Health Physics Questions and Answers - Question 75

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)