Process Monitoring with High-Resolution CZT

During nuclear power plant operation and maintenance, knowing the quantity and presence of radioisotopes in sub-system piping is critical for providing a comprehensive understanding of plant operation and for reducing worker dose. Two new instruments, Polaris-S and Polaris-S Shield, have been designed to monitor key piping segments in real time for changes in radiological conditions and for the appearance of new isotopes. Polaris-S is based on large-volume pixelated CZT detectors with better than 1.1% FWHM energy resolution at 662 keV. The features needed to make this system suitable for such measurements will be discussed, including being able to operate in a wide range of dose rates and wirelessly transmit data. Representative results in nuclear-power measurements will be discussed, showing the instrument's capabilities and limitations. Further, analysis methods required to make best use of these data will be presented.