Lithium-containing alloys are considered promising liquid-metal materials for functional and plasma-facing components of nuclear and fusion reactors. The interaction of deuterium with a liquid GasaLiss gallium-lithium alloy was investigated in the temperature range relevant to deuterium interaction (300-600 degrees C), with subsequent temperature-programmed desorption (TDS) heating up to 900 degrees C. The Ga-Li alloy with a nominal composition of 64 at % Ga and 36 at % Li was synthesized under controlled vacuum and inert atmosphere conditions. The alloy composition and homogeneity were verified by inductively coupled plasma mass spectrometry (ICP-MS), while its phase state and melting behavior were characterized using differential scanning calorimetry (DSC). A series of TDS experiments was carried out on Ga-Li alloy samples pre-saturated with deuterium at temperatures of 300, 350, 400, 450, 500, 550, and 600 degrees C under a deuterium pressure of approximately 18 kPa. During TDS measurements, the samples were heated from 50 to 900 degrees C at a constant heating rate of approximately 15 degrees C & sdot;min-1, allowing investigation of deuterium release kinetics. Based on the experimental data, the main parameters governing deuterium interaction with the Ga-Li alloy, including the desorption rate, solubility, and activation energy, were determined. The temperature dependence of the Sieverts' constant for the investigated Ga-Li alloy in the range of 300-600 degrees C was also obtained and is described by the expression: The obtained results provide new quantitative insight into hydrogen isotope behavior in gallium-lithium systems and contribute to the assessment of Ga-Li alloys as liquid-metal materials for nuclear and fusion reactor applications. Ks(T) = 1.318 & sdot;109 & sdot;exp ( ) _ 24220 R & sdot;T
A conceptual assessment of the conversion of the Impulse Graphite Reactor (IGR) from high-enriched uranium (HEU) fuel to high-assay low-enriched uranium (HALEU) fuel is presented. The proposed conversion concept is based on the expansion of the core and the application of uranium-impregnated graphite fuel using IG-430 graphite. The study investigates whether the key performance characteristics of the reactor can be preserved under HALEU conditions while maintaining the existing operational modes and addressing primary safety considerations.The analysis was performed using a previously validated methodology for coupled neutronic and thermal transient simulations of the IGR reactor. Five representative transient scenarios, including regulated pulses, long-duration transients, and self-terminating neutron bursts, were analyzed for both HEU and HALEU configurations. The performance criteria considered include neutron flux and fluence parameters, pulse kinetics, energy release in an experimental device (ED), reactivity margins, shutdown capability, and thermal limits of the graphite core.The results demonstrate that all required conversion criteria can be achieved for the proposed HALEU configuration without approaching limiting thermal conditions. The obtained reactivity margins and shutdown characteristics additionally provide significant tolerance to uranium concentration variations in graphite fuel blocks.
The article provides an overview of a number of studies on the use of alloys and intermetallic compounds for hydrogen storage. Among them, a particularly important place is occupied by the inter-metallic compound LaNi₅ eye. The latest achievements in the development of intermetallic compounds of the AB₅-type are analyzed. These compounds, in particular LaNi₅ and its alloyed counterparts, are widely used due to the ability to regulate their properties by replacing elements. The article also provides an overview of the methods of synthesis and modification of AB5 alloys aimed at improving their efficiency in hydrogen technologies. Both traditional production methods and modern technological approaches, including Spark plasma sintering and mechanical activation, are considered. A review of the scientific literature has shown that mechanical activation is an effective way to modify the LaNi₅ intermetallic compound to improve its hydrogen absorption properties. According to a number of studies, the effect of high-energy ball milling leads to significant changes in the microstructure of the material. It is shown that to increase the effectiveness of practical applications of LaNi5 in hydrogen energy, additional comprehensive studies are needed to establish the relationship between mechanical processing parameters, structural characteristics, and functional properties of the material.The aim of this work is to use mechanical activation to modify the microstructure of a material, reduce the size of crystallites, increase the density of defects, and promote the formation of amorphous or nanostructured states, which together can significantly affect the structure and interactions with hydrogen.
Methane pyrolysis is considered a promising method for hydrogen production without CO2 emissions, simultaneously yielding valuable carbon materials. However, the nanostructure of carbon formed in the absence of catalysts remains insufficiently understood. In this study, a detailed analysis of the microstructure of carbon materials synthesized by plasma methane pyrolysis at various temperature regimes was performed using transmission electron microscopy. The carbon structures exhibited features ranging from amorphous aggregates to partially graphitized domains, demonstrating characteristics of turbostratic ordering. Comparison of the carbon materials obtained with those produced via catalytic methods revealed that, at the same pyrolysis temperatures, the mechanisms of carbon formation are fundamentally different. The catalyst-free process leads to the formation of turbostratic and partially graphitized structures with locally ordered domains. In contrast, catalytic pyrolysis is accompanied by the directional growth of carbon on the metallic centers of the catalyst, resulting in more ordered graphite-like structures, such as nanotubes. It was shown that the formation of carbon structures under catalyst-free conditions is consistent with the classical model of turbostratic carbon particles.
Research at the Institute of Atomic Energy of the National Nuclear Center of the Republic of Kazakhstan (IAE NNC RK) is focused on developing effective technologies for the management of spent nuclear fuel (SNF) from the BN-350 fast reactor. Among the approaches under consideration is a dilution and immobilization technology developed for irradiated uranium–graphite fuel from the Impulse Graphite Reactor (IGR). The process involves dry mixing of highly enriched uranium (HEU) fuel with depleted uranium dioxide, followed by immobilization through cementation. This study presents a comprehensive assessment of radiation conditions throughout the technological cycle of HEU fuel processing. Radiation field analysis at each processing stage is essential for establishing design requirements, optimizing facility operation, and ensuring personnel protection. Monte Carlo simulations performed using the MCNP code were employed to evaluate dose distributions and support radiation safety justification of the facility design. Based on the simulation results, several design modifications were implemented to improve shielding effectiveness and reduce occupational exposure. The proposed approach introduces a systematic methodology for radiation field assessment under conditions of incomplete information on fuel distribution, providing a conservative framework for safety analysis. Given the absence of direct international analogues for the management of irradiated HEU graphite fuel, the developed methodology offers both practical value for the IGR fuel immobilization project and potential applicability to future SNF management technologies for the BN-350 reactor. Keywords: Spent Nuclear Fuel, Management, measured effective dose, radiation situation.
