The improvement of image processing and noise reduction scheme of HERV and results of gamma-imaging

HERV is system for visualization in X- and gamma-ray regions developed by RECOM during last years. Its last version is real industrial prototype that was tested in conditions of complex gamma-field in strongly contaminated nuclear facilities in Russia and Germany. New special processing procedures of CCD camera frames, which operates in slow repetition mode, allow to carry out imaging without using of heavy shielding during long exposure time. Image processing procedures which allow to take into account background radiation and noise and drift of electronics are described. The results of imaging of contaminated pipelines and vessels by HERV are presented. Background dose rate in premises with contaminated equipment was up to 1 R/hour and at detector head place was from ImR/hour up to 50 mR/hour. Main contaminating nuclides were Co-60 and Cs-137. Imaging time was 0.2-1 hour. Data acquisition and processing procedures were good enough to exclude the influence of high background dose rate at place of measurement head of a device. Superposition of gamma images over optical images shows that the contaminated parts of pipelines are bends of pipes, places of their connection, valves