in the image is the blue sphere out the plutonium / uranium pithissingnoise - 11-12-2008 at 11:08
Try it in Italian, as nicodem asked; I'm monoglot but Italian can't be this opaque!ItalianXKem - 11-12-2008 at 11:30
''but Italian can'tbe this opaque!''
?
scrivo in Italiano : cosa è il plastic boron shell nella fat man ?hissingnoise - 11-12-2008 at 11:55
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. . .ItalianXKem - 11-12-2008 at 13:14
e da che cosa è formato , chimicamente , dovrà avere una composizione o miscela chimica12AX7 - 11-12-2008 at 13:25
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?
TimJohnWW - 11-12-2008 at 17:28
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]ItalianXKem - 12-12-2008 at 05:20
thank you !
the neutron bombing molecules of explosives and can ignitefranklyn - 12-12-2008 at 23:47
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.
.JohnWW - 13-12-2008 at 00:35
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.ItalianXKem - 13-12-2008 at 05:31
thank very much john an franklin stoichiometric_steve - 13-12-2008 at 05:48
what is it with those italians today, asking for nerve gases and nuclear weapons?ItalianXKem - 15-12-2008 at 10:42
notKlute - 15-12-2008 at 11:24
Planning a revolution? Good thing I moved north then franklyn - 22-12-2010 at 07:04
