United States Nuclear Regulatory Commission - Protecting People and the Environment

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)

Page Last Reviewed/Updated Thursday, March 29, 2012