|
06 Nov 19 - 05:33 PM (#4017583) Subject: BS: nuclear fusion From: The Sandman is this the futre for our energy needs |
|
06 Nov 19 - 05:36 PM (#4017585) Subject: RE: BS: nuclear fusion From: Rapparee Terrestrial? I hope so. Off Earth? Well, there's the sun. |
|
06 Nov 19 - 05:41 PM (#4017587) Subject: RE: BS: nuclear fusion From: Stanron Isn't this what we've always had. The sun is our nuclear fusion device. All our energy fuels are stored solar energy. No one seems to be worried over the fact that using current solar energy may reduce future stored solar energy and that may have significant repercussions on the planet's future. |
|
06 Nov 19 - 07:59 PM (#4017617) Subject: RE: BS: nuclear fusion From: Raedwulf Plenty of people are worried, Stan. The OP is a pretty feeble one; I've no idea what point Sandman wants to make or discussion he/she/it wants to start, so I'll interpret how I see fit... The history of Homo Sapiens is, I think, one of energy thresholds. We wandered around hunting / gathering in family groups. Then some bright spark (pun intended) discovered that fire could change our food, could make more things more edible, and fire could do other things too, such as harden wooden points. We mastered fire (to some degree); we learnt to make it when we wanted it & to use it when we had it. That's your first energy threshold. Next, around 12,000 years ago, we started developing agriculture & domestication. Actually, domestication was likely something that had been ongoing for a long time, but it's difficult to pinpoint when it began. The point is that it now wasn't just what we could gather with our own muscle. Now, we are growing our food, not simply wandering around hoping to find some. We are raising our own animals, both as food and, importantly, as helpers. Dogs help us hunt, various herbivores help us as beasts of burden, sources of resources, etc. We cross another energy threshold. With more food, more reliable food, available we grow in population. We start to form larger communities, because we can sustain them. We start to form more static communities because we don't have to keep moving around to find our own energy. We create an environment in which specialists can innovate & thrive. Who will become a smith or a carpenter when the first & only thing that matters is food in your belly? But if someone will supply you with food in exchange for what you can provide them with that they can't make... If you look at it closely, this is an inarguable thing. The rate of change of technology is a parabolic curve. It is very slow to start with, almost flat. But one 'invention' leads to two, and two lead to four, and... The rate of change of technology is always on the up. Think how much the world has changed in the last 50 years compared with the last 500. So, Homo Sapiens proceeds slowly after agriculture, from the first building blocks of civilisation. We do invent sails for our boats, windmills where there's enough wind, folk figure out how to make bronze, to smelt iron, and what we can do grows along with our population. But, essentially, we are still within the same energy threshold - what we can do with our own muscle & with the muscle of our domesticated animals. That's still all we have. Then cometh coal, cometh the industrial revolution. We've known about coal for years, burnt it for years; hell, we even char wood to make a similar energy dense fuel known as charcoal. But we're still within the same threshold. And then some clever bugger figures out a way to release the energy from coal to work for us in a way that we & our animals cannot do. Some clever bugger invented the steam engine. Which needed & begat so much innovation... The Industrial Revolution is probably, so far, our biggest innovation and the biggest energy boundary we've crossed. Oil is no different to coal, essentially. Easier to manage, more versatile, more energy dense, but still. And nuclear fission - not what anyone hoped it would be & with difficult to manage consequences. We are still very firmly in the the Industrial Revolution Age, in the fossil fuel age. Our next energy threshold is cracking fusion. Imagine that, if you can. Fusion is limitless energy with few, if any, consequences. That's what see & hope for, anyway. What will we do if we can master that? The sky is not the limit, only a beginning... |
|
06 Nov 19 - 08:16 PM (#4017620) Subject: RE: BS: nuclear fusion From: Jack Campin The OP is probably referrng to some recently hyped advances in tokamak reactors. They are not much less polluting than fission plants. The reactor linings are made radioactive by neutron flux and become a massive disposal problem, comparable to a breeder reactor. Meanwhile Scotland generates double its electrity needs from renewable sources. Almost every nation on earth can do the same. |
|
07 Nov 19 - 03:30 AM (#4017629) Subject: RE: BS: nuclear fusion From: Joe Offer I made frequent visits to the Lawrence Livermore National Laboratory and other U.S. national labs over the years, and I've followed the science of nuclear fusion for decades. It always seems like we're just on the brink of being able to use nuclear fusion as a safe, clean, inexpensive source of power - and yet, we never quite find success. -Joe- |
|
07 Nov 19 - 12:18 PM (#4017650) Subject: RE: BS: nuclear fusion From: BobL In the computer industry, or the early computer industry at least, the estimated time to reaching a given milestone was known as its Hartree Constant. In this case it seems to be about twenty years. |
|
07 Nov 19 - 01:16 PM (#4017667) Subject: RE: BS: nuclear fusion From: The Sandman feeble, what is feeble about trying to learn from informed mudcatters |
|
07 Nov 19 - 02:14 PM (#4017691) Subject: RE: BS: nuclear fusion From: Donuel This is a job for quantum computers. While we were napping, a quantum computer in 200 seconds has outpaced all prior super computers by about 10,000 years Our nuke plants are a bit like a locomotive that runs a piston. Were just using nuclear heat to boil the water instead of coal. There is another power source that is greater than fusion but baby steps are best for now. |
|
07 Nov 19 - 02:27 PM (#4017693) Subject: RE: BS: nuclear fusion From: Raedwulf It's feeble Sandman, for exactly the reasons already given - I've no idea what point you were trying to make or what discussion you wanted to stimulate. If you'd like to explain what you were after, I'd be delighted to listen & to contribute if I can (if I haven't already)! ;-) |
|
07 Nov 19 - 04:57 PM (#4017726) Subject: RE: BS: nuclear fusion From: robomatic The old saying is: "Controlled nuclear fusion to generate power is twenty years away and always will be!" |
|
07 Nov 19 - 05:59 PM (#4017739) Subject: RE: BS: nuclear fusion From: EBarnacle I hope not, Robo. We know where we're going, we just need to learn how. It's sorta like flying. We knew how but it didn't quite happen until 1903. Now look at it. Ben Franklin said it, when at a demonstration of a Montgolfier balloon. Someone commented "What use is it?" He replied, "Of what use is a baby?" We are using fission. At some point, there will be a breakthrough and we will be in the age of fusion. When I was a kid, we played with model airplanes. They were noisy and unreliable. Now, they use electric motors. Quiet and reliable. |
|
07 Nov 19 - 06:11 PM (#4017745) Subject: RE: BS: nuclear fusion From: Black belt caterpillar wrestler It seems reasonable to presume that a fusion reactor will not be small and portable, so we will still need a great deal of improvement in battery technology to power vehicles etc. , just as we will for efficient use of wind and water power. I am still hopeful though:) Robin |
|
07 Nov 19 - 06:29 PM (#4017752) Subject: RE: BS: nuclear fusion From: robomatic What seems to be making the most progress toward electrical transportation right now is more powerful magnets hence smaller powerful electric motors, and great improvements in the safety and reliability of lithium based batteries and speed in charging them. This is what's given us drones and electric vehicles and a lot of the progress in robots and assisted living for the disabled. |
|
08 Nov 19 - 04:20 AM (#4017838) Subject: RE: BS: nuclear fusion From: Iains The only trouble is that modern magnets are made fro malloys containing the aptly named rare earths. China produces more than 95% of rare earth elements, and produces about 76% of the world's total rare-earth magnets. Therein lies a couple of potential problems |
|
08 Nov 19 - 12:04 PM (#4017951) Subject: RE: BS: nuclear fusion From: Raedwulf Actually, Iain, rare-earths aren't that rare, empirically speaking. They're a lot more abundant than people realise (not least because their name is somewhat misleading). It's just that they're generally a sodding nuisance to isolate / extract economically! |
|
08 Nov 19 - 02:00 PM (#4017984) Subject: RE: BS: nuclear fusion From: Rapparee Yttrium and a couple others were found along the southwest border of Montana a couple years ago. |
|
08 Nov 19 - 02:25 PM (#4017992) Subject: RE: BS: nuclear fusion From: Iains Raedwulf I was quoting economically viable sources. Since China hiked the price and established export quotas other countries have started to bring reserves on stream, so the existing dynamics will change. |
|
09 Nov 19 - 07:38 AM (#4018113) Subject: RE: BS: nuclear fusion From: Mr Red the fact that using current solar energy may reduce future stored solar energy Well! The fact is that all coal reserves were laid down before fungii evolved. So there won't be any coal in the future, because trees rot by the mycological vector now. Oil maybe OK because it was made in anaerobic conditions (bacteria of that persuasion), and we may not have enough oxygen in future. Though that supposes the human race can survive the 200 million or so year for it to be made. It is all solar energy (nuclear excepted), hydro, wind, PV. All driven by insolation. And several hydro schemes are less eco than coal. EG Brazil, because they have drowned rain forest that should be soaking up CO2 and is now releasing CO2 from the rotting trees submerged. There are many experiments going on to tame nuclear fusion, the US one with multi megawatt lasers has just about produced more energy than that put in, for seconds! And, recently reported in the New Scientist, there are several cold fusion experiments going on, which the US military are keen to make work. But it may be some time. Particularly since a dubious claim it had been found was never replicated. |
|
11 Nov 19 - 02:04 AM (#4018423) Subject: RE: BS: nuclear fusion From: Joe Offer I did a lot of work at the Lawrence Livermore National Laboratory in California until I retired in 1999. They had a fascinating museum that heralded their accomplishments (other than nuclear bombs). They had achieved nuclear fusion; but it took more energy for them to produce fusion, than the energy the fusion produced. And it's still that way. -Joe- |
|
11 Nov 19 - 04:11 AM (#4018436) Subject: RE: BS: nuclear fusion From: Mr Red I can't remember which lab had achieved positive power for a few seconds, but it may very well have been Lawrence Livermore. Saw it on TV too, at least 8 humongous lasers in a radial pattern firing at one small spot. Wiki on Fusion gain factor which claims the Tokamak in the UK has the best record currently. Q=0.67 but it says that Q=5 is the target for positive power because of losses, unusable energy and input power. A notable point is that nuclear fusion produces neutrons and some alpha particles - er - radiation however you describe it. The interception of neutrons (mostly) is the method of generating heat and thus electricity. |
|
11 Nov 19 - 07:40 AM (#4018451) Subject: RE: BS: nuclear fusion From: Steve Shaw "The fact is that all coal reserves were laid down before fungii evolved." Not so. There were plenty of fungi around in the Carboniferous. It was also likely that fungi were digesting lignin (the stuff that makes wood wood). What you've probably read is that fungi hadn't evolved the ability to digest lignin. But that can't be right. Read this article: "Delayed fungal evolution did not cause the Paleozoic peak in coal production" (it's at pnas.org). In a nutshell, had lignin (wood) accumulated at the rate it would have had to in order to produce the coal measures (which it did), and not been broken down by fungi (read on), all the atmospheric carbon dioxide would have been removed in a short time. Lignin is a carbon-rich polymer, after all, and you're talking about wholesale carbon capture on a massive scale. The numbers are in the article. So no carbon cycle, no photosynthesis, no life on earth and a drastically reduced greenhouse effect. Didn't happen. Some of that trapped carbon must have been released back into the atmosphere, and that happens by the action of decomposer fungi and bacteria. The latter, by the way, are even more problematic when it comes to digesting lignin. The likeliest explanation for the peak in coal formation is a unique combination of climatic and tectonic events. And maybe a bit of a contribution from fungi scratching their heads wondering how to deal with this new-fangled polymer. They got there, but they probably got there before the explosion of woody plants happened. |
|
12 Nov 19 - 04:37 AM (#4018587) Subject: RE: BS: nuclear fusion From: Mr Red "Fungii evolved" - says nothing about presence, only ability for the context. And the coal being laid down for the next 200 million years of profligacy? Er- the message is: it will be concrete, tarmac (which could be used as fuel) and plastic are the layers they will find. Tell you what, lets wait for that time and we will see if predicting the future is a viable sport - eh? Just an outside thought, but (should we achieve) massive amounts of fusion generation means appreciable amounts of alpha particles. Spots before yer eyes, anyone? |
|
12 Nov 19 - 04:49 AM (#4018592) Subject: RE: BS: nuclear fusion From: Raedwulf Good argument, Mr S. There's another one. What we're digging up now was laid down... Admittedly, what we will have to dig up if we want (which many of us don't) to continue on this course will be more peat than anthracite, because it isn't getting as long to be squeezed into anthracite. But even if it were a fact that "...", that fact has no relevance to NOW. We are digging up NOW & we will continue to NOW dig up what took millions of years to lay down. Whatever the rights or wrongs of the bacteria argument, what has been happening to wood in the geological eye-blink for which we've been present is irrelevant. Either we quit the fossil fuel addiction we currently have in the next 50 years or... The world is going to be very different. It's a finite resource in a world where the demand for energy is only ever going to rise (& this is all never mind the damage to the environment). |
|
12 Nov 19 - 05:58 AM (#4018605) Subject: RE: BS: nuclear fusion From: Steve Shaw Well, Mr Red, had you written that in an 'A' Level essay you'd have had a big red line scrawled through it. For all the world you seemed to be saying that there were no fungi around at that time. I wasn't selective in quoting your sentence. Still, point taken. But do study that article. The supposed ineptitude of Carboniferous fungi may not have been to blame for our abundant coal seams after all. I should also like to point out to you that not "all" coal reserves were laid down at the time in question. There are considerable coal deposits of tertiary (post-Cretaceous) age in the US, India, south-east Asia, Ireland and elsewhere, all with economic potential. Indeed, in a clay pit a few miles from me there are coal seams of tertiary age. These were even exploited on a small scale at one time. The Carboniferous represented a peak, not the whole. It's not only a finite resource, Raedwulf, it's the source, along with oil and gas, of the unlocked carbon that is rapidly increasing CO2 concentration in the atmosphere. What is unsustainable is the rate at which we are unlocking the carbon (which far outstrips the rate of renewal), not because we'll run out of fossil fuel but because of the effect on climate, not to speak of the toxic nature of pollutants associated with fossil fuel burning. A peat bed may have taken ten or twelve thousand years to grow a few metres thick. If that peat is stripped to the bedrock in a hundred years, it will have been removed a hundred times faster than its rate of renewal - even if the conditions are still right for its renewal. Which climate change may dictate that they're not. We're in trouble, aren't we? I suppose we could "get round it" by pledging to take just a hundredth of all the peat each hundred years. Not how it goes, though, is it? |
|
12 Nov 19 - 06:09 AM (#4018607) Subject: RE: BS: nuclear fusion From: Raedwulf Red - You are overstating the radiation problem, I think. Whilst it is certainly not desirable to be bombarded with neutrons, neutrons also aren't radiation in the generally understood sense. Most isotopes of most elements are stable & bombarding them with neutrons doesn't make them emitters, even if they actually absorb any neutrons. Neutrons don't ordinarily create radioactive waste, in other words. And if they do, the chances are they will be alpha-emitters anyway. As for alpha particles, they can be stopped with a sheet of paper! At least, in theory. Alpha radiation, again, is not especially dangerous & whilst it can create radioactive waste, this is relatively low level & easy to deal with. It's beta and, especially, gamma emitters that are dangerous & there's little reason to fear that fusion technology will generate much in the way of either. |
|
12 Nov 19 - 06:43 AM (#4018612) Subject: RE: BS: nuclear fusion From: Raedwulf Indeed, Steve. I burn wood myself, for preference. Not only can I put the ash in the compost bin (too much sulphur in coal ash), it's carbon neutral in the sense that any CO2 generated is releasing carbon that is already IN the current ecological cycle, rather than having been locked away for millions of years. On top of which, at least one of the local suppliers reckons he tries to plant two trees for every one he fells, not least to ensure he still has work in 20 years time! ;-) Whilst we won't necessarily run out of fossil fuel any time soon (I'm not up to date with current estimates & can't be bothered to go looking, to be honest), the point is our energy demands are ever-increasing & we are well into our most accessible stocks. As with the rare-earths, it's a question of economics. No-one is going to spend $100 getting a barrel of oil out of the ground if they can do it for $10, but once you run out of $10 oil... So not only does the demand for energy grow, the cost of fossil fuels has been increasing for years. If the proportion of energy generation doesn't alter significantly, it's not inconceivable that the British coal industry might see a revival. We've no deep mines any more (the last closed in '15, I believe), and although we've still a number of open cast mines (mostly in Scotland, apparently), they only produce about a quarter of the 18M-odd tonnes we currently use in the UK (about a tenth of peak usage). But if the cost of producing coal keeps rising... And ours, like our oil is comparatively high quality i.e. energy dense, too. We now, I believe, import most of our natural gas, which (again, I believe) accounts for the largest percentage of our energy generations. Our North Sea oilfields are starting to run down (again, don't know the current estimates), though that's, yet again, the more cheaply extracted stuff; there may well be more 'expensive' deposits still down there. So we really do need to do something significant to change the way we generate energy (electricity, primarily), given that demand is going to do nothing other than grow & grow & grow. Economics demands that we do so, even if one doesn't give a crap about environmental concerns (which, like you, I do!). As I said in my first post here, you can view human history in terms of energy thresholds - Personal, Fire, Domestication, Fossil Fuel. Fusion is the biggie, I think - crack that one & I can't imagine how the world will subsequently look in a century, given the rate of change of technology thing! |
|
12 Nov 19 - 06:53 AM (#4018617) Subject: RE: BS: nuclear fusion From: Donuel The sky looks vast but that is an optical illusion. What we put into Earth's atmosphere is a tiny space which is thinner than the transparent skin of an onion, if an onion were the Earth. |
|
12 Nov 19 - 08:07 AM (#4018633) Subject: RE: BS: nuclear fusion From: Raedwulf Errrrr… Three-quarters of the Earth's atmosphere is reckoned to be within the troposphere, which is anything from 7 to 17 km deep. Or high, if you prefer. But the furthest extent of it is up to 10,000 km altitude (although the Karman Line at 100 km (1.57% of Earth's radius) is often considered the boundary between Earth & space). The Earth's diameter is, of course, roughly 12,700 km. I am clueless as to what point you think you are making, Don. But I think you've got it wrong! ;-) |
|
12 Nov 19 - 08:51 AM (#4018644) Subject: RE: BS: nuclear fusion From: Steve Shaw If you're anything like me, you don't know when to stop peeling an onion.... Donuel's point is that the atmosphere is little enough for us to have a big impact via what we put into it, even though the sky looks boundless when we look up. |
|
12 Nov 19 - 02:44 PM (#4018741) Subject: RE: BS: nuclear fusion From: Donuel Try breathing above a mere 20,000 feet but don't overdo it. I also liked your comments about folk ledgends and stories and that travel was more limited. You are right but your mistakes are usually only by degree. So what. I also wonder if climate change will one day reduce the amount of viable breathable air. I don't know but with enough fires, ocean die off of diatomic fauna and flora and forest defoliation, there has to be an emergence of a lower concentration of oxygen. Today suffocation is not a popular recognized outcome of climate change. There was an ancient time in Earth history when the planet did not have an oxygenated atmosphere. In fact oxygen was a poison for the life forms that existed back then. Cyano bacteria was the culprit that releaased O back then. |
|
12 Nov 19 - 02:53 PM (#4018743) Subject: RE: BS: nuclear fusion From: robomatic We are living in a fool's paradise, by which I mean we have been burning what we want for the least of reasons and encouraging each other that the fuel is boundless, and the wastelands where we dump are boundless, and yet since the photograph of the small blue marble we've been shown that we have one planet, we can encompass it, and there is no ready alternative. We don't know for sure if fusion is an answer or another problem, but it's an interesting possibility. |
|
12 Nov 19 - 02:57 PM (#4018744) Subject: RE: BS: nuclear fusion From: Donuel Am I making a point, naw. Jus musin on a stream of consciousness as I drift along and watch the catfish jump. If you ever get a chance to see Earth's visible atmosphere from near dark space, do it. Its very exciting and a remarkable point of view. |
|
12 Nov 19 - 07:51 PM (#4018770) Subject: RE: BS: nuclear fusion From: Donuel That is an excellent question robo. Besides obtaining a consistent fusion reaction the other problem is distribution and transmission. You wouldn't want these N plants near cities in case of a runaway fusion reaction. I believe it is never impossible to make a mistake |
|
15 Nov 19 - 10:10 AM (#4019369) Subject: RE: BS: nuclear fusion From: Mr Red Whilst it is certainly not desirable to be bombarded with neutrons, Er - the neutrons would be intercepted and create heat, that is how fusion is proposed to be harnessed. They would hopefully be all absorbed, but 100% is a tough task master. The alpha particles would be harder to use, if not impossible, as an energy source. So.......... All those dis-used deep coal mines would be a good place to site fusion reactors. The rock & soil would then shield us from alpha particles and stray neutrons, and not overly many microbes would be hurt in the process. But who can put a value on those microbes, we don't even know who they are! But they are reckoned to be there, deep in the rocks. Waiting to be discovered. And might be a lot hardier than homo sapiens. Ain't no such thing as a free lunch. Don't ya know? |
|
18 Nov 19 - 07:18 AM (#4020012) Subject: RE: BS: nuclear fusion From: Donuel Are you really advocating for the lives of microbes? I am for preserving microbes on Mars from Earth germs but I never considered protecting earth germs that may have come from elsewhere. You may not be wrong. |
|
18 Nov 19 - 09:08 AM (#4020032) Subject: RE: BS: nuclear fusion From: Mr Red Well the New Scientist reports that microbes are being found quite deep in the crust in all sorts of places. Called extremophiles, like the ones happily living around smokers (hot subsea vents). The problemo is - we don't know what they do exactly, but if they have existed for a long time they may be doing something to the rock that makes the planet what it is, and if it ain't broke don't fix it - by destroying some of the cogs! |
|
18 Nov 19 - 06:59 PM (#4020212) Subject: RE: BS: nuclear fusion From: robomatic And just last night 60 Minutes (US) had a segment on the coming 'harvest' of millions of nodules on the deep sea floor in the Clipperton zone... Many countries are preparing for the deep sea mining operation except the U.S. can't because Congress hasn't recognized U.N.s jurisdiction to divvy up the world rights hence U.S. has not standing. Every Senator objecting to this recognition is a member of the same Replicant party. |
|
18 Nov 19 - 07:01 PM (#4020213) Subject: RE: BS: nuclear fusion From: robomatic The point of the previous post being that those aforementioned 'nodules' are loaded with just the nickel and rare earths necessary to continue manufacturing semiconductors and batteries of the highest tech variety. |
|
20 Nov 19 - 05:05 PM (#4020569) Subject: RE: BS: nuclear fusion From: Mr Red My bro-in-law was talking about those nodules 30 years ago, they knew about some nearer to NZ then. And he is a marine geologist, and was at the time working for the NZ Gov. I think we will be mining those long long before anything from asteroids or moons. Despite the depth of the ocean. |
|
20 Nov 19 - 05:22 PM (#4020571) Subject: RE: BS: nuclear fusion From: Donuel There are also ocean floor manganese nodules that make a good high temp alloy. And we wonder about UFOS that go to the bottom of our seas. Its their junk yard for spare parts. |
|
21 Nov 19 - 04:18 PM (#4020697) Subject: RE: BS: nuclear fusion From: Donuel https://www.space.com/fusion-powered-spacecraft-could-launch-2028.html Fusion may be achieved in space before it comes to Earth. |
|
22 Nov 19 - 06:56 AM (#4020776) Subject: RE: BS: nuclear fusion From: Mr Red Hmmm........ From the New Scientist Nov 19, 2016 Fusion also creates radioactive waste, albeit a type that decays in decades rather than hundreds or thousands of years. |
|
22 Nov 19 - 08:18 AM (#4020786) Subject: RE: BS: nuclear fusion From: Raedwulf As I said above, Red, I can't see any successful fusion power creating much by way of medium or high level radioactive waste. The most likely by-product, perhaps, would be tritium (half-life @12.3 years, and a beta-emitter, interestingly; decays into Helium 3!). But that, presumably, would be considered useful as additional fuel, if it could be economically extracted! Do you have a link for the NS article? |
|
22 Nov 19 - 09:01 AM (#4020788) Subject: RE: BS: nuclear fusion From: Jack Campin One estimate I read was that it would be comparable to a fast breeder reactor for the same energy output. The neutrons have to go somewhere, and they will irradiate the materials the reactor is made of to make them intensely radioactive. You cannot construct a real piece of engineering (magnet cores, laser optics, field coils, vacuum pumps, boiler tubing, pressure vessels, shielding) entirely out of isotopes that won't turn into a waste problem. |
|
22 Nov 19 - 09:01 AM (#4020789) Subject: RE: BS: nuclear fusion From: Raedwulf Mmmmm… Some interesting facts about Tritium... Beta particles from tritium can penetrate only about 6.0 mm of air, and they are incapable of passing through the dead outermost layer of human skin. Tritium is produced in nuclear reactors by neutron activation of lithium-6. This is possible with neutrons of any energy, and is an exothermic reaction yielding 4.8 MeV. In comparison, the fusion of deuterium with tritium releases about 17.6 MeV of energy. For applications in proposed fusion energy reactors, such as ITER, pebbles consisting of lithium bearing ceramics including Li2TiO3 and Li4SiO4, are being developed for tritium breeding within a helium cooled pebble bed (HCPB), also known as a breeder blanket. Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a quite small absorption cross section, making heavy water a good neutron moderator, and relatively little tritium is produced. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. Ontario Power Generation's "Tritium Removal Facility" processes up to 2,500 tonnes (2,500 long tons; 2,800 short tons) of heavy water a year, and it separates out about 2.5 kg (5.5 lb) of tritium, making it available for other uses. According to a 1996 report from Institute for Energy and Environmental Research on the US Department of Energy, only 225 kg (496 lb) of tritium had been produced in the United States from 1955 to 1996. Since it continually decays into helium-3, the total amount remaining was about 75 kg (165 lb) at the time of the report. Tritium figures prominently in studies of nuclear fusion because of its favourable reaction cross section and the large amount of energy (17.6 MeV) produced through its reaction with deuterium. Like the other isotopes of hydrogen, tritium is difficult to confine. Rubber, plastic, and some kinds of steel (!!) are all somewhat permeable. This has raised concerns that if tritium were used in large quantities, in particular for fusion reactors, it may contribute to radioactive contamination, although its short half-life should prevent significant long-term accumulation in the atmosphere. As of 2000, commercial demand for tritium is 400 grams per year and the cost is approximately US$30,000 per gram (!!). Tritium is an important fuel for controlled nuclear fusion in both magnetic confinement and inertial confinement fusion reactor designs. The experimental fusion reactor ITER and the National Ignition Facility (NIF) will use deuterium-tritium fuel. I presume, therefore, that any tritium created by the fusion reactor could & would be economically recycled back into it. Nice! |
|
22 Nov 19 - 09:03 AM (#4020790) Subject: RE: BS: nuclear fusion From: Mr Red Sadly you have to be a subscriber. But I could scan it and send, or put it on my website for you. PM me & we can sort something. The issue is about predicting the future to 2076, because in 2016 the NS was 60 years old. I can't claim to have read it that far back but I did read it at college and that was a loooooong time ago! |
|
22 Nov 19 - 10:10 AM (#4020800) Subject: RE: BS: nuclear fusion From: Raedwulf That's a shame. No, never mind going to all that trouble. After all, I'm not the only one reading the thread & others would be interested, I'm sure. Could you, perhaps, do a quick precis of what NS has said also creates radioactive waste? That's the bit I'm curious about! ;-) |
|
22 Nov 19 - 11:02 AM (#4020811) Subject: RE: BS: nuclear fusion From: Jack Campin As a waste problem tritium isn't relevant. Try making a boiler out of something that will only turn into tritium when blasted with neutrons. Or how else do you intend to get the energy out of the system? |
|
22 Nov 19 - 02:02 PM (#4020835) Subject: RE: BS: nuclear fusion From: Raedwulf Jack - as I said before, neutrons themselves aren't "radiation" in the commonly understood sense, and they don't necessarily make whatever they hit radioactive. I'm not planning to go through the list of possible elements that might possibly be involved in the construction of a putative fusion reactor. But where most common stable isotopes are concerned, the absorption of a single neutron isn't going to create an unstable radioactive one. I'll grant you in advance that in a fixed construction, any given atom is likely to be subjected to multiple chances to absorb a neutron & therefore some will absorb multiple neutrons & become radioactive. That's why I am curious as to how & what NS thinks may be created as radioactive waste. Assuming the article has any detail on the topic! |
|
23 Nov 19 - 07:29 AM (#4020914) Subject: RE: BS: nuclear fusion From: Mr Red From Wiki ...... Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy (in terms of mass in its rest frame) by radiation, such as an alpha particle, beta particle Which was linked from en.wikipedia.org/wiki/Nuclear_fusion which also mentions the products like - alpha particles. The problem, as described, with Tokamacs is the science of finding materials that can cope with the temperatures of the plasma and maybe alpha particles. Particularly the ITER being slated for success in 2035, when it is projected to produce 500Mw of excess energy for a few seconds. At an accumulated cost of 50 Billion (currency could be any given it is a guess!). The NS article is not specific on the radioactive mechanisms, the article is a discussion of 2076 among other articles focusing on other areas of futurology. |