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dose rates
More thinking out loud...
In most cases, particularly outdoors, the radium is volumetrically
distributed in the rocks and soils. In this case, the plane source
approximation is probably most appropriate, and I would think you could
develop an effective radius based on the distance at which Ra-226 (and
progeny) gammas will deliver a measurable dose. This is described somewhat
in Eisenbud and Gesell and in considerably more detail in excellent papers
by Kocher & Sjoreen as well as (much earlier) by Beck & DePlanque. The
highest dose rate I noticed at a meter above the ground was about 1 mr/hr,
and the highest recorded was about 2.8 mr/hr (11 and 28 uGy/hr,
respectively).
Also, I should note that Ted de Castro was kind enough to remind me that
readings taken "on contact" are, in and of themselves, difficult to
interpret because of calibration, geometry, and other concerns. At the very
least, you get into the whole mess of what distance to assign to an "on
contact" reading. So, from this perspective, dose rates at 10 cm, 30 cm, 1
m, or other discrete distances are more appropriate to report.
Sincerely,
Andy
Andrew Karam, CHP (716) 275-1473 (voice)
Radiation Safety Officer (716) 273-2236 (fax)
University of Rochester
601 Elmwood Ave. Box HPH Rochester, NY 14642
Andrew_Karam@URMC.Rochester.edu
It is a capital mistake to theorize before one has data. Insensibly one
begins to twist facts to suit theories, instead of theories to suit facts.
(A Scandal in Bohemia, Arthur Conan Doyle)
-----Original Message-----
From: Kevin G. Pearce [mailto:kpearce@vdh.state.va.us]
Folks,
I know I have been out of loop since my submarine days, but. If the contact
measurements are solid at the 2.2 mr/hr, could you not inverse square the
dose
rate to gain the body burden estimate based on times of exposure? Just
thinking, "out loud"...
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