RE: Skyshine from Burial Vaults

[Richard, Orthen]

J.R.--Is this your 95th or 99th percentile recommendation?



Cheers.



Rick Orthen

Earth Sciences Consultants, Inc.

One Triangle Lane

Export, PA

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

  From: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of JPreisig@AOL.COM

  Sent: Monday, July 14, 2003 11:45 PM

  To: radsafe@list.vanderbilt.edu

  Subject: Re: Skyshine from Burial Vaults





  Hmmmmm,



       This is from:     jpreisig@aol.com   .





        Hello Radsafers,



              MCNP4C is proven (i.e. tried and true) computer code for doing

this

        type of work.  I don't think you have to benchmark it much (or at

all???).

        What you have to do is make sure all your mcnp modelling assumptions

        are correct and accurate.  Then, with mcnp, you might want to make

        a series of mcnp runs with various thickness roofs on the vault.

You should

        have a tally (detector) at some distance above the center of the

vault

        and a tally detector which looks at photon fluxes at some distance

        away from the center of the vault (i.e. the skyshine).  You might

want

        to compare the results of a skyshine analytical model with the

        mcnp results.  Once your vault roof is thick enough to stop the

photon

        radiation, then I don't think you have to make the roof too much

thicker.



         MCNP is great stuff; the trouble with Monte Carlo work is you end

up

         thinking in terms of probabilities (all the time --- kind of like

being

         a junior Enrico Fermi???).  It's hard to give anyone a straight rad

         health answer (to an honest question), after having done Monte

Carlo

         for a while.  Oh Well...



         Regards,               J.R. Preisig, Ph.D.