COMBINING INNOVATIVE MEASUREMENT TECHNIQUES FOR RADIOLOGICAL CHARACTERIZATION OF PROCESS EQUIPMENT

摘要

The combined use of different measurement techniques is described as applied to in situ radiological characterization of process equipment items. Gamma imaging, CdZnTe gamma spectrometry and dose rate measurement are coupled for activity assessment purposes through the use of calculation code models. This method has been applied for radiological characterization of components before or during decontamination. This article describes the measurement of large (approximately 100 m{sup}3) highly radioactive (several thousand TBq) fission product solution tanks. The innovative techniques are first briefly described: gamma imaging, developed and implemented by the CEA over the last ten years and operational up to high irradiation levels, and CdZnTe gamma spectrometry, a technique particularly suitable for measuring high-activity components. The procedure for estimating the activity is then described. Two types of contributions are considered: activity holdup in hot spots that are localized and quantified by gamma imaging, and more uniformly distributed activity. The component is subdivided virtually into segments on which the activity is assumed uniform. The activity of each segment can be estimated by inverting a vector equation using a suitable algorithm. Having been tested for radiological characterization of high-level tanks, the method can be applied to determine the activity of other types of components. The text concludes with a mention of the development prospects of the techniques and the method used.