Re: Shielding cyc. penetrations

[JPreisig@aol.com]

Hmmmmmm,



       This is from:   jpreisig@aol.com   .



       Radsafe Bunch:  Greetings and Salutations....



       Hi, Eric Hill....  So, what is the maximum (proton???) energy of this

       cyclotron???  If your maximum (proton ???) energy is 20 Mev or less,

       one can use MCNP (Monte Carlo Neutral Particle Program) to 

       do computer modelling studies of your shielding, before you actually

       build it.  Maybe there is a proton computer code out there too.



            Penetrations???  Go see what other cyclotron facilities do --- 

visit a

       few of them...



            Parafin sounds like it will deform in time, or on a hot day.  Why 

not use

       concrete blocks and cut-to-shape concrete blocks, with the small voids

       filled with quick concrete???  Depending on the proton energy, you 

want

       to STAY AWAY from concrete with steel or iron re-inforcing --- 

iron/steel

       creates a window where neutrons flow right through the shielding.

       Plastic may also be a better alternative to parafin???



            For higher energy proton facilities, Peter Gollon has written at 

least

       one paper on penetrations.  The reference(s) may be in the Accelerator

       Health Physics coursebook by Cossairt (FermiLab).  I give the Cossairt

       reference in some of my earlier radsafe e-mails.



            Alan Stevens and I (in shielding design work for RHIC --- the 

Relativistic

       Heavy Ion Collider at Brookhaven Lab) generated some Internal Lab

       Memoranda looking at what happens when protons hit the dirt (mound)

       area surrounding a chimney extending through the dirt shielding above 

the

       RHIC accelerator.  Contact Alan Stevens --- he was/is (???) in the 

       RHIC or accelerator division at Brookhaven for more information.



            As for radionuclides being concentrated in various areas of the

       Kirkwood/Cohansey aquifer in New Jersey, one needs to realize that 

these

       aquifer rock units dip down and to the east in a direction towards the 

east

       coast of New Jersey.  If radionuclides are being concentrated in the 

       Toms River area, then perhaps there is a structural (rock) feature 

trapping

       the radionuclides or perhaps there is a clay rock layer under Tom's 

River.

       The usual effect of water entering a down-dipping (to the east) 

aquifer

       is for the water to travel in an eastern direction with dilution of 

the radionuclide

       concentration, if sufficient water is present.  This may be too 

simplistic

       a description of what is actually is going on.  Hi, Dr. Gerry 

Nichols...



             Good Luck with your shielding work, Eric Hill...



        Regards,             Joseph R. Preisig, Ph.D.