Fisson Bomb Geometries...

[JPreisig@AOL.COM]

Hmmmmm......



     This is from:  jpreisig@aol.com.



     Hi All You Radsafe Types!!!!



     Someone on this here message board was talking about making spherical

fission weapons, the tolerances necessary, etc.



     Well, in the good old days (at Los Alamos) a fellow names Louis

Slotin (Slotkin???) was pushing two half-spheres of fissionable material

together with a screwdriver, trying to see if he could get these babies to

go critical.  (I read about this first in junior high school in a short story 

about

the incident).  Well, the screwdriver slipped and a blue flash was observed

(Cerenkov Radiation???), Slotin pushed the spheres apart (saving further 

damage)

and most of the people in and around the room died fairly soon thereafter.

Other people I know have more precise information about the incident.



       The first thing to observe about all this is that if you mess with 

this stuff,

you really should practice in half-space (i.e half of a full sphere) only at 

one

time.  Never work with a full sphere of uranium or plutonium at one time.

You will kill yourself if you do so.  Things don't necessarilly have to 

explode 

to be lethal.



      One can easily approximate a half-sphere by cutting the corners off of 

a 

half-cube in a regular manner.  The more corners you cut off, the closer to

a half-sphere you get.  Think about it.



     Do you really think the US Government makes fission weapons that push

two hemi-spheres together???  It is possible, and perhaps has been done.

I'd believe it more likely that an inner cylinder is being pushed into an 

outer

cylinder;  that way nothing goes critical until the time of detonation.

Clearly, close metal machining work (with close tolerances) is needed here.

One could probably do such work on a good lathe and/or a milling

machine, on molded metal pieces.  Do ALL the  work in half-space, and then

combine the pieces when needed.  Never assemble all the pieces together

as a unit while you are sitting there.  If necessary, test the shapes out 

with

one piece of uranium and a piece of non-fissionable metal (iron, copper, 

etc.).



     I think one should rather work with uranium (enriched, of course) as 

opposed

to plutonium.  I guess the US government can work with plutonium in glove 

boxes

with inert atmospheres.  The triggering of such a device is not very hard to

do, although the timing of the triggering is non-trivial.  Clearly, one needs 

some

sort of mechanical drive system to place one cylinder into another.



     I don't have a security clearance, so none of this is based in 

government-fact.



    One does need highly enriched uranium or plutonium to make this all 

a reality.  Such material is not readily available in the USA (anymore).

The Russians have lost some of their suitcase-based fission systems, although

I don't know the number of weapons involved.  I hope the number is small.

Apparently, some of these weapons were available on the black market.



     Funny, lately, there has been much chatter on this message board about 

the

availablilty of Amerecium sources, either in the form of smoke detectors or

in pure radiation source form.  These Amerecium sources (AmBe) are 

neutron sources (fairly unusual and not usually available).  I was thinking 

one 

could only trigger a fission weapon with a (D,T) neutron generator, but 

lately

I've been thinking of ways a fission weapon could be triggered with an AmBe

source.  It's not all that hard to do.  And without the necessity of 

generating 

high voltages to support a (D,T) generator, an AmBe triggered fission weapon 

would be easy to fit in a suitcase.



     I've been thinking about such things, as an intellectual exercise, for 

many 

years now.  If I can make it work in my mind (as an over-educated health

physicist/geophysicist/physicist), someone else can make it work in a

laboratory (with the correct equipment and financial support).



     I think we should NOW keep our Amerecium sources under lock and key.

Our future could depend on it.



     Have a pleasant evening/morning!!!!



                                                             J.R. Preisig, 

Ph.D.







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