Samplers and Instrumentation

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

prospective approach uses measured dissolution rate of potential contaminants for analysis and treatment of

an accidental exposure. Determination of retention class should be a valuable precaution in uranium

facilities.

A realistic determination of retention class can be made by collecting a sample of airborne material by

using a size-selective sampler and drawing the sample from a process that has a potential for a significant

release. The material collected on the filter represents that which would be deposited in the lungs by

inhalation. Methods and instruments are now available with the sensitivity needed to precisely measure the

rate of dissolution of this small mass of uranium in simulated lung fluid. The same methods can be used on

filter samples in operation at the time of an accidental exposure, but the time required to measure

dissolution rate (at least 60 days) makes the information essentially retrospective. Prospective measurement

of retention class provides for better risk assessment.

4.1.5 Samplers and Instrumentation

Air sampling equipment and monitors exist in a wide range of designs and capabilities, with

characteristics specific to the application and need. Samplers range from small portable units that can be

worn by an individual to high-volume units permanently mounted in the facility. Flow rates are from a few

liters per minute to a few cubic meters per minute.

Key Factors in Selecting Air Samplers

Sensitivity of Detection. In general, the sensitivity required is at least DAC levels; however, in some

applications, sensitivity to a small fraction of DAC is desired for early detection of loss of containment,

low level trends, etc. Continuous air monitors may only need to alarm at multiple DAC levels in order to

be effective in preventing or mitigating personnel exposures to an accidental airborne release.

Type of Sample. In most uranium facilities, particulates in the air are the primary concern, although

gaseous forms may be most important in some areas. It may be of interest to collect samples that will allow

characterization of the particle size distribution or define a "respirable fraction." In each application, the

sample type will dictate the sampler design, filter media, flow rate, etc.

Convenience. Available space, noise level tolerance, portability, and weight also dictate specific

designs and capabilities of air samplers and monitors.

Power Requirements. Requirements for battery-powered versus 110-120-VAC line power may

dictate sampler selection.

Accuracy. Some sampling is performed to simply detect or make relative measurements of activity

levels for whic h the accuracy requirements are not great. In other situations, accurate measurements of the

air breathed by personnel may require an entirely different sampler design to achieve the needed quality

assurance.

Reliability and Maintainability. Cost-effective operation and reliability need to be considered for

selection of equipment design and for redundancy of components.

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