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Author: Subject: Super-Containment?
agent_entropy
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[*] posted on 20-7-2006 at 08:46
Super-Containment?


I have a question that I have been pondering for a while now and I’d like to see what you guys think.

Suppose you have a high explosive charge at whatever density is optimum for that compound. Suppose you contained the charge in some sort of container, which is strong enough that the charge cannot burst it when detonated, and none of the gases produced can escape. This container is to be small enough on the inside that the charge fills it completely, and the container is to be designed such that the charge will not deform the cavity in the container that contains the charge (the cavity will not get bigger).

Now the question, what would happen if one were to detonate a high explosive charge under such conditions? Would you end up with a highly pressurized container that has been heated by the energy released? Or would the limiting conditions keep the detonation on a very low order if it could detonate at all?
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YT2095
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[*] posted on 20-7-2006 at 09:15


I`m REALLY glad you asked this, I also asked this same thing here: http://www.scienceforums.net/forums/showthread.php?t=2267 and am still awaiting a satifactory answer.

I even gave simple parameters for it.

I`m looking forwards to seeing the outcome of this thread ;)




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franklyn
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[*] posted on 20-7-2006 at 10:57


I'm really not the one to provide information on this but here goes,

First this is a hypothetical problem you propose, since there

exists no form of matter that has the properties to withstand

the pressures generated by a high order detonation. The volume

of the chamber will enlarge, however providing that the elastic

limit of the material is not exeeded, the envolope would collapse

back to its original volume. Trust me, even diamond becomes soft

and runny at these pressures. That said the only containment which

comes to mind would be the case of a hydrogen bomb which has to

withstand the action of the explosives on the fissionable A-bomb

to ignite the thermonuclear reaction. That however only serves as

a tamp so much of the force is directed inward. Calirometric bombs

used to assay the heat of formation of compounds are made of

Tungsten and heavily built although only to support combustion

with oxygen inside while sitting in an icewater bath.

.
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Rosco Bodine
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[*] posted on 20-7-2006 at 11:36


It would certainly be the ultimate form of constipation ,
a good example of an " immovable " object for the
containment .....feeling the need to " go " but can't
do a thing .....Oh the pain! :o:D
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agent_entropy
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[*] posted on 20-7-2006 at 11:52


Rosco: ROFL!

YT2095:
In the link you posted (to scienceforums.net), I like budullewraagh's answer the best so far, I had considered the same thing but I thought I would ask to see what other's thought.

Quoting budullewraagh: "after much thinking, i've come to the conclusion that i don't think the explosion would occur. if it did occur, very little product would be yielded. a simple principle of thermodynamics is that increased pressure will cause the reaction to favor the side with the least moles of gas, which would be the reactant."

The only part of that answer I don't like is that he says the reaction favors the reactant, implying an equilibrium. I think that the reactant would be the main thing left after the charge is "initiated", but as BenSon suggested (from the link to scienceforums.net) I don't think the reaction is reversible. The products of what part of the charge detonates may very well react with each other to re-form solids, but I doubt they would re-form the original reactant.

[Edited on 20-7-2006 by agent_entropy]
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Nick F
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[*] posted on 20-7-2006 at 12:34


Reminds me of something interesting I learned a little while back.
If you mix hydrogen and oxygen in a 2:1 molar ratio at low enough pressure and ignite it, it will not explode. Common sense. Increase the pressure to atmospheric and it will explode. Increase it further and it won't, increase it more and it will! All to do with the rates of the propagation and termination processes at different pressures.

The simple answer to your question is that the container will deform, but it would be interesting to try it! Get a big block of steel, bore a hole in it an thread the hole, put in some explosive, and screw a long bolt into the threaded hole, then chuck it in a fire...
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Chris The Great
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[*] posted on 20-7-2006 at 14:03


I'm pretty sure you'll just end up with some really, really high pressure gas. The detonation process would deform any container, of course, but if we pretend it does not, you'll just get a piece of gas. The only difference with an "indestructable" confinement is that the pressure will be higher, since the volume the gas occupies is smaller.

Remember, the pressure of gas after detonation and before expansion is only around 100 to 300 thousand atmospheres!
Which makes me think that the threaded rod in Nick's plan might possibly blast right out of there! Who knows though, maybe those rods can take a huge amount of pressure if they are long enough....
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BromicAcid
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[*] posted on 20-7-2006 at 14:59


I remember reading a really good reply to this question (an identical question) on a usenet faq page sometime back but for the life of me I can't find it. (And I'm sick of searching 'explosive small wires contained' on google) I side more with Chris, you're just going to end up with high pressure gas, initally hot but cooling as the heat dissipates outside of the container and the water would eventually start to condense. Since nitrogen cannot condense by pressure alone (or so I've learned).



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YT2095
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[*] posted on 20-7-2006 at 23:22


oh? well I never knew that, I thought all gasses given sufficient pressure would eventualy liquify, even at room temp. is there anything perculiar about nitrogen that precludes this action then?

and the CO2 gasses under that pressure, would they form the solid "Dry Ice"?

assuming the container chamder has had long enough time to cool from several thousand centigrade to something a little more reasonable.




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Boomer
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[*] posted on 21-7-2006 at 06:31


1. Of course it will detonate. Say you have the trigger in the center, the det front will go through all HE and reach the steel before it "knows" it is trapped. What then? Reaction products think "oh shit, lets re-form NG molecules" or what?

2. The container WILL deform, no material on earth can withstand the shock of a HE. If the steel sphere is big enough, it will be unchanged on the outside (no spalling either), but around the original cavity it will be powdered, and maybe slightly denser.

3. I tried exactly that. Put 1g MHN into about a pound block of cast steel, deep in a threaded hole closed with a screw including cable. The steel went into 20 pieces. Should have taken wrought steel, not cast which is brittle....
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neutrino
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[*] posted on 21-7-2006 at 06:36


A gas cannot be liquefied at a temperature higher than its critical point, no matter what the pressure. Instead it becomes a supercritical fluid, like the type used for removing the liquid from aerogels. Here is a good phase diagram of a typical gas.




Nitrogen's critical point is at -147*C, so there is no way it could liquefy at room temperature.




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Nick F
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[*] posted on 21-7-2006 at 06:37


Yeah, you don't want to be using cast, and you might like to try more than a lb of steel if you're using a whole gram of HE!
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[*] posted on 21-7-2006 at 07:42


Boomer, are you CRAZY!??? LOL (got any pics btw?) :P

Neutrino, Thanks for that, it Kinda Makes sense now :)




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[*] posted on 22-7-2006 at 12:17


Assuming H2O, CO2, N2 ets are the products is the major flaw in the question.

Free carbon, CO, nitrogen oxides etc will be produced as well and the amounts will depend on the rate of cooling.

The Det wave only needs to produce enough energy to continue, the explosion/reaction isn't done after it passes.

A detonation as Boomer has said is essentially self confining, inertially confined, in its own time scale.
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Rosco Bodine
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[*] posted on 22-7-2006 at 13:49


Extreme example .....

Underground nuclear tests can be pretty well contained
completely if they are deep enough . I am pretty sure
they leave a substantial cavern in the rock . Nukes have been considered for their potential usefulness as a mining and excavation tool in this regard , but it would seem that a device of special design would be needed due to the contamination problem .
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[*] posted on 25-7-2006 at 09:16


Ok, so, the answer is that there is no known type of container that will not at least deform. But, if such a container could be used, the detonation would still occur, and the gases produced would become supercritical fluids and/or the gases would react to form various products (but definitely not re-form the high explosive compound).

Rosco:
I think it's interesting to note that the nuclear fission reaction itself produces no gases (at least in theory). Certainly this is not much of an issue since rapidly expanding gases are still produced by the conventional HE 's used to detonate the fission device not to mention the fission reaction releasing enough energy to vaporize pretty much everything near it. For the mining example I'm picturing a nuke underground going off and vaporizing the dirt/rock/whatever around it leaving just a big round cavern.

Here's another thought, one could probably completely contain some detonating silver acetylide (not the double salt with the nitrate, just Ag2C2) since that decomposition (in theory) produces only solid products. Any further thoughts on this?

[Edited on 25-7-2006 by agent_entropy]
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Rosco Bodine
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[*] posted on 25-7-2006 at 11:13


IIRC there has been an idea for creation of large underground caverns on the moon and on mars using nuclear explosive charges , and then later using the caverns for habitats . I don't know exactly how long would be the wait before the excavations could be used
for habitation , or what sort of shielding might be required .....but I am pretty certain I read about this offworld habitat construction proposal many years ago .
Given the right geology it would seem possible .
Another possibility would be targeting an existing crater
of the right size and geology with an " airburst " nuke
which would fuse the surface to a layer of glass . Later
sweep out any dust and build a dome over it to close it .
A crater of desired proportions could possibly be created by a first charge , then have its surface fused by a second
charge . A correct mixture of minerals fused by heat into
a glass layer of sufficient thickness could result in a strong
construction material , even if it was just a flat layer of the stuff which could be sawn into slabs after cooling .
It might require a sequence of airbursts above a molten lake of the stuff to get it melted deeply enough to be useful later , as a quarried product .
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Chris The Great
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[*] posted on 26-7-2006 at 09:41


Nukes can't create gas, because every atom in the nuke is blown right off the nucleus (well, not every, the uranium/plutonium only loses about half), making it plasma, not gas. :p
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