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Experimental Study of New Type Reflector Element based on beryllium pebbles

Project Status: 8 Project completed
Commencement Date: 11.07.2022
Duration in months: 0 months

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Participating Institutions



Institute of Nuclear of Physics of the Ministry of Energy of the Republic of kazakhstan



Japan Atomic Energy Agency


Today radiation technologies are developed all over the world on a base of research reactors, where various irradiation modes are required as applied to a specific technology. For example, “hard” neutron spectrum is required for radiation “coloring” of gemstones, whereas thermal spectrum is needed for production of such radiopharmaceuticals as iridium -192 and molybdenum-99.In view of the studies in the reactor neutron field, special irradiation devices are developed and fabricated. The devices make it possible to create a required task-specific irradiation mode (the neutron flux and spectrum). Adjustment of the neutron spectrum is fulfilled via relevant choice of the irradiation device structural materials, where such neutron-slowing and neutron absorbing elements are used as carbon, cadmium, boron, etc.. However, this technique reduced useful volume in the capsule for allocation of specimens under study and makes the capsule’s design more complicated.Beryllium is used as neutron reflector in research reactor for many years [3-6] due to its unique nuclear physical characteristics (a small thermal neutron capture cross-section, a large cross-section of the reaction (n,2n), high electric conductivity, good mechanical properties, high melting point [1, 2]) .JAEA has developed a reflecting element of the new type with beryllium pebbles inside [7]. Adjustment of the neutron flux and spectrum is carried out directly in the reflecting element, making it possible to enlarge useful volume of a cavity for allocation of an object to be irradiated.In frame of the project, an element of the beryllium reflector is proposed to be made with various densities of beryllium pebble packing. The neutron spectrum in irradiation capsule will be adjusted via a change in the pebble packing density; thus required irradiation modes in the research reactor core will be created. Development of the proposed technique for neutron spectrum adjustment will make it possible to take away extra restrictions on an amount and sizes of irradiated specimens, as well as to reduce an amount of radioactive waste, because the proposed element of beryllium reflector can be used repeatedly.Experimental studies will be carried out at critical facility of the Kazakhstan Institute of Nuclear Physics.The proposed technique for adjustment of the neutron spectrum has not yet been applied anywhere; so implementation of the project will contribute to development of a new technique for irradiation technologies throughout the world.