Special Bioassay as Supplements to Routine Bioassay Programs

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

relative to regulatory limits, rather than substantially lower administrative levels. Selection

of bioassay frequency depends on the facility experience with potential intakes, the

perceived likelihood of intake, and the MDD of a program. Annual urinalyses and in vivo

chest counts are fairly typical. More frequent (e.g., semi-annual or quarterly) measurements

may permit more timely review of workplace indicators in the event that an abnormal

bioassay result is obtained, but do not necessarily mean a more sensitive program.

Plutonium facility decommissioning projects may present a different set of challenges for

worker protection. In particular it is likely that clean up of areas will involve more

plutonium that is not contained than is the case during normal operations. In addition, the

workers involved may be relatively transient as the project progress through phases

requiring different craft labor mixes. This being the case, more frequent bioassay may be

necessary to provide good assurance that dose limits are not exceeded. As discussed in

Section 5.3.1, it is likely that program administrators will require a baseline measurement

prior to the start of work and another at the termination of work. However, if the worker

moves between tasks, it may be difficult to determine the source of an uptake without

intermittent bioassay. In such cases, the use of breathing zone air samplers may be

appropriate.

5.4.3 Special Bioassay as Supplements to Routine Bioassay Programs

Special bioassay programs for workers with known or suspected acute inhalation intakes of

plutonium or other alpha-emitting radionuclides should include both urine and fecal

sampling. Special bioassay measurements should be initiated for each employee in a

contaminated work area when surface contamination is detected by routine surveillance if it

is possible that the contamination resulted in a CEDE of 100 mrem or greater. Excreta

samples should not be collected where they may be contaminated by external sources of

plutonium. Ideally, total urine and feces should be collected for about a week following

intake. This permits a sensitive assessment of potential intake and internal dose. Longer-

term special samples collected at various times from a month to a year following intake can

help to discriminate between ingestion, class W inhalation, and class Y inhalation. See

Section 5.9 for indicator levels where special bioassay should be considered.

5.4.4 Long-term Follow-up Bioassay Programs

Following an intake a long-term follow-up bioassay program may be required for a worker

to compare the actual excreta or in vivo results with those projected by the evaluation. This

is important to verify the accuracy of intake and dose assessments. The frequency and

duration of a special program is dependent upon the projected values; it is suggested that as

long as a worker continues to have detectable bioassay results, he or she should continue to

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