Target unit for radiation test of materials under bremsstrahlung of electron accelerator

Abstract

There is a necessity to provide an immobilization of the long-lived radioactive waste into radiation-resistant structure (a cement matrix, container capsule, geological disposal environment and so on) for it safely disposal. The material of the every of these barriers should have resistance corresponding to the absorbed dose value up to 10⁸ Gy for the period of time up to 1000 years. The method of imitation exposure of the materials under bremsstrahlung of the high-current Linac was developed for prediction behavior and material selection. For realization of this method in a wide range of exposure conditions (by temperature, humidity, rate and amount of the doze) the special target unit was designed. It has a modular construction and includes two chambers for samples (one for exposure in liquid and another one – in the atmosphere) that are placed along the irradiation axis and integrated together spatially. Also, the target unit has plane-parallel ionization chamber for continuous monitoring of the photon flux intensity and absorbed doze. The copper thermistor is used as a temperature probe. The structure and characteristics of measurement channels are described as well.