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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Postby Joseph Chikva » Tue Nov 08, 2011 2:57 am


Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 3:31 am


JdeJ
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Postby JdeJ » Tue Nov 08, 2011 8:50 am


Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 10:26 am


Stoney3K
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Postby Stoney3K » Tue Nov 08, 2011 1:00 pm

Because we can.

Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 3:57 pm


Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 5:08 pm


erblo
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Postby erblo » Tue Nov 08, 2011 6:50 pm

Regarding the LHC 'explosion' (which was covered here in detail if I remember correctly) se for example page 12.

Summary: The SC is surrounded by a Cu bus bar that, in case of a local quench, takes the current while the SC is forcibly quenched with heaters and large external resistors are connected to absorb most of the energy. When the quench occurred (in a badly made SC-SC connection with ~100 times the normal resistance) the surrounding bus bar was also badly connected resulting in an arc. The arc dissipated 275 MJ (@2-6MW) but 'only' partially destroyed the joint (between two magnets) where it occurred. This would have meant repairing/replacing those two magnets and some cleaning.

The arc did however also breach the LHe cooling circuit and the cryogenic insulation vacuum envelope leading to a flow of 13 kg/s (average, peak 20 kg/s - 10 x 'maximum credible incident'). This flow was also heated by the arc. The pressure inside the envelope rose to 8 bar (design maximum 1.5 bar), things started to move and cause further arcs/leaks and ta-da! - the repairs and delays got a little bigger.

Relevance to ITER (and SC energy storage): it is probably designed to handle both a benign quench and some fairly unlikely series of failures without much damage, but even a little damage to one of the coils would likely be a major pain in the ***. For spectacular/catastrophic failures I think one would have to involve the other subsystems (like cooling, vacuum, Li blanket as already suggested) in very unlikely scenarios (like the LHC).

(personally, I'm more curious about how they will deal with any relativistic runaway electron beams...)
Last edited by erblo on Tue Nov 08, 2011 6:52 pm, edited 1 time in total.

D Tibbets
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Postby D Tibbets » Tue Nov 08, 2011 6:51 pm

Thanks JdeJ for the link.

I continue to disagree that comparing a helium coolent / quench failure as the same as a hole in a steam line. This ignores the liquid flashing to steam as the temperature increases (by even a small amount or not at all if there is any starting positive pressure in the system/ liquid container.
In a liquid helium system, if the internal pressure is small the only driver for vaporization is the temp. If due to ohmic heating the temperature increases a few degrees K, the helium is now boiling and gas overpressure is now building. Once the pressure builds enough that the vessel fails the pressure falls, and the superheated helium flashes into vapor. This provides a large volume of pressurized gas that progressively expands what ever is in it's way untill it disperses in air or meets a containment wall that resists the further expansion.

It is not that steam is leaking out via a small or large hole so much as what this does to the pressure in the system and if there is superheated liquid that can then flash into a much larger volume of steam/ gas.
This is what drives the explosion of Steam Locamotives, and steam boilers in general. A valve becomes stuck or for some other reason the pressure builds to a point where the containment fails, there is a very large hole which allows for rapid decompression and resultant vigerous boiling of the superheated liquid. Another good example is a video of the Italian (?) battleship around the time of WWI that rolled over. Presumably the boiler venting was blocked, the boiler walls failed and the the resultant superheated steam explosion blew the battleship in in half. It wasn't that the water (or helium) hat much of a change in temperature, it was that due to the drop in pressure the liquid became superheated, and the resultant rapid change in volume drove and explosive expansion. The temperature of the solid materials is trivial. What is important is the amount of liquid that can flash to vapor, how fast it does it, and volume considerations of surrounding structures that it can push against.

The best estimate of stored (superconducting) magnetic energy in ITER that I have seen comes from here. ~13 T central magnet with ~ 6.4 GJ of stored energy.

http://www.iter.org/newsline/122/182

PS: The steam explosion that destroyed the battleship was not due to a increase in temperature, in fact the temperature of the steam/ liquid water was probably significantly decreasing due to the heat of vaporization. It was purely a pressure containment issue, with subsequent physics effects.

Dan Tibbets
To error is human... and I'm very human.

Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 7:19 pm


D Tibbets
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Postby D Tibbets » Tue Nov 08, 2011 8:14 pm

To error is human... and I'm very human.

Joseph Chikva
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Postby Joseph Chikva » Tue Nov 08, 2011 8:29 pm


ladajo
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Postby ladajo » Tue Nov 08, 2011 10:06 pm


D Tibbets
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Postby D Tibbets » Tue Nov 08, 2011 10:42 pm

To error is human... and I'm very human.

Stoney3K
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Postby Stoney3K » Tue Nov 08, 2011 11:02 pm

Because we can.


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