United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 54: Must bioassay be performed for a worker who,

without respiratory protection, is likely to receive an

intake in excess of the applicable ALI (s) but who is not

likely to receive such an intake with respiratory

protection?

Answer: A "Note" in the statement of considerations (56

FR 23377, column 2) says that ". . . the concentrations to

be used for evaluating monitoring thresholds are those of

the ambient atmosphere before credit is taken for

respiratory protective factors." That note is a

conservative assumption that is appropriate if there will

be no "further verification" that the assigned respiratory

protection factors actually will be achieved.



At nuclear power plants, if the "surveys and bioassays, as

appropriate," required by 10 CFR 20.1703 (a) (3) (ii),

include reasonable measures to verify that the expected

degree of respiratory protection will be achieved, "the

concentrations to be used for evaluating monitoring

thresholds" may be those that include credit for the

protection factors when respirators are to be used.

Measures to verify that the expected degree of respiratory

protection has been achieved may 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 representative 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.



At fuel cycle and materials facilities using large

quantities of unsealed radioactive materials, the nature of

the operations is such that bioassays are required for

workers who are likely to receive an intake in excess of

ten percent of the applicable ALIs without respiratory

protection. Because of the types and quantities of

radioactive airborne particulates at fuel cycle and

materials licensees, it is advisable to not take credit for

respiratory protection factors when determining if

monitoring (e.g., bioassay) is required. NRC will consider

licensee proposals to allow using respiratory protection

factors when determining if internal dose monitoring is

required, if the licensee demonstrates a verification

method that the respiratory protection factor is actually

achieved for all workers wearing respirators. Unless

authorized in the license, fuel cycle and materials

licensees should understand that the threshold level for

monitoring in 10 CFR 20.1502 (b) is ten percent of the

applicable ALIs without credit for respirators.

(Reference: 10 CFR 20.1502 (b), 10 CFR 20.1703)

Page Last Reviewed/Updated Thursday, March 29, 2012