[ RadSafe ] Fwd: Current Dose Conversion Factors for Thoron

[Chris Alston]

Peter

Is this just the dose from the Tn and Rn proper, or does it include
progeny?  Thoron's t1/2 is 55 seconds; radon's of course is nominally four
days.

Cheers
ca
---------- Forwarded message ----------
From: Peter Collopy <chaosforthefuture at yahoo.com>
Date: Tue, Dec 20, 2016 at 4:51 PM
Subject: [ RadSafe ] Current Dose Conversion Factors for Thoron
To: "radsafe at health.phys.iit.edu" <radsafe at health.phys.iit.edu>
Just finished reading an UNSCEAR report (UNSCEAR, United Nation Scientific
Committee on the Effect of Atomic Radiation. Annex B: Exposures from
Natural Radiation Sources. UnitedNations, p. 104 (2000).) and they showed a
conversion for radon and thoron air concentrations to dose as follows:

My question is why is thoron more limiting (i.e. a lower concentration) in
these calculations? In 10CFR20 (I know its out of date) and some other
publications the ratio is the opposite. i.e. you need more thoron inhaled
to deliver an equivalent dose to a lesser amount of radon.
I assume the total energy delivered is greater for the thoron but why was
that not reflected in previous dose/DAC estimates? Peter Collopy, CIH, CHP,
CSP
Director, Entropy Control
Chaos for the Future