Survey on radioactive materials

Re: Instance: 10:22 Alison Wain's remarks (28/8/96) on
radioactive minerals and objects

In the UK, everything to do with the display and storage of
radioactive materials is controlled by the Ionising Radiations
Regulations (1985), which are administered by the National
Radiological Protection Board (NRPB).  A radioactive substance is
defined as one having an activity greater than 100 Bequerels per
gram, which is a pretty low level. In a survey carried out by the
NRPB in 1983, 'Radiation hazards to collectors of geological
specimens containing natural radioactivity' by D W Dixon, NRPB
report R131, samples of uranium-containing minerals collected in
Cornwall (SW England) were found to have activities up to several
thousand Bequerels per gram.

The general requirement for storage and display is that members of
the public (everyone except classified radiation workers) should not
be exposed to instantaneous dose rates exceeding 2.5 micro Sieverts
per hour, measured at the surface of the container or display case.
This is not too onerous for small or not very active specimens.

We had an interesting case recently of a small plastic ball coated
with radium-containing luminous paint, which had been loaned to us
for an exhibition.  This was found to be far too radioactive to
display, and we had to advise the owners that in the interests of
safety their object would have to be disposed of.  This became a
bureaucratic problem because the object was sufficiently radioactive
to be classed as a sealed source.  You are not allowed to dispose of
sealed sources without authorisation, and you are not allowed to
acquire them without authorisation.  Eventually this was resolved,
and the ball is now stored in a nuclear waste repository.  However,
it cost us 1000 pounds to dispose of the ball through the proper
channels, so the moral is, don't acquire highly radioactive objects
in the first place: check everything you suspect of being
radioactive with a Geiger counter.

Barry Knight
English Heritage
London

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                  Conservation DistList Instance 10:29
                Distributed: Friday, September 20, 1996
                       Message Id: cdl-10-29-004
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