U.S. Nuclear Regulatory Commission
Question 117: Does the requirement of 10 CFR 20.2101 (a) to use the unit curie (for activity) mean that it will not be permissible to record the results of contamination surveys in units of disintegrations per minute (dpm) or mrad smearable?
Answer: No. The 10 CFR 20.2101 (a) requirement as it applies to units of activity (curies) is intended to apply to records of quantities of material directly related to the explicit requirements of Part 20 (e.g., storage and control, posting and labeling, waste disposal, concentrations in air, and individual intakes of radioactive material). It is not intended to apply to surveys for contamination. Note: There are requirements in 10 CFR 35.70 (h) which apply to medical licensees to record the results of surveys for removable contamination as disintegrations per minute per 100 square centimeters.
(Reference: 10 CFR 20.2101)