A study of performance evaluation of advanced CVD system

UV-II type ICVD(Improved Cerenkov Viewing Device) is used to identify LWR spent fuel assemblies stored in a pond. However, it is difficult or impossible to apply ICVD to low burnup or long cooling time assemblies because of their feeble Cerenkov glow images. Then, ACVD system has been developed. ACVD uses newly developed proximity focused type UV-II, a CCD camera and an image processor to improve Cerenkov glow image quality. In this paper, an observation range of ACVD is discussed based on the performance comparisons between ICVD and ACVD system and the characteristics of human eyes. The observation range of ACVD is extended more than 2 times compared to that of ICVD with the real time operation mode of CCD camera (30 frames/second). When an image is integrated 1 second in the CCD camera, the observation range of ACVD system is extended more than 4.5 times. Moreover, when an image processor is used with the CCD camera, it is extended more than 10 times compared to that of ICVD. As the result, this system can detect Cerenkov glow image radiated from spent fuel assembly which burnup and cooling time range more than 4,000(MWD/MTU) and less than 30 years. (author)