[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: To Bioassay or not to Bioassay!!
Robert, thanks for the response. I have answered your questions below and
provided a bit more information. In particular I am interested in anyones
views on my assumption of 1% uptake of the total activity of all
radioisotopes handled by workers.
>>To receive an effective dose of 30% of the limit 0.3ALIs must be
>>ingested/inhaled. Since 1% is ingested/inhaled, the number of ALIs required
>>to be handled is 30 (ie 0.3/0.01).
>>
>
>What are the Regs down-under for when individual monitoring is required?
>I assume from your basis that they are no less stringent than 30% of an ALI.
Unfortunately our regs were written in 1961 and are deficient in many
respects. In particular, all provisions relating to monitoring apply solely
to external irradiation (ie TLD/film). Rather than defining a "dose which is
likely to be received" above which external monitoring is required, the regs
literally say 'at the direction of the Director General of Health'.
>This seems a bit relaxed (IMHO). For comparison purposes, the USNRC
>requires monitoring when an individual is likely to exceed 10% of an ALI and
>the USDOE requires monitoring at 2%.
> Assuming that your Regs limit total effective dose equivalent (EDE + CEDE)
to >0.05 Sv, and doesn't specify when to establish bioassay monitoring, I
would >suggest a monitoring level of 10% as being adequate. I personnally
would not be >comfortable in establishing a bioassay program where the
"missed dose" was as >high as 0.015 Sv (1.5 Rem).
The regs do limit total effective dose to 50mSv however I have adopted
ICRP60 recommendations for the Radiation Procedures Manual. Thus I am using
a limit of 20mSv and ICRP61 ALIs. Thus the missed dose could be as high as
6mSv (0.6 rem).
>Would you not require TLDs (or film) when external exposures were of the
>order of 0.01 Sv (1 Rem)?
Yes but that is another issue!!
Alex Zapantis
Radiation Safety Officer
Queensland University of Technology
Health & Safety Section
Locked Bag No.2
Red Hill Qld 4059
AUSTRALIA
Ph : 61 7 864 3566
fax : 61 7 864 3993
email : a.zapantis@qut.edu.au