RE: Asking for opinions -Reply

[L_K_II_Les_Aldrich@RL.gov]

I've been working at this site for 20 years and have been responsible
for the external dosimetry program for most of the site for the last 3
years.  We have been taking our dosimeters home for that entire period,
and I don't see any evidence of loss of control.

Occupational dose is dose received on the job.  Non-occupational dose is
dose the dosimeter receives outside the job environment.  When the
question comes up, we distinguish occupational dose by comparing it to
the supplemental dosimetry that was worn on the job, by comparison with
other workers doing the same job, by comparison with job dose rate
surveys, by evaluating the access control entry system records to see
what areas the worker was in, and a variety of other methods.
Non-occupational dose identification usually starts with the worker,
after receiving his dosimetry report, saying, "I didn't work anywhere
that I could have gotten that high a dose."  After going through the
identification of what part of the employee's dose was occupational, we
look for the source of the rest of the dose recorded on the dosimeter.
Sometimes we find it, sometimes we don't.  If we find it, we document it
and adjust the occupational dose accordingly.  If we don't find it, and
we (dosimetry, line management, and the employee) can document what part
of the dose was occupational, we record that dose.  If we cannot
differentiate occupational from non-occupational, we call the whole dose
occupational and live with it.

With 5,000+ employees wearing dosimeters, we average 5-10 cases a year
where non-occupational doses show up on the dosimeters.  In addition,
there are 15-20 employees who wear their dosimeters to work immediately
after having medical radionuclide injections - those are easy to detect,
they set off every portal monitor they get close to.

I once did a calculation on the hot dashboard fade for one of our annual
dosimeters, based on temperatures encountered on dashboards in this
area, and concluded that we lose, at most, 60% of the recorded dose.
Only employees expected to receive 100-200 mrem/y wear annual
dosimeters, so the lost dose would be between 60 and 120 mrem, maximum.