Development of a prototype apparatus visualizing on a screen the gamma sources superimposed on the image of the vision field

摘要

Mapping the gamma activity of irradiating zones is often an important prerequisite in dismantling nuclear facilities. This report summarizes the work carried out under CEC contract FIED-0055, covering a prototype imaging system designed to display radioactive sources superimposed in real time over a visible light image on a video monitor. This project was developed from an earlier off-line system. The gamma photons are collimated by a double cone system. The imaging system comprises a transparent scintillator bonded to the fiber-optic window of an ultrasensitive camera. The camera was miniaturized to meet specification requirements: with its radiological shielding, the gamma camera weighs 40 kg and is 120 mm in diameter. The processing system is compatible with a realtime camera, and small enough for use at any nuclear site. The point-source angular resolution is 1.4 deg. for Co-60 and 0.8 deg. for Cs-137. The dose rate sensitivity limit is approximately 0.01 mGy/h. Process reliability was confirmed by tests in a high-level radio-metallurgy cell at actual decommissioning site. (authors). 7 figs. (Atomindex citation 28:031366)