ItalianXKem
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Boron Plastic Shell ?
what is this ?
I see there (qui) :
http://upload.wikimedia.org/wikipedia/commons/8/83/Fat_Man_I...
in the image is the blue sphere out the plutonium / uranium pit
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hissingnoise
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Try it in Italian, as nicodem asked; I'm monoglot but Italian can't be this opaque!
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ItalianXKem
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''but Italian can'tbe this opaque!''
?
scrivo in Italiano : cosa è il plastic boron shell nella fat man ?
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hissingnoise
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The boron plastic seems to be a protective covering on the normally non-fissionable U238 tamper-plug.
Boron plastic has very high strength and low weight.
It could, though, be there for other reasons. . .
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ItalianXKem
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e da che cosa è formato , chimicamente , dovrà avere una composizione o miscela chimica
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12AX7
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Boron absorbs neutrons. I'm thinking radiation shield, possibly to protect explosives. It may also reflect some neutrons, but this effect is
probably smaller than the absorbtion capacity.
I don't know that they had "boron plastic" in those days, whatever that might be... boron composites are a more modern thing, so maybe it was plastic
with a boron something filler?
Tim
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JohnWW
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| Quote: | Originally posted by 12AX7
Boron absorbs neutrons. I'm thinking radiation shield, possibly to protect explosives. It may also reflect some neutrons, but this effect is
probably smaller than the absorbtion capacity. |
B-10 can absorb neutrons to become B-11; while B-11 (the other stable isotope) can absorb neutrons to become B-12, which very quickly decays to stable
C-12 with an half-life of 20.31±0.20×10^-3 sec by beta-emission ( http://prola.aps.org/abstract/PR/v122/i6/p1871_1 )
[Edited on 12-12-08 by JohnWW]
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ItalianXKem
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thank you ! 
the neutron bombing molecules of explosives and can ignite
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franklyn
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First I have seen or heard of this. Glaringly obvious is the absence of standoff
anywhere along the radius. No wonder the first " fat man " implosion device was
so large. By comparison the " Hamlet " design is the size of two basketballs and
can sit on your lap, yet has 250 % greater yeild.
As to this " boron plastic " ? . I guess polymer bonded boron powder. Boron is
brittle and has poor mechanical properties so if you want it present in high
concentration, plastic composite fits the need. As to having it as a moderator
that is because the aluminum housing or tamp is a good reflector of emitted
neutrons and the " pit " or fissionable center is at a concentration close to
critical where chain fission begins to run away uncontrolled. It could without
much provocation heatup very rapidly and being metal expand, damaging the
close tolerances of the assembled device. The boron absorbs the emitted
neutrons rather than reflecting them back into the pit obviating this potential.
.
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JohnWW
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At the time of the "Fat Man", the first atomic bomb, used against Japan in 1945, the only military "boron plastics" for absorbing neutrons would have
been some high-melting organic plastic filled with boron powder. At that time the highest-melting known plastics would probably have been PTFE
(Teflon) and PVF. It is likely that, since then, polymers have been developed in which boron is chemically bonded; for example, polymers with
alternating negatively-charged B atoms and positively-charged N atoms. BTW N-14 also absorbs neutrons, becoming N-15, also stable, while the much less
abundant N-15's absorption of neutrons would result in N-16, which quickly decays to O-16 with a half-life of 7.2 seconds. Graphite is also used as a
lightweight absorber of neutrons, C-12 becoming C-13, also stable, but the much smaller content of natural C-13 would become C-14, with an half-life
of over 5,000 years.
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ItalianXKem
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thank very much john an franklin 
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stoichiometric_steve
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what is it with those italians today, asking for nerve gases and nuclear weapons?
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ItalianXKem
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not
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Klute
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Planning a revolution? Good thing I moved north then
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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franklyn
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http://www.sciencemadness.org/talk/viewthread.php?tid=11209
,
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blogfast25
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That link gives me a 404...
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franklyn
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and your post gives me heartburn.
A little initiative is a basic requirement of internet literacy.
Go to www.wikipedia.org ( inferred from the url that's 404 )
=> http://upload.wikimedia.org/wikipedia/commons/8/83/Fat_Man_I...
now search " fat man " , and you're there => http://en.wikipedia.org/wiki/Fat_man
The original gif image is now in png format
http://upload.wikimedia.org/wikipedia/commons/1/1e/Fat_Man_I...
.
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blogfast25
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No need for that fella. If someone posts a link then it's reasanble to expect it to work... You must get heartburn a lot!
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bfesser
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Thread Moved
13-10-2013 at 12:09 |
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