AW: [ RadSafe ] Re: Residential radon risk

[Bernard Cohen]

Dear Philippe:
Many thanks for this info. If the variation of unattached fraction is so 
large, why do mines depend solely on WL? In any case, the variation in 
homes can be very much larger because of systems for dust removal in 
common use.

Philippe Duport wrote:

> Dear Dr. Cohen,
>
> More recent data on the unattached fraction in U mines:
> Keng Wu-Tu, Isabel M. Fisenne and Adam R. Hutter.  SHORT - AND 
> LONG-LIVED RADIONUCLIDE PARTICLE SIZE
> MEASUREMENTS IN A URANIUM MINE.  DOE-EML Report EML-588, April 1997
>
>
>
>
>
> Unattached fraction : 0.3 % to 23.9 % in a Canadian uranium mines in 1995
>
>
>
> Wu-Tu et al data confirm, independently, those obtained in French U 
> mines some 30 years ago.
>
> Dr. Cohen, you may have a point, the unattached fraction may be quite 
> variable and the raw WL value may not be the right parameter to 
> characterize the risk of lung cancer due to radon decay products, and 
> upon which to base lung dose calculations.
>
>
>
> Wu-Tu et al found also a sizable amount of ultrafine long-lived 
> aerosols (elements of the U 238-235 decay series other than 
> short-lived Rn decay products) between 10 and 100 nm (mode at 30 nm).  
> These were never taken into account in lung dosimetry.
>
>
>
> P Duport
>
>
> ----- Original Message ----- From: "Bernard Cohen" <blc+ at pitt.edu>
> To: "Philippe Duport" <pduport at uottawa.ca>
> Cc: <GELSG at aol.com>; <radsafe at radlab.nl>; "Bernard L Cohen" 
> <blc at pitt.edu>
> Sent: Wednesday, June 01, 2005 11:55 AM
> Subject: Re: AW: [ RadSafe ] Re: Residential radon risk
>
>
>>
>>
>> Philippe Duport wrote:
>>
>>> Please see "Determination de la fraction libre d'activité existant 
>>> sous forme de RaA non attaché dans l'atmosphère d'une mine 
>>> d'uranium" by A. Chapuis, A. Lopez, J. Fontan, Health Physics Vol. 
>>> 25, pp. 59-65 (1973). At that time, Health Physics accepted papers 
>>> in French!  The fact that some papers were published in French or in 
>>> languages other than English does not imply that the research has 
>>> not been done and the information does not exist.
>>>
>>> Chapuis et al report unattached fraction values from 1 or 2% close 
>>> to an active stope, up to 15 to 20% without, or far enough from, 
>>> active mining operations.  Miners do not spend all their time in 
>>> close proximity to active mining operations.
>>>
>>> I measured  unattached fraction values of the order of 30% in an 
>>> isolated, inactive part of an underground uranium mine with forced 
>>> ventilation (P. Duport, G. Madelaine, A. Renoux. Mesure de la 
>>> fraction libre dans l'air d'une mine d'uranium laboratoire, 
>>> Chemosphere 4(5):283-288, 1975) - sorry, another paper in French.
>>>
>>> The unattached fraction is of course very sensitive to aerosol 
>>> concentration, but it is a serious mistake to assume that it is 
>>> always negligible in mines.
>>>
>>> Philippe Duport
>>
>>
>>       ----My apologies for aaying unattached fractions were close to 
>> zero in mines. The point is that they are presumably small enough and 
>> have little enough variability that they do not affect the radiation 
>> dose. If they did, it would not make sense to use WL as an index of 
>> radiation in mines
>>
>