Re: Open Pit Uranium Mines

[David Bromwich <D.Bromwich@ens.gu.edu.au>]

I used to work as a Health Physicist with the Uranium Mines in the
Northern Territory as a Mines Inspector. I've moved out of HP to
occupational hygiene.

The top meter or so of ore will shield what is beneath it, so the
effective thickness of ore is about 1 m. You may find that the dose rates
too low to give a good reading on your dosimeters, especially with a short
(days) visit.  Check the ore grade - if the grade was high, you would
expect that it would have been mined.  I'm not sure what a 3M HEPA is, but
I assume it is a 3M 8710 or 9920 for toxic dusts. These (or any HEPA) mask
would tend to filter out radon progeny, but not radon.  The limiting
factors would be the degree of disequilibrium between the progeny (usually
high for open cut mines), the concentration of condensation nucleii (low
in the absence of a lot of dust and diesel fumes), and the facial fit. 
You could probably assume a protection factor of 10 for disposable masks.

Hope this is of use.

David Bromwich
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David Bromwich                            
Lecturer, Occupational Hygiene            tel +617 875 7487
Faculty of Environmental Sciences         fax +617 875 5105
Griffith University            Internet D.Bromwich@ens.gu.edu.au
Nathan, Queensland, AUSTRALIA  4111
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