On-line measurement of stack-gas particulate radionuclides

This paper describes an advanced process-monitoring system for the automatic sample collection, analysis, reporting, and alarming of the concentration of long-lived radionuclides in nuclear process stack-gas effluents. This system, the Moving Filter Radioactive Aerosol Monitor, collects particulates in a conditioned sampling chamber, under computer control, for subsequent and separate alpha and beta counting and analysis. The alpha measurement is performed with a solid-state surface-barrier detector. Beta analysis is performed with a phoswich scintillation detector. A unique alpha-energy analysis program that provides automatic energy calibration and lowered detection limits for plutonium in the presence of high quantities of interfering 212Bi/Po is described. The 212Bi/Po alpha results are further used to monitor system quality and to compensate for the radon daughter beta components in the beta system. Results of the system calibration and detection limits are also presented. 8 refs., 6 figs