Development of new UV-I.I. Cerenkov viewing device

Abstract

The Cerenkov glow images from boiling-water reactors (BWR) and pressurized-water reactors (PWR) irradiated fuel assemblies are generally used for inspections. However, sometimes it is difficult or impossible to identify the image by the conventional Cerenkov Viewing Device (CVD), because of the long cooling time and/or low burnup. Now a new UV-1.1. (Ultra-Violet light Image Intensifier) CVD has been developed, which can detect the very weak Cerenkov glow from spent fuel assemblies. As this new device uses the newly developed proximity focused type UV-I.I., Cerenkov photons are used efficiently, producing better quality Cerenkov glow images. Moreover, since the image is converted to a video signal, it is easy to improve the signal to noise ratio (S/N) by an image processor. The new CVD was tested at BWR and PWR power plants in Japan, with fuel burnups ranging from 6,200-33,OOO MWD/MTU (megawatt days per metric ton of uranium) and cooling times ranging from 370 to 6,200 d. The tests showed that the new CVD is superior to the conventional STA/CIUEPI CVD, and could detect very feeble Cerenkov glow images using an image processor.

Measurement of Cerenkov Radiation Induced by the Gamma-Rays of Co-60 Therapy Units Using Wavelength Shifting Fiber

“…This type of radiation can be easily observed in water at nuclear facilities such as boiling-water reactors, pressurized-water reactors, and spent fuel storage pools [2]. Here, burn-up of a fuel assembly can be estimated by measuring the intensity of Cerenkov radiation [3].…”

“…Cerenkov radiation is produced in a dielectric material when a charged particle passes through the medium with a velocity greater than the phase velocity of light in the same medium [ 1 ]. This type of radiation can be easily observed in water at nuclear facilities such as boiling-water reactors, pressurized-water reactors, and spent fuel storage pools [ 2 ]. Here, burn-up of a fuel assembly can be estimated by measuring the intensity of Cerenkov radiation [ 3 ].…”