Health Physics Questions and Answers - Question 90

Question 90: Can a licensee require its workers to routinely take potassium iodide (KI) when handling large quantities of radioiodine and take credit for the reduction in occupational dose that results from the use of the KI?

Answer: No. Requiring the use of KI for this purpose is neither a "process or engineering control...to control the concentration of [radioiodine] in air" 10 CFR 20.1701). Furthermore, because KI blocks uptakes (not intakes), the use of KI for thyroidal blocking cannot be considered to be among the "other controls" required by 10 CFR 20.1702 for limiting intakes. The following cautionary note in NRC Information Notice 88-15 (4/18/88) continues to be applicable under the Revised Part 20:

"It is important to stress that the use of potassium iodide is not a substitute for preventive measures; e.g., proper handling techniques, control measures, and emergency procedures that protect the individual from exposure to radioactive material."

A licensee should optimize design and engineering controls, as well as operating procedures, as a means of ensuring that doses from airborne radioiodine are ALARA. However, in situations where KI has been administered following a suspected intake, the licensee may take credit for the protection if bioassays support the effectiveness of the KI in blocking the thyroid.

Finally, although licensees are not authorized to require their employees to routinely take KI when working with radioiodine, nothing in NRC regulations prohibits an individual from taking KI on a purely voluntary basis; however, the NRC does not recommend the voluntary use of KI in this manner.

(Reference 10 CFR 20.1701)