Evaluation of an L-shell X-ray based continuous air monitor for airborne plutonium for use in the waste isolation pilot plant

A continuous air monitor (CAM) for airborne plutonium was evaluated. The CAM is proposed for use in the underground Waste Isolation Pilot Plant (WIPP), a partially completed underground repository for transuranic wastes from national defense activities. The prototype CAM uses L-shell X-ray detection instead of alpha counting because of potential interferences by background aerosols consisting of salt dust and radon progeny. The CAM will provide a reliable alarm, in 4 h, for airborne 239Pu at a concentration of 4.0 x 10-11 μCi/cc (1.48 Bq/m3), the MPC for insoluble 239Pu. Performance was also compared with an alpha-spectroscopy-based CAM of the type typically used by the nuclear industry in relatively clean environments. 2 references