Source Expiration Dates -Reply

[Alan Jackson <AJACKSO1@SMTPGW.IS.HFH.EDU>]

Ben and RADSAFE,

Be careful with "expired" sources.  If you want to use them past the
expiration date you will need to document that the source integrity is
unaffected and that the source functions properly.  Regulators have
been known to issue violations for using expired sources without this
documentation.  Many counting laboratories avoid this by using only
unexpired sources.

Some sources can be degraded over time.  Important lines may be lost
due to decay, ingrowth may occur or physical integrity may become
compromised.  The cynic in me believes that another reason for a
manufacturer to expire sources is you might forgo the trouble of
certifying a perfectly usable source and buy more sources.  I think that
this wastes money and increases your radioactive waste volume.  If you
buy new sources, and it is appropriate, specify with the manufacturer
that no expiration date be placed on the sources or the certificates.

I consulted an ex NBS/NIST scientist about these issues in the past and
he believes that old sources are often better than new ones.  The key is
to pay attention to the nuclide production method (trace nuclides
included), decay chains and source integrity.

-Alan Jackson
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