Health Physics Questions and Answers - Question 434

Question 434: How are occupational dose limits applied in regard to the revised Part 20 definition of "year"? The purpose of this question is to obtain additional clarification of the intent and application of the "year" as it is defined in the revised Part 20 and discussed previously in Question 40. Apparently, licensees may establish a year that is other than January 1 through December 31 (e.g., Question 40 addresses a year that is from January 31 of one year through January 30 of the following year). In responding to the question, consider the following example. A worker receives dose sequentially at facilities of two different licensees, the first licensee using a year of January 1 - December 31, and the second licensee using a year of January 31 - January 30. The worker receives 4 rems total effective dose equivalent (TEDE) at the facility of the first licensee during the period January 1 - January 30, and then transfers to the second licensee's facility, arriving for work on February 1. For work performed at the second licensee's facility, is the individual's remaining available TEDE 1 rem or 5 rems?

Answer: Five rems. For a particular licensee, the relevant time period for determining compliance with an annual dose limit is the year beginning and ending on the dates specified by that licensee, providing that the time period chosen by the licensee is consistent with the definition of "year" in 10 CFR 20.1003. In the example provided, the worker started work at the facility of the second licensee at the beginning of that licensee's "year" and, therefore, the worker had no prior occupational dose during that licensee's "year."

(Reference: 10 CFR 20.1003)