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Re: Re[2]: Rn, Epidemiology + thoron
Ilia and Bill
Thoron in air is harder to measure than Radon in air, but I would guess that
the reverse is true for the progeny. A good (but old) reference is the 1985
NEA Group of Experts report "Metrology and Monitoring of Radon, Thoron and
their Daughter Products". OECD, 1985.I haven't reviewed this report
recently.
My expertise is in vivo monitoring, dosimetry and risk, not air monitoring,
and some related publications are
DOSIMETRY ASPECTS OF EXPOSURE TO RADON AND THORON DAUGHTER PRODUCTS
Report by a Group of Experts of the Organization for Economic Co-Operation
and Development Nuclear Energy Agency (1983).
A MODEL TO DESCRIBE THORON EXHALATION FOLLOWING AN INHALATION EXPOSURE TO
THORIA POWDERS
J.R. Johnson and B.F. Peterman
Published in the Conference Proceedings of the Workshop on Lung Modelling
for Inhalation of Radioactive Materials, Oxford, UK, 1984 March. Published
in "Lung Modelling for Inhalation of Radioactive Materials", EUR Report
9384, Commission of the European Communities, Luxembourg (1984) 193-196.
THE RELATIVE EFFECT OF VENTILATION ON THE POTENTIAL ALPHA ENERGY FROM RADON
AND THORON DAUGHTERS
J.R. Johnson
AECL-8823, Health Physics 49 No. 5 (1985) 996-998.
John R Johnson
____________
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idias@interchange.ubc.ca
----- Original Message -----
From: Yarmoshenko IV <ivylist@ECKO.URAN.RU>
To: R. William Field <bill-field@UIOWA.EDU>
Cc: RADSAFE <radsafe@list.vanderbilt.edu>
Sent: Saturday, February 16, 2002 12:01 AM
Subject: Re[2]: Rn, Epidemiology + thoron
> Bill,
> Some clarifications on thoron.
> Half life of Pb-212 (thoron daughter) is about 10 h consequently
> thoron progeny is equally distributed within the room. Due to high
> variability of thoron equilibrium factor indoor, thoron gas
> concentration measurement does not surrogate thoron progeny exposure
> assessment (as in the radon case). Unfortunately I'm not familiar with
> any integral passive technique of thoron progeny measurements and as
> far as I understand the retrospective measurements of thoron progeny
> is impossible (am I right?). We used the grab sampling techniques for
> surveys in Ural region of Russia, by which results thoron progeny
> contributes from 5 to 30 % to total average Rn+Tn exposures by
> settlements.
>
> Regards,
> Ilia
>
> Ilia Yarmoshenko
> Radiation Laboratory
> Institute of Industrial Ecology
> Ekaterinburg
> Russia
>
>
> RWF> Regarding thoron, because of its short half life, the distance it
travels is
> RWF> much less. But, if you are sleeping right next to a source, you can
get a
> RWF> significant exposure. The glass based detector we used in Iowa has
> RWF> specificity for thoron so we do plan to look at that down the road as
we
> RWF> clear some other hurdles. We do have those measurements already
performed.
> RWF> One interesting note is that outdoor thoron exposure may be greater
than we
> RWF> thought.
>
>
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