Samples and Instrumentation - doe-std-1128-98

DOE-STD-1128-98

airborne contamination, but to assure that samples are representative of the air that

the workers are breathing and have a low enough limit of detection that only

negligible doses could go undetected. Bioassay and in vivo analysis of plutonium

should confirm the negligible exposure that the air monitoring program documents

and provide a baseline for any accident- or incident-related exposures. The need for

an effective sampling and monitoring program is even more critical in the rapidly

changing environment of decommissioning activities.

Numerous factors enter into any determination of plutonium contamination levels

and the risk to workers. Some of these factors are detection efficiency of the

measuring instrument, collection efficiency of the smear media or air sample filter,

the location of the smear or air sample in relation to the source of contamination, the

physical and chemical properties of the contamination, the representativeness of the

air sample to the air being breathed by the worker, the engineered controls available,

and the protective equipment used. All of these factors must be considered in the

development of a plutonium contamination control program and in evaluating the

actions required for personnel protection.

4.1.5 Samples and Instrumentation

For plutonium facilities, both air sampling and air monitoring are essential elements

of the radiological control program. Real-time air monitoring using alpha-sensitive

continuous air monitors (CAMs) should be used to alert workers to rapid degradation

of radiological conditions. The air sampling system with a lower limit of detection

must be adequate to provide continuing assurance that personnel exposures are within

limits and ALARA.

The characteristics of a good plutonium CAM include:

-- A lower limit of detection equal to or better than 8-DAC-h

-- high reliability with a minimum of spurious alarms

-- a stable and constant flow air mover

-- stable and documented detector efficiency with geometry, filter collection

efficiency, self-attenuation, etc., considered

-- methodology for radiation discrimination and natural radioactivity discrimination

-- system for activating an alarm

-- shielding for extraneous sources of interference such as radiation,

radiofrequency, temperature, and vibration

-- mechanical and electrical ruggedness

-- ease of maintenance and calibration.

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