Shielding of Ra-226 Gammas by Concrete

[SENES Consultants Limited <senes@senes.on.ca>]

A mundane question - Does anyone have a good reference for the transmission of U-238 series (or Ra-226 ) gamma radiation through standard concrete (specific gravity = 2.3 to 2.4)?  I am specifically interested in the shielding provided by 6 inches (15 cm) of concrete over an extended plane source  of Ra-226-bearing material.

The Radiological Health Handbook (Nucleon Lectern Associates)  gives a graph of transmission of Ra-226 gammas versus thickness of concrete (hard to read in my copy and I don't have the quoted reference) but it disagrees (by about a factor of  2) with calculations using MicroShield.  What should one use for the attenuation coefficient or half-value thickness of  concrete?  Any information on similar materials (gravel, soil, etc) would also be appreciated.

If desired, you may reply directly to me.  Thanks.


Leo M. Lowe, Ph.D.
Senior Health and Environmental Physicist

SENES Consultants Limited
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