For a good time:
https://commons.m.wikimedia.org/wiki/File:B61internals.png#/search
-george
Sent from my iPhone
On Jan 19, 2017, at 3:46 PM, Peter Fairbrother <zenadsl6186@xxxxxxxxx> wrote:
On 18/01/17 11:13, James Padfield wrote:
...but then there are the 'linear implosion' devices that use only two
simultaneous detonators...
Not much of a secret that nearly everything has used only two points since
Swan in 1956 (Redwing Inca). That became W-45.
I wasn't going to say that, but as you already have, and if it is "not
much of a secret"...
Not much. See Wikipedia:
https://en.wikipedia.org/wiki/Nuclear_weapon_design#Two-point_linear_implosion
and
https://en.wikipedia.org/wiki/Nuclear_weapon_design#Two-point_hollow-pit_implosion
Or nuclearweaponarchive.org if you want lots of slightly out-of-date detail.
My point I think is still valid - that full yield detonation requires
*both* dets to fire simultaneously, and within (probably) microseconds
More like nanoseconds. Shock wave travels in HE at say 6km/s or 6cm in 1
microsecond. You need the ~6cm pit to be squozen evenly, if one side is being
squoshed 6cm out ..
I'd guess the shocks should arrive within a good bit less than a mm of each
other - so <15 nS detonation accuracy.
(actually less, but that's another story)
of each other (which is why EBW dets were developed for nukes -
conventional dets just aren't fast enough to detonate within the
required microsecond tolerances). Anything less than simultaneous
firing of the two dets "merely" scatters plutonium everywhere. At
least, that is my understanding...
From slightly unreliable memory, there were about 25 US "one-point-safe"
tests, where (speaking loosely) one det was set off just to see what would
happen. About 10 had nuclear yields in the 1-10 ton range, 5 or 6 resulted in
significant nuclear yield, in the 100 tons range, with one result about 500
tons.
US bombs were redesigned to minimise this, at large cost in terms of design,
development, and replacement. The present standard is less than 1 in a
million chance of >4lb TNT equivalent nuclear yield for detonation at any
point on the explosive surface.
(Hmm, if it's zero elsewhere, but there's one point in a million - a det -
where the yield is like 3,999,999 lb TNT - would that count as safe? I
digress.)
But for other people's bombs, who knows how one-point-safe they are?
NNSA also developed a "multi-point-safe" technology where if two or more
detonations were set off without 30 microseconds the yield would still be
less than 4 lb TNT equivalent, but it isn't used.
Yields that small tend to kill by prompt ionising radiation at distances
where blast and thermal effects are survivable. For a 5 ton yield the kill
radius is about 200m by prompt ionising radiation, versus about 50m by blast
and thermal.
http://www.alternatewars.com/BBOW/ABC_Weapons/Nuke_Effects_Calculator.htm
-- Peter Fairbrother
