What would happen if an energy storage device failed?

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Joseph Chikva
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Post by Joseph Chikva »

D Tibbets wrote:
ladajo wrote: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
Helium spill

The machine has more than 1,200 "dipole" magnets arranged end-to-end in the 27km-long, ring-shaped tunnel that houses the LHC.

These magnets carry and steer beams of protons which will whizz around the machine at close to the speed of light.

At allotted points around the "ring", these beams cross paths, smashing together near four massive "detectors" that monitor the collisions for interesting events.

Cern said the most likely cause of the equipment failure was a faulty electrical connection between two of the accelerator's magnets.

This connection melted during testing of the machine and caused a huge leak of super-cool helium.

This helium is used to chill the magnets to a temperature of 1.9 kelvin (-271C; -456F) - which is colder than deep space.

This makes the magnets "superconducting", allowing them to generate the large magnetic fields required to steer the beams while at the same time consuming relatively little power.

A quench occurs when part of a superconducting magnet heats up and causes superconducting properties to be lost.
http://news.bbc.co.uk/2/hi/7632408.stm
For note: dipole magnet is a bending magnet storing very small amount of energy. And as I understand the problem had very local aftereffect for such a big machine. Yes, failure of one of more than 1200 dipole magnets stops the machine for some time. But that was not catastrophe with people deaths and other terrible things as here has been described.

KitemanSA
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Post by KitemanSA »

Ok, so about 14 tonnes, not 14ktons. That is a big differencew, but still a big bomb too.

Joseph Chikva
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Post by Joseph Chikva »

KitemanSA wrote:Ok, so about 14 tonnes, not 14ktons. That is a big differencew, but still a big bomb too.
Not like a big bomb, as strength of bomb is in its power and not only in energy. Large inductance can not release stored energy as fast as high explosive. If that energy has some way to flow, that will not make massive damage like explosive. I am repeating once again that energy stored in magnetic field can be released only in self-induction EDF form like that is happened in the car ignition coil about 50 times in second.

KitemanSA
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Post by KitemanSA »

Joseph Chikva wrote:
KitemanSA wrote:Ok, so about 14 tonnes, not 14ktons. That is a big differencew, but still a big bomb too.
Not like a big bomb, as strength of bomb is in its power and not only in energy. Large inductance can not release stored energy as fast as high explosive. If that energy has some way to flow, that will not make massive damage like explosive. I am repeating once again that energy stored in magnetic field can be released only in self-induction EDF form like that is happened in the car ignition coil about 50 times in second.
Doesn't the energy stored in the current in the superconductor convert to heat almost instantaneously (L/c)? This is not a controlled discharge we are talking about here.

Anyone other than Joe want to wade in here?

Joseph Chikva
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Post by Joseph Chikva »

KitemanSA wrote:Doesn't the energy stored in the current in the superconductor convert to heat almost instantaneously (L/c)? This is not a controlled discharge we are talking about here.

Anyone other than Joe want to wade in here?
What is energy stored in current? Please explain.
Energy stores in mag field.
V*B^2/2μ=L*I^2/2
V- volume
B-mag field induction
μ-permeability of vacuum
L-inductance
I-current
If by some reasons current switches off, self-induction EDF will appear regardless to will anyone here in this board support me or no.

MSimon
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Post by MSimon »

Joseph,

I agree with you. However, the rate of energy "loss" depends on the circuit. The higher the voltage in the loss element the faster the loss. The time constant is L/R. Bigger R gives faster discharge. The reason is that the current is "constant" while the voltage is higher.

For the EEs - think of the energy stored in the inductor as if it was a boost circuit. The "off" time is shorter in such a circuit with the higher boost.
Engineering is the art of making what you want from what you can get at a profit.

Joseph Chikva
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Post by Joseph Chikva »

MSimon wrote:Joseph,

I agree with you. However, the rate of energy "loss" depends on the circuit. The higher the voltage in the loss element the faster the loss. The time constant is L/R. Bigger R gives faster discharge. The reason is that the current is "constant" while the voltage is higher.

For the EEs - think of the energy stored in the inductor as if it was a boost circuit. The "off" time is shorter in such a circuit with the higher boost.
I agree with you too. That all depends on circuit or I said about "design issue". And in case of proper design nothing catastrophic will happen.
Regarding resistivity and voltage, as a rule such circuits are fed with voltage of tens or hundreds Volts and even in case of break of SC (superconducting) the resistivity of matrix in which SC filaments are placed is only fractions of Ohm. E.g. for generating of 100 thousands A with circuit resistivity of 0.001 Ohm (including internal resistivity of power supply source) the voltage of only 100 V is required. And these parameters are very close to reality (real numbers).
Nevertheless switch off of such a circuit can create very high voltage in also fraction of second. For example by switching off of low voltage but high capacity inductive energy storage we can charge high voltage and rather big capacitor bank.

Added: the ratio between working and resultant voltage we can estimate if recall how high voltage is fed in our cars in which 25-35 kV is supplied on candles through ignition coil (bobbin) and switching off asset (mechanical or electronic) being fed with only 12 V many times in second.
Saying "design issue" I mean that circuit should not contain anything generating big volume of gases. As only in this case we will get an explosion.

bk78
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Post by bk78 »

Joseph Chikva wrote: Regarding resistivity and voltage, as a rule such circuits are fed with voltage of tens or hundreds Volts and even in case of break of SC (superconducting) the resistivity of matrix in which SC filaments are placed is only fractions of Ohm. E.g. for generating of 100 thousands A with circuit resistivity of 0.001 Ohm (including internal resistivity of power supply source) the voltage of only 100 V is required.
That's true, but the problem is that the small volume where the quench occurs will heat up very quickly (there is no way to conduct away 10MW heat), increasing resistance, eventually vaporizing, and then it will release the energy almost instantanously.
Even "low power" explosions i.e. caused by cracking natural gas tanks, when the fuel has to combust with air first, can be very dangerous.
It is also true that it will be a bit different from normal explosives, where you want to get gases at high speed, i.e. for cutting through metals. Energy density of TNT is not that high.

Joseph Chikva
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Post by Joseph Chikva »

bk78 wrote:That's true, but the problem is that the small volume where the quench occurs will heat up very quickly (there is no way to conduct away 10MW heat), increasing resistance, eventually vaporizing, and then it will release the energy almost instantanously.
Here are two but very important mistakes.
First of all not 10MW of power but some amount of energy. The problem is not in flowing current but in energy stored in mag field which have to be dissipated. As current has near zero energy content.
Second - what is "almost instantaneously"? How instantaneously? As fast as TNT explodes? Or may be a little bit or significantly slower? It is important.

KitemanSA
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Post by KitemanSA »

How long would it take for the ITER fields to collapse?

Joseph Chikva
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Post by Joseph Chikva »

KitemanSA wrote:How long would it take for the ITER fields to collapse?
Magnets are not a problem. Each toroidal coil of ITER weighs not less than 20 tons with near K zero temperature and allowed temperature not less than 600 deg K. Specific heat of copper or somewhat else matrix * 20000 kg * 600 of ΔT ? Plus some other tricks how to dissipate suddenly released heat.
You are searching ITER's problems not in right place. Not big energy stored in the fields is the problem but absence of way how to increase the energy stored in plasma to required ~520MJ value.
As required 15keV for ignition, projected number density 2E20 m^-3, plasma volume 840 m^3 means that energy stored in plasma should have such a number.
Ohmic heating can not provide temperature more than 1keV (most common 200-300eV) and very powerful 70MW neutral beam needs 6.9 sec for pumping into plasma the energy corresponding to remaining 14keV. In case of 100% of energy absorption. 100% is possible?

KitemanSA
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Post by KitemanSA »

Joseph Chikva wrote:
KitemanSA wrote: How long would it take for the ITER fields to collapse?
Magnets are not a problem.
...
Bunches of useless info.
...
I asked, "How long would it take for the ITER fields to collapse"? Do you know or not? If so, please answer.

Joseph Chikva
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Post by Joseph Chikva »

KitemanSA wrote:
Joseph Chikva wrote:
KitemanSA wrote: How long would it take for the ITER fields to collapse?
Magnets are not a problem.
...
Bunches of useless info.
...
I asked, "How long would it take for the ITER fields to collapse"? Do you know or not? If so, please answer.
Certainly not. But know about extremally high inductance. But also without numbers. But sure that very skilled people have designed ITER. Do not worry. Nobody will lost in hell fire of melted litium. As Dan has frightened us with horrors. And you with kilotons. At least my weak knowledge of ITER is more closer to reality.

Stoney3K
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Post by Stoney3K »

One thing I do think is interesting food for thought is the amount of energy strored in the entire faclilty. For security concerns.

Let's imagine a worst-case scenario: A Polywell facility with direct-conversion electronics and related substations, vacuum pumps, and cooling, and a rogue terrorist group placing a small explosive near the main reactor building, just enough to rupture any critical components (e.g. vacuum vessel, LHe2 cooling conduits) of the system.

What would be the most substantial element storing energy in the facility? Would it be the Magrid coils with superconductors at high current? These would amost certainly start to arc (probably across the fuel) if a quench occurs.

The direct-conversion electronics can also have some really interesting properties that make it go boom big time, since it would probably involve some hefty RLC circuits to store the energy short-term to convert all of the electricity down from the MV-DC range to several Kilovolts of AC.

The total amount of energy stored in a facility like this is quite immense, but I suppose the blast would not be enormous when compared to other 'high-risk' installations.
Because we can.

mdeminico
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Post by mdeminico »

Joseph Chikva wrote:
D Tibbets wrote: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.
That was my original question, if a single-coil shaped into a toroid had a break in it, with the equivalent of 10 kT of TNT, my worry is that all that magnetic field would attempt to induce a current across that break, causing essentially instant heat in the entire system, quenching the rest of the system an instant later, causing more heat as the rest of the current encounters a non-superconductive state, and causing, yes, the equivalent of a 10 kT of TNT.

But, if as you state, the discharge of the energy takes place over a matter of seconds, rather than microseconds, the "explosion" doesn't really happen nearly as much.

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