Performance Specifications for a Bioassay Laboratory

DOE-STD-1121-98

Example 4.3. Use of Breathing Zone Air Samples to Supplement Routine Bioassay for

Plutonium

To illustrate the detection capability of breathing zone air monitoring, consider the DAC for

class Y Pu of 6E-12 :Ci/mL (10 CFR 835, Appendix A). Multiplying by 2.4E9 mL/year breathed

239

by Reference Man, one derives DOE's nonstochastic annual limit on intake (NALI) for class Y 239Pu

as 1.44 E-2 :Ci = 14.4 nCi (533 Bq). The complementary "5-rem" stochastic annual limit on intake

(SALI) from ICRP 30 is 16.2 nCi (600 Bq). Then, 2% of a SALI (that is, the intake that would result

in a HE,50 of 100 mrem) is 324 pCi (12 Bq), or 720 dpm of Pu. (The SALI for class W material is

about 3 times lower.)

Suppose a worker was exposed to an atmosphere in which, breathing at Reference Man's rate

of 20 liters per minute, he would experience an intake of 2% of a SALI. A BZ or personal air sampler

operating at 20 L/min would collect this same 720 dpm of Pu activity. A lapel air sampler operating

at 1.8 L/min would accumulate about 64 dpm (1.1 Bq). Thus, for a single air sample, there is no

difficulty (in the sense of counting statistics problems) achieving detection capabilities comparable to

those that the DOE requires for external radiation monitoring using BZ or personal air samples for a

single filter.

Personal air sampler filters are likely to be changed every day, or 250 times in a year. Thus,

the 720 dpm, which is 2% of the SALI, could be on one filter or spread among many or all. The

minimum detectable intake for uniform, chronic exposure based on 250 samples is higher than the

minimum detectable intake for a single, acute exposure. See Example 4.4.

Another benefit of BZ air monitoring programs is that they give workers feedback about work

practices. The experience at Apollo, Pennsylvania, showed that workers develop better radiological

control habits based on BZ air sample results.

It is well known that bioassay is much more accurate than BZ or personal air monitoring when

bioassay results are available and adequate. However, when bioassay methods are not adequate or

unavailable, BZ or personal air monitoring should be used. (See 10 CFR 835.209(b).) When there is

technology shortfall for routine bioassay, DOE sites should consider using BZ or personal air monitoring

programs to supplement their routine bioassay programs. Such use should be tempered with an

understanding of the limitations described in Example 4.5.

4.4.6 Performance Specifications for a Bioassay Laboratory

10 CFR 835.402 requires internal dose monitoring programs implemented to demonstrate

compliance with 10 CFR 835 be accredited by the U.S. Department of Energy Laboratory Accreditation

Program (DOELAP) for Radiobioassay (DOE 1998a). Radiobioassay laboratories utilized by the internal

dose monitoring programs will be evaluated against the requirements of the "Department of Energy

Laboratory Accreditation Program for Radiobioassay" (DOE 1998b) which incorporates the

recommendations of HPS N13.30-1996, "Performance Criteria for Radiobioassay" (HPS 1996a). In

addition, they may wish to consider the requirements of ANSI N42.23-1996, "Measurement and

Associated Instrumentation Quality Assurance for Radioassay Laboratories" (ANSI 1996). Additional

specifications for the bioassay or service laboratory should be negotiated between the site and the

laboratory. Example 4.7 gives performance specifications for a radiobioassay laboratory.