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)