Ask MIT Researchers About Fusion Power 318
Nuclear fusion power is the process of fusing light nuclei together to release energy, and ultimately, to put electricity on the grid. Today, we have six researchers from MIT's Plasma Science and Fusion Center here to answer your questions about fusion power, tokamaks, and public support and funding in the U.S. for this research. The Obama Administration's budget request for fiscal year 2013 is paying for the U.S. share of ITER construction out of the domestic program, starting with the closure of the MIT fusion lab. The interviewees are ready to answer technical and policy questions, so don't be shy! And, as always, please break unrelated questions into separate posts. Read on for information about the researchers who will answer your questions.
Dr. Martin Greenwald is a Senior Scientist and Associate Director of the MIT Plasma Science and Fusion Center. His experimental work focuses on turbulence and transport, density limits, and pellet fueling of magnetically confined plasmas. More recently, Dr. Greenwald has been heavily involved with data management, computation, simulation, networks, and remote collaborations for fusion research.Professor Ian Hutchinson is interested in plasma control in tokamaks, as well as spatially resolved measurements of the radiated power coming from the plasma. He is the author of the standard fusion textbook Principles of Plasma Diagnostics. Prof. Hutchinson also works on particle-in-cell simulations of astrophysical and laboratory plasmas.
Assistant Professor Anne White researches turbulence phenomena on the Alcator C-Mod tokamak, developing new diagnostics to resolve the small fluctuations which cause energy and particles to leak out. She is the recent recipient of the U.S. Department of Energy Early Career Award.
Professor Dennis Whyte pursues research into plasma–material interactions; that is, the way the hot plasma in a magnetic fusion reactor interacts with the surrounding solid materials walls. His team is also developing novel diagnostics for fusion nuclear science, which is critical as fusion reactors start producing power (and neutrons) over long periods of time.
Nathan Howard and Geoff Olynyk are Ph.D students on the Alcator C-Mod project. Nathan, who is in the final year of his studies, studies turbulent transport phenomena experimentally and through simulation. Geoff, in his fourth year, is working on disruption mitigation, which is a way to quickly and safely shut a tokamak plasma down in a few thousandths of a second.
Polywell fusion (Score:5, Interesting)
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Re:Polywell fusion (Score:5, Interesting)
It does not violate the 2nd law of thermodynamics beause it's not claiming to do so without energy. There is a constant energy input into the system. As Rider's work shows (Rider being the "scientist who showed..." that you mention), you can maintain fusion in a non-Maxwellian plasma but only if you selectively accelerate low energy ions instead of the bulk plasma.
Does Polywell do that? I doubt it, but I'm not versed enough to make a judgement.
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If it's complete bull why is it's funding classified and why has the Navy replaced Richard Nebel with somone that does not want to publish? Have you ever considered that it might be a very well guarded national secret? (Like the manhattan project?)
And as for papers here's just a few.
The Polywell: A Spherically Convergent Ion Focus Concept
[PDF] from askmar.com
NA Krall - Fusion technology, 1992 - askmar.com
Abstract The Polywell spherically convergent ion focus concept for controlled thermonuclear
fusio
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Light nuclei (Score:4, Funny)
> fusing light nuclei together
Light nuclei? They're just photons.
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Yeah, it took me 3 tries reading that bit to realize what they were saying.
Re:Light nuclei (Score:4, Funny)
Power Loss Scenario in Alcator C-Mod? (Score:5, Interesting)
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The plasma DOES come in contact with the 'divertor', which is a part of the interior of the reactor where the cool outer edge of the plasma outside the last set of closed field lines is drawn out over a large surface area to trap and remove the helium 'ash' and other contaminants from the plasma.
Actually the plasma never comes into contact with the divertor The divertors are at the bottom of the torus where the field lines are twisted and the contaminants can be pulled off. There is no plasma here but the heat of the reaction is still very much present.
The plasma never comes into contact with anything as doing so means it would cool enough to lose the reaction
I think the most important question... (Score:5, Interesting)
When will fusion power my house?
2050 (Score:4, Funny)
just skip the Microwave Power Plant in 2020
Expanding on this: (Score:5, Interesting)
Could you break down the various barriers/bottlenecks to the introduction of commerical fusion?
What are the technical problems in the state of the art, what other factors (political, economic, etc.) do you see at play?
How do you and your labs collaborate with others, and how is technology transferred? Is there much international cooperation?
Are there policy communities (China, India?) that might be more primed for the introduction of fusion technology into their grids than in North America? What would need to happen for North America to start using fusion?
I have many more questions, but those are the ones that popped into my head first. This is such a great opportunity -thank-you for taking the time today!
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or my DeLorean?
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What's the problem in building the future. (Score:5, Interesting)
As a non-scientist, what are the biggest stumbling blocks for effective fusion reaction? is this truly throwing money down the energy hole, or are there verifiable, measurable benchmarks that lead us from one point to the next. Something like, we got x to work, now we need y, when we get y, we get z and then we get fusion. Is it technology holding us back, politics, or the science?
Re:What's the problem in building the future. (Score:5, Informative)
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Do neutrons react weakly with matter? That's kind of news to me. In fact, the radiation damage that you mention would seem unlikely to happen if the neutrons interact weakly. Are you sure you're not thinking of neutrinos with that first line? The rest of the post seems to make sense. There are some fusion reactions which don't directly produce neutrons, such as hydrogen-boron-11, but even those would almost certainly produce some neutrons through secondary effects.
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tl;dr: Neutrons interact weakly enough to penetrate, but strongly enough to be annoying.
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I see what you mean about nuetrons, but, relative to other things that are said to interact weakly, neutrons seem to interact pretty strongly. When physicists talk about things interacting weakly, they generally seem to be talking about things that are much harder to detect than neutrons which is what led to my objection.
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NIMBYA (Score:5, Interesting)
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Not In My Back Yard ... Asshole?
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I don't know how it became trendy, but frankly I think if people don't want things in their back yard asshole, then they shouldn't have put an asshole in their back yard.
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It should, perhaps, be noted that people are still terrified of fission plants, in spite of them being "in production and delivering the power"....
lower limit on tokamak design (Score:5, Interesting)
What do the numbers really look like? (Score:5, Interesting)
In a lot of areas where research is done on things which don't work yet -- rockets, bridges, transmission systems, etc -- there's a general idea of how things might be able to "scale up" to meet the goals.
Is tokamak fusion really in sight of being commercially viable source of energy? If we need unobtanium to make a commercially viable reactor, wouldn't it make sense to wait until the materials are viable before making even larger tokamaks? What do we learn from making these new, bigger, more expensive reactors?
Or are we trying to build ever-bigger spark gap transmitters as a way to make radio better? Maybe we should look at other schemes?
Or, alternatively, we know of a nice, large, gravity-fed fusion reactor fairly nearby, is the engineering simpler to harness energy from that on a large scale?
ISS = 5x ITER (Score:2)
I wouldn't call ITER cheap either, but it's an international project (and the Chinese aren't locked out, as is currently the case on the ISS) and the cost is distributed over several decades and billions of people. Germany's share is on the order of $2bn over 35 years. That's $0.70 per capita per year. Much less than a lottery ticket, but with much better chances than 1 in 140mio for winning the jackpot.
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IEC's / Fusor (Score:5, Interesting)
Why aren't IEC reactors based on Farnsworth's designs taken more seriously? From what I understand, IEC's have been more effective at producing fusion, and they are cheap to build. People even build them in the garage [electricalfun.com]. From everything I've read, no one really takes the "fusor" seriously in the fusion science realm, and it's considered a dead line of inquiry. I've never understood why.
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I spent my fusion time at NBTF (Neutral Beam Test Facility at Berkeley). Fusor type stuff is really easy and the plasma discharge is great to watch (got lots of photos). Making a few D-D fusion neutrons is easy. Making enough to be useful requires a larger machine. After a bit of quality slide rule time one ends up with a REALLY BIG tokamak or mirror machnine (MFTF, my project).
Sorry, fusor type setups are for show. I did work with a fusor like project afew years ago that might work as a neutron source, b
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Will I live to see Fusion power available? (Score:3, Interesting)
Is fusion power going to be feasible in the next 60 years (extrapolating my expected lifespan)?
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What level of investment would get fusion going? (Score:5, Interesting)
Do you think a program of the size of the Apollo program could kickstart fusion to general availability? Or would a rather smaller program suffice?
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Re:What level of investment would get fusion going (Score:4, Funny)
$-15 trillion
Patents (Score:5, Interesting)
Will patents get in the way of your research?
Future Prospects, Laymen Versus Experts (Score:5, Interesting)
From the outside fusion research looks like a desperate field that's always struggling with its fundamental research/engineering questions. I know more than most laymen: I know the reactions work, I know the sun is powered by (very slow) fusion, I know fusion reactors have produced at least around 50% return on the electricity put in. Still, it feels like it's possible it'll never work, even knowing that difficult problems take time to solve.
This is the outside view. What does the future of fusion look like when you experts look at it from the inside? Does it look like a gamble? Or does it look more like "just give us proper funding and we'll give you your reactor."?
Are Tokamaks practical? (Score:2, Interesting)
The late Dr. Bussard of EMC2 [emc2fusion. org] claimed that the fundamental concepts of Tokamak fusion did not provide a platform for cost-effective positive-return power reactors. With the enormous ITER project reactor still not expecting positive return, at what point, if ever, will Tokamak research benefit the power grid?
What could you do with unlimited resources? (Score:5, Interesting)
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Reactor comparison (Score:2)
Given that fusion creates (shorter-lived) nuclear waste, the cost of it is unknown and the timeframe is unknown, how can you justify the relatively large amounts of money going towards fusion research reactors when so little goes towards fission research reactors?
I know that the economics of larger reactor = more economical are well known with tokomaks. Does this mean you ha
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Since fission power is actually a (theoretically) commercially successful industry, one could expect funding for fission research to be more readily available from private sources. More speculative, but still potentially valuable, research like fusion is more the domain of public funding. Then, when the public funding has produced something that could be commercially viable, the private interests get to swoop in and the ones with the right connections get patents on everything.
Why is this more useful than exploiting thorium? (Score:5, Insightful)
I understand that long term, we would want fusion, but we face increasing energy problems over the next 50 years and severe energy problems before 2100. Wouldn't it make sense to allocate research and development resources to something that we know works?
The talk is always about break-even with fusion (Score:4, Interesting)
But about capturing the power? Are we generating heat that will drive steam turbines?
What schemes to capture and harness the power exist?
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JET almost broke even in 1997 - they got Q=0.7. Theoretically, they could achieve Q=1, but what's the point in that? The turbine has an efficiency of about 33% (give or take), so you'd need Q=3 just for steady state operation without further losses. Economical power generation will need more than this, on the order of q=20. However it's not as bad as it sounds. The plan is to try to achieve plasma ignition at ITER (which is Q hitting infinity - the fusion reaction sustaining itself, needing no outside heati
Dense Plasma Focus (Score:5, Interesting)
Re:Dense Plasma Focus (Score:5, Interesting)
I would mod up, but I have already commented.
Their reactor design is certainly the most elegant, being the only device I've seen that proposes collecting the energy in a solid-state manner, and not just boiling a damn great kettle like everything else. It's also one of the smaller scale devices, the design reactor fitting in a shipping container and projected to cost on the order of a million dollars rather than being in the billions, producing on the order of 5 MW, making it a shoe-in for military funding to prime the development pump (the military would go ape for something the size of a shipping container that can produce 5 MW without having to ship in diesel fuel).
It doesn't require rare and expensive tritium fuel. If their project manages to prove over-unity it would also seem to have the fewest engineer hurdles to becoming a commercial product, the difficulties mostly surrounding the construction of really fast high power switches, and an X-photoelectric collector.
Their operating budget is tiny compared to the likes of NIF and ITER as well ; it would be great to see even a few percent of these budgets distributed to alternative approaches.
Fusion Milestone Prizes (Score:5, Informative)
In 1995, Robert W. Bussard submitted this legislation to all relevant Congressional committees, copying all US plasma physics laboratories.
Needless to say, the legislation wasn't passed.
Do you think the time is right?
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I didn't take it that way.
Like the OP said this is much like the Xprize series of challenges and rewards. Most of the teams and companies competing for those prizes are spending considerably more than the prize money to try and win. The prize is just a PR trophy and a bit of funding aid.
I wouldn't advocate for a system like that being the sole source of federal dollars for fusion research. But there isn't any good reason to not consider adding it to what is already out there.
And as others have said there ar
Scaling of Tokamaks (Score:2, Interesting)
I haven't really found a concise statement on this so far. Assuming the current state of the art in plasma dynamics, how do fusion reactors scale with respect to size and magnetic field strength? Both in terms of the Q value of D-T reactions and D-D reactions. So, what happens when you scale up the size or magnetic field strength by a factor of 2?
(What Q values have been achieved with D-D fusion anyway? I've seen 0.7 for JET in a real-world D-T trial in 1997. What's typical fori D-D? How much effort does it
ITER (Score:3)
Is the ITER project good science?
Or, is it a politically motivated, pork laden boondoggle?
Infighting by fusion researchers? (Score:2, Interesting)
Researchers studying different types of reactors (Bussard polywells, tokamaks, LENR like the Rossi eCat, Farnsworth fusors, etc.) seem to spend an inordinate amount of time making negative public statements about each others' work.
Are there any researchers outside your own field that have attacked your work? Do you see this as a problem? Is it an unavoidable consequence of trying to gain funding when fission is the favored technology? Does all non-fission research suffer when fusion researchers fight amo
NIF (Score:4, Interesting)
Is the NIF approach even plausibly capable of generating electricity in a useful way, or is it purely a research platform / smokescreen for nuclear weapons research?
Helium3 ? (Score:2)
I've always heard that fusion was very, very difficult without Helium3, which is in short supply Earth-wise, but more available on the moon.
How is your process dealing with the Helium3 issue (if at all), and how did you overcome the difficulties involved?
Ironically, if we still had a space program, we'd probably have had fusion since the mid-80's since we'd be mining all that Helium3....
Hes3 is the decay product of Tritium, no shortages (Score:3)
Sorry to tell you, but the whole He-3 story is a bunch of crap.Neither is He-3 rare, as it is absolutely no problem to make Tritium out of Lithium - you just need to wait 11 years for half the tritium to turn into He-3.
That said, D-He-3 fusion is as hard to achieve as D-D and certainly much harder than D-T fusion. Worse yet, in D-He3 fusion there is a parasitic D-D fusion process that is actually favoured (by nature) over D-He-3. The whole thing is just irrelevant and a huge strawman.
Ignoring all questions of *can* they work... (Score:3)
and even ignoring all questions of whether they can generate net useful, saleable electricity... how likely do you feel that descendants of tokamaks like ITER are to produce economically viable electricity (including capital cost amortization), given their large scaling requirements, and on what sort of timeframe? What about inertial confinement alternatives based on the HiPER [wikipedia.org] approach? As an ousider, it seems to me that the HiPER concept can be scaled down much more, and hence looks more attractive as a generation method.
Your Favorite Books? (Score:4, Interesting)
So, quite simply, what are your favorite books for all minds young and old? Also, can you annotate which are written for the layman's entry into the given field and which are written to encompass the field for the researcher? I find that some books start off with the jargon so strong and the references and footnotes so thick that you start to have to reread every paragraph as they're clearly condensing entire historic papers into lengthy sentences. Any fiction books worthy of influencing your work and desires?
Ranking different fusion concepts (Score:3, Interesting)
There are many potential routes to economic fusion. Assuming each of these concepts were funded at ITER levels, how would you rank the potential for economic fusion (cost competitive with nuclear) coming from each of the following concepts within the next 25-30 years:
1/ Field Reversed Configuration - eg Helion Energy, Tri Alpha
2/ Electrostatic Confinement - eg Polywell/EMC2
3/ Magnetised Target Fusion - eg General Fusion
4/ Laser Inertial Confinement - eg NIF, HiPER
5/ Heavy Ion Inertial Confinement - eg Fusion Power Corporation
6/ Tokamaks - eg ITER, DEMO
7/ Stellarator - eg Wendelstein 7-X
8/ Levitated Dipole - eg MIT LDX
Logistical Simulation Determination? (Score:2)
I figure, right about now, that in the back of the room that holds the team meeting for this project, 3 or 4 Engineering Gieniuses are vapor locking.
Where do you see the answers to the questions? (Score:2)
Where are the answers posted?
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there's usually a follow up post in a few days or a week or so with Answers to a number of questions. It's not a live chat.
Fusion fuel. (Score:2)
Achieving break-even fusion seems like it has to be an eventually achievable goal. After all, stars show us that it's just a matter of scale in the end and it's been achieved non-sustainably with fusion bombs (some have argued that sustainable fusion power is achievable now by detonating fusion bombs in giant underground chambers). The question I have is, once we have sustainable fusion reactors, are they really viable as a general-use power source? The reason I wonder is because, unlike stars which run on
Extracting the heat (Score:3)
How do you extract the heat once you are successful in fusion? Is there a safe zone where it is just right to run water to convert to steam? With fusion running so hot and containment being such an issue it makes me think that extracting the energy could also be a fair challenge.
If you could have anything you wanted... (Score:3, Interesting)
Focus Fusion / aneutronic fusion (Score:5, Interesting)
They've spent billions on a dead end solution! (Score:3)
Making fusion power with a massive laser and a tiny bit of deuterium, is what's holding them back, it's rediculous! How about speeding a matter stream of deuterium atoms around a toroid, in a vacuum using superconductive "pinch points" around the circumference? it would set up tiny shockwaves of very high temperature and pressure. As the system is refined the matter stream could become self propelling, sacrificing only a very small percentage of deuterium atoms per cycle. And the potential power generation could be accomplished not through heat, but by using the spinning matter stream as the armature (rotating center) of a generator/alternator.
Really!
Relative price (Score:2)
Do you have an estimate for how much fusion will cost per kWh relative to today's technologies, like fission, coal, and natural gas?
I'm interested in knowing whether fusion will bring down the cost of electricity. A pet idea of mine for some time has been that commercial fusion power could bring down the cost of desalination enough that access to fresh water will no longer be a problem for countries that can afford to build the infrastructure in the first place.
General Fusion approach? (Score:2)
The issue of lead time (Score:2)
It takes a long time to build merely the infrastructure needed to house and support a fusion facility. For political reasons, the sooner fusion is on-tap after we know how to achieve it. It probably wouldn't be a bad thing if there was a massive construction job program right now, given the current slump.
Do we know enough about the needs of a fusion facility to start work on these surrounding projects?
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That will knock at
Tritium supply (Score:2)
At this time, it seems prudent to say that the only reaction likely to ever produce commercially useful energy will involve copious quantities of tritium. Would you please address the main points of tritium self-sufficiency raised by Swiss physicist Michael Dittmar?
The issue is raised in part 4 of his study, page 20, The illusions of tritium self-suciency [arxiv.org]
More background: http://www.technologyreview.com/blog/arxiv/24414/ [technologyreview.com]
a simple open question: (Score:4, Insightful)
Fusion is one of those technologies that is always '50 years away', even 50 years ago, maybe even 50 years from now. So, looking at what's actually happened recently:
What do we actually know now that we didn't know 10-15 years ago that gives support to the notion that we're making progress? Or, what are the 'big' things we know now?
Similarly, what are the things we still don't know that we could reasonably expect to find answers for in the next 10-15 years?
I'm assuming it's not that we've figured it all out and it's just a matter of engineering a working prototype.
Power Requirements vs. Power Output (Score:2)
This may be a stupid question, but...
The power that it takes to generate electricity from a nuclear plant, I assume, is fairly immense. Does the power that a nuclear plant generate put out more pwer than it takes to generate it? I know that, for the most part, it is steam pwer, right? The rods get hot and they boil water that, in turn, generates steam. some of these plants seem pretty massive and must take a lot of power to operate.
Thanks!
"Religion" and fusion (Score:2)
How will the waste product be removed? (Score:3)
The byproduct of fusion is Helium? Or is it some other atomic number they are shooting for now (boron?) Anyway, if the plan is to make this a drop-in replacement for coal and natural-gas burners, then how will you keep the unit up and running if its filling up with waste prodcuts. Does it have to be taken down intermitantly? Then what is the startup-time / power requirements / redundancy requirements of a fusion reactor that has to be restarted every 10 days.
why multiple US tokamaks? (Score:2)
Why are 3 US tokamaks necessary for the US to benefit from ITER? Do they have different specialties or something?
The argument here seems to be that in order to benefit from ITER construction, the US needs to have a domestic program counterpart. However, why, in a technical sense, are all the current facilities necessary in addition to the new ITER facilities? I'm sure particle physicists would love to keep Fermilab up and running, but its a harder argument to keep the hardware (the expensive part) in p
Cost/Benefit -- tokamak vs. other options (Score:3)
At some point, practical planning would say that a portion of the money -- even a very small portion -- being spent on ITER projects should be redirected to make sure that the pre-occupation with ITER isn't starving other options that may turn out to be better ideas. It's often been the outliers that succeed even in technology areas where lots of attention and money have been spent on some "standard" solution.
I'm not against pure science but in this situation I'm likely to appear so to some: it's annoying to me that ITER, the long term "solution of the future and always will be" is getting so much money that other options are being starved out. Am I completely out to lunch for some reason?
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Cannibalising as a mistake: I'm with you here and t
Propulsion? (Score:3)
Given that solar energy is so plentiful, and that it will likely be widely available in the time frame that fusion power will be available, would it make more sense to apply the expertise of scientists into using fusion for spacecraft propulsion, which is an application that absolutely requires concentrated and compact energy? It could be a game-changer for travel within our solar system.
In addition, could the techniques used for fusion (both magnetic and inertial confinement) be applied to fission propulsion, for compressing fissile pellets to critical density? And would that be more within reach of current technology than the very high temperature and pressure needed for fusion? Why is no one researching that? It would literally open up the solar system for us.
Power plant size? (Score:3)
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Know Unkowns (Score:2)
In this case I think the issue is Know Unkowns.
If I understand correctly, the steps needed to get to a commercial reactor are known. How we are going to execute those steps are unknown – and have been harder to solve than planned.
A Unknown Unknown would be brand new unexpected problems popping out. Think Black Swans.
i.e. For a Tokamak reactor to work you need a magnetic field of a known strength. The issue has not been with weird, unexpected issues occurring with the field strength (Unknown Unknown),
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Your question seems to be about fission reactors - anything that involves anything heavier than iron as a fuel is not a fusion reactor.
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Well, one of the major arguments for fusion research is that fission is dangerous and dirty. If we can have clean and safe fission, there absolutely no reason to pursue the fusion pipe dream.
The most important item in the economic equation of a nuclear plant are the capital costs. If we already established fusion needs to be big in order to work, probably much bigger than existing fission plants, then we should stop spending money on large experimental fusion reactors - it is not a solution in it's current
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The safety issues you talk about for fission reactors shouldn't be much of an issue for fusion reactors. The huge problem in fusion is getting the fusion to even happen in the first place. Pretty much every system for getting it to work involves carefully pumping in a lot of energy in a controlled manner in some way or another to keep the fusion going. If the equipment regulating the fusion stops working, the fusion just stops. You shouldn't really be able to get a melt-down type situation where the fuel me
Re:Computational methods in plasma/tokamaks (Score:5, Interesting)