Re: Working life of sealed industrial sources

[b.mckavanagh@cqu.edu.au (Byron McKavanagh)]

>        These are old stories (>15 y) but may be relevant. Other events exist.
>        Probe first + Presence of mind + Absence of body.
>
>        Roger Gelder

These accounts by Roger should be of interest to the West Australian
authorities who made the intital enquiry.

I think they are being a bit reticent to discuss a case that occurred in
their State, where a Cs-137 source from a gauge that had been mounted on a
crusher (Mining?) developed a "severe" leak during testing in a hot cell by
a consultant.  Decontamination costs were quite large.  The case has been
discussed widely amongst the various State authorities in Australia, so
Mike Williamson would remember more details.  I understand that the
vibration levels were thought to have contributed to deterioration of the
source capsule.

Another factor may have been the presence of PVC plastics in contact with
the source capsule.  I understand that hydrochloric acid can be released as
a result of radiolysis, which then attacks the stainless steel.

As I recall, this is the only documented case of a leaking sealed Cs137
source in Australia we could find 12 months ago.   Several more are known
to have occurred, but were discovered at a late stage of accretion of
sources during disposal, and the individual sources couldn't be traced.
The attitude of authorities here is to require the disposal of a source at
the end of the manufacturer's Recommended Working Life, unless the User is
willing to do an annual re-certification of the source.  Most (all
industrial users?) are not willing to do this, preferring to dispose of the
source to the manufacturer & install a new one  The remoteness of many of
the mining sites makes this understandable.  The RWL is generally 15 years
for industrial sources.  One state, New South Wales, requires disposal
after 10 years under their Environmental Protection Act.



---------------------------------oOOo-(_)-oOOo--------------------------
Byron McKavanagh,
Radiation Officer,
Department of Applied Physics,
Central Queensland University
Rockhampton 4702 Australia.
Ph 079-309625                   Fax: 079-309209
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"Just remember you are unique.  Just like everyone else."
(Dictionary of Cynical Quotations, 1996 ed.)
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