"Chad Irby" wrote in message
m...
In article ,
"Kevin Brooks" wrote:

"Chad Irby" wrote in message
m...

But there is a rather scary little piece about suitcase nukes at the
Nuclear Weapons Archive, which says about suitcase nukes:

"We can now try to estimated the absolute minimum possible mass for a
bomb with a significant yield. Since the critical mass for alpha-phase
plutonium is 10.5 kg, and an additional 20-30% of mass is needed to
make
a significant explosion, this implies 13 kg or so. A thin beryllium
reflector can reduce this by a couple of kilograms, but the necessary
high explosive, packaging, triggering system, etc. will add mass, so
the
true absolute minimum probably lies in the range of 11-15 kg (and is
probably closer to 15 than 11)."

http://nuclearweaponarchive.org/News/DoSuitcaseNukesExist.html

He is talking apparently about the nuclear material in the core only
being
somewhere around 11-13 kg (it is going to take more than 2 to 4
kilograms of
HE, Be, triggers, etc to handle the rest of the equation);

Not particularly. The high explosives would add up to a couple of
kilograms, for sure, but the beryllium won't need to be thick (and
therefore would not add much to the weight), the triggering system would
be negligible in weight (a handful of detonators, a timing system, and
some batteries). At most, you're looking at *maybe* 15 kilograms for
the whole device. My personal toolkit weighs more than that, full up.

You gotta wonder, if this is the case, why a smaller weapon was never
developed or deployed by the US; W-54 was the smallest of the sherical
implosion devices, and in its SADM form it weighed in at over 100 pounds all
up and (allegedly) between 50 and 70 pounds for the internals alone. We
never fielded linear implosion warheads that weighed any less (based upon
the 155mm rounds).


Note that you're not going to build something this small on a shoestring
budget or from public documents, either. Very small nukes take very
large mathematics.

in that same article he refers to the W-54 as being the smallest
practical sherical device ever fielded, and then also describes the
linear implosion devices (which are narrower, but also longer) used
in arty rounds. None of the fielded weapons ever got below around 100
pounds or so.

The artillery shells and Davy Crockett were all *projectiles*, and had a
lot of extra weight in casings and shockproofing. A lightweight nuke
would need none of that,

I disagree. Unless you want your initiators and HE shell to be exposed to
all manner of damage, an outer casing is going to be trequired around the
physics package. A dent in the HE covering can be the difference between a
significant detonation and a fizzle. The US military was extremely
interested in developing (a) the smallest possible deployable warhead for
use by ADM and SOF elements, and (b) found that SADM, with a full-up weight
of over 100 pounds, was the best they could do.

and would be *much* lighter and smaller. The
SADM had a lot of failsafe and ruggedization extras in the mix, and was
a very different sort of device (and had a variable yield to boot).

Have you ever seen what the PAL on the SADAM consisted of? And I doubt the
variable yield function added much to the weight, if anything. Yes, it was
"ruggedized"--but if you want your small nuke to be reliable at all, it
better be able to withstand being transported.


The warhead for the 155mm artillery round was much smaller in diameter,
and somewhat longer, in a steel casing, and still fell below 100 pounds.

The same source indicates the minimum weight for the W-48 155mm projectile
was 118 pounds--the upper limit was 128 pounds. I have no idea what the
specs, or material used, for the casing was, nor do I have any idea what if
any restrictions there were on propellent charges for it. We can surmise
that it likely had a rather thin shell because getting the physics package
small enough to fit into the tube was challenge enough.

Brooks


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