United States Nuclear Regulatory Commission - Protecting People and the Environment

Health Physics Questions and Answers - Question 192

Question 192: 10 CFR 20.1206 (e) says that licensees may not authorize PSEs for workers whose doses from previous PSEs and all "doses in excess of the limits" exceed certain limits.

(a) What and whose limits apply?

(b) Does the actual limit (e.g. 3 rem/quarter, 1.25 rem/quarter, etc.) apply, or does the equivalent annual limit apply?

(c) Do doses from non-licensed sources (e.g., x-ray sources) that were in excess of the facility's limits apply, especially if the facility was not a licensee?

(d) It appears that overexposures will require the licensee to back-calculate the dose in excess of the limits, particularly when that dose was received from an intake of radioactive material. However the Footnote 5 of 10 CFR 20.2106 says that assessments of dose equivalent and records made using units in effect before the licensee's adoption of this Part need not be changed. Will the licensee have to, in fact, convert the old doses in excess of the limits to committed effective dose equivalent?


(a) The regulatory limits at the time and place of the overexposure apply. If the individual worked for the Department of Energy (DOE), then the DOE limits apply. If the individual worked in a foreign country, then that country's limits apply.

(b) The actual limit applies.

(c) Yes. It is the purpose of the regulation to control licensed material in such a manner that the total dose to an individual, from licensed and non-licensed sources, does not exceed standards prescribed in the regulations.

(d) Yes.

(Reference: 10 CFR 20.1206, 10 CFR 20.2104, 10 CFR 20.1001, Regulatory Guide 8.35)

Page Last Reviewed/Updated Wednesday, October 07, 2015