Answer to Question #1145 Submitted to "Ask the Experts"

Category: Policy, Guidelines, and Regulations — Guidance Documents

The following question was answered by an expert in the appropriate field:

A year or two ago I seem to recall a proposal to reduce the general public dose rate limit to 1 mR h^-1 from 2.0 mR h^-1. Can you verify this?

No, there has been no proposal under consideration to reduce the public dose rate limit from 2 mrem h^-1 to 1 mrem h^-1. It is important to note two points in connection with this question, the first being that the 2 mrem is not a dose rate limit of 2 mrem h^-1 but a dose limit of 2 mrem in any one hour. This means that a licensee may permit the dose rate to exceed 2 mrem h^-1 by a substantial margin for short periods of time, provided the total dose in any one hour does not exceed 2 mrem. This is important for applications involving such activities as the use of pulsed radiation generating machines, where the dose rate may be quite high for small fractions of an hour but zero most of the rest of the time. The second point is that the 2 mrem in any one hour is not a general public dose rate limit; it is the hourly dose value that must not be exceeded in any unrestricted area due to external radiation as a result of the licensee's operations. The public dose limit is 100 mrem y^-1.

Sami Sherbini

Nuclear Regulatory Commission

Answer posted on August 31, 2001. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.