Issue:

Introduction:

Discussion:

As specified in 10 CFR 835.403(a)(1), air sampling requirements are based upon exposure potential, rather than airborne radioactivity concentrations, in order to allow consideration of occupancy times, respiratory protection, and other site-specific factors. Due to the flexibility available with modern air sampling systems (including advantages such as high sample rates, flexibility of sampler location, correspondence with working times, and sturdy construction), performance of discrete air sampling (using grab or lapel samplers) is generally more consistent with the requirements for sampling for exposure assessment purposes. Positioning options and sample rates of CAMs are generally more limited. In light of these limitations, 10 CFR 835 does not prescribe CAMs for situations in which air monitoring results are to be used for exposure assessment. This does not preclude the use of CAMs (see 58 Federal Register (FR) 65474), particularly where the airborne concentrations are known to be relatively homogeneous and stable. Ultimately, the operating entity must be able to demonstrate that the sampling technique in use is capable of detecting and evaluating the level or concentration of airborne radioactive material at work locations, as required by 10 CFR 835.403(a)(1).

Continuous air monitors are most often used to provide early warning of fluctuations in airborne radioactivity concentrations that may result in unplanned exposures. This condition may occur when airborne radioactivity is unexpectedly transferred beyond the boundaries of a posted area or containment device or structure or where individuals are working in a contaminated area without respiratory protection, thus creating the potential for exposure of unmonitored and unprotected individuals. As specified in 10 CFR 835, CAMs must have alarm capability and sufficient sensitivity to provide this warning function.

During the public comment period on proposed 10 CFR 835, several individuals noted that DOE did not prescribe an averaging period for airborne radioactivity concentrations. Therefore, the requirements of the rule could be construed to mean that use of CAMs is required for even momentary fluctuations of airborne radioactivity concentrations above 1 DAC. The Department recognizes that use of CAMs to monitor momentary changes is generally not effective and has, therefore, left the prescription of averaging periods and alarm setpoints up to the contractors' determination, dependent upon site-specific conditions (see 58 FR 65474).

The continuous air monitoring requirement of 10 CFR 835.403(a)(2) does not provide guidance regarding consideration of the effects of respiratory protection devices when specifying air monitoring using CAMs. Specifically, the words "...where an individual is likely to be exposed..." do not clearly indicate whether or not the exposure being considered may be ameliorated by use of respiratory protection equipment. The wording of the RadCon Manual article 555.3 is unclear regarding the application of respirator protection factors. DOE will undertake efforts to clarify the RadCon Manual consistent with the Technical Position provided below.

Some facilities have indicated that difficulties exist with demonstrating compliance with the internal dose assessment requirements of 10 CFR 835, particularly when individuals are chronically exposed to low concentrations of plutonium or radon and their associated daughter products. The presence of radon in concentrations that have been heightened due to previous or current activities may cause particular concern due to difficulties in discerning "background" levels of radon as opposed to "occupational" levels. Note that 10 CFR 835.209(c) specifically allows for determination of internal dose using air monitoring results when bioassay data are inadequate or less accurate than air monitoring results. The use of air monitoring data to determine occupational exposures to radon may require performance of statistical studies, using on- and off-site monitoring data, to establish reasonable bases for assigning doses based upon the occupational fraction of the total exposure. 

Technical Position:

10 CFR 835 and the RadCon Manual:

• Site-specific temporal and spatial averaging techniques may be used in determining the requirements for air monitoring. Justification for these techniques should be documented and retained and the results of these analyses used in documentation of the RPP. 
• Approved respirator protection factors may be considered in specifying application of CAMs if all individuals in the affected area will be wearing respiratory protection devices. This provision supplements the Department's reliance upon engineering and administrative controls for airborne radioactivity control (see the RadCon Manual article 316) and does not diminish the need to perform workplace monitoring as required by 10 CFR 835.401(a). In addition, the accompanying provision regarding the need to alert individuals to unexpected transients remains in effect and must be considered. Criteria requiring the use of CAMs should be fully described in the RPP. 
• Any of the various available air sampling methods (high or low flow rate grab samples, CAMs, lapel samples, etc.) may be used to demonstrate compliance with 10 CFR 835.403(a)(1). Specific guidance should be developed and provided to individuals performing the sampling (such as in site procedures) to ensure proper application of the specified method. 
• Air monitoring results may be used for determination of internal doses but only under the conditions specified in 10 CFR 835.209(c). Efforts should be made to acquire and analyze air samples using the most representative and accurate techniques that are available, considering site-specific factors such as available resources and potential for missed dose. 
• When performing air monitoring to demonstrate compliance with either 10 CFR 835.403(a)(1) or (2), the method used must be appropriate for the existing environmental conditions, consistent with 10 CFR 835.401(c)(3). Any conflicts between this requirement and the specific monitoring requirements of 10 CFR 835.403(a) should be considered in development of the RPP. 

References:

1. 10 CFR 835, "Occupational Radiation Protection," U.S. Department of Energy, December 14, 1993. 
2. G-10 CFR 835/E1, "Instrument Calibration for Portable Survey Instruments Implementation Guide," U.S. Department of Energy, Revision 1, November 1994.
3. ANSI N42.17A, "Performance Specifications for Health Physics Instrumentation - Portable Instruments for Use in Normal Environmental Conditions," American National Standards Institute, 1989. 
4. DOE Order 5480.4, "Environmental Protection, Safety, and Health Protection Standards," U.S. Department of Energy, 1984.