Frequency Based on Program Sensitivity

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

The rationale for the selected bioassay measurement frequency should also be documented. It is

appropriate to evaluate the probability of intake and to modify the sampling frequency based on

The frequency of bioassay measurements should normally not be decreased because analytical

results are below the detection level. The bioassay program should be maintained to confirm the

proper functioning of the overall internal exposure control program and to document the absence of

significant intakes of radionuclides.

5.4.1 Frequency Based on Program Sensitivity

The minimum detectable dose concept refers to the potential dose associated with an MDA

bioassay measurement at a given time interval post-intake. The pattern of retention of

activity in the body, the MDA for a bioassay measurement technique, and the frequency

with which that technique is applied define a quantity of intake that could go undetected by

the bioassay program. An intake of such a magnitude would not be detected if it occurred

immediately after a bioassay measurement and if it were eliminated from the body at such a

rate that nothing was detected during the next scheduled measurement. The dose resulting

from such an intake would be the MDD for that particular measurement technique and

frequency.

Estimates of MDD in terms of CEDE should be documented for each measurement

technique, MDA, and frequency. Retention functions specific to the various chemical forms

and particle size distributions found in the facility should be used. Examples of MDD

tabulations can be found in La Bone et al. (1993) and Carbaugh et al. (1994). In establishing

MDD tables, it is important to consider dose contributions from all appropriate radionuclides

in any mixture, rather than just the dose contribution from the bioassay indicator nuclide.

5.4.2 Frequency Based on Potential Risk of Intake

As discussed in Section 5.3.2, although plutonium workers are not generally considered to

be at high risk of incurring intakes that might result in CEDEs of 100 mrem or more, any

plutonium worker can be considered to have the potential for such an intake. However,

having the potential for intake does not mean that they are likely to incur an intake.

Workers who have the highest potential risk for an intake are those most closely working

with plutonium or plutonium-contaminated material. Typically, these workers are glove-box

workers, maintenance workers, and operational health physics surveillance staff. These

workers should be on a routine plutonium or americium bioassay program, including

urinalysis and in vivo measurements. Such programs are relatively insensitive compared to

the 100-mrem CEDE goal and are a safety net intended to catch intakes of significance

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