STUDY OF THE AXIAL NEUTRON FLUX DISTRIBUTION IN THE IRRADIATION DEVICE WITH A CADMIUM-SCREEN

Non-uniform distribution (both vertical and radial) of the neutron field in the reactor core of the research reactors is one of the most important task to solve in the process of neutron-transmutation doping of semiconductors. Since 2017, using the critical facility, the Institute of Nuclear Physics (Republic of Kazakhstan), in cooperation with с Chiyoda Technol Corporation (Japan), has been developing an irradiation device for the maximally reduce axial non-uniformity factor of the thermal neutron flux. The developed device allows to reduce the axial non-uniformity factor from 18% to 4%. The present work shows the methods to measure axial distribution of the neutron flux density, and the results of the experiments conducted on the critical facility. Cadmium was used for thermal neutron absorption. The irradiation device has a cadmium-screen formed of cadmium rings 0,5 mm wide and from 3 mm to 5 mm high.

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