Development of a Gamma Spectrometry System for In-Situ Measurement of Radioactivity Within Piping

Abstract

The shielding requirements for measuring feeder pipe activity by in-situ gamma spectrometry inside the feeder cabinets at Pickering and Bruce were considered. An annular detector shield was accordingly fabricated from uranium metal and tungsten alloy. A circular uranium slab was also devised to shield the detector from radiation originating behind the pipe of interest. The efficiency of the detector for a pipe source was measured to enable the interpretation of spectral data. At short distances between pipe and detector, the efficiency was well predicted by a parallel plate model. In-situ measurements of active pipe sections compared reasonably well with direct assay of appropriate specimens from the pipe sections.