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#1 Deepwater6

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Posted 09 September 2011 - 09:08 AM

This story is about the UK joining forces with US to create a fusion plant for future energy needs. If they are succesful would this be safer than the nuclear plants we have or just as dangerous?







http://www.bbc.co.uk...onment-14842720

#2 CraigD

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Posted 09 September 2011 - 08:02 PM

This story is about the UK joining forces with US to create a fusion plant for future energy needs.

I’d characterize this news more along the lines of “The UK has switched from backing the http://en.wikipedia....European_Torus'>JET (a Tokomak) to backing the NIF (a laser-powered inertial confinement fusion device)” than simply a new US-UK partnership, but putting aside lab politics, the major news here is that some folk who live and breath this research now appear to think LICF is more likely to reach the break-even point (when the energy from the fusion of a device exceeds the energy used to cause the fusion) than a magnetic confinement device.

Still, I think the old joke about the break-even point for controlled fusion having been 30 years away for over 50 years (which the article mentions, though it version says "50 years away, no matter what year you ask") is still applicable. Though the BBC article is accepting of NIF and UK scientists optimism for the NIF or similar devices breaking even “within the next couple of years”, many other reports from the NIF suggest that some show-stopper problems remain to be solved, with no sure guarantee they can be. Making a tiny star core using lasers is a very complicated business, on the bleeding edge of technology, with nearly every new experiment bringing surprises, so I’m inclined to wait “a couple of years” ‘til the predicted break-even before joining in the optimism. Even once break-even is technically reached, the devices needs to much better than break even to produce practical power, and be productionalized from experimental machines to ones that can run for sustained periods at affordable costs. While the basic fuel for a fusion power plant – hydrogen from water – is practically free, the rest of it is likely to be very expensive, even after the break-even milestone is passed.

If they are succesful would this be safer than the nuclear plants we have or just as dangerous?

How safe a fusion or a fission power plant is depends critically on its design. On the plus side for fusion power, their fuel is non-toxic, but like fission power plants, they’re capable of producing all sorts of exotic, dangerous material byproducts. At this early stage in their design, I think speculation about how well a practical fusion power plant design will avoid creating dangerous waste (possibly instead creating valuable byproducts – given the right design, the mess of high-energy particles is a fusion device can in principle transmute lead into gold, or make large quantities of antimatter) is premature.

What is certain, in principle, is that, given what’s available on and near Earth, the total energy from fusing light elements into heavier is orders of magnitude greater than that from fissioning heavy into lighter, and the primary reactants for fusion – hydrogen and helium – are inherently safer than fission’s uranium and lead. The potential power-to-mass ratios for fusion is also higher than for fission. In short, if it can be done, fusion is simply better than fission.

The problem is that it’s much harder to do fusion than fission. Fission can literally happen accidentally – put too much radio material waste in the same place, and you can get an unplanned fission reactor. There’s pretty good evidence that at least one uranium deposits was a natural fission reactor for a few hundred thousand years or so. The only way you can make a fusion reactor following a simple, natural, “throw a bunch of stuff together” approach involves throwing together at least 30,000 times the Earth’s mass of hydrogen to make a small star – engineering on a scale far beyond anything we’re capable of now, and fairly pointless, as we’ve a perfectly good, natural star powering our world already.

#3 Ludwik

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Posted 12 November 2011 - 02:33 PM

This story is about the UK joining forces with US to create a fusion plant for future energy needs. If they are succesful would this be safer than the nuclear plants we have or just as dangerous?







http://www.bbc.co.uk...onment-14842720


It depends on which plants is this question about. According to Andrea Rossi (see Wikipedia) a commercially available (as of October 28, 2011) 1 MW plant is very save. But I would not invest in it.

Ludwik Kowalski

#4 jchardy

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Posted 17 March 2012 - 05:06 PM

I’d characterize this news more along the lines of “The UK has switched from backing the http://en.wikipedia....European_Torus'>JET (a Tokomak) to backing the NIF (a laser-powered inertial confinement fusion device)” than simply a new US-UK partnership, but putting aside lab politics, the major news here is that some folk who live and breath this research now appear to think LICF is more likely to reach the break-even point (when the energy from the fusion of a device exceeds the energy used to cause the fusion) than a magnetic confinement device.

Still, I think the old joke about the break-even point for controlled fusion having been 30 years away for over 50 years (which the article mentions, though it version says "50 years away, no matter what year you ask") is still applicable. Though the BBC article is accepting of NIF and UK scientists optimism for the NIF or similar devices breaking even “within the next couple of years”, many other reports from the NIF suggest that some show-stopper problems remain to be solved, with no sure guarantee they can be. Making a tiny star core using lasers is a very complicated business, on the bleeding edge of technology, with nearly every new experiment bringing surprises, so I’m inclined to wait “a couple of years” ‘til the predicted break-even before joining in the optimism. Even once break-even is technically reached, the devices needs to much better than break even to produce practical power, and be productionalized from experimental machines to ones that can run for sustained periods at affordable costs. While the basic fuel for a fusion power plant – hydrogen from water – is practically free, the rest of it is likely to be very expensive, even after the break-even milestone is passed.


How safe a fusion or a fission power plant is depends critically on its design. On the plus side for fusion power, their fuel is non-toxic, but like fission power plants, they’re capable of producing all sorts of exotic, dangerous material byproducts. At this early stage in their design, I think speculation about how well a practical fusion power plant design will avoid creating dangerous waste (possibly instead creating valuable byproducts – given the right design, the mess of high-energy particles is a fusion device can in principle transmute lead into gold, or make large quantities of antimatter) is premature.

What is certain, in principle, is that, given what’s available on and near Earth, the total energy from fusing light elements into heavier is orders of magnitude greater than that from fissioning heavy into lighter, and the primary reactants for fusion – hydrogen and helium – are inherently safer than fission’s uranium and lead. The potential power-to-mass ratios for fusion is also higher than for fission. In short, if it can be done, fusion is simply better than fission.

The problem is that it’s much harder to do fusion than fission. Fission can literally happen accidentally – put too much radio material waste in the same place, and you can get an unplanned fission reactor. There’s pretty good evidence that at least one uranium deposits was a natural fission reactor for a few hundred thousand years or so. The only way you can make a fusion reactor following a simple, natural, “throw a bunch of stuff together” approach involves throwing together at least 30,000 times the Earth’s mass of hydrogen to make a small star – engineering on a scale far beyond anything we’re capable of now, and fairly pointless, as we’ve a perfectly good, natural star powering our world already.


As a physician, I am way out of my league here, but I wonder if the concept of a "catalyst" approach is being tried in promoting the process of fusion in these settings? Specifically, I was thinking of focused harmonics (i.e., using phonons) to accelerate the process at the quantum level? Or is that just too simple minded? JCH

#5 CraigD

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Posted 19 March 2012 - 09:57 AM

Welcome to hypography, jchardy! :)

As a physician, I am way out of my league here …

Don’t fret – most of us are out of our leagues here, the point of these fora being to be a place to discuss interests we don’t much in our professional or academic lives.

... but I wonder if the concept of a "catalyst" approach is being tried in promoting the process of fusion in these settings?

The only thing that comes to mind when I think of “catalyst” and “fusion” in the same context is the vaguely disreputable field of low-energy nuclear reactions. While a good, descriptive name, LENR is in large part a rebranding of the field from the scandal and pseudo/pathological science association plagued name “cold fusion”: the terms are synonymous, as the LENRs of interest are always ones where the atomic number of some element in a sample (usually not hydrogen) increases, that is, fusion reactions.

Specifically, I was thinking of focused harmonics (i.e., using phonons) to accelerate the process at the quantum level?

As we know that sound in a gas is essentially moving regions of compression, it makes intuitive sense to me that this could be useful for producing the very high pressures and temperatures needed for fusion. Since candidate fusion materials are usually so hot they’re no longer a gas but a plasma – electrons disassociated from their nuclei – I’m unsure what their acoustic physics are. We’re talking about a pseudo-gas of protons or proton+neutron nucleons where, in classical terms, we’re trying to overcome their like-charge mutual repulsion, but I can’t think of any reason sound would travel through such a medium fundamentally differently than it does in an ordinary gas.

I’m not sure if you mean harmonics – multiple sound signals with wavelengths that are integer fractions of some primary wavelength – or the timing of multiple sound signals so that they arrive at a target simultaneously, producing greater compression than. I can’t see how harmonics are much use in doing this, as they’re usually found in things like strings with rigidly fixed ends (eg: guitar strings) or hard-walled cavities of air (eg: organ pipes), and can’t imagine clearly how something analogous to this could be done in a fusion chamber.

Again drawing from pathological science, I’m reminded of “sonofusion”, the idea that the collapse of small bubble produces by sound in a liquid could produce tiny fusion events, in the same way they’re credibly observed to produce light in sonoluminescence. While sensible in principle, the evidence of this being real is suspect, as many researchers claiming to have experimentally supported it appear to be dishonest.

As the term phonon is a specific technical quantum physics term referring only to solids, not gases and plasmas, I'd not use it here.