This study investigates the formation of combined wear-resistant coatings on steel rings of face impulse seals (FІS) aimed at improving their operational performance under aggressive environments and radiation exposure. A multistage technology is proposed, including electrospark alloying using a W-Zr-B electrode system, plasma nitriding, deposition of copper and carbon-containing layers, and final treatment by non-abrasive ultrasonic finishing (NAUFT). The formation of a gradient-strengthened layer without a “hardness drop” has been established, along with an increase in hardness up to 970…1490 HV and a reduction in surface roughness to Ra = 0.2…0.4 μm. The obtained results confirm the effectiveness of the proposed approach for FІS applications.
Maritime decarbonisation and restoration of Ukraine's nuclear power generation motivate small modular reactor deployment. A floating nuclear power plant concept based on two certified SMART100 units without thermalhydraulic modifications received ABS Approval in Principle in December 2025. Thermal-hydraulic and neutronic calculations and a parametric robustness analysis under critical heat flux degradation from ship motion are presented. A robustness indicator δcrit ‒ the degradation level at which the departure from nucleate boiling ratio (DNBR) reaches the regulatory limit – is proposed. The calculated δcrit = 63.1% exceeds the literature maximum (45%) by 18%, justifying SMART100 application without modifications.
Using X-ray diffraction and scanning electron microscopy, changes in the structural and stress state in layered W/QC/steel, QC/W/steel, and W/steel magnetron-deposited composites, as well asin bulk tungsten samples, irradiated with hydrogen plasma at a thermal load of up to 0.6 MJ∙m-2 , were studied. According to the results of irradiation of bulk samples and magnetron coatings, annealed and unannealed, the changes in macrostresses, structure and substructure caused by plasma irradiation are determined by the structure in the initial state: namely, the type, density and distribution of dislocations and point defect complexes. The initial residual internal compressive stresses decrease with an increase in the number of plasma irradiation pulses, regardless of their initial level and the magnitude of the thermal effect, with a subsequent transition to tensile stresses. The scale and rate of the stress reduction vary for different compositions. Taking into account the studied features of layered systems based on W and Ti-Zr-Ni quasicrystals under conditions of radiation-thermal loads of varying intensity and dose, these compositions are proposed to be used to increase the radiation resistance of materials in nuclear and thermonuclear energy.
In-690 alloy is widely used in nuclear power systems, requiring reliable filler metals for welding. In-52, a Ni‑Cr‑Fe alloy, performs well in industrial welding but shows limitations in remote repair operations due to ductility dip cracking. The advanced In-52MSS, dispersion‑strengthened with NbC precipitates, demonstrates superior structural stability, wetting behavior, and resistance to hot cracking. Comparative studies revealed that In-52MSS avoids the ductility dip observed in In-52. In-52MSS proves to be highly reliable and is recommended for challenging repair tasks, including manual and remote welding, in radiation‑intensive environments of the nuclear energy industry. Locally developed analogues of these alloys have been tested across 4.2…400 K, showing stable properties and offering an economically viable replacement for foreign welding fillers In-52 and In-52MSS.
The geopolymer based on an alkali-activated mixture of fly ash, blast furnace slag and metakaolin was produced and tested as a matrix for immobilizing the wood ash, obtained by pyrolysis of inactive pine, simulating radioactively contaminated wood from the Chernobyl zone. Ukrainian raw materials, hot pressing and casting were used to produce samples. The rheological properties of pastes, mechanical characteristics and structures of hardened samples were analyzed. Optimized hot pressing parameters: T = 80 °C and P = 60 MPa facilitate to form dense geopolymers containing 10…40 % wood ash with increased compared to casted samples properties, which meet the European Waste Acceptance Criteria.
