What would happen if an energy storage device failed?

[ladajo]

Your question has been answered. Any high energy magnetic field collapses and seeks the easiest way to do so. In the case discussed, it will either backlash some switching component, or it will seek to dissapate in a spectaular manner at the physical point of interuption as that point will more than likely provide the path to do so as part of the failure mechanism.
Keep it simple in your head, as the field seeks to collapse it does so using the "Left hand rule" mechanism. This is the very principle used in hybrid cars to regeneratively brake and in turn charge the battery. I was using this principle back in the early nineties, but not for cars. I also had some very cool failures doing so as noted above as I refined the design.
This approach is powerful enough that you can effectively immediate stop any running three phase motor. There is a lot of energy in the fields.

[D Tibbets]

High density energy storage can and do fail spectacurly. As noted above. Superconducting magnets are an example of this . The large powerful super conducting magnets in the ITER tokamac could make an impressive explosion if the supetconducter quenches. Apparently there are safty measures - very quick switching through robust busses into a large heat sink (like a lake). This has been discussed on this board before. A Polywell with as strong but smaller superconducting magnets is to a degree less forbidding. I wonder if a quench in this case might do ~ the same amount of damage as did the failure of a magnet in the LHC a couple of years ago.

I do not know what here has been discussed but fast switching off of large inductance would damage some components of circuit (may be melt down because of self-induction). That's all.

At LHC as I know (may be not correctly) as result of failure very powerful beam hit wall and burnt out the hole.

No. Mechanical failure followed by a large release of stored magnetic field energy.

An actual picture and brief description of what happened at the LHC

[EDIT] Added missing link in another post, edited here also for new readers.

http://www.youtube.com/watch?v=YnAVjkuQ ... re=related

Dan Tibbets

[ladajo]

Link?

[mdeminico]

Your question has been answered. Any high energy magnetic field collapses and seeks the easiest way to do so. In the case discussed, it will either backlash some switching component, or it will seek to dissapate in a spectaular manner at the physical point of interuption as that point will more than likely provide the path to do so as part of the failure mechanism.
Keep it simple in your head, as the field seeks to collapse it does so using the "Left hand rule" mechanism. This is the very principle used in hybrid cars to regeneratively brake and in turn charge the battery. I was using this principle back in the early nineties, but not for cars. I also had some very cool failures doing so as noted above as I refined the design.
This approach is powerful enough that you can effectively immediate stop any running three phase motor. There is a lot of energy in the fields.

So, if the coil broke at a certain point. The material is now a superconducting toroid with a 0.1mm gap in it (let's assume in a vacuum). Since a pure vacuum is impossible, if it's a powerful enough field and a small enough gap, it will likely bridge that gap with a plasma. The gap will continue to get bigger, building up more and more heat, making some spectacularly massive explosions (well, one very spectacularly massive one).

When you say it will backlash a switching component, what do you mean? If there's a switch to a ground that's open when the failure happens, then it's possible that the failure can result in a bridging of that switch's circuit, essentially closing it, and causing all the current to flow into the ground?

In any case, it just seems like a big massive explosion.

[Skipjack]

Well, large capacitors are being used all over the world and while accidents do happen and these things do explode, I have never heard of anything even remotely simillar to a bomb going off.
So I think that people here are somewhat exaggerating.

[Joseph Chikva]

Case in point, the 27th ionization energy of Nickel is just shy of 1 MJ/mol, and the 28th is over 1 MJ/mol. So only 59 grams of nickel could in theory store the 28th + 27th + 26th + ... + 2nd + 1st ionization energies, which is over 4 MJ.

I can not imagine how this is relates to capacitors. Breakdown of capacitors is only pass of electric current between two foils separated by dielectric. Energt stored in a single capacitor can not be 4 MJ.
Let's say very high voltage 300kV capacitor. Stored energy is equal to CU^2/2. Let's capacitor's capacitance 50nF=50E-9F. Such a capacitor weighs about 50 kg (For convenience of installation makes capacitors heavier 100 kg)
Energy stored in it: 2.25kJ
So, 4MJ stored in the bank comprising ~1778 capacotors connected paralelly. How they can breakdown at one moment?

For you note the cost of such a capacitor bank reaches 40 millions USD.

[Joseph Chikva]

And going back to my second question, imagine this scenario...

A toroidal SMES unit. Charged with a fairly high amount of power (let's just say 100MWh), to be used for grid energy load leveling.

Now, say an earthquake or something happens. The circuit in the coil of superconducting wire is interrupted.

What happens to the magnetic field? Where does it go? See all the questions in my previous question.

Mr. mdeminico, situation is more prosaic. SMES as I understand is inductive energy storage. Your assumption on 100MWh of stored energy seema very phantastically as 100MWh is equal to 3.6E11 J= 360GJ. And the biggest energy storage I know 0.9GJ.
Then

say an earthquake or something happens

Well, mechanical damage breaks off circuit. Self-induction creats EDF equal to V=-L*dI/dt. Stored energy E=L*I^2/2
So, faster break off creates bigger EDF (as dI/dt). And energy stored in magnetic field transfers in high current making some job. For explosion as worried it is needed that inducted current will flow through something generating the gas. For shrapnel it is need that extending gas would drive something hard. So, that is only design issue.
Do not worry. People know how to design such things. And even bigger.

[Joseph Chikva]

An actual picture and brief description of what happened at the LHC

Dan, does LHC store big energy?
As I know there is not axial mag field at whole circumference, but used sextupole and quadrupole magnets. Those do not store much energy in mag field.
But there is used magnetic or/and electrostatic inflectors, deflectors, kickers, etc. steering the beam in time and position. Damage of one of those will drive beam on the wall with catastrophic aftereffect only locally. Yes, will "drill" the hole. Weld that hole and may be change or repair something being behind and go on experiment.

[KitemanSA]

Well, large capacitors are being used all over the world and while accidents do happen and these things do explode, I have never heard of anything even remotely simillar to a bomb going off.
So I think that people here are somewhat exaggerating.

There is a transformer station several blocks from my house. For some reason, one of the phases fed by the transformer goes out with some regularity, often acompanied by the transformer explosively deconstructing. We hear it happen at home. I can only imagine what a superconductor magnet quench would be like!

[Joseph Chikva]

There is a transformer station several blocks from my house. For some reason, one of the phases fed by the transformer goes out with some regularity, often acompanied by the transformer explosively deconstructing. We hear it happen at home. I can only imagine what a superconductor magnet quench would be like!

What do you think why every single fusion experiment is called "shot"? Because first Z-pinch discharge (discharge of capacitor bank into rare gas) has been acompanied with shot like sound.

[Skipjack]

There is a transformer station several blocks from my house. For some reason, one of the phases fed by the transformer goes out with some regularity, often acompanied by the transformer explosively deconstructing. We hear it happen at home. I can only imagine what a superconductor magnet quench would be like!

Yeah, but that is not taking out half the block every time, is it.

[KitemanSA]

Yeah, but that is not taking out half the block every time, is it.

Npe, but then it is just the end of the distribution chain low voltage neighborhood transformer, not a high tesla superconductive electro-magnet. Didn't I read somewhere that ITER would release ~14 kiloton equivalent energy if it were to quench?

Anyone?

[D Tibbets]

Link?

Opps..

Here is the link. Specific part about the failure is at ~ 2 minute mark.

http://www.youtube.com/watch?v=YnAVjkuQ ... re=related

It was surprisingly difficult to find this video again. Many of the Google provided links to to the quarry: 'LHC magnet failure'. returned fantasy black hole formation, or songs. I had to dip into related videos on the U Tube pages to find this again.

Dan Tibbets

[D Tibbets]

Yeah, but that is not taking out half the block every time, is it.

Npe, but then it is just the end of the distribution chain low voltage neighborhood transformer, not a high tesla superconductive electro-magnet. Didn't I read somewhere that ITER would release ~14 kiloton equivalent energy if it were to quench?

Anyone?

There was a discussion on Talk Polywell where an ITER magnet explosion was involved. I believe Tom Ligon quotes a Bussard estimate. I cannot find it, but my recollection was that it was in the neighborhood of a few hundred tons of TNT, not thousands. I don't know if this was a single magnet failure or all of them. Such an explosion would not destroy a city, but it would demolish the Tokamack reactor, along with all of its molten lithium, tritium, steam plant, blding, etc. Between the heat from the magnet meltdown/ explosions, the flamable tritium containing lithium, and rupture of the steam plant associated with a multi gigawatt plant (a commercial Tokamak) would be intimidating. Any nearby plant workers would probably be killed and the reactor and building would be a complete write off. The clean up would not be as bad as a fission plant, but there would be tritium to deal with and all of the neutron induced radioactive structure to deal with. Somewhere the Polywell maintainance cycle has been discussed (by Bussard?). In a D-D reactor, there is a significant danger in approaching the reactor due to significant short half life radiations from the neutron transmutted structural elements. I forget if the 'cool time period was several hours of several days. Presumably a much larger Tokamak magnifies this problem both because of the D-T fuel, the larger size and potential explosive energy of the magnets. The first wall lithium blanket may reduce the radiation exposure of more peripheral components, but with the increased neutron flux from D-T fusion and the larger fusion power in a single machine, the neutron radiation concerns may be as bad or even much worse than the Polywell.
Engineering must be included to prevent these uncontrolled quenches and minimize effects if they do occur.

A pure guess, but I'm wondering if the explosions at the nuclear plants (at least the one that had a hydrogen gas explosion)in Japan would be comparable to the failure of the magnets in a commercial Tokamak. One point is that the Japanese fission reactors were shut down when they exploded, so there was less steam in the pipes. In a commercial operating Tokamak it might have more than 10 GW of energy tied up in the steam pipes. If they rupture on a large scale in a superconducting magnet explosion, the explosive force may be amplified significantly.

Dan Tibbets

[Joseph Chikva]

I cannot find it, but my recollection was that it was in the neighborhood of a few hundred tons of TNT, not thousands. I don't know if this was a single magnet failure or all of them. Such an explosion would not destroy a city, but it would demolish the Tokamack reactor, along with all of its molten lithium, tritium, steam plant, blding, etc. Between the heat from the magnet meltdown/ explosions, the flamable tritium containing lithium, and rupture of the steam plant associated with a multi gigawatt plant (a commercial Tokamak) would be intimidating. Any nearby plant workers would probably be killed and the reactor and building would be a complete write off.

This is more similar to Hollywood catastrophe movie than real scenario.
First magnets.

The 18 Toroidal Field (TF) magnets produce a magnetic field around the torus, whose primary function is to confine the plasma particles. The ITER TF coils are designed to have a total magnetic energy of 41 gigajoules and a maximum magnetic field of 11.8 tesla

http://www.iter.org/mach/magnets
Yes,

TNT contains 4.184 megajoules per kilogram.

http://en.wikipedia.org/wiki/Trinitrotoluene
So, by energy content toroidal field of ITER corresponds to 10 ton of TNT.
But what is explosion? That is energy release in very short time, the time much shorter than very big inductance can give.
How you imagine the simultaneous failure of all eighteen magnets? And if self induction current has proper way to flow, nothing dangerous will happen.
For note 2 tons of gasoline or diesel fuel also have energy content equal to 10 t TNT. But we use crude oil storage tanks with capacity 50'000 cubic meters and tanker "Globtic Tokyo" has (or had) about 500'000 tons of displacement.
My advise is not to believe to gossip.


Edited: How much jet fuel carries the conventional passenger airplane? Not about 40 t? Not corresponds to 200 t TNT by energy content? I do not speak on such monsters as Boeing-747, Airbus-380 or C-17 but about much smaller aircrafts.