Internal Dosimetry cont'd - doe-std-1128-98

DOE-STD-1128-98

Participation in internal dose evaluation programs is required by DOE for conditions

identified in 10 CFR 835.402(c) (DOE, 1998a). The internal dose evaluation program must

address both general workplace conditions and individual intakes.

Workplace conditions are monitored through air sampling programs as well as

contamination surveys. For work that can have variable or changing conditions, more

intensive surveillance may be required, using supplemental portable air samplers,

continuous air monitors, or personal air samplers.

Individual worker monitoring for intakes is commonly performed using bioassay

procedures. Bioassay monitoring includes both direct (in vivo) measurements of

radioactivity in the body and indirect (in vitro) measurements of material excreted or

removed from the body. Refer to Section 5.7.4 for information on assessing internal

exposures from air supply data.

10 CFR 835.402(c) (DOE, 1998a) specifies the requirements for participation in a

radiological bioassay program Because most plutonium facilities have a high degree of

radiological control and containment for plutonium, chronic exposure to levels of

occupational concern is unlikely and it is not considered likely that a worker would incur

more than one unplanned intake in a year. Thus, participation in a bioassay program is

generally based on the possibility that a single intake causing a dose in excess of 100-mrem

committed effective dose equivalent (CEDE) might occur. Bioassay is also required if an

intake is suspected for any reason.

Indications of intake include (but are not limited to) detection of facial or nasal

contamination, air monitoring or sampling that indicates internal exposure, or any wound in

which contamination is detected or suspected (See Section 5-9 for internal dosimetry

recommended indicator and action levels.) The most common internal exposure monitoring

program for workers is the bioassay monitoring program, which must be designed for the

specific nuclides and forms of material at a particular facility. Likely candidates for internal

exposure monitoring include personnel who may be routinely exposed to surface or

airborne contamination, or those identified by the foregoing workplace indicators.

Workplace monitoring for potential internal exposures is performed to verify the adequacy

of containment and work practices. This monitoring includes air sampling, continuous air

monitoring, personal contamination surveys, and workplace contamination surveys.

Facilities are to be designed and operated to minimize internal exposure. Details regarding

workplace monitoring and control practices are discussed in Section 4.0.

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