Nuclear-excited source of coherent and incoherent radiation with direct nuclear pumping.

Uranium fission fragments, as well as the products of He(n,p)H and B(n,α)Li nuclear reactions were utilized in the nuclear reactor for gas ionization and excitation. However, the Li(n,α)H nuclear reaction was less examined. The use of lithium-6 as a surface source of excitation of the gas medium, due to the long path length of tritium nuclei in the gas, allows to excite large volumes of gas as opposed to using U or B.

Influence of the Change of Phase Composition of (1 - x)ZrO-xAlO Ceramics on the Resistance to Hydrogen Embrittlement.

The article describes the influence of the change in the phase composition of ceramics on the stability of the crystal structure and retention of thermo-physical parameters during hydrogenation of the surface layer in the proton irradiation process. The selection of irradiation conditions allows modeling the degradation processes of ceramics associated with gas swelling during hydrogenation, as well as revealing the patterns of the effect of phase composition on embrittlement, de-strengthening, and structural degradation resistance. In the course of the conducted studies, dose-dependencies of irradiation-induced structural changes and consecutive accumulation of radiation-induced damage in ceramics as a result of hydrogenation of the damaged near-surface layer were established.

Calculation of Temperature Fields in a Lithium Ceramic Pebble Bed during Reactor Irradiation in a Vacuum.

Two-phase lithium ceramic LiTiO-LiSiO is considered as a tritium multiplier for use in the solid blanket of fusion reactors. To date, the most accurate understanding of the processes of tritium and helium production and release occurring in the breeder blanket materials under neutron irradiation can only be obtained from experiments in fission research reactors. At that, irradiations in vacuum give the possibility to register even very fast gas release processes (bursts) from the ceramics' voids and pores, although it reduces the thermal conductivity of the pebble bed.

Features of Helium and Tritium Release from LiTiO Ceramic Pebbles under Neutron Irradiation.

The operation of fusion reactors is based on the reaction that occurs when two heavy hydrogen isotopes, deuterium and tritium, combine to form helium and a neutron with an energy of 14.1 MeV D + T → He + n. For this reaction to occur, it is necessary to produce tritium in the facility itself, as tritium is not common in nature.

Synthesis and Characterization of the Properties of (1-x)SiN-xAlO Ceramics with Variation of the Components.

The aim of this paper is to study the effect of variation in the component ratio of (1-x)SiN-xAlO ceramics on the phase composition, strength and thermal properties of ceramics. To obtain ceramics and their further study, the solid-phase synthesis method combined with thermal annealing of samples at a temperature of 1500 °C typical for the initialization of phase transformation processes was used. The relevance and novelty of this study lies in obtaining new data on the processes of phase transformations with a variation in the composition of ceramics, as well as determining the effect of the phase composition on the resistance of ceramics to external influences.

Evaluation of the Influence of Grain Sizes of Nanostructured WO Ceramics on the Resistance to Radiation-Induced Softening.

The main purpose of this study is to test a hypothesis about the effect of grain size on the resistance to destruction and changes in the strength and mechanical properties of oxide ceramics subjected to irradiation. WO powders were chosen as objects of study, which have a number of unique properties that meet the requirements for their use as a basis for inert matrices of dispersed nuclear fuel. The grain-size variation in WO ceramics was investigated by mechanochemical grinding of powders with different grinding speeds.

Study of Morphological, Structural, and Strength Properties of Model Prototypes of New Generation TRISO Fuels.

The purpose of this work is to characterize the morphological, structural, and strength properties of model prototypes of new-generation TRi-structural ISOtropic particle fuel (TRISO) designed for Generation IV high-temperature gas reactors (HTGR-type). The choice of model structures consisting of inner pyrolytic carbon (I-PyC), silicon carbide (SiC), and outer pyrolytic carbon (O-PyC) as objects of research is motivated by their potential use in creating a new generation of fuel for high-temperature nuclear reactors. To fully assess their full functional value, it is necessary to understand the mechanisms of resistance to external influences, including mechanical, as in the process of operation there may be external factors associated with deformation and leading to the destruction of the surface of fuel structures, which will critically affect the service life.

Study of Corrosion Mechanisms in Corrosive Media and Their Influence on the Absorption Capacity of FeO/NdFeO Nanocomposites.

This paper presents the results of a study of the change in the stability of FeO/NdFeO nanocomposites when exposed to aggressive media over a long period of time. The main purpose of these studies is to investigate the mechanisms of degradation and corrosion processes occurring in FeO/NdFeO nanocomposites, as well as the influence of the phase composition on the properties and degradation resistance. According to the X-ray phase analysis, it was found that the variation of the initial components leads to the formation of mixed composition nanocomposites with different FeO/NdFeO phase ratios.

Synthesis, Properties and Photocatalytic Activity of CaTiO-Based Ceramics Doped with Lanthanum.

The aim of this work is to study the effect of lanthanum doping on the phase formation processes in ceramics based on CaTiO3, as well as to evaluate the effectiveness of the ceramics as photocatalysts for the decomposition of the organic dye Rhodamine B. The methods used were scanning electron microscopy to evaluate the morphological features of the synthesized ceramics, X-ray diffraction to determine the phase composition and structural parameters, and UV-Vis spectroscopy to determine the optical properties of the ceramics. During the experiments it was found that an increase in the lanthanum dopant concentration from 0.

Study of Degradation Mechanisms of Strength and Thermal-Physical Properties of Nitride and Carbide Ceramics-Promising Materials for Nuclear Energy.

The dependences of changes in the strength properties of nitride and carbide ceramics under high temperature irradiation with Kr and Xe heavy ions at irradiation doses of 10-10 ions/cm are presented in this work. The irradiation was chosen to simulate radiation damage processes that are closest to the real conditions of reactor tests in operating modes of increased temperatures. Polycrystalline ceramics based on AlN, SiN nitrides, and SiC carbides were chosen as objects of research, as they have great prospects for use as a basis for structural materials for high-temperature nuclear reactors, as well as materials for nuclear waste disposal.

Study of Magnetic Properties of FeNi Nanostructures Using the Mössbauer Spectroscopy Method.

Hyperfine interactions of Fe nuclei in FeNi nanostructures synthesized in polymer ion-track membranes were studied by Mössbauer spectroscopy. The main part of obtained nanostructures was FeNi nanotubes with bcc structure for 0 ≤ x ≤ 40, and with fcc structure for 50 ≤ x ≤ 90. The length, outside diameter and wall thickness of nanotubes were 12 μm, 400 ± 10 nm and 120 ± 5 nm respectively.