Re: Radiation from an A-bomb

[JPreisig@AOL.COM]

Howdy,



      This is from  jpreisig@aol.com   .



      Hello Kai and Radsafers,



      You can do this kind of calculation yourself.



      I'm assuming this is an ordinary A-bomb (not a Hydrogen Weapon).

      I don't think you will see much in the way of neutrons outside of such 

a

      suitcase bomb.  A (D,T) neutron generator used for triggering an

      atom-bomb will not generate neutrons until around the time the bomb is

      being set off.  And if the triggering device is just an AmBe source 

with

      some sort of shielding and/or shutter, then the AmBe source also must

      be shielded until the bomb is to be triggered.  A large number of

      prematurely emitted neutrons could trigger the atom-bomb before its

      intended explosion time.  



           As for gammas outside of such a device, for an approximation, just

      assume the bomb is a cylinder or a sphere.  The bomb material is

      largely U-235 or Pu-238 (95% - 100% enriched).  What gammas do

      U-235 or Pu-238 emit????  See your Rad Health handbook.  Remember, 

      such a device is somewhat large, such that gammas arriving from the

      center of such a device (to the outside surface of the device) will be

      shielded by the intervening Uranium or Plutonium material.  I guess you 

could

      do a shielding calculation which considers the gammas from thin layers

      of a sphere or cylinder of Uranium or Plutonium.



      Easier still, just whip out your copy of MCNP (Monte Carlo Neutral 

Particle

      Program), set up your bomb geometry and compute the gamma flux 

      densities (or fluences) outside of your simulated bomb.  Try bomb 

masses

      of 1 kilogram to 20 kilograms.



           My guess is you would want a nice portable MultiChannel Analyzer 

with

      some sort of gamma sensitive probe attached.  I don't know much about 

the

      alphas coming from U-235 or Pu-238.  The alphas will be stopped by the

      suitcase around the bomb.



      Many Atomic bombs probably have some sort of moderating or reflecting

      material to allow the bomb to work efficiently.  Account for this in 

your    

      calculations.



      Have fun.  I hope this 9/11 is a peaceful one.









                                                    J.R. Preisig, Ph.D.





      

************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.

You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/