United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

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)

Page Last Reviewed/Updated Thursday, March 29, 2012