The article certainly does, even if Lockheed does not.
"U.S. submarines and aircraft carriers run on nuclear power, but they have large fusion reactors on board that have to be replaced on a regular cycle."
US naval vessels have fission reactors, not fusion. I'm also pretty sure that although they would refuel a reactor, that rather than replace the reactor they'll likely replace the ship.
While Wiktionary has "A device which uses atomic energy to produce heat" as one definition, other dictionaries all include the ability to regulate/control/sustain a nuclear reaction. I'm inclined to agree with them.
Well, we all understand that a nuclear warhead is technically a reactor but not what we mean in practice when we use that word. The typo in the article was just a bit unfortunate.
It's only technically a reactor if you accept Wiktionary's definition of what a reactor is, instead of any of the "real dictionaries". I'm of a mind that setting off an uncontrolled nuclear reaction doesn't make something a reactor.
AFAICT, ²H + ²H produce ³H (which is the burned), H, ³He, and ⁴He, plus some neutrons and gamma rays. The latter must bring the energy out of the chamber, by heating some blanketing. Then it must be the same as with fission reactors.
From the article Flexie posted, for production they're planning to use deuterium-tritium, which produces helium and high-energy neutrons, which breed more tritium from lithium. Like most fusion projects they use deuterium alone for testing.
Basically you catch electrons flying out of the plasma arc (where fusion is taking place), and ground them back into the plasma (which is positively charged).
Helion here. There are pretty big differences. They did get the high Beta and compact/modular parts right. The primary differences are that Helion operates entirely pulsed with simple non-superconducting magnets. That allows us to go to higher temperatures, cleaner fuels, directly recovery energy, and if everything works as planned should eliminate the wall concerns and need for particle beams.
I do think what they are doing is interesting. If its like the Gas Dynamic Trap or Tandem Mirror it has promise, atleast from the fundamental physics point of view. Researchers in Novosibirsk had encouraging results in the last 5 years. They still have a long road ahead to get to fusion-relevant temperatures, but we are staying tuned to this one.
If you really are Dr. Kirtley let me say you have one of the most, if not the most important job in earth right now. Fusion energy has the potential to stop wars and re-start the space revolution. I wish you the best.
I'm all about the space revolution, but the only way to stop wars is to have one so big there is no one left to wage them. In a way, fusion does have that potential, but I suspect you were going for something more positive.
Of course it will not stop all wars, but it will stop most oil-related wars. You still will have resource-related wars like cultivable land, and fresh water but with the space-revolution soon humanity will have plenty of land and water too.
Well... if fusion energy is abundant, the price of oil will drop rather abruptly. A lot of people in a lot of places, where the population has been expanding, and there is a lot of religious extremism and political instability and modern weapons, will have to find a new way to feed themselves. And someone to blame if they can't. So I'm not that optimistic it will stop any wars.
Aha thanks for the explanation, that does make things clearer. Also a huge thanks to you for being at the forefront of technology. I consider energy research the single most important thing we can do for humanity, and I'm incredibly grateful to see real progress on fusion in my lifetime.
> Initial work demonstrated the feasibility of building a 100-megawatt reactor measuring seven feet by 10 feet, which could fit on the back of a large truck, and is about 10 times smaller than current reactors, McGuire said.
So that would power 50k to 100k typical houses in the US... not bad!
Compact is good, because until you can fuse helium-3, the reactor is producing neutrons, which will transmute the reactor and its shielding into other, often radioactive elements. So the entire thing will have to be regularly replaced and disposed of (which we can do safely, but too many people believe otherwise).
I do not see how compact matters much here. As far as I understand, the basic reaction used is the same, so that compact design will produce the same number of neutrons per Watt produced as a large one.
Wouldn't the effect of its smaller mass be that the container will have to be replaced more often, more or less in the ratio of the masses of the machines?
We really don't know the practical consequences of this systematic transmutation (for all we know, neutron liberating fusion reactors will never be economic). It's entirely possible the device will have to be replaced more often, I'm just pointing out the less mass in it, the less that has to be disposed of when that happens.
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fusion reactors on board that have to be replaced on a regular cycle.
sigh To the extent this is true I suspect those "large fusion reactors" are tuned not so much for generating electricity and a great deal for annihilating whatever the carrying missile is pointed at.
But never mind fuzzy thinking at Reuters right now. This is amazing news if holds up. Fingers crossed.
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fission reactors on board that have to be replaced on a regular cycle.
Even the need for regular replacement went away long ago. Our current (old) designs get refueled only once, and new ships don't get refueled at all (the core lasts as long as the hull does). They do all need regular maintenance, but that's true for all U.S. warships.
I believe you're misunderstanding, those ships run on power generated by a nuclear reactor. A reactor is like when you think of a regular nuclear power plant, it's not part of a missile.
He's making a joke about how fusion has been used successfully for decades, but only for bombs. Thus, aircraft carriers and submarines do have fusion devices on board, but they're only used for destructive purposes.
Maybe you're just less bothered than I about the writer conflating fission and fusion when the difference between them makes for a good deal of the newsworthiness of the article.
I'm well aware of the fission reactors in large military ships, but if there is any application of nuclear fusion on them then pretty much the only option today is thermonuclear warheads. It would be really nice if that's about to change.
Most warheads have hollow plutonium pits that are filled with tritium (right before implosion) triggering a fusion reaction from the high heat of the plutonium fission reaction. So no, it's not only the H-Bombs, though those are primarily fusion while tritium is only used to "boost" classic implosion fission warheads.
Civilian power reactors need refueling at about that pace, but Nimitz-class carriers "are capable of operating continuously for over 20 years without refueling"
The article is completely wrong about US Navy ships having fusion reactors. They have fission reactors, not fusion. I wonder if they are even reporting the breakthrough right since they clearly don't know the difference. For all we know the breakthrough may be smaller fission reactors too, which isn't a big deal at all.
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fission reactors on board that have to be replaced on a regular cycle.
Just in case someone skipped out on the relevant day of middle school science, it should be 'fission'.
The difference is that fission is taking heavy elements, breaking them apart and using the released energy. Radioactivity, Thorium, Uranium, Plutonium, all the yucky stuff. Research has been going on for decades into making these reactors safer, and with breeder reactors and modern conventional designs that appears to have been achieved. Nevertheless, they appear on their way out anyway.
Fusion fuses together light isotopes and uses the energy thus released - they basically do what the sun does. And are clean. For various definitions of clean.
And if you're wondering how they are the complete opposite yet both work, it all pivots around iron. Copying from Wikipedia on iron:
> Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where the production of nickel-56 (which decays to the most common isotope of iron) is the last nuclear fusion reaction that is exothermic.
And yes, that means that everything in this universe will one gigayear end up right at the pivot between fission and fusion, ever onwards oscillating further towards it. Our universe is ever tending tiwards irony. A pivot that we're probably going to see humanity go through too, but in a different way. Hopefully sooner rather than later.
This bothers me immensely. Clearly, neither the author nor the editor for a "Scientific American" article (for pete's sake, science is in the name!) know the difference between nuclear fission and nuclear fusion.
This article is the cognitive equivalent of parrots squawking, because they don't even understand why the news actually is news.
People calling this a "typo" are giving too much credit. It could be a mistake, but the whole point of having an editor is to catch typos and mistakes! And it's a simple, short article!
This article provides a lot more engineering information and other background and is well worth a thorough read. Thanks to flexie for finding and sharing the link.
Hyperloop case doesn't have 50 years of track record of being "just few years from now", and as far as I remember, the design was more-less feasible if only someone would get around to building it. It didn't have such hard problems to be solved as fusion still has.
I don't believe this is the case. I'm pretty sure there have been "hard" limits so far on what can be achieved. I'm not a physicist, not even close but as I understand it two issues remain. One is that sustaining the fusion reaction has been problematic. I believe the longest sustained reactions have been less than one second. Two is that currently we have to put more energy into creating and sustaining the reaction than it yields. These two things make this categorically different than a challenge like building the hyperloop which as far as I know didn't have any unsolved science or engineering problems.
Again, I could be wrong on my physics but as I understand it, fusion power is still a question of "is it even possible" whereas the hyperloop was more of a question about socioeconomic will.
One of the problems with creating longer-running fusion reactions is that if they do it, in order for the reactor to not wildly overheat almost instantly, they need a massive cooling system to carry the generated heat away. At that point, you almost might as well hook up a steam turbine loop and generator and put the power on the grid.
There's lots of other problems too - I don't think they have a well-tested solution for adding fresh fuel and disposing of the fused products on an ongoing basis.
JT-60 in Japan has done about half a minute, actually. There is less of an issue with sustaining reactions (since there has been steady progress over the years) than with coming up with materials that would stand up under a commercial fusion reactor's duty cycle.
> Hyperloop case doesn't have 50 years of track record of being "just few years from now"
There have been steady incremental advancements in the field. I think your knee jerk reaction is coming from "cold fusion" which does have the problems you are talking about. Two very different fields.
The main issue with fusion is that it can't be weaponized and therefore doesn't have a nice military grant behind it. It lacks a Manhattan Project. It's probably always been "a few years from now" under the assumption of adequate funding.
The events following this announcement will probably be a good time to form a concrete opinion on fusion. It's being given a fair chance, so lets first see if it can prove itself.
This is promising stuff. Most of the other reactors have been Tokamak reactors - which are better suited to research and not practical applications, so we could be seeing some interesting results here.
It's true that there were people in the early 70s who said fusion was thirty years away. However, they conditioned that on a certain level of funding. For the funding they got, the same people said it would never happen.
Thanks for the graph, and @DennisP for saying the same in written words. I recall seeing that graph once on HN, but for some reason I didn't pay attention to it back then.
"Until now, the majority of fusion reactor systems have used a plasma control device called a tokamak, invented in the 1950s by physicists in the Soviet Union. The tokamak uses a magnetic field to hold the plasma in the shape of a torus, or ring, and maintains the reaction by inducing a current inside the plasma itself with a second set of electromagnets. The challenge with this approach is that the resulting energy generated is almost the same as the amount required to maintain the self-sustaining fusion reaction."
On a similar vein, I wonder what are the strategical consequences of such an advance. Assuming it works as described in the article, do you allow the technology to be exported ?
Because a whole fleet of fusion air carriers, battleships, submarines and bombers versus a conventional army has plenty of implications in term of autonomy, reach, etc.
But on the other hand, there is a such demand for energy everywhere that it would really hard to morally ban all the civilians applications.
Energy use of the US (2011): 25,484 TWh
Power needed: 2,900 GW = 25,484 TWh / 365 / 24 h * 1000
Number of 100 MW CFRs: 29,000
Civilian use will happen. The benefits are just much to great. There will be regulation and oversight for them. But you won't need one in every truck. It's overkill. As you can see from the above calculation 29 thousand CFRs could cover all the US energy needs. So there will be hundreds of thousands worldwide. It will be hard to keep all of them under control
But this would basically solve all of humanities energy problems and decrease CO2 production, and destruction of the environment from mining immensely.
Having large amounts of energy available enables new weapon systems to become feasible: high powered lasers, coil guns and rail guns. They can be added to any air, land, or sea vehicle that's above the size of a small truck.
Ships are pretty large anyway and aren't as restricted as land or air vehicles when carrying big machinery. Aircraft carriers won't change so much. You can build them a little smaller and their defensive weapons might improve. Nuclear submarines otoh could be built as small as modern diesel powered subs like the Dolphin class.
You could build a drone with an extremely long loitering time. If it uses a laser or rail gun, it will also have lots of ammunition. Instead of carrying a couple of hellfire rockets and having to refuel after several hours it could stay in an area for months.
Our main reason for war right now is scarce energy.
Cheap clean electricity means no-one needs to care about the Middle East for starters — most of the fighting there is superpower proxy fighting — e.g. Assad would be gone if not backed by Russia and China, so no Islamic State. No Oil, no Iraq war x2. No oil, no Hugo Chavez for that matter.
I would only be cautiously optimistic : even if our energy problems are solved, the construction of reactors, for example the superconductors, might require some rare materials. The grab for energy could become a grab for minerals. It will probably involved other regions of the world though and change the whole dynamic.
I'm used to hearing that nuclear fusion is going to become mainstream "in 30 years"; I've heard it for ~25 years. If it's 10 years now, some progress has been made.
The mainstream magnetic confinement community has been very cautious about overhyping lately. Unfortunately, the over zealousness of groups like this and NIF saps credibility from them anyway.
I have the link to xkcd 678 "Researcher Translation" bookmarked for those occasions. Quoting the appropriate row here:
If a researcher says a cool new technology should be
available to consumers in... -> what they mean is...
[...]
ten years -> "we haven't finished inventing it yet,
but when we do, it'll be awesome."
I'm not sure why this article is focusing on things like whether the reactor can fit on a truck, where you get deuterium, and how many coal power plants it can replace - instead of the actual question which is how they managed to produce a stable exothermal fusion reaction.
As far as I can tell from reading various articles (including the Aviation Week article linked elsewhere in the comments), they haven't. The expectation is that they will have a prototype in five years. For that reason, I wouldn't get too excited about this.
As someone who still remembers the excitement and the disappointment due to Pons and Fleischmann (I was a teenager at the time), I'm going to wait for independent verification. But I can't deny I'm a bit excited.
Remembering that there's no possible way we could know how many years away a thing is; the numbers are clearly a guesstimate.
They're more of a rounded (hence the clustering at or away from given numbers) measure of the remaining 'effort' versus 'difficulty'. Very likely there is some absolute time required (experiments take time to run), but throwing more people (and more importantly, more resources to run experiments and gather data) at the problem /would/ get to an end result faster (though how much faster is open to debate; it's sort of like asking how much effort does it take to win a top 30th percentile prize from a lottery).
What's different this time (yeah, I know, I know) is that, if what they and EMC2 are separately claiming is true, it's gone from being a fundamental physics problem to relatively tractable engineering, with well-understood risks and timelines.
Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day.
>Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day.
the Skunk Works and EMC2 haven't even reached the stage where they would face the same issue of material - all of them would ultimately have to contain the same type of fast neutrons and there is no good known material to do it.
What part of the reactor degrades so quickly? Can't it be replaced continuously? Why isn't the shielding done with some non-degradable matter, like water or some oil?
If the shielding is made of matter, then the nuclei of the atoms in that matter will absorb neutrons and become radioactive. Clearly the solution is to make it out of the many materials which are not composed of matter.
As an example of the problem, anything made of metal will become brittle. For why this might be a problem, take a look at what's in the middle of the ITER toroid: you've got a stack of magnetic coils, which have to be physically braced against a colossal magnetic repulsion by a great big pre-stressed metal core.
I'm sure someone at ITER has done the maths and figured out how long that core can last under operation before it becomes too brittle to keep the coils together, but I wouldn't be at all surprised if that was one of the reasons why ITER isn't designed for long-term power generation.
That's true as far as it goes, but it's not the problem I was actually thinking of.
The problem is related to how you get rid of the post-fusion products. ITER is designed with divertor plates in the floor to scoop off the fusion ash and shunt them outside the core. My understanding is that these plates have to be a) solid, and b) capable of withstanding contact with absurdly high temperature plasma. There are some candidate materials which are hypothesised to be able to stand up to temperatures somewhere near what's required, but to my knowledge (which admittedly might be out of date) nothing's actually known to be suitable.
The reason I don't think the neutron absorption issue is such a problem here or on Polywell is because with a smaller reactor, replacing the vessel when it stops working is a far less terrifying prospect, even if you have to do so every few months. And even this is far less insane than some of the proposals for how you might do commercial laser fusion. That's just bananas.
Beyond that, you actually want some fast neutrons from the reaction to give you a tritium source.
There are still some serious basic physics issues to be worked out.
They dismiss the concerns of the scientific community. Why shouldn't they? They're getting rich off of the ignorance of generals and venture capitalists.
So, they've come up with a way to make a fusor that produces more energy than it consumes? Also, I'd be interested in knowing what kind of scram mechanism they develop. If the superconductors were to fail, the expansion of the plasma would be catastrophic, right?
It certainly wouldn't produce a runaway fusion reaction, if that's what you mean. A hot plasma would dissipate pretty quickly once confinement fails, so the only energy would be that in the plasma itself. Might be bad for whoever is in the room, but probably not the county.
Right, I meant catastrophic for the reactor. Definitely not worried about blowing up the country. Probably shouldn't have typed that phrase. NSA is probably all over me now.
"McGuire said the company had several patents pending for the work and was looking for partners in academia, industry and among government laboratories to advance the work."
I'm guessing this means that they will try and maximize profit rather than maximize cheap and clean energy for the entire world. That is a bit disappointing if true.
"I'm guessing this means that they will try and maximize profit rather than maximize cheap and clean energy for the entire world. That is a bit disappointing if true."
I don't understand what you expect? You want them to give it away for free? After paying very intelligent, expensive engineers decades worth of salaries to create it? You want them to create a fund where people can donate their hard-earned money for this noble goal? I'm sure you could give them a call with that idea, or you could create your own fund, even.
Or you could badger your "government" to fund such a project. Seeing as government is a very good analogy for a bunch of people giving their collective earnings for society-level goals. Let me know how that goes.
> 100-megawatt reactor measuring seven feet by 10 feet, which could fit on the back of a large truck
A typical thermal power station has an efficiency below 50% for electricity generation, so the plant dissipates at least as much heat as it generates electrical power.
I wonder how you could get rid of 100MW of waste heat from a volume small enough to fit on a truck. That's a heat flux of more than a megawatt per square meter of surface area.
In addition, in the step before where the heat is transferred away from the reactor walls to the turbines, a heat flux is needed of 100MJ/s. Assuming a contact surface of 100m2, that is 1MJ/s per m2. That sounds like a huge flux and I am not sure if there is any medium that could do this.
That's an excellent point! Perhaps they intend the truck to be sitting at the bottom of a fast moving river.
But what gets me is that they are burying the lead. No fusion reactor of any size has reached sustainability...so why is the story here talking about size at all? Small size would be a very nice added bonus; fusion reactors that don't consume more energy than they produce are earth-changing.
I agree that the announcement is a bit burying the lead here, though maybe the size is actually important to making it work. From Aviation Week[0]:
"But on the physics side, it still has to work, and one of the reasons we think our physics will work is that we’ve been able to make an inherently stable configuration.” One of the main reasons for this stability is the positioning of the superconductor coils and shape of the magnetic field lines. “In our case, it is always in balance. So if you have less pressure, the plasma will be smaller and will always sit in this magnetic well,” he notes."
As far as I understand this (IANAP), they're saying that smaller size = less pressure, and that helps their design to work (in theory).
What the commenter is pointing out is that it may not matter how you cool the reactor. It could be in interstellar space and it might not matter because the material the reactor itself is made of may not be able to transmit the heat away from the reactor. And no such material may exist.
I think it is more a matter of tolerances than of size what makes ITER take so long. Also, it is experimental. That means that it is not just a matter of ordering stuff and putting it together.
Normal cooling (cooling towers or similar) requires a huge structure to dissipate 100MW. The cooling infrastructure can't fit in a truck. What you can to is transport the plant to somewhere where the environment can help with the cooling, such as where there is a good supply of cold water.
One can imagine these to be simple drop in replacements for existing coal plants with existing cooling infrastructure,which would be a huge environmental win in places where those are still built.
The Bugatti Veyron 16.4 has 1200 hp and therefore probably produces around 2.5 MW waste heat at full power. A factor of 40 is still quite a difference but it does not sound like an unsolvable problem.
That's peak power, though. Basically no street car is designed to be able to produce peak power for more than a minute or two at a time, and probably very few can do it for more than a few seconds. I'm pretty sure that car doesn't have the cooling capacity to cool itself at full power like this plant would have to.
You can drive your average care at peak power for an hour without problems. The problem with the Veyron is that at top speed the tires will wear off in 15 minutes and you will run out of fuel after online 12 minutes but I think it is not really limited by its cooling capacity - at 400 km/h a LOT of air passes through its 10 radiators.
temperature difference between air entering and leaving the radiator ~ 10degC
==> 1MW
So handling 2.5MW waste heat doesn't seem out of the question from this analysis.
As another ballpark "upper bound" analysis, consider that copper is one of the most thermally conductive materials, with thermal conductivity ~ 400 Wm/(m^2 degC), let's round that up to 1kWm/(m^2degC).
Let's assume that there is a thermal conducting surface of 1m^2 (i.e. the surfaces of the pipes that interface with the radiators). Let's assume that the copper is 1mm thick (= 1m/1000). Let's see what temperature difference would be needed to transfer 1MW of heat across:
As another ballpark "upper bound", the convective heat transfer coefficient for forced air is ~ 100W/(m^2degC), which means that assuming that the radiator fins are 100 degC above the air temperature, in order for the fins to transfer 1MW of power to the air, you would need an area of
1MW == 100W/(m^2degC) * 100 degC * area m^2
==> area ~ 100m^2 of surface area in the radiator, which doesn't seem unreasonable (a radiator 1m^2 area * 10cm deep, made up of thin plates spaced 1mm apart has this total surface area).
So they Veyron dissipating ~ 1MW in waste heat at 400km/h doesn't fail any of these basic sanity tests.
More complicated though is the interaction between the stages considered here. For example, how do we interface our 1m^2 of copper with our 100m^2 of radiator? Making the radiator fins thin lets us pack more surface area into the same volume, but also makes it difficult to keep the "edges" of the fins at a sufficiently high temperature so that they pull their weight transferring heat to the air: since the "copper tubing" has significantly less surface area, it only contacts (and thus transfers heat to) the radiator fins "sparsely".
My point may not have been as strong as I thought, but that tends to support it - airplane and boat engines do need to operate at max power nonstop, so they're designed for it. Consumer automobiles usually just accelerate for a few seconds and cruise at relatively modest speed, and I'm pretty sure their cooling and other related systems are designed around that.
That's because you usually have a speed limit. If you have a car with say about 100 hp your top speed will be about 200 km/h and that is a speed you can drive at for extended period on an Autobahn in low traffic. A more powerful car will of course make it harder to keep the pedal at the metal.
FWIW, a single Boeing 747 engine does about 100MW. Such an engine can be considered to "fit on a truck" for some definition of truck.
Also consider that much of the size is due to the fan on the front (which is not part of the actual engine power plant), which makes the engine's area in the plane transverse to the axis of rotation seem larger.
However, jet engines have the advantage of burning their fuel directly in the air that is flowing through the engine, which results in an extremely rapid transfer of heat to the air compared to other (this is why 10 Boeing 747 engines == 1 GW coal/nuclear plant which is "buildings" in size).
Note that it converts ~100kW thermal into ~37-47 kW electric. It also has high air flow. I suspect that means that they are aiming to make their fusion reactor small enough that it can replace the burner section of the turbine.
Thermal transfer is still going to be a challenge, unless (Idea!) they are planning on spraying water into the airflow and using heat from neutron moderation in the water to provide primary heat transfer. Hmm, I wonder how much water you would need for 14 MeV neutrons? Let's see, half-value layer is around 10 cm, so if you threw a 40 cm thickness of water across a neutron flux, you'd absorb most of the heat (you could probably catch the rest in the duct casing). That's a lot of water in a pretty small space, but physically possible.
Note that the above is a seat-of-pants calculation and should not be taken as accurate by any means.
Based on the image of the machine, this is a magnetic mirror with neutral beam injection. Mirrors were some of the first plasma confinement devices. An issue they have is that they lose charged particles out the ends in a way that depends on the ratio of perpendicular to parallel velocity and the magnetic field strength. It may be that they think they can use the neutral beam injectors to inject the fuel in such a way that it's well confined in the machine...
Never mind, another linked article says that the injectors are only used for ignition.
374 comments
[ 3.1 ms ] story [ 439 ms ] thread"U.S. submarines and aircraft carriers run on nuclear power, but they have large fusion reactors on board that have to be replaced on a regular cycle."
US naval vessels have fission reactors, not fusion. I'm also pretty sure that although they would refuel a reactor, that rather than replace the reactor they'll likely replace the ship.
[0] - https://news.ycombinator.com/item?id=8458426
Lockheed Martin is, indeed, saying they have a workable fusion reactor. Author of this article is the one that's confused.
http://en.wikipedia.org/wiki/High_beta_fusion_reactor
This is not the first time they have gone public with this - Charles Chase gave a talk at Google X last year, recorded and publicly-available:
https://www.youtube.com/watch?v=JAsRFVbcyUY
Basically you catch electrons flying out of the plasma arc (where fusion is taking place), and ground them back into the plasma (which is positively charged).
Umm its largely theory at this point.
I do think what they are doing is interesting. If its like the Gas Dynamic Trap or Tandem Mirror it has promise, atleast from the fundamental physics point of view. Researchers in Novosibirsk had encouraging results in the last 5 years. They still have a long road ahead to get to fusion-relevant temperatures, but we are staying tuned to this one.
So that would power 50k to 100k typical houses in the US... not bad!
Wouldn't the effect of its smaller mass be that the container will have to be replaced more often, more or less in the ratio of the masses of the machines?
sigh To the extent this is true I suspect those "large fusion reactors" are tuned not so much for generating electricity and a great deal for annihilating whatever the carrying missile is pointed at.
But never mind fuzzy thinking at Reuters right now. This is amazing news if holds up. Fingers crossed.
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fission reactors on board that have to be replaced on a regular cycle.
Submarines and carriers run on a fission reactor. And it powers everything - drives turbines for locomotion, electricity...
I'm well aware of the fission reactors in large military ships, but if there is any application of nuclear fusion on them then pretty much the only option today is thermonuclear warheads. It would be really nice if that's about to change.
http://en.wikipedia.org/wiki/Nimitz-class_aircraft_carrier#P...
[1]http://en.wikipedia.org/wiki/Refueling_and_Overhaul
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fission reactors on board that have to be replaced on a regular cycle.
I don't think so.
The difference is that fission is taking heavy elements, breaking them apart and using the released energy. Radioactivity, Thorium, Uranium, Plutonium, all the yucky stuff. Research has been going on for decades into making these reactors safer, and with breeder reactors and modern conventional designs that appears to have been achieved. Nevertheless, they appear on their way out anyway.
Fusion fuses together light isotopes and uses the energy thus released - they basically do what the sun does. And are clean. For various definitions of clean.
And if you're wondering how they are the complete opposite yet both work, it all pivots around iron. Copying from Wikipedia on iron:
> Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where the production of nickel-56 (which decays to the most common isotope of iron) is the last nuclear fusion reaction that is exothermic.
And yes, that means that everything in this universe will one gigayear end up right at the pivot between fission and fusion, ever onwards oscillating further towards it. Our universe is ever tending tiwards irony. A pivot that we're probably going to see humanity go through too, but in a different way. Hopefully sooner rather than later.
This article is the cognitive equivalent of parrots squawking, because they don't even understand why the news actually is news.
People calling this a "typo" are giving too much credit. It could be a mistake, but the whole point of having an editor is to catch typos and mistakes! And it's a simple, short article!
http://blogs.wsj.com/venturecapital/2014/08/14/vc-funding-y-...
Again, I could be wrong on my physics but as I understand it, fusion power is still a question of "is it even possible" whereas the hyperloop was more of a question about socioeconomic will.
There's lots of other problems too - I don't think they have a well-tested solution for adding fresh fuel and disposing of the fused products on an ongoing basis.
http://iopscience.iop.org/0029-5515/48/8/085002
There have been steady incremental advancements in the field. I think your knee jerk reaction is coming from "cold fusion" which does have the problems you are talking about. Two very different fields.
The main issue with fusion is that it can't be weaponized and therefore doesn't have a nice military grant behind it. It lacks a Manhattan Project. It's probably always been "a few years from now" under the assumption of adequate funding.
The events following this announcement will probably be a good time to form a concrete opinion on fusion. It's being given a fair chance, so lets first see if it can prove itself.
This is promising stuff. Most of the other reactors have been Tokamak reactors - which are better suited to research and not practical applications, so we could be seeing some interesting results here.
RF and neutral beam heated steady reactor with very high mirror ratio and superconductors.
I can't see how heat energy is supposed to be flowing out of that plasma envelope yet the magnets are supposed to stay at near-zero temps?
"Until now, the majority of fusion reactor systems have used a plasma control device called a tokamak, invented in the 1950s by physicists in the Soviet Union. The tokamak uses a magnetic field to hold the plasma in the shape of a torus, or ring, and maintains the reaction by inducing a current inside the plasma itself with a second set of electromagnets. The challenge with this approach is that the resulting energy generated is almost the same as the amount required to maintain the self-sustaining fusion reaction."
We always find a reason to go to war. Or it finds us and we return the favor.
Because a whole fleet of fusion air carriers, battleships, submarines and bombers versus a conventional army has plenty of implications in term of autonomy, reach, etc.
But on the other hand, there is a such demand for energy everywhere that it would really hard to morally ban all the civilians applications.
Energy use of the US (2011): 25,484 TWh Power needed: 2,900 GW = 25,484 TWh / 365 / 24 h * 1000 Number of 100 MW CFRs: 29,000
Civilian use will happen. The benefits are just much to great. There will be regulation and oversight for them. But you won't need one in every truck. It's overkill. As you can see from the above calculation 29 thousand CFRs could cover all the US energy needs. So there will be hundreds of thousands worldwide. It will be hard to keep all of them under control But this would basically solve all of humanities energy problems and decrease CO2 production, and destruction of the environment from mining immensely.
Having large amounts of energy available enables new weapon systems to become feasible: high powered lasers, coil guns and rail guns. They can be added to any air, land, or sea vehicle that's above the size of a small truck.
Ships are pretty large anyway and aren't as restricted as land or air vehicles when carrying big machinery. Aircraft carriers won't change so much. You can build them a little smaller and their defensive weapons might improve. Nuclear submarines otoh could be built as small as modern diesel powered subs like the Dolphin class.
You could build a drone with an extremely long loitering time. If it uses a laser or rail gun, it will also have lots of ammunition. Instead of carrying a couple of hellfire rockets and having to refuel after several hours it could stay in an area for months.
Cheap clean electricity means no-one needs to care about the Middle East for starters — most of the fighting there is superpower proxy fighting — e.g. Assad would be gone if not backed by Russia and China, so no Islamic State. No Oil, no Iraq war x2. No oil, no Hugo Chavez for that matter.
I’m sure I’ve heard that somewhere before…
The mainstream magnetic confinement community has been very cautious about overhyping lately. Unfortunately, the over zealousness of groups like this and NIF saps credibility from them anyway.
The team acknowledges that the project is in its earliest stages, and many key challenges remain before a viable prototype can be built
This falls under the xkcd 10 year plan:
"we haven't finished inventing it yet, but when we do, it'll be awesome"
http://xkcd.com/678/
That's the standard issue joke. "Nuclear fusion has been just ten years away for the last fifty years"
It is so common as a joke I'm surprised the article didn't mention it.
10 - 765,000 results
15 - 9,730 results
20 - 793,000 results
25 - 8,750,000 results
30 - 709,000 results
35 - 4,700,000 results
40 - 472,000 results
45 - 10 results
50 - 493,000 results
Definitely not 45 years away.
They're more of a rounded (hence the clustering at or away from given numbers) measure of the remaining 'effort' versus 'difficulty'. Very likely there is some absolute time required (experiments take time to run), but throwing more people (and more importantly, more resources to run experiments and gather data) at the problem /would/ get to an end result faster (though how much faster is open to debate; it's sort of like asking how much effort does it take to win a top 30th percentile prize from a lottery).
Compare this with ITER, where they still don't know what material some fairly critical components can even be theoretically made of. It's just night and day.
the Skunk Works and EMC2 haven't even reached the stage where they would face the same issue of material - all of them would ultimately have to contain the same type of fast neutrons and there is no good known material to do it.
I'm sure someone at ITER has done the maths and figured out how long that core can last under operation before it becomes too brittle to keep the coils together, but I wouldn't be at all surprised if that was one of the reasons why ITER isn't designed for long-term power generation.
The problem is related to how you get rid of the post-fusion products. ITER is designed with divertor plates in the floor to scoop off the fusion ash and shunt them outside the core. My understanding is that these plates have to be a) solid, and b) capable of withstanding contact with absurdly high temperature plasma. There are some candidate materials which are hypothesised to be able to stand up to temperatures somewhere near what's required, but to my knowledge (which admittedly might be out of date) nothing's actually known to be suitable.
The reason I don't think the neutron absorption issue is such a problem here or on Polywell is because with a smaller reactor, replacing the vessel when it stops working is a far less terrifying prospect, even if you have to do so every few months. And even this is far less insane than some of the proposals for how you might do commercial laser fusion. That's just bananas.
Beyond that, you actually want some fast neutrons from the reaction to give you a tritium source.
They dismiss the concerns of the scientific community. Why shouldn't they? They're getting rich off of the ignorance of generals and venture capitalists.
I'm guessing this means that they will try and maximize profit rather than maximize cheap and clean energy for the entire world. That is a bit disappointing if true.
I don't understand what you expect? You want them to give it away for free? After paying very intelligent, expensive engineers decades worth of salaries to create it? You want them to create a fund where people can donate their hard-earned money for this noble goal? I'm sure you could give them a call with that idea, or you could create your own fund, even.
Or you could badger your "government" to fund such a project. Seeing as government is a very good analogy for a bunch of people giving their collective earnings for society-level goals. Let me know how that goes.
A typical thermal power station has an efficiency below 50% for electricity generation, so the plant dissipates at least as much heat as it generates electrical power.
I wonder how you could get rid of 100MW of waste heat from a volume small enough to fit on a truck. That's a heat flux of more than a megawatt per square meter of surface area.
Or are my assumptions way off?
But what gets me is that they are burying the lead. No fusion reactor of any size has reached sustainability...so why is the story here talking about size at all? Small size would be a very nice added bonus; fusion reactors that don't consume more energy than they produce are earth-changing.
"But on the physics side, it still has to work, and one of the reasons we think our physics will work is that we’ve been able to make an inherently stable configuration.” One of the main reasons for this stability is the positioning of the superconductor coils and shape of the magnetic field lines. “In our case, it is always in balance. So if you have less pressure, the plasma will be smaller and will always sit in this magnetic well,” he notes."
As far as I understand this (IANAP), they're saying that smaller size = less pressure, and that helps their design to work (in theory).
[0] - https://news.ycombinator.com/item?id=8458524
That's exactly what I was thinking. They'd better call the Truck a submarine, though.
One can imagine these to be simple drop in replacements for existing coal plants with existing cooling infrastructure,which would be a huge environmental win in places where those are still built.
400km/h ~ 100m/s
air intake cross section ~ 1m^2
==> ~ 100m^3/s of air going through radiator
density of air ~ 1kg/m^3
==> ~ 100kg/s of air going through radiator
specific heat of air ~ 1kJ/(kg * degC)
==> 100kJ/(s * degC) == 100kW/degC
temperature difference between air entering and leaving the radiator ~ 10degC
==> 1MW
So handling 2.5MW waste heat doesn't seem out of the question from this analysis.
As another ballpark "upper bound" analysis, consider that copper is one of the most thermally conductive materials, with thermal conductivity ~ 400 Wm/(m^2 degC), let's round that up to 1kWm/(m^2degC).
Let's assume that there is a thermal conducting surface of 1m^2 (i.e. the surfaces of the pipes that interface with the radiators). Let's assume that the copper is 1mm thick (= 1m/1000). Let's see what temperature difference would be needed to transfer 1MW of heat across:
1MW == 1kWm/(m^2degC) * 1m^2 * (1000/1m) * deltaT degC
==> deltaT ~ 1 degC
which again doesn't seem out of the question.
As another ballpark "upper bound", the convective heat transfer coefficient for forced air is ~ 100W/(m^2degC), which means that assuming that the radiator fins are 100 degC above the air temperature, in order for the fins to transfer 1MW of power to the air, you would need an area of
1MW == 100W/(m^2degC) * 100 degC * area m^2
==> area ~ 100m^2 of surface area in the radiator, which doesn't seem unreasonable (a radiator 1m^2 area * 10cm deep, made up of thin plates spaced 1mm apart has this total surface area).
So they Veyron dissipating ~ 1MW in waste heat at 400km/h doesn't fail any of these basic sanity tests.
More complicated though is the interaction between the stages considered here. For example, how do we interface our 1m^2 of copper with our 100m^2 of radiator? Making the radiator fins thin lets us pack more surface area into the same volume, but also makes it difficult to keep the "edges" of the fins at a sufficiently high temperature so that they pull their weight transferring heat to the air: since the "copper tubing" has significantly less surface area, it only contacts (and thus transfers heat to) the radiator fins "sparsely".
Also consider that much of the size is due to the fan on the front (which is not part of the actual engine power plant), which makes the engine's area in the plane transverse to the axis of rotation seem larger.
However, jet engines have the advantage of burning their fuel directly in the air that is flowing through the engine, which results in an extremely rapid transfer of heat to the air compared to other (this is why 10 Boeing 747 engines == 1 GW coal/nuclear plant which is "buildings" in size).
See slide 25 (page 13) of http://ronney.usc.edu/AME436S13/Lecture1files/AME436-S13-lec...
Note that it converts ~100kW thermal into ~37-47 kW electric. It also has high air flow. I suspect that means that they are aiming to make their fusion reactor small enough that it can replace the burner section of the turbine.
Thermal transfer is still going to be a challenge, unless (Idea!) they are planning on spraying water into the airflow and using heat from neutron moderation in the water to provide primary heat transfer. Hmm, I wonder how much water you would need for 14 MeV neutrons? Let's see, half-value layer is around 10 cm, so if you threw a 40 cm thickness of water across a neutron flux, you'd absorb most of the heat (you could probably catch the rest in the duct casing). That's a lot of water in a pretty small space, but physically possible.
Note that the above is a seat-of-pants calculation and should not be taken as accurate by any means.
Never mind, another linked article says that the injectors are only used for ignition.