United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 43: The licensee initially was required to

monitor internal dose. The results indicate that monitoring

is not required, i.e., levels are positive but less than

10% of the allowable limits. Can the measured internal

dose values be ignored? If yes, will the licensee be in

noncompliance if it sums internal and external doses?

Answer: The licensee was required to monitor internal

dose [because the licensee had made a prospective

determination that the individual (s) was (were) "likely to

receive" an intake in excess of 10% of the limits]. The

internal dose values cannot be ignored regardless of the

fact that they are less than 10% of the limits. If the

licensee was not required to monitor internal dose because

the licensee had made a prospective determination that the

doses likely would be less than 10% of the limits but

elected to monitor internal dose anyway, the licensee could

choose to "ignore" the measured values that are less than

10% or to add those values to the external doses to obtain

the sum of the internal and external doses. Nothing in

Part 20 prohibits the licensee from monitoring or summing

internal doses at less than 10% of the limits; therefore, a

licensee can never be in noncompliance for summing the

internal and external doses. (Reference: 10 CFR 20.1502)

Page Last Reviewed/Updated Thursday, March 29, 2012