940-9 Portable Continuous Air Monitor

The Code of Federal Regulations requires assurance that radioactive materials within gaseous effluents do not exceed maximum permissible concentrations (MPC) as set forth in the United States Nuclear Regulatory Commission (USNRC) radiation protection standards. This simply means that any effluent that could possibly contain radioactivity must be monitored. Besides the legal implications, sound industrial hygiene practices require that personnel be protected against the possibility of exposure to excessive radioactivity from any source. Off-line gas monitors are frequently used in conjunction with particulate monitors. This is particularly the case with a stack or duct where effluent is released into the environment. Used in this manner, the particulate monitor serves as a pre-filter for the gaseous monitor and also as a monitor of airborne radioactive particulates. Where an off-line gas monitor is used independently, without the aid of a particulate monitor, a separate filter assembly is installed to prevent contaminated particulate buildup inside the sensitive volume. The off-line effluent monitor incorporates its own pumping system to insure a positive displacement of the effluents being monitored. Off-line effluent monitoring is normally utilized where optimum geometry is desired to gain maximum sensitivity. Scintillation detectors are used because of their sensitivity and reliability.