This work is devoted to the methodology for conducting experiments to study the process of cooling by a low-pressure gas–droplet flow under conditions of high energy loads on the receiving surface of a lithium divertor module (LDM) layout. The paper describes in detail the design of the LDM model, all the main systems, parameters, and layout of the test bench. The operating modes of water and gas cooling systems have been calculated under thermal action on the LDM layout with a power equal to 5 MW/m 2 . A description of the experiment on the development of a technique for cooling an LDM layout with a low-pressure gas–droplet flow has been given.

Comparative studies of the diffusion and accumulation of hydrogen in the Zr–1 wt.

The results of studying the interaction of hydrogen with commercially pure titanium VT1-00, zirconium alloy Zr–1% Nb and the Ti/Zr–1% Nb system are presented. The Ti/Zr–1% Nb system is obtained by the plasma-immersion ion implantation of titanium from a vacuum-arc discharge into Zr–1% Nb zirconium alloy. The results of X-ray phase analysis of the Ti/Zr–1% Nb system and the depth distribution profiles of chemical elements measured by high-frequency glow-discharge spectroscopy before and after titanium implantation into zirconium alloy, as well as after saturation of the samples of the obtained system with hydrogen, are presented. It is shown that at a titanium-ion current density of 5 mA/cm 2 and bias potentials of 500, 1000, and 1500 V applied to the sample, a thin (~300 nm) nanostructured layer containing mainly titanium is formed in the implanted surface region of the sample. When the Ti/Zr–1% Nb system is saturated with hydrogen (by the Sieverts method), titanium and zirconium hydrides are formed in this region. The possibility of detecting (by the method of thermally stimulated gas evolution) thin nano-structured layers of titanium hydrides, to which X-ray phase analysis method is not sensitive, is proved. Data are obtained on the process of hydride formation upon saturation of the Ti/Zr–1% Nb system with hydrogen at different concentrations in the range 70–300 ppm.

An experimental study is performed of the thermally stimulated evolution of hydrogen in the linear mode of heating (1°C/s). Hydrogen is released from plane-parallel plates of Ti, Zr, Ni, and Pd metals of different thicknesses (0.05–1 mm), preliminarily saturated with hydrogen via electrolysis. Analytical and numerical models of non-stationary processes of the diffusion release of hydrogen from samples are considered with allowance for diffusion and desorption. Programs for numerically modeling processes of thermal gas release are proposed, developed, and perfected.

This paper presents a description of research works to determine the thermophysical properties of a tin-lithium alloy with a different percentage of lithium and tin atoms in the alloy. The method of differential scanning calorimetry (DSC) was used for the studies, by which the thermophysical properties of the alloy (temperature of phase transition and enthalpy) were determined. The work was carried out at the TiGrA experimental complex. Studies to determine the enthalpy and temperature of phase transition of prototypes of tin-lithium alloy were carried out in the temperature range from 150°C to 500°C at a heating rate of 10°C/min. The experiments were carried out with a pristine sample of tin (reference) and prototypes of a tin-lithium alloy, the percentage of lithium in which was 20, 25 and 27 at. %. As a result of the work performed, the melting point of the prototypes was determined, which was 224°C and 218°C. The values of the specific heat of fusion (enthalpy) of the investigated alloys were determined, which amounted to 76.5 J/g, 80.7 J/g and 86.3 J/g, respectively.

New the experimental results of thermally stimulated hydrogen release (TCHR) from plane-parallel plates of Ti, Zr, Ni, Pd, Pt metals with various thicknesses (0.05-1 mm), presaturated with hydrogen, under linear heating (1 degrees C s-1) presented. The electrolytic and Sieverts method for saturate were used. Theoretical models for diffusion and desorption hydrogen release from flat metal samples into vacuum with linear heating were developed. In this case, the processes of diffusion and thermal desorption were taken into account to select the optimal conditions and experimental methods. The TSHR spectra simulated using the MATLAB software package to test the consistency of theory with experiment. By modeling in MATLAB using both the developed models and experimental TSHR spectra, the activation energies of desorption, diffusion and decomposition of hydrides, as well as the preexponential factors in the diffusion and kinetic equations, were determined. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The release of hydrogen isotopes (H, D) from Pd is studied under linear heating (a) by an accelerated electron beam, (b) by alternating current Joule heat (50 Hz) passed through the samples, and in external coaxial furnaces in (c) metallic (stainless steel) and (d) quartz vacuum cells. The cathode saturation of Pd samples with hydrogen and deuterium is used. The studies are performed in a high-vacuum installation. The recording of gases leaving the materials is carried out by mass spectrometry. The maximum shift in the position of the temperature maxima of the thermal-gas release of hydrogen and deuterium from palladium to the low-temperature region is observed when the samples are heated by electric current and heated in the quartz vacuum cell. The mechanisms of the release of hydrogen isotopes from metals due to the accumulation of electron-beam energy and electromagnetic field by the hydrogen subsystem of the crystals are considered.

Thin films of TiN are deposited onto Zr–1% Nb alloys using vacuum-arc plasma in two steps. First, the plasma-immersion ion implantation (PIII) of titanium is implemented; then, without interrupting the experiment, the vacuum-arc deposition (VAD) of TiN is carried out. The VAD and PIII modes for obtaining the most effective coating (from the viewpoint of protecting the substrate from corrosion and hydrogen embrittlement) have been previously determined. Within studies of the mechanical properties of the obtained coatings, a study of changes in the adhesion of coatings under Arctic conditions (at a temperature of –20°C, seawater ice) and hydrogenation of the samples is carried out. It is established that coatings that are frozen in seawater ice for 24 hours without preliminary saturation with hydrogen have the best adhesive strength. The mechanism of the established effect is briefly discussed.

The results of studying the interaction H atoms with ZnS–Tm3+ surface using the phenomena of heterogeneous chemiluminescence (HCL) are presented. HCL is luminescence excited in the strongly exothermic interaction acts of hydrogen atoms on the surface. The kinetic and nonstationary characteristics of luminescence are studied in depending on the excitation conditions, which serve as light indicators of physicochemical processes, occurring on the surface. The interaction parameters of hydrogen atoms with the surface of zinc sulphide: cross-sections, frequency factors, activation energies based on kinetic and non-stationary characteristics of HCL are determined.

Problems of plasma-facing materials degradation and in-vessel element destructions, tritium accumulation and plasma pollution can be overcome by the use of liquid metals with low atomic number. The best candidate as a material for divertor receiving plates and other in-vessel devices is lithium. One of the problems associated with the use of such lithium systems in the fusion reactors is to determine the parameters of the working gases interaction with plasma facing surfaces under conditions simulating real operation, i.e. under conditions of neutron and gamma radiation. This paper describes a technique of the reactor experiments to study lithium capillary-porous systems (CPS) interaction with deuterium under neutron irradiation. The neutron-physical and thermophysical calculations were the basis for the design development and further manufacture of a unique irradiation ampoule device with a lithium CPS sample. Several experiments were performed to calibrate the deuterium fluxes through experimental cell with lithium CPS; and preliminary results of these experiments were obtained.

The results of studying the hydrogen isotopes (H, D) yield of Ni, Pd, Pt, Ti, Zr metals with linear heating: a) by the accelerated electrons beam with energy up to 35 KeV, b) by joule heat of AC (50 Hz) through samples, c) by external coaxial furnace samples in metal (stainless steel) and d) quartz vacuum cells are presented. The highest temperature of the position of the maximum intensity hydrogen isotopes release at the linear heating corresponds to the samples heating in a metal vacuum cell, an external coaxial furnace. The lowest temperature position of the maximum intensity hydrogen isotopes release corresponds to the heating by accelerated electrons beam. The difference in these positions of the maximum is Delta T approximate to 350 degrees C. Difference in maxima position of the hydrogen and deuterium release into the low-temperature region is significant (Delta T approximate to 50-100 degrees C) for the Ni, Pd, Pt samples, and insignificant (Delta T <10 degrees C) for the Ti and Zr samples was found, when metals are heated by electric current or in a quartz vacuum cell compared to their heating in a metal vacuum cell. Possible mechanisms of non-equilibrium stimulation of the hydrogen isotopes release from metals, due to the accumulation of external energy by the hydrogen subsystem of crystals considered theoretically. The notions used wherein are in agreement with the obtained experimental results. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Data on the hydrogen isotopes (H, D) yield of Pd with linear heating: a) by the accelerated electrons beam with energy up to 35 KeV, b) by joule heat of AC (50 Hz) through samples, c) by external coaxial metal furnace (stainless steel), d) in quartz vacuum cell are presented and e) UV stimulation during thermal heating (the research article [2]). The highest temperature position of the maximum hydrogen isotopes intensity release corresponds to the samples heating in a metal vacuum cell by external coaxial furnace. The lowest temperature position of the maximum intensity hydrogen isotopes release corresponds to the heating by accelerated electrons beam. The difference in these positions of the maximum is Delta T approximate to 300 degrees C. Shift of maxima position in the hydrogen and deuterium release into the low-temperature region is significant (Delta T approximate to 50-100 degrees C) for the Pd sample when metal are heated by electric current or in a quartz vacuum cell compared to their heating in a metal vacuum cell and under UV stimulation during thermal heating. (C) 2019 The Author(s). Published by Elsevier Inc.

AbstractIn this study, we have considered interaction between an aluminum oxide film magnetron-sputtered on commercially pure VT1-0 titanium and a hydrogen atmosphere. The time the system was exposed to hydrogen varied from 1 to 4 h with all other parameters remaining the same. Data for the distribution of hydrogen over the depth (film thickness) and its content in the thin-film system have been obtained, and the influence of the hold time in hydrogen on the adhesion and friction coefficient of the film has been revealed. In addition, the surface conductivity and hydrogen distribution in the aluminum oxide film have been determined.

The relevance of this work is caused by possible prospect of creating a Kazakhstani high-temperature gas-cooled reactor, in which a number of new materials science solutions will be applied regarding the graphite matrix and fuel cells. Silicon carbide (SiC) coatings will be used on reactor fuel cells, in which graphite is the main constituent material. The aim of the research is to evaluate the corrosion rate of reactor graphite with SiC-coating in the temperature range from 750 to 1400 degrees C at the initial pressure of water vapor in the chamber 100 Pa. Object isotropic fine-grained graphite of IG-110 brand with a protective SiC-coating thickness of 200 microns. Methods: programmable thermal desorption of samples in the presence of water vapor, mass spectrometric recording of the gas composition in the working chamber, microstructural studies, Raman spectroscopy, energy-dispersed X-ray spectroscopy. Results. It is shown that at pressures of water vapor of 100 Pa, the SiC-coating interacts with steam through a passive (forming an additional protective layer of amorphous silicon dioxide) mechanism. Corrosion of SiC in water vapor at temperatures of 1100-1400 degrees C occurs by orders of magnitude more intense than at 750-900 degrees C. A model for analytical description of the experimental results was developed and the parameters of the rate constant for water vapor interaction with a SiC-coating were calculated for sample temperatures of 1400, 1300, 1200, 1100, and 1000 degrees C. Microstructural studies of the samples before and after corrosion tests were carried out, which showed that a protective SiO2 film is formed on the surface with a SiC carbide coating during passive corrosion. The research results allow us to conclude that the prototype of a fuel with a SiC-coating has improved anti-corrosion properties and can be successfully used to reduce carbon chemical activity in fuel cells and fuel assemblies of high-temperature gas-cooled reactor without deteriorating their mechanical and temperature properties.

In this study, we have considered interaction between an aluminum oxide film magnetron-sputtered on commercially pure VT1-0 titanium and a hydrogen atmosphere. The time the system was exposed to hydrogen varied from 1 to 4 h with all other parameters remaining the same. Data for the distribution of hydrogen over the depth (film thickness) and its content in the thin-film system have been obtained, and the influence of the hold time in hydrogen on the adhesion and friction coefficient of the film has been revealed. In addition, the surface conductivity and hydrogen distribution in the aluminum oxide film have been determined.