Aqueous I-125 disposals

[D J Hornsey <bssdjh@bath.ac.uk>]

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>