Hotter than the Sun: JET – Earth’s biggest fusion reactor, in Culham I’m in a room that, in normal circumstances, is not fit for human habitation. It features a number of big red buttons surrounded by illuminated yellow rings – just in case. “Push button to switch off Jet. Press only in case of extreme emergency,” the signs read, informatively. This is the Torus Hall, a 40,000m3 space the size …
When I first went there in the early 1990s there was a fair bit of humour and caution about the place.
Put simply, if there is a serious plasma breach at running temperatures then the plasma was not going to stop for much - walls, buildings people. The humour at the time revolved around how fast you could run and whether or not you thought suddenly becoming religous would be a good idea or not.
Yes, but the main point is that after such an event, all fusion would stop dead as the plasma dissipates: exactly the opposite of a hydrogen bomb. So people very nearby would be fried, but neither explosive power nor radiation would be an issue outside the site.
I was there while JET was being built. They pointed out that the safest place to stand when JET was running would be right outside the concrete containment building with your back to the wall. Radiation from JET would be negligible and you would be protected from half the normal dose of cosmic rays.
I'll refrain from my Brexit rant for today...
seems like "bigger" is better for tokomak, as far as efficiency goes.
I wish them luck, though I have my doubts about the practicality of using a scaled up tokomak to get 500MW out of 50MW of laser+microwave+whatever.
Keep in mind, that the thermal efficiency of a power plant might be 20-25%. So in theory, the 500MW (thermal) plant is generating only about 25% of that as electricity. Then 10% would be required to sustain the fusion reaction, leaving 10-15% for powering light bulbs and computers etc.
it's all about the physical capabilities of devices (assume steam system) that can turn thermal energy into electricity. Because we're dealing with the limits of known materials, you probably won't go over 1200 psi, or about 550 deg F (as I recall). The carnot efficiency at that temperature is around 30% as I recall, meaning practical efficiency is a bit lower, hence the 20-25% number [which is a ballpark guess, I've been out of the power generating world for quite some time].
I can't think of a more practical way to turn gamma+neutron radiation into power than a steam system. Maybe someone has come up with a better way, but water absorbs radiation really well, and if you have THAT much, then all of that energy needs to be absorbed and turned into "something" that can become electricity.
So you've got ginormous "gamma panels" that are like solar panels? 20% efficiency I think, is the best you can do. So not much better, and they're more expensive and more environmentally 'unfriendly' from all of the toxic materials you'll need to make them.
Anyway, steam is the most practical approach to make 'trons' out of 'gammas'. So we're looking at HALF of the electicity going back into the plant.
I'm not complaining so much about that, as pointing out the gross inefficiencies of the tokomak design. Not saying "don't bother making them". I'd love to spend 99 watts to get 1 usable watt out of fusion energy. But let's be realistic and manage expectations a bit, too.
Tokomak is probably not the best method to use in order to get fusion power to work. There are better methods, and some of them are very very interesting. I think that maybe so much money has gone into Toikomak designs that someone out there wants to see a payoff, one way or another, dammit, and there better be SOMETHING or there's HELL to pay!
Or something like that.
"Incontrovertibly you know so much better than these scientists, so why are you not running this project?"
Well, on the one hand there's a certainty that some version of fusion can eventually produce useful energy. We're just not sure when we'll get to it.
The whole thing has been sold on the idea of "harnessing the power of the Sun", but it turns out that the Sun generates net energy at about the same rate, per cubic metre, as a compost heap. Less indeed than a human body (100 W per person). This explains the use of deuterium and tritium: plain old hydrogen is NBG for our purposes because it won't fuse fast enough. The reaction time for two protons becoming deuterium is on the order of a billion years. The Sun has jillions of protons to work with, so it generates enough energy to warm our planet. To get a useful reactor, we need to use the rarer isotopes of hydrogen and up the reaction temperature by a lot. Eventually, maybe, we'll have a useful reactor that's smaller than, say, a skyscraper.
Maybe.
Scaling is nearly always more efficient in production. But more costly in deployment/construction. You do get diminishing returns in most systems though. Sometimes it also depends on what you mean by "bigger", is 100 size 1 units bigger or smaller than 1 unit of size 100?
"Eventually, maybe, we'll have a useful reactor that's smaller than, say, a skyscraper."
Skyscraper sized - if we stick with Tokomak, yes, could be.
But of course, they SHOULD do it. At least one. As a proof of concept.
Like the first 'general use' computer, which was ginormous and had to be programmed by re-wiring it. That wouldn't be the specialized 'Collossus' machine developed by Turing and the Bletchley Park group [I don't know how that one was programmed, exactly] which was not 'general purpose', but still pretty damn good at the time. I think the first 'general use' computer was Eniac, which had to be re-wired to re-program it. And it was ginormous. That's the point.
As for my preference, there's a design that's based on keeping the plasma flow all at the same velocity, that twists and turns in somewhat unusual ways, producing a 'ribbon' effect as I recall. I can't remember what it is called, though...
And there are other possibilities with 'linear' rather than 'cyclic' accelerators.
And I don't know if they're at least looking into RESONANCE ENERGIES and other physical effects to assist with the fusion process. A linear system could employ something similar to a 'travelling wave tube' to bunch the protons/deuterons together at ideal energy levels, as one example. It would be a type of 'resonance confinement'.
Anyway you'd think they'd be talking about this stuff if it were being done, right?
Talk on JET at the IET last night.
Power out/Power in is "Q". Jet manages a Q of around 0.6. ITER is targetting 10. But this is just the plasma power in/out ratio. It ignores the power used by the excitation systems and, of course, losses in energy extraction for Useful Work.
For a commercial system, you need a Q of 30. So ITER is the next step on the road towards that. But it won't get there.
The Stellerator is the interesting shape you describe. The (quite believable) view of the tokamak guys is that they will be very difficult to maintain given their shape.
@ Ishtiaq
It so happens that I live near leading boffins of ITER and they do not believe they can reach anywhere near a surplus of energy .... simply, because the conditions are so extreme that to keep the plasma going for more than mere seconds they have to replace have the bloody housing, while the plasma is still active (you and I know this is impossible).
Their prototype was due for 2014, alas, that failed miserably ... since then, they try to win time ... ITER is a money well, many governments backing, so where is the incentive ? There is none ... and the problems they face are nothing like humanity has ever faced before, they still cannot cool the chamber appropriately and they know that they are there to give fission an extension of life .... how would that make you feel ? In their situation I commit suicide ...
And the idiots on here who claim whatever, ITER cannot make their system run for more than 7 seconds, have tried for a decade ... any material they use deteriorates too quickly ... make it bigger, sure, good luck, more Watts to dissipate ...
Again, I know REAL BOFFINS from ITER, their kids go to the SAME SCHOOL AS MINE, I see them EVERY FUCKING DAY.
Fusion is a mirage that the fission idiots have cast on us to win time so they can use up all the uranium that is economically feasible to harvest ... and fission by products will be around for not centuries but millennia, but the fission scum don't get to pay the price, we pay it, like we paid for the reactors, the profits are, for the most part, already in private hands ... they need to hold on some more, by any means, doesn't matter ....
French Nuclear Industry has to come up with something like €450bn. 250 to dismantle existing reactors and 200 to build new ones, EDF and Areva are almost bankrupt, who is gonna pay that ... the French ... merci, hein ! The worst thing is, reactors need water, lots of water .... heard of climate change ? The flow in rivers in France already causes enough trouble to the existing fission reactors ...
To the downvoters, you are wrong, you do not believe me ...
> It so happens that I live near leading boffins of ITER and they do not believe they can reach anywhere near a surplus of energy
ITER was never intended to produce a surplus, it's just another step on the road to working out the bugs in order that the next iteration will be more likely to do so.
ITER was never intended to produce a surplus, it's just another step on the road to working out the bugs in order that the next iteration will be more likely to do so.
THEY WERE SUPPOSED TO HAVE A WORKING PROTOTYPE BY 2014 that would "survive" mere seconds .... not ANYWHERE NEAR that yet.
The worst is, these guyz are the top boffins when it comes to fusion, they banked their professional life on it, and they have hurdles in the physics, that are way beyond their imagination, Ok, and political ones, too - Massive project with lazy arrogant civil servants....
Again, if you have a precise question, I will forward and get the answer ... on here.
Anybody who knows anything about large projects knew better than to believe a 2014 date for exothermic ITER. It's well known that you have to provide dates that are near enough to make a politician wet their pants to get budget for this sort of thing. It's also well known that controlled fusion is a hard nut to crack - we've been trying since ZETA in 1957, after all. And yes, there are surely materials science problems, which is why you have to contain the plasma electromagnetically so that it never touches the vacuum chamber's walls. That's been understood since 1957, as well. And that's the tricky part. The problems aren't physics, the physics is well understood - it's all engineering.
"The worst thing is, reactors need water, lots of water .... heard of climate change ? The flow in rivers in France already causes enough trouble to the existing fission reactors ..."
That's because they used shallow water supplies which got to warm during a heatwave.
A problem easily solved, you use these things called cooling towers, lakes and dams.
"Smart arse, do you have a question for the boffins ?"
No, I have a question for you. Do you think insulting people is somehow a sign of your intelligence and superiority? Your post is full of inaccuracies and nonsensical ranting.
Now go away, have a nice rest and then try to engage in conversation and debate without looking like an arse.
Has anybody sat with a geiger counter downstream of Drax?
Didn't coal ash or flue gas contain usable amounts of germanium I've got an old 60's science book somewhere that says so,,,, all these legacy power stations must have kept Mullard, NKT, GEC, Ferranti etc wallowing in germanium ..
Mines is the one with the OC44/2N1302/AC127/AC128's in the pocket... incidentally the germanium NPN 2N1302 work well in {google it} Joule Thief due to the low VCEsat as well as computers :)
I think you've confused Nuclear fission - braking apart very heavy elements. With Fusion - Squishing light elements together.
Fission has ben practical reality since 1956 when The world's first commercial nuclear was connected the National grid in 1956. I went to produce produce power for 2005 without significant issues or problems.
Also roughly 70% of Frances's base line electricity comes from conventional fission reactors.
The JET (Joint European Torus) has been researching not only how to squish Hydrogen in together using electromagnetic plasma confinement. The main with fusion if stupendously high temperatures which can only generated by using Extremely large electromagnets. So large they use more energy to create the required confinement field then resulting fusion of the hydrogen fuel releases.
The electrically charged plasma dissipates as it heats up meaning the magnetic confinement dissipates as it heats up. This the main barrier is keeping the plasma in state of fusion for longer periods making heat for electricity possible.
"ITER is a money well"
that's one way to put it, yeah.
Back to my original point: They need to use something that's NOT a Tokomak. Thanks for pointing out the bit about replacing the housing after operating for a short period of time. that's not something that ended up in the article.
It's also why I would favor a linear design, embedded within a tank of water, which would act like heat exchanger and boiler, or just heat exchanger if you want to use a primary/secondary system like a PWR fission plant. Radioactive steam, due to neutron activation of various things in the water, is kinda, uh, bad.
The problem with a linear design is you'd have to make THAT large, too, and put lots of fuel through it, just to get it running. That might frighten the scientists because 'too much fuel' could become an H bomb. yeah, no risk involved in coming up with a design. However, the advantage would be the 'continuous operation' aspect. You'd have to magnetically and/or electrostatically confine the plasma, but you wouldn't have to worry about bending its direction of travel, nor the 'twisty/turny' aspect of having the outside portion going faster than the inside portion. You could use resonant cavities to 'bunch' the protons at ideal energy levels, and thereby allow their own energies to confine the fuel into tight enough bunches to cause fusion to happen THAT way. But I can't see this happening in a short distance, and I'm not sure how long the thing would actually have to be. CERN long? probably not, but if nobody builds the thing, how would we know?
"Keep in mind, that the thermal efficiency of a power plant might be 20-25%."
Er, no.
The efficiency of a modern coal fired power plant is about 33%.
The efficiency of a modern natural gas fired power plant is about 60%.
The reasons to move away from fossil fuels for electricity isn't efficiency, as typical solar panels are a bit under 20% efficient. The reasons to move away from fossil fuels are (1) consumption of a limited resource that has other uses and (2) collateral damage to the environment due to the extraction from the ground & the effluents from the power plants like CO2, mercury & ash (in the case of coal), etc.
(regarding the post by 'The Man Who Fell To Earth')
Uh, I visited the first link and did not see any of that information. The 2nd one was interesting [keep in mind I was talking about steam plants, not gas turbines].
I might as well give a bit of background on max efficiency:
Carnot Efficiency: https://www.e-education.psu.edu/egee102/node/1942
Here are some calculations based on Carnot efficiency.
For a 1200 psi steam plant, appx 550 deg F with 60F rejection temperature - that would be 1010R and 520R, approximately. Yeah I'm using deg R. deal with it. Would you prefer an El Reg unit?
max efficiency = (1010R - 520R) / 1010R, approximately 44.5%
That's the theoretical maximum assuming 100% efficiency everywhere else. A bit better than I expect, actually.
Of course In actual practice it's considerably lower than this. So achieving better than 30% is actually VERY good, so I won't doubt your claims outright.
But if you assume ~30% total efficiency instead of ~25%, you STILL end up using a third of that electricity just to run the fusion reactor. And THAT was my point, along with pointing out that Tokomak is probably NOT the best design for an actual power plant.
As for overall plant efficiency, you have turbine blade efficiency, the effects of condenser vacuum [or lack of it], delta-temperature across the condenser, generator efficiency, secondary steam systems, superheaters, and power required to run all of the support equipment (in particular all of the pumps, like cooling water pumps, and primary coolant pumps for a nuke plant).
And when you consider that 70% of the thermal energy goes out through the cooling system, those pumps have gotta be BIG. A high 'delta T' on the condenser would reduce its efficiency even more, so the flow rate for the cooling water has to be MASSIVE to keep efficiency up. Big pumps, with big electricity consumption, in other words.
Again, I've been out of the industry for a while. I remember what I've worked with. So kudos to steam plant makers who've squeezed an extra few percent efficiency out in the last 30 years. Well done.
Of course gas fired plants would have higher efficiency than steam plants, because they're not limited by the physics of steam.
But good luck transferring a bunch of gamma energy into a gas.
Nuclear aircraft were tried, at one time, and that one big problem of transferring nuke heat into air for a jet engine's turbine cycle became impractical. Sure, you COULD do it, if the heat transfer surface were 'big enough'. You'd need something that could absorb gamma AND neutron radiation, and would tolerate the higher temperatures. And pressurized water would land you back in the same realm as a fission plant. So there ya go.
And that was my point all along [so thanks to everyone for all of the thumbs down, a testament to your ignorance of practical applications in the realm of power plant engineering].
In answer to another question, the only reason they don't hire _ME_ is because I don't have their "lovely academic pedigree". After all, a paper pedigree makes you SO smart these days... [academic arrogance, yeah]. And yet I see it often enough, where "those who can't, teach". In the IT realm, professors who call themselves 'programmers' generate some of the most impractical, inefficient, and unmaintainable code I've ever seen. In Python. [used to be BASIC]
Question: how many people in this forum have ACTUALLY OPERATED a nuclear reactor or even a steam plant? (I have, just sayin')
i've come to believe that the tokomak fusion reactor is a technology that's destined to go straight from "experimental" to "obsolete" without ever stopping at "viable". (Much like Uber's business model.)
Solar cell and battery technology are both improving year on year. Currently it's viable for maybe 3% of consumers to go off-grid using this technology. In a couple of years, it'll be 6%. In a couple more, 10%. By 2030, something like 75%. And the tokomak still won't be viable even on an experimental level.
By the time it is working, all our power stations will be burning agricultural waste or methane and actively reducing pollution. Nobody will need a new, big, capital-intensive power station, no matter how clean it is.
seems like "bigger" is better for tokomak, as far as efficiency goes
Nope. It's a function of size/plasma pressure.
Recent engineering dictates smaller is better. Higher pressure, smaller size - cheaper to build. It's actually why ITER's budget is teetering on the edge of death march. There's a couple of projects (in the US and the UK, separately) building these reactors with commercial rather than state funding.
Also high temp superconductors are playing a big role.
"Also high temp superconductors are playing a big role."
the fact that they're using superconductors are even NECESSARY is a big problem in and of itself.
Gamma radiation disrupts superconductivity. The primary energy output of a fusion reaction is GAMMA ENERGY, and the secondary is neutron energy. This would be due to conservation of momentum, actually. And let's not mention the COOLING REQUIREMENT for these superconductors. Consider that the closest thing to a gamma source will absorb MOST of the energy, like the innermost part of the walls of the containment vessel. Magnets would be right outside of that, I'd expect. They'd get a nice heavy dose of gamma and neutrons, and heat up rapidly [which we know is bad for superconductors also, not just the effects that gamma radiation have on superconductivity].
So there ya have it. The very operation of the reactor causes its confinement mechanism to fail.
(it's another reason why I favor a more linear design, to limit the need for strong superconducting magnets that operate at extremely high temperatures, and also to rely more on electrostatic effects for confinement)
The SEM fusor is a kind of linear design: sidewards the deuterium ions and electrons are confined by a relatively modest magnetic field of about 1 or 1,5 tesla, and vertically by an electrostatic field generated by a couple of charged rings and spheres. In the computer simulation the particles stay confined, with speeds up to 3E6 m/s (for fusion is needed about 2E6 m/s). As in a Farnsworth-Hirsch fusor, the ions move more or less also back and forwards towards the centre of the vacuum chamber, only now there isn't an inner grid. To find out if this is really an easy way of accomplishing nuclear fusion a real experimental setup should be built...
Sad as I must say this, on certain points Bob is correct, as much as he is annoying:
1. Size, for some reason they are obsessed with building bigger and bigger reactors. These designs run on Magnetism, anyone heard of the inverse square law.
2. Neutron/Gamma generation - this, I think, is the power generation lobby, all they know is steam generation for large scale systems.
There are other options for fusion other than D+T, such as Aneutronic reactions (He3, being one form), these typically produce ions from the reaction, which depending on the reactor type can be used to generate electricity directly from the reaction.
Many years ago I saw a weird conspiracy theory stating that the Tokamak was invented (in Soviet Russia) to bankrupt the West, as much as I hate to think that there is any truth in what a lot of these nut jobs are coming up with, in this case, there is a possibility.
The real issue with JET and ITER is what it is doing to Fusion research funding, they have been pouring billions in over the last few decades and while I definitely believe the research performed at JET has been very useful, ITER is a white elephant government funding vacuum.
Taking away funding from other concepts, the phrase "Don't put all your eggs in one basket!" comes to mind.
stating that the Tokamak was invented (in Soviet Russia) to bankrupt the West
lul.
If it was anything it'd be Stellarators the other way - it never ceases to amaze me how much new money goes into them despite being debunked as a potential future source of energy at commercial scale. The science of tokamaks is solid, and it's simple (which is the power of tokamaks versus say inertial confinement) even in engineering terms (it's a big vacuum chamber and some magnets at its most complex), what is not solid is getting enough funding into disruptive engineering projects. If there's conspiracy anywhere it's not dropping ITER like it's hot 3-4 years ago. Now the problem is ITER is a giant boat anchor of a project which has left the global fusion community what we call in poker pot committed. It's almost as if so much money has been spent on it that they have to keep spending more money on it and go all in until it's finished. It worked with the LHC and ISS so it must be the solution with ITER. Problem is ITER is being quickly outmoded, and the budget and timeline is getting more insane. It's too big and expensive for its own good and somebody needs to put a stop to it - maybe Trump might be useful for something after all.
"Try that in Centigrade and you'd be nearer the mark."
uh, what? I could run the calculations in 'El Reg' units and it wouldn't change the efficiency. duh.
"The pressure for modern supercritical coal and oil plants is about 2x that."
2400psi? if you base that on the mollier diagram, that wouldn't be a whole lot hotter.
https://en.wikipedia.org/wiki/Mollier_diagram
It's a bit hard to read in that zone, but the temperature would be just under 1100R as I recall. The boiling point at 2000 psi was in the 600F range (1060R), if I remember correctly. the temperature change for a large pressure change in that zone is not very large. A few deg F gives you a major change in saturation pressure, maybe even doubling it.
So now by doubling the steam pressure you change your temperature by about 60F or so, which isn't a whole lot for the Carnot efficiency. You'd do better by trying to pre-cool the coolant more, get condenser vacuum up.
Not to mention the kinds of materials you'd need to handle 2000psi steam at 600F. But like I mentioned, it's been 30 years or so since I was "in the industry" so to speak. Tech has advanced a bit. but it hasn't managed to break the laws of physics. You still have limitations based on the physics characteristics of water and steam.
…must …not …step …away …from …European …Union. …Can’t …afford …to …do …this …on …our …own.
Being a bit disingenous here, this is not an EU project and the EU couldn't afford to do it on their own either.
ITER is an international project, proposed by General Secretary Gorbachev of the former Soviet Union to US President Reagan in 1985. Work started between the USSR, the USA and participating EEC nations in 1988. Currently, participation is the EU, China, India, Japan, Korea, Russia and the United States.
While there are sound economic arguments for remaining in the Single Market, there is no convincing reason that we cannot agree to continue to participate in ITER after leaving the EU.
@werdsmith
It's one of Theresa May's red lines - complete removal from the jurisdiction of the European Court of Justice. This article from the Grauniad might help - extract below.
What’s special about Euratom compared with other EU regulatory agencies?Unlike the dozens of other, equally sensitive, regulatory arrangements for industries such as aviation or pharmaceuticals, Euratom has been singled out for special treatment because it is not technically part of the EU. Instead, the treaty that established this body to coordinate Europe’s civil nuclear energy industry was born in parallel with the birth of the European economic community in 1957.
Britain’s participation in this largely untouched relic of atomic camaraderie therefore required a separate legal relationship with the European court of justice to enforce it. Since Theresa May has committed the country to severing all ties with the ECJ, it also required a separate clause announcing our intention to leave in the article 50 legislation that triggered the start of the two-year Brexit process in March.
Icon for when things go into meltdown...
As to whether a country can afford to do this on it's own, I seem to recall that the proposed budget for ITER was 35billion dollars and there was much huffing and puffing about the cost. Remember this cost is between many nations over many years.
Lets put 35billion in context it is about what the US spends on defence per MONTH.
must ....blame ... everything ... on ... Brexit ... when ... I... don't ... actually ... have ... a ... frikkin' ... clue ... what ...I ... am ...talking ... about.
JET's future was handed to the UK Govt on a plate and tipped in the bin during the noughties, allowing the french to take the project's future right from under our noses. If you want to go kick something, find Mandelson, for it was he.
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
