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Boron carbide with different boron-10 isotope content is used in the control rods of liquid sodium-cooled fast neutron nuclear reactors as absorbing material. “Trap” type control rods with heterogeneous placement of absorbing (B4C or EU2O3) and moderating (ZrH2) materials were developed. These products did not become widely used due to the high activity of europium radioisotopes and the high damageability of boron carbide. This article examines the design of next-generation control rods with boron carbide in the form of large diameter rings, hafnium hydride (HfHx, where x = 1.0-1.5) and made from a mixture of europium oxide and cobalt (Eu2O3 + Co) for fast neutron reactors . The use of a closed cycle using boron-10 isotopes, as well as spent absorbing kernels from Eu2O3+Co as gamma-ray sources is examined. It also deals with the prospects for the use of control rods with dysprosium hafnate (nDy2O3mHfO2) for lead-cooled fast reactors type BREST-OD-300.

At present, there are two ways to produce ⁹⁹Mo in a reactor: 1) fission process—from U fission product by reaction ²³⁵U (n, f) ⁹⁹Mo and 2) activation process—by radiation capture reaction ⁹⁸Mo (n, <i>γ</i>) ⁹⁹Mo. This paper presents the results of experiments performed with molybdenum carbide nano-powder to produce ⁹⁹Mo. These results show the implementation of the above idea in practice