U.S. Nuclear Regulatory Commission
Question 1: If a licensee decides to implement Part 20 in
mid-year, how does the licensee treat the annual dose
limits? Prorated? Add contributions from beginning of
year before the revised Part 20 was adopted?
Answer: The licensee must define the "year" consistent
with the definition in 10 CFR 20.1003. If a licensee
intends to implement the revised Part 20 at any time other
than the beginning of the year, the licensee must subtract
the dose received for the current year prior to the revised
Part 20 dose being adopted from the revised Part 20 dose
limit. The difference need not be prorated. For example,
assume a licensee adopts the revised Part 20 on July 1,
1992, and defines its dose year as January 1 - December 31.
If the worker had received 1.5 rems between January 1 and
June 30, 1992, he or she would have (5 - 1.5) = 3.5 rems
available for the remainder of the year. If the worker
already has more than 5 rem (e.g., two 3-rem quarters), the
licensee must shift the worker to tasks in which the worker
will receive no occupational radiation exposure.
(Reference: 10 CFR 20.1003)