to a point where we are working on stabilising the reaction to the level where it produces commercial results.
And by the way, the classic quote was '50' years, not 15!
since when does a fossil fuel power plant produce radioactive waste? :)
Take a look at some of the research and data on how much naturally radioactive particles are released into the atmosphere through burning of fossil fuels, you'll probably be surprised. I believe it's a few orders of magnitude more than the amount generated in current fission plants.
-Jesse
Nothing says "unprofessional job" like wrinkles in your duct tape.
Sorry to be a nathering nabob of negativism, but...
Practical nuclear fusion would be the best thing that ever happened to our planet: we'd lose our dependence on the Middle East for energy, and dramatically cut pollution. If it were up to me, I'd launch a nuclear fusion program on the scale of the Manhattan Project.
However, the Bush family and that crowd will never allow nuclear fusion to become a reality - they make too darned much money on oil, and cash is all they understand.
Not to reveal my age, but when I was an engineering student in the early 60s the big science news was that flat screen TV was only 2 years away, and that CRTs would be rendered obsolete. Flat screen TV was perpetually 2 years away in the future for most of my life, but it finally did arrive.
Our goal should be to have commercially useful fusion energy in operation by the end of the 21st century. It's vital, but not easy, for the public to support such long-term goals. That's particularly true when we can't visualize the links in the chain that will connect now with then.
The actual breakthroughs that make energy power cheap and safe are likely to come closer to the end of the century, and we can't imagine what they might be. Still, we must support constant inquiry and scientific research to create the fertile conditions for breakthrough discoveries.
The only reservation I have about supporting big science is a serious one. Money should go for science, not to feed the egos of the pricipals. The bigger the project, the harder it is to assure that.
The Joint European Torus (JET) fusion lab in Culham, Oxfordshire, UK 'jumped' a few years ago. The plasma touched the wall of the reactor vessel and dissipated. The entire reactor 'jumped', and the event is visible on seismograph traces. (The reactor, in total, was quite heavy)
This is not good for the retaining magnets - the magnetic field quenches, and the energy goes into heating up the magnets. Even the superconducting (and therefore cooled) ones warm up - boiling off a lot of refrigerant, and possibly/prbably distorting/damaging the coils..
Afer this event, th reactor was shut down for a long period (I think months), while the coils were checked for damage and realigned.
As for the amount of energy in the plasma itself - it's relatively small. Although the temperature is high, the particle density is actually quite low, so the total energy contained is (relatively) small. It *won't* go up like a hydrogen bomb.
The core lining in JET was lithium. It gets mildly radioactive due to being bombarded by neutrons all the time, but this is not a big deal. The neutron activation of the concrete and steel rebar used in the construction of the core (it has to withstand high mechanical forces from the magnetic fields) is more of an issue.
The plasma isn't meant to touch the tokamak wall, as it causes long and expensive downtime, but it's not as catastophic as (say) setting light to an oil well.
I think you are missing the point the writer was making. The 30 is a constant, ie we are always 30 years from fussion. This is not a return in 30 years, but a return an infinite amount of time in the future.
Now, I think the fusion experiments are worth funding because they are fun. I think it's a shame that the political environment is such that the scientists need to pretend there is gold at the end of the rainbow, when the rainbow is so beautiful itself.
We aren't talking big money here in government terms. Eg IIRC the proposed ITER budget is 10 billion Euro over 30 years. The EU pours approximately 100 billion into the common agrecultural policy every year and I presume the USA is operating on basicly the same level, just to prop up buisinesses who produce food no one wants to eat.
_O_
.|< The named which can be named is not the true named
I am a Nuclear Enginneer,and work in Britain on the Joint European Torus Fusion Device. Check it out... http://www.fusion.org.uk When we fuse together the hydrogen, the helium formed is more stable and highly energetic. The thing to consider here is potential energy too. Just as there is chemical potential energy in the gun powder of a bullet, which allows the weapon to be fully automatic, so there too is nuclear potential energy. For large enough plasmas it is possible to use the highly energetic helium to sustain the fusion reaction, in a process known as ignition, so more energy can be retrieved than was put in. If all energies are considered, no laws are violated. You are right about the electricity generating process. The use of steam pressure and turbines is limited by the laws of thermodynamics, namely the Carnot cycle, so can only ever be approximately 40% efficient. The next step is the International Thermonuclear Experimental Reactor (ITER). As the politicians couldn't decide whether to build it in Japan or France, Europe has declared its going to build it anyway, and we're now just waiting for people to take sides :)
What are the civilian applications?
Nuclear fission does split nucleii into fragments. U-235 fission absorbs thermal neutrons (room-temperature kinetic energy) and splits in half, P-239 fission absorbs fast (high-energy) neutrons and splits in half. The resultant atoms form an assymetric distribution called the 'Mae West' curve because it forms two big peaks (mapped # vs Z) that look like mammaries to lonely nuclear engineers that don't see nekkid women that often.
While Uranium/Plutonium do decay naturally (stability of a nucleus is determined by the Nuclear Shell empirical formula, which is a rough analog of the electron shell theory - everybody wants to be Iron Fe/26, the most stable nucleus), there's another form of decay that's an outcome of genuine nucleus splitting. That's is the decay of of these usually-radioactive fragments. This decay is important to the operation of a fission reactor, but only in determining the criticality of a nuclear pile. 'Critical' == exactly as many neutrons are released in any time period as are absorbed, meaning steady power output. Basically, over 99% of the neutrons necessary to keep a steady level of fission events come from 'prompt' neutrons - neutrons that are freed in the splitting of an atomic nucleus. You get one small chunk (which could very well be gold), one big chunk, and a couple free/fast neutrons.
If these 'prompt' neutrons were enough to sustain criticality, then the number of fission events would increase geometrically. Since the time between generations is about a millionth of a section, this means that a reactor core that's 'prompt-critical' would quickly escalate in temperature until the structural integrity of the core failed, and you have a molten slag of Uranium - which is exactly what happened at Chernobyl.
So the way to avoid this, you have to put in neutron-absorbing control rods to keep the number of 'prompt' neutrons below the number necessary to sustain the next generation of fission events. If 'prompt' neutrons were the only neutron source, your nuclear reactor would quickly cool down. But the decay of the fragments (which are ususally radioactive isotopes of stable elements) release additional neutrons. The 'art' of tuning a nuclear reactor is to insert the control rods just enough so that the reactor isn't prompt-critical, but the decay neutrons are just barely enough to make the pile critical.
One of the biggest problems with fusion in general is fuel. The easiest fusion reaction is deuterium-tritium. Deuterium is plentiful - the ocean is full of 'heavy water' where one of the hydrogen atoms in a water molecule has a proton and a neutron. Tritium, however, is radioactive with a pretty short halflife. You have to make tritium by getting Lithium to absorb a neutron, then decay.
Last time I was up-to-date on fusion research, there was only an estimated 300 years of Lithium to sustain the predicted energy needs of the world. However, with fission fast-breeder reactors like they use in France, there would be 5000 estimated years of power. Fission fast-breeder reactors can be built today - it's just that to make them passively safe, you need to use a liquid metal coolant like sodium, and any disaster like Chernobyl (from terrorists, for example) would be catastrophic. Liquid sodium will explode if it gets wet, so it's a huge engineering challenge. Argonne Nat'l Labs has reactor designs like this, but the US population is scared of nuclear power plants (plus, the cost overruns at plants made them economically unfeasible).
[I am a published principal author and presentor of a fusion reactor design (presented at the 8th Topical Meeting on the Topic of Fusion Energy in Salt Lake City), so I have a tiny bit of credibility. I got out of the field specifically because of the 15-year carrot-on-a-stick paradox.]