# Will the new ITER fusion reactor actually work?

I am hopeful that the new large ITER tokamak style fusion reactor will be successful.

According to wikipedia:

The ITER fusion reactor itself has been designed to produce 500 MW of output power for 50 MW of input power, or ten times the amount of energy put in. Hereby the machine is expected to demonstrate the principle of getting more energy out of the fusion process than is used to initiate it, something that has not been achieved with previous fusion reactors. Construction of the facility began in 2008 and first plasma is expected in 2018.[6] When ITER becomes operational it will surpass the Joint European Torus which is the current largest magnetic confinement plasma physics experiment in use.
http://en.wikipedia.org/wiki/Iter

i would appreciate any comments on the chances of ITER actually producing more energy through fusion than the energy used to initiate fusion.

what is it about the design of ITER that leads researchers to predict a net production of energy, whereas other tokamak fusion reactors have as yet failed to pass the break even point?

jimgraber
Gold Member
ITER scientists are extremely hopeful and rather confident that it will work as planned, but no one knows for sure until it actually runs. The main difference between ITER and previous tokamaks is that ITER is larger. Experiments on previous tokamaks have shown and theoretical calculations predict that as the tokamak gets larger the energy out increases faster than the energy in. If this pattern continues to hold, ITER will produce more energy than it consumes. There are many complicated details, but that's the big picture.
Best,
Jim Graber

So this is like a perpetual 'motion' machine or am I getting it wrong?

Pengwuino
Gold Member
So this is like a perpetual 'motion' machine or am I getting it wrong?
No, perpetual motion machines do not require fuel. This does.

Think of how you would start a fire, you need just a little match, a little flame, and boom your fire is lit. You gave the fuel (paper and wood) a tiny bit of energy and it ignited to give a lot of energy. Fusion is really awful at this concept. So far we have to give massive amounts of energy for the fusion to give us energy back. It would be like having to set off a bomb just to lite your fire place.

^^ Thanks i get it now =)

There is another fact besides size. Iter, like the SouthCorean Tokamak ''K-Star'' will use super conducting magnets, therefore the energy lost by Ohms law, and Ohms heating is literally out of the picture. Im sure that adds up to reducing the amount of input energy.

jimgraber
Gold Member
There is another fact besides size. Iter, like the SouthCorean Tokamak ''K-Star'' will use super conducting magnets, therefore the energy lost by Ohms law, and Ohms heating is literally out of the picture. Im sure that adds up to reducing the amount of input energy.
Yes, there are many engineering details to make tokamaks more reliable and more efficient that still need to be discovered and tested. It might not work, but I think that's very unlikely. In my mind, the riskiest part of the whole business is whether taxpayers around the world will keep putting out the big bucks until it is obvious that fusion in general and tokamaks in particular will eventually pay for themselves. At this point, it looks like ITER has enough backing to be completed, but more than ten years to a live-fuel break-even test is a long time in politics.
Best.
Jim Graber

phyzguy
northernbear;3074497what is it about the design of ITER that leads researchers to predict a net production of energy said:
The main reason that ITER is expected to have a net energy production while other tokamaks have not is that ITER is simply larger than past tokamaks. Since energy is lost through the surface (which scales as L^2), and energy is produced in the volume(which scales as L^3), scaling up the size of the reactor inevitably improves the ratio of energy produced to energy lost. The attached slide shows how much larger ITER is than past machines, and the impact that this is expected to have on energy loss rates (and hence confinement time).

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I would like to ask, where did you get that pdf about the sizes of tokamaks?

That is great!, thanks a lot. BTW, what do you know about the Erasmus Mundus program in Fusion, I just remebered it because I saw the Gent University logo. Is it only focused on engineering and technology of Fusion?..or it also includes theoretical work on plasma physics?

phyzguy
That is great!, thanks a lot. BTW, what do you know about the Erasmus Mundus program in Fusion, I just remebered it because I saw the Gent University logo. Is it only focused on engineering and technology of Fusion?..or it also includes theoretical work on plasma physics?
Sorry, I know nothing about it.

As with all engineering processes, shutdown is a test of design.
How will ITER react to a shutdown or more seriously failure?
Most of us are aware that when stars die they do so catastrophically.
This is in fact a "star" which is going to die.
Maybe it's not big enough but everything dissappearing into a "black hole" is a superb plot for the next disaster movie! - Roland are you there?

mheslep
Gold Member
As with all engineering processes, shutdown is a test of design.
How will ITER react to a shutdown or more seriously failure?
Most of us are aware that when stars die they do so catastrophically.
This is in fact a "star" which is going to die...
Is fusion the only component of a star? Are their other factors comprise a star that are lacking in a terrestrial fusion reactor? What factors combine to make a star explode?

etudiant
Gold Member
No expert, but the problem of fusion devices has never been getting fusion to start, but rather how to keep it going.
Indeed, in the early days of hydrogen bomb research, the summary report about the progress of the fusion reaction was 'icicles are beginning to form'.
The ITER is most likely going to join a long list of interesting and useful fusion devices which generate some fusion reactions, perhaps for as long as a few seconds if they are lucky.
Shutting it down will not be a problem, all it would take is a minute air leak to allow the atmosphere to chill the very thin plasma essential for the fusion reaction.
As for stellar type explosions, the inside of ITER holds a high class vacuum, not superdense matter crushed by the gravity of a star. It could not explode, although the powerful magnetic fields needed to focus the plasma do put big stresses on the ITER structure.

mheslep
Gold Member
I suppose there is some chance the ITER HTSC magnets might explode in a quench event, like CERN's LHC did at start up.

Drakkith
Staff Emeritus
As with all engineering processes, shutdown is a test of design.
How will ITER react to a shutdown or more seriously failure?
Most of us are aware that when stars die they do so catastrophically.
This is in fact a "star" which is going to die.
Maybe it's not big enough but everything dissappearing into a "black hole" is a superb plot for the next disaster movie! - Roland are you there?
The amount of plasma in the reactor is on the order of a few grams. This will never explode or collapse into a black hole. If the reactor is suddenly shutdown, confinement is lost and the plasma simply impacts the wall of the reactor and cools instantly.

Ive read something that
total energy input to total
energy output suppose to
be close to 1:1 in ITER if
you count looses anywhere
in the system.But in any case
tokamaks similar to ITER are
going to be too expensive to
be competetive with most of
other energy sources.What is
concerning to fusion there is
proposition in Europe to build
HiPER for $100 mln.It is going to be 10 times cheaper tnan ITER.But still there is to many problems and expenses.Just uneconomical for nearest decades. etudiant Gold Member ITER is not a prototype, at best it is a proof of principle installation, a little like Mike was the US hydrogen bomb demonstrator, an installation, not a workable product. If ITER works reasonably well, there will be lots of effort spent to make useful reactors using the tokamak design. Imho, none of them has a prayer of coming close to the economics of current LWRs, despite the handicaps those installations bear. Maybe a conspiracy to make us accept solar power at$1/kw ;)

Drakkith
Staff Emeritus
total energy input to total
energy output suppose to
be close to 1:1 in ITER if
you count looses anywhere
in the system.But in any case
tokamaks similar to ITER are
going to be too expensive to
be competetive with most of
other energy sources.What is
concerning to fusion there is
proposition in Europe to build
HiPER for \$ 100 mln.It is going
to be 10 times cheaper tnan
ITER.But still there is to many
problems and expenses.Just
Keep in mind that our knowledge of the way plasma behaves in a device such as a tokamak is still increasing. ITER will only increase that knowledge and hopefully let us build workable fusion power plants.

Ryan_m_b
Staff Emeritus
ITER is not a prototype
IIRC the plan is for ITER to be suceeded by a project called DEMO in which a reactor capable of producing continuous electrical power will be built which will then lead on to the next project called PROTO which will be a prototype commercial nuclear fusion reactor.

In other words if all goes to plan ITER is the grandma of the first prototype.

Drakkith
Staff Emeritus
The key thing to remember for ITER is that it is the next step in a long line of research into fusion power. We've been trying to get fusion power to work for about 60 years. This may seem like it is a futile effort but the key is that we ARE making progress. The past half century has driven fusion reactors closer and closer to breakeven. It's a long slow process, but we are getting there.

I am pretty convinced that the humungous Tokamak that ITER is going to develop will work. The .pdf posted earlier - thanks Phyzguy - shows the logarithmic increase in plasma confinement time with size. "Bigger is better" is the name of the game.
If the physics works the engineering can be sorted out.
The old adage "... the difficult we do now , the impossible takes a bit longer..." applies.
The skepticism around the Manhattan project prevailed profusely before it was shown that nuclear fission works, maybe this is a re-run of a similar scenario
My biggest concern is around the magnetic flux which needs to be shielded to protect personnel working close to the Tokamak. TMS (transcranial magnetic stimulation) is a fact and ITER could have a group of mad scientists running around the site needing to be confined.

Drakkith
Staff Emeritus