Re: LNT and Collective Dose

["Marissa Bartlett" <Marissa_Bartlett@health.qld.gov.au>]

I'm suprised you are required to calculate collective dose.  Surely it'd be of more interest to work out the worst-case exposure (e.g. person living right by the road who sits on their front verandah all day every day) and maybe best-case exposure and report those two.  Then at least you could multiply by the 0.0005 and the answer would have some kind of meaning.



In shielding for medical facilities, we have to design the sheilding so a single person who spends their entire working life leaning against their office wall at the point of highest dose rate, will not get more than the specified limit.



Marissa Bartlett

marissa_bartlett@health.qld.gov.au 



=====================================================

>>> <RuthWeiner@AOL.COM> 15/02/02 6:53:35 >>>



I do transportation risk assessment and have published a number of studies in 

this area.  The method we use may be outline (without details) as follows:

1.  There is an external (surface) dose rate associated with radioactive 

materials during transportation.  We usually use the maximum permissible  dose rate for the source.

2.  The exposed population is the population resident in a half-mile wideband 

on either side of the transportation route.

3.  We calculate the collective dose in person rem, with an expression that I 

won't bore you with here, but which has been extensively reviewed and 

verified and validated, and has been in use since about 1977.

4.  I would prefer to leave it at that, but at the insistence of our 

sponsors, we multiply that collective dose by 0.0005 and report potential excess latent cancer fatalities attributable to the radioactive emissions from thge material being transported.  The numbers, as you can imagine, are 

tiny.  We also report collective dose, by the way.









===============================

Dr Marissa Bartlett

Dept of Nuclear Medicine

Royal Brisbane Hospital



marissa_bartlett@health.qld.gov.au

ph: + 61 7 3636 7569

fax: + 61 7 3636 8481







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