United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 201: Why is it that releases to sanitary sewers

are not included in the dose limit for members of the

public while other effluent releases are?

Answer: The practice of having separate limits for

discharge to sewers is a practice that has been in place

since 10 CFR Part 20 was proposed in 1955. If the dose

limit for individual members of the public included the

dose contribution of licensed material into sanitary

sewerage, there would be no practical way for the licensee

to determine the magnitude of that dose contribution for

the purpose of demonstrating compliance with the limit

because of the remoteness of the individual being exposed

from the point of discharge. Water released into the

sanitary sewer is considered unavailable until it passes

through the sewage treatment plant. Effluent concentration

limits (as in Table 2 of Appendix B) have always been

calculated under the premise that a member of the public

lives at the licensee's site boundary and utilizes the air

and water available at that point. Release limits are set

in Table 3 so that if the releases from the sewage

treatment facility were the only source of ingestible

water, the dose to the individual would be a committed

effective dose equivalent of 0.5 rem per year. (Reference:

10 CFR 20.1301)

Page Last Reviewed/Updated Thursday, March 29, 2012