United States Nuclear Regulatory Commission - Protecting People and the Environment

Health Physics Questions and Answers - Question 40

Question 40: Assume a licensee has defined its compliance year as January 1, 1993 to December 31, 1993. What is the mechanism to change its definition of year? For example, the licensee wants to monitor from January 31, 1994 to January 30, 1995, how should it account for the lost days January 1 - 30, 1994? Is it acceptable to prorate the doses?

Answer: No. The question refers to the definition of "year" in 10 CFR 20.1003. The licensee is not allowed to make the one-step change as postulated in the example in the question because that change involves omitting certain days. Omitting days, even with dose proration, is not allowed. However, the license could accomplish the desired change in two steps, one step in each of two consecutive years, that would give a "year" beginning 1/31 of one calendar year and ending 1/30 of the following year. The first step, using the example, would be a change, at the beginning of 1993, to a "year" of 1/1/93 to 1/30/94 (13 months). The second step would be a change, at the beginning of 1994, to a "year" of 1/31/94 to 1/30/95. This two-step change meets the requirement of "years" that begin in January with no day omitted or duplicated in consecutive years.

(Reference: 10 CFR 20.1003)

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