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
-- system for activating an alarm
radiofrequency, temperature, and vibration
-- mechanical and electrical ruggedness
-- ease of maintenance and calibration.