United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 179: If a licensee implements the revised Part 20

in July, 1993, is the licensee required to go back and

evaluate internal dose for the purpose of determining total

effective dose equivalent for the year?

Answer: No. The footnote to 10 CFR 20.2104 (d), as

amended in 57 FR 57877, 12/8/92, states, "Licensees are not

required to partition historical dose between the external

dose equivalent (s) and the internal committed dose

equivalent (s)." As long as all of the licensee's worker's

doses are below the old limits and/or the workers will not

participate in planned special exposures, the licensee need

not reevaluate prior doses before implementing the revised

Part 20. However, the licensee must subtract the dose

already received during the year from the new annual dose

limits to find the limits for the remainder of the year, as

explained in Question 1, Set 1. (Reference: 20.1202, 10

CFR 20.2104)

Page Last Reviewed/Updated Thursday, March 29, 2012