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RE: aquous I-125 disposal
REPLY: In Canada, we have a licence condition under our isotope licence that
we have to make sure that scheduled quantities (SQ) per kg, per liter or
per volume are not exceeded in our waste if we want to dispose of them in
"domestic waste". For exemple, 1 SQ/kg for I-125 would mean 1 uCi (37
kBq)/kg or for H-3, it would mean 1 mCi/kg. For liquid waste you divide the
numbers by 100 and for gases you divide it by one thousand. So it is
possible to dispose of any isotope via "domestic facilities" if there are
homogenous and uniformly distributed (no sealed sources...) but some
municipal laws simply forbid any activity in the sewre system or "domestic
waste". So it will depend...
At Merck Frosst, we simply have two type of disposal: decay (10 half-lives,
P-32 being the longer half-life that are manage in this fashion) and
incineration or disposal via a specialized radwaste company for longer
half-lives. Nothing "active" in the "domestic waste" !
You may found a totally diffirent answer from other institutions because of
applicable laws and regs. Some big hospital simply dilute the I-125
activities (water running in the sink the whole day) to meet disposal
criterion in the sewer systems.
Stephane Jean-Francois Phys, Eng.
RSO Merck Frosst Canada Inc.
Montreal Canada
stephane_jeanfrancois@merck.com
This note is my personal opinion and do not imply Merck Frosst Canada in any
way.
________
You wrote:
##Dear Radsafers - I would be interested in some information with regard to
##aqueous waste disposals in the USA, Europe and the Antipodes. I have
##specifically itemised I-125 because I have just read a paper by Edwards
##et al. in the September issue of Health Physics (vol 71 #3 p 379) on an
##I-125 aqueous waste reduction protocol being used at Harvard University
##Medical School and it made me somewhat relieved that I was not a health
##physicist in the States. Basically the institution concerned generates
##several 200L drums of aqueous waste per month with an actvity
##concentration of 100 Bq/mL. That is 20 MBq per drum, and if several is say
##6, then 120 MBq of iodine waste per month. These Boston researchers have
##gone through what sounds like a fairly labour intensive investigation and
##protocol to reduce the activity of the waste in the water by transferring
##it to resins and carbon filters, and then having to store for decay the
##solids before release.
##In the UK, I have just applied for and been granted authorization under
##our Radioactive Substances Act permission to dispose of 200 MBq I-125 per
##month into our foul water drains and this is for a small Institution of
##some 30 researchers working in the centre of Bath, a city a quarter the
##size of Boston. To get this permission, we had to apply to our Environment
##Agency with full environmental impact analysis which is vetted by outside
##inspectors who have to be satisfied that what we are planning is of
##minimal environmental and hence public risk. Like everyone we have the
##ALARA directive and all Institutions in the UK will keep discharges as low
##as possible. Incidentally the 200 MBq only applies to I-125, I can
##discharge in the same month 400 MBq H-3, 650 MBq P-32, 650 MBq S-35, 200
##MBq Cr-51 etc. etc. The University I work for being a much larger
##Institution than the example I have just given, has a different
##authorization, because it is on a different site and at present I can
##allow a discharge to the normal waste of 500 MBq I-125, 20 GBq H-3
##etc.etc. per month. Naturally we have to keep audited records and we must
##demonstrate compliance with our authorization but our dilute and disperse
##policy makes life a lot less complex than our colleagues in the States.
## So what does the rest of the world do? Is the UK alone in this policy?
##My University has many International researchers in its laboratories and I
##would welcome knowing from RSOs from their own country exactly what
##restrictions are placed on them there. There is often a distinct sense of
##disbelief (and relief) when told of our local requirements.
##Personal replies to address below welcome or to the mailbase if you feel
##it could be of general interest.
##David Hornsey
##University of Bath
##Bath BA2 7AY
##<d.j.hornsey@bath.ac.uk>