RE: Fisson Bomb Geometries...

["Neil, David M" <neildm@id.doe.gov>]

Close, but off in a few details.  If you read the same story I did in

school, at a junior high grade level, it was not very accurate.  Whether

this was for security or storyline, I can't say.



The configuration was a subcritical Pu sphere with hemispherical Be

reflector shells. The assembly was subcritical at all but full assembly, and

the reflectors should have been separated on spacer shims at a subcritical

point.  Instead, they were merely held apart by a hand-held screwdriver, to

allow the geometry to be varied.  The researcher was also holding the upper

unit by means of a hole in the polar point. The screwdriver slipped and the

sphere was fully assembled.  Around 3E15 fissions later, he separated the

assembly.  This was half a second or less in time.



He received about 2100 rem, and died nine days later.  The seven observers

got from 37 to 360 rem.



The lesson here is not what geometry to use, as this is dictated by the

experiment, but that safety systems and parameters should not be bypassed.

That's what double contingency means, folks.  It should also be pointed out

that a criticality accident is a lot easier to achieve than a weapons

assembly, as the energy release causes "self-disassembly" (translation - it

goes pop instead of BOOM) if everything isn't perfect.  



All this is from a public release document, unlimited distribution.



Dave Neil		neildm@id.doe.gov









-----Original Message-----

From: JPreisig@AOL.COM [mailto:JPreisig@AOL.COM]

Sent: Monday, April 22, 2002 10:06 PM

To: radsafe@list.vanderbilt.edu

Subject: Fisson Bomb Geometries...





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).  

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