U.S. Nuclear Regulatory Commission
Question 192: 10 CFR 20.1206 (e) says that licensees may
not authorize PSEs for workers whose doses from previous
PSEs and all "doses in excess of the limits" exceed certain
limits. (a) What and whose limits apply? (b) Does the
actual limit (e.g. 3 rem/quarter, 1.25 rem/quarter, etc.)
apply, or does the equivalent annual limit apply? (c) Do
doses from non-licensed sources (e.g., x-ray sources) that
were in excess of the facility's limits apply, especially
if the facility was not a licensee? (d) It appears that
overexposures will require the licensee to back-calculate
the dose in excess of the limits, particularly when that
dose was received from an intake of radioactive material.
However the Footnote 5 of 10 CFR 20.2106 says that
assessments of dose equivalent and records made using units
in effect before the licensee's adoption of this Part need
not be changed. Will the licensee have to, in fact,
convert the old doses in excess of the limits to committed
effective dose equivalent?
Answer: (a) The regulatory limits at the time and place
of the overexposure apply. If the individual worked for
the Department of Energy (DOE), then the DOE limits apply.
If the individual worked in a foreign country, then that
country's limits apply.
(b) The actual limit applies.
(c) Yes. It is the purpose of the regulation to control
licensed material in such a manner that the total dose to
an individual, from licensed and non-licensed sources, does
not exceed standards prescribed in the regulations.
d) Yes. (Reference: 10 CFR 20.1206, 10 CFR 20.2104, 10
CFR 20.1001, Regulatory Guide 8.35)