United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 375: In supporting a conclusion that individual

monitoring of internal occupational dose is not required

[10 CFR 20.1502 (b)] and, therefore, that summing of

internal and external dose is not required [10 CFR 20.1202

(a)], what is considered to be acceptable for bioassay

frequency, DAC-hour administrative limit, and whole-body

counting minimum testing level?

Answer: Under 10 CFR 20.1502 (b), there is no required

frequency for bioassay, DAC-hour administrative limit, or

minimum testing level for whole-body counting either for

individuals for whom monitoring is required or to support a

conclusion that individual monitoring is not required.

However, the answer to Question 54 provided a number of

examples of measures that could be used at nuclear power

plants to verify that the expected degree of respiratory

protection will be achieved so that the concentrations of

radionuclides in air after credit is taken for respiratory

protection may be used in making the prospective assessment

that individual monitoring for internal dose is not

required. These measures "include, (but are not limited

to) measurements of nasal smears from workers who have used

respirators and whole body counting, relatively soon after

a job, of one or more workers among a group of workers who

wore respiratory protective equipment while working on the

job and periodic whole-body counting (e.g., annually) of

all workers who wear respiratory protective equipment."

It should be recognized that in addition to the bioassay

requirements of 10 CFR 20.1502 (b), there is the bioassay

requirement of 10 CFR 20.1703 (a) (3) (ii), which is

related to the use of individual respiratory protection

equipment. If whole body counting is to be used to verify

the effectiveness of the respiratory protection program, it

must be able to demonstrate that estimates of intake based

on exposure calculations (i.e., on air concentrations and

on taking credit for protection factors) are consistent

with estimates of intake based on bioassay. The licensee

should take into account the fact that demonstrating

effectiveness of the respiratory protection program may

have to be based on exposures over durations much shorter

than a year, particularly for materials that are expected

to be cleared rapidly from the body. Some general guidance

on air sampling is provided in Regulatory Guide 8.25, Rev.

1, (which states that this guide does not apply to reactor

facilities), and general guidance on bioassay will be

provided in Regulatory Guide 8.9, Rev. 1. (References: 10

CFR 20.1502, 10 CFR 20.1202, 10 CFR 20.1703, Regulatory

Guide 8.9)

Page Last Reviewed/Updated Thursday, March 29, 2012