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)