United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 75: Representatives of the nuclear power industry

have expressed a concern regarding 10 CFR 20.1502, which

requires licensees to monitor individual internal or

external doses for each individual likely to exceed 10% of

the applicable annual limit. Licensees are required to

maintain records of individuals for whom monitoring was

required under §20.1502 [§20.2106 (a)]. The handling of

internal doses at less than 10% of the limit is of

particular interest. Since a licensee cannot predict

future exposures at other licensee facilities during the

remainder of the year, a question arises regarding summing

of doses at these small fractions of the limit if a worker

transfers to another licensees during the year. The

following procedures have been suggested regarding

reporting of internal doses at nuclear power plants that

are less than 10% of the limit.

1. At nuclear power plants, an entrance bioassay is

typically performed for all incoming radiation workers.

Upon departure from the facility, an exit bioassay is

typically performed. If no net internal contamination is

detectable in the exit bioassay, no internal dose

assessment is required. If internal contamination is

detected, an assessment will undoubtedly be made. Any

positive result above the LLD is available for reporting.

2. Respiratory protection programs are required, under

§20.1703, to monitor workers to assess intake. Air

sampling results and bioassay measurements are acceptable

methods to perform this monitoring, with the results used

to perform an intake assessment.

3. Therefore, if a worker is monitored for potential

internal exposure, data regarding the results of such

monitoring will be available and must be recorded. Since

these records are available, positive results, above LLD,

should be reported to subsequent licensees, even if there

is no reason to expect the worker will exceed 10% of the

annual internal committed effective dose equivalent limit.

Does the NRC have any objections to this procedure?

Answer: No. This procedure for nuclear power plants goes

beyond the requirements of the revised Part 20 for

monitoring, recording, and reporting internal doses to

workers. See the answer to Question 114. (For example,

routine entrance and exit bioassays for all workers are not

required by Part 20). However, the procedure is not

inconsistent with the Part 20 requirements. (References:

10 CFR 20.1502, 10 CFR 20.2106)

Page Last Reviewed/Updated Thursday, March 29, 2012