Portable gamma-ray imager and its application for the inspection of the near-reactor premises contaminated by radioactive substances

GammaVisor is a portable system for imaging in the soft gamma-ray energy region developed by RECOM in recent years. Its industrial prototype has been tested under the complex gamma-field conditions of highly contaminated nuclear facilities in Russia and Germany. Special options for initial CCD camera frames processing (CCD camera operates in slow repetition mode) allow imaging without heavy shielding during a long exposure time. The results of contaminated equipment imaging with GammaVisor are presented. Background dose rate in rooms with contaminated equipment appeared to be up to 1 R/h and from 1 mR/h up to 50 mR/h at the detectorʹs head location. Imaging time was chosen to be 0.2–1 h. Data acquisition and processing procedures enabled us to avoid the high-background dose rate influence at the device measuring head location. Superposition of gamma images on optical images indicates that the major contaminated parts of the pipelines were their bends, places of pipes connection, and valves.