Assessment of monitoring procedures for airborne plutonium particles in the workplace

Recent U.S. Department of Energy regulations require upgrades of fixed airheads and selective air monitors (SAAM) to verify that the lowest possible radiation exposures are achieved. Airheads establish the level of routine worker exposure, and SAAM gives an alarm if confinement fails. Monitoring effectiveness was systematically determined to provide input on worker protection decisions. Airflow patterns were studied in the workplace with an air tracer system that simulated glove-box leaks. The aerosol tracer was tracked by laser particle counters in real time in the 0.5- to 5- and >5-μm-diameter ranges. Flow in the entire room and in specific areas was compared to the response of fixed airhead samplers and SAAM. Particle inhomogeneity near fixed airhead samplers limited the usefulness of exposure estimates. Increasing the number of airheads did not effectively improve estimation of worker exposure. For critical work, lapel samplers provide effective exposure data based on tracer tests. Tracer tests showed that the SAAM alarm nearest a simulated leak may not go off first. The SAAM should be located at each exhaust to assure room coverage. A portable SAAM is recommended for unusual operations such as box modifications. The SAAM should be located near a local air flow in combination with a tracer particle counter