Re: shielding contaminants

[a.zapantis@qut.edu.au (Alex Zapantis)]

Try and get a hold of some "old" lead. This however can be quite expensive.
You might want to consider using a graded shield. That is, use a copper
liner within the lead shield to get rid of the Pb 210 gammas (low energy)
and most of the fluorescent x-rays which may originate in the lead.

Just an idea!!



>> I have a rather unusual shielding problem to solve.  I have to shield some 
>> scintillation detectors from ambient background radiation, and want to do
it in 
>> the most cost effective manner.  The radiation level has to be reduced by a 
>> factor of 1000.  I have determined the thickness required of lead, steel,
and 
>> concrete (in order of decreasing cost) to provide this level of shielding
for a 
>> 1 MeV photon (the average background gamma energy I used for the shielding 
>> calculations).  However, I am concerned that I will be adding as many
background 
>> gammas from the shielding material that I am removing if the shielding
material 
>> has low-level radiation in it.  Does anyone know which of the three
alternatives 
>> will provide the least background?  What are the level of contaminants in
the 
>> proposed shielding materials relative to "normal" soil?
>> 
>> Thank you in advance,
>> 
>> Daniel Low, Ph.D.
>> 
>> 
>>  -----------------------------------------------
>> |     _/_/_/    _/     Daniel A. Low, Ph.D.     |
>> |    _/    _/  _/      Assistant Professor      |
>> |   _/    _/  _/       Mallinckrodt Institute   |
>> |  _/_/_/    _/_/_/_/     of Radiology          |
>> |                     Division of Radiation     |
>> |                         Oncology              |
>> |                   510 South Kingshighway Blvd.|
>> |                 St. Louis, MO 63110  USA      |
>> |               (314) 454-5021 (Office)         |
>> |             (314) 454-5276 FAX                |
>> |           low@castor.wustl.edu                |
>>  -----------------------------------------------
>> 
>> 
>
>


                I know that you believe you understand what you think I said 
                but I am not sure that what you heard is actually what I meant.

                        Alex Zapantis
                        Radiation Safety Officer                               
                        Queensland University of Technology          
                        Health & Safety Section                             
                        Locked Bag No.2
                        Red Hill Qld 4059
                        AUSTRALIA

                        Ph     : 61 7 864 3566
                        fax     : 61 7 864 3993
                        email  : a.zapantis@qut.edu.au