Half a croissant, on a plate, with a sign in front of it saying '50c'
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nuclear melt-down heat sink

make a massive heat sink and protect against melt-downs with it
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(+2, -1)
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A thin layer of tungsten underlaid with a layer of copper or other heat-sink material, this underlaid with another layer of tungsten in such a shape as to help the heat-sink material keep its shape.

This huge heat sink would be placed as part of the foundation to nuclear reactors. In the case of a melt-down the hot liquid would rest on the tungsten overlay which would transmit heat through to the copper before it melts. The copper may melt but would retain its shape and still carry heat away from the reaction.
Voice, Apr 03 2011

Tungsten is not a great choice... http://en.wikipedia.org/wiki/Demon_core
... nor copper for that matter. [4whom, Apr 04 2011]

Banana equivalent dose http://en.wikipedia...ana_equivalent_dose
[Ian Tindale, Apr 05 2011]

Boiling water in plastic bottle http://www.youtube....plastic+bottle&aq=1
[rcarty, Apr 07 2011]

Boiling water in plastic bag http://www.youtube....watch?v=9zFo3vQAIeM
No flame visible / over hot coals [rcarty, Apr 07 2011]


       I have a plasma cutter in my welding shop that can hack through tungsten (albeit not very well). The core of a nuclear reactor in full meltdown is many, many times hotter and would go through your thin layer of tungsten like my mother-in-law at a christmas-store clearance sale. Sorry.   

       I'm not boning this idea because I want you to keep thinking. I've been shot down for not doing my homework plenty of times. Come up with something new and amaze us!
Alterother, Apr 04 2011

       oh no you didn't! Your plasma cutter is producing energies well in excess of 25,000 *C. Whereas at Chernobyl during the core collapse the last stable core temperature was no higher than 2000 degrees. This temperature would be fine for a tungsten element. You sir are not a rocket scientist. Please take your seat. This idea is silly for many other reasons but that isn't one of them. This idea is silly because it simply would not be feasible to produce a geothermal heatsink of the size needed, nor could you ever produce an efficient enough contact without using a fluid, at which point it might as well be water and thus it would serve no new purpose, other than working less well than a current cooling pond and thus not really worth considering.
WcW, Apr 04 2011

       By pretending it was intentional.
Ian Tindale, Apr 04 2011

       No, I am not a rocket scientist, I am merely a welder and metal fabricator who reads a lot. The more I learn, the more I become aware of my own ignorance. In this case, however, I was not referring to Chernobyl, in which the fissile material was exposed to the open air and never achieved the 'doomsday scenario' meltdown stage that is theoretically possible in a contained reactor meltdown. Fortunately for us, this has never happened. Still, my numbers may well be wrong, and I'm fully prepared to admit that, but not to be belittled for it.   

       Just for everyone's benifit, tungsten melts at around 3,200*(C), not outside the bounds of a Gen 1 reactor core the size of, say, 3-Mile Island going up in smoke. And my plasma cutter produces 24,600*(C), thank you very much.
Alterother, Apr 04 2011

       Forget melting/freezing temps, neutron reflection is enough to make this a horrendous idea, both for tungsten and copper.
4whom, Apr 04 2011

       Add a layer of hafnium over the tungsten. This will melt long before the tungsten and sop up any neutrons from melted fuel rods. And best that the tungsten layer have a waffle upper surface to contain pools of hafnium.
ldischler, Apr 04 2011

       You can boil water over an open flame in a thin plastic bag. In the same manner a thin coating of tungsten over copper will be stable in the face of great heat. The hard tungsten will transfer the heat to the copper before it melts.
Voice, Apr 04 2011

       [Voice], No one, at least no one sensible, is arguing the principles of heat transfer. If you have enough plutonium in your melt you will trigger a critical reaction (re-critical, to be pedantic) with tungsten in close proximity.   

       I stand under correction, you could get to critical mass even without the plutonium.   

       The heat is not the problem (well not in the way you think it is), this is not a chemical reaction. Taking heat away will not mitigate against nuclear activity. Removal of heat is just to prevent a puddle of nasty shit forming, you are already talking of removing heat AFTER the puddle of nasty shit is there. No good.   

       Hafnuim, xenon, boron, etc and so forth, all good moderators and controls, all currently in use.   

       I don't understand the problem. A long life reactor got hit by known knowns, known unknowns, and unknown unknowns and is emitting about as much radiation as a banana plantation, ehhh?
4whom, Apr 04 2011

       //emitting about as much radiation as a banana plantation//   

       Let's have numbers on that.
ldischler, Apr 05 2011

       According to TEPCO radiation at a typical point near the reactor at the time of this anno is 3.4 microsieverts per hour. According to Wikipedia typical background radiation averages 5 millisieverts per year or .5 microsieverts per hour.

Now the amount of radiation emitted by a banana plantation has nothing to do with the dose one obtains by eating a banana as no one would be able to eat a plantation full of bananas.

I feel safe assuming the background radiation near a banana plantation is about the same as anywhere else and that the radiation output of the sun dwarfs any output from the plantation. So we have these two numbers:

Fukushima: 3.4 microsieverts per hour.
Plantation: .5 microsieverts per hour.
Voice, Apr 05 2011

       I'm wondering whether a great big mass of concrete and sand, interspersed with several hundred tons of boron bb's would do the trick.
RayfordSteele, Apr 05 2011

       The sand would glass and you would have a mess on your hands.
Voice, Apr 05 2011

       How about just not having melt down in the first place?
MaxwellBuchanan, Apr 05 2011

       That was a design feature.
ldischler, Apr 05 2011

       Exactly, so what's wrong with a pile of glass?
RayfordSteele, Apr 06 2011

       //Whats wrong with a pile of glass?//   

       Thats the sort of thinking we need, make the nuclear meltdown work for you, not the other way around...   

       Why not just have Plutioniom just sit in the (melted) copper above the tungston? Besides the fact that the two together would make a wacky goo.
xxobot, Apr 06 2011

       //You can boil water over an open flame in a thin plastic bag.//   

       Has anyone actually really tried this for real in practice?
MaxwellBuchanan, Apr 06 2011

       Nuclear power stations generally use the heat they generate to boil water from a river, with then goes through turbines. This provides excellent cooling, far more than a large heatsink could acheive. Better to just build it large so it can heat lots of excess water.
Bad Jim, Apr 06 2011

       [mb] [link] and [link]
rcarty, Apr 07 2011

       //Has anyone actually really tried this for real in practice?//   

       Yes. Water will boil in plastic bottles and even paper plates over an open flame as well.
My kids were blown away that I could rest a paper plate full of water directly on the campfire and the plate would only scorch above the water line.

       // as much radiation as a banana plantation// I have been known for infinitesimally minute amounts of hyperbole, none of which should detract from the fact that by the time this stuff is a puddle, placing tungsten in the immediate vacinity is not a good idea. Molten gloop of this nature should not be encouraged to become critical (re-critical). Subtracting IR photons as fast as humanly possible will not mitigate against this. Only a few things will and they are all more expensive and more difficult that burying the whole thing in a tomb of concrete. Fukushima's days are over. The world will not end. The soils will not be contaminated for eons, the waters will circulate and eliminate the problem (if there is one). Life will go on. The true casualty of this process is, once again, public opinion of a safe and reliable technology capable of powering an overpopulated and wasteful society of Homo sapiens sapiens.
4whom, Apr 10 2011

       The Chinese have mentioned the use of tungsten containment for spacecraft reactors, but in general, it appears to be too expensive to fabricate. (And esp. as no one seems to anticipate melt downs actually happening.)
ldischler, Apr 10 2011

       Tungsten containment no problem, in fact encouraged, just a bit pricey on a large scale. And a bit risky when temps get high and geometries change. Unregulated geometries with tungsten in close proximity, (one supposes this is what happens with liquid fissile material), big problem. Please, no more of this...
4whom, Apr 10 2011

       Tungsten has also been studied for cladding thermionic fuel rods. Again, this would be regarded as probably too expensive for commercial steam plants, but it might have prevented melted fuel from escaping the rods.
ldischler, Apr 10 2011

       I smell bait in the water...
4whom, Apr 10 2011


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