Introduction. In this study, the synthesis of TiO2 nanotubes was carried out via the hydrothermal method, following two hours of ultrasonic pretreatment to evaluate the role of ultrasound in nanostructure formation. The hydrothermal process was conducted for 4, 6, 8, and 10 hours to investigate changes in morphology and crystalline phases.

Research aims and objectives. This study aimed to optimize the ultrasonic-hydrothermal method for synthesizing TiO2 nanotubes by reducing the reaction time without compromising the morphological and structural characteristics.

Materials and methods. The synthesized specimens underwent characterization by scanning electron micro­scopy (SEM) for morphological and dimensional analysis, while Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) served to identify phase composition and crystal structure.

Results and discussion. The results indicated that the obtained nanotubes exhibited lengths ranging from approxi­mately 808 to 1,226 nm and diameters from 172 to 242 nm. A sequential phase transformation occurred, beginning with the initial H2TiO3 phase, progressing through intermediate titanate phases (H2Ti3O7 and H2Ti6O13), and culminating in rutile crystallization at extended reaction times. The anatase phase appeared only in trace amounts throughout the process.

Conclusions. This study highlights the positive impact of ultrasonic pretreatment on the development of TiO2 nanotube structures and provides a scientific basis for optimizing process parameters in the fabrication of nanostructured TiO2 materials.

Introduction. Proper assessment of the fire hazard of building materials is a critical stage in the design and operation of buildings. As glued laminated wood materials such as plywood are increasingly used in the interior and exterior of buildings, it is important to determine their behaviour during a fire.

The object and subject of the study. Specimens of flame-retardant plywood were selected as the object of the study. The subject of the study is the determination of the flammability group of this material.

The aim of the work. The aim of the work is to assess the convergence of test results conducted in various testing laboratories, using the example of the flammability index of hard-to-burn plywood and to develop recommendations for improving methodological approaches.

Materials and research method. The determination of the flammability group of refractory plywood was carried out in 10 accredited laboratories in accordance with GOST 30244–94 “Building materials. Methods of testing for flammability”. The following characteristics were investigated: flue gas temperature, surface damage area, mass loss by the specimen, and self-combustion time.

Results and discussion. The existing methodology for determining the flammability group does not ensure the reproducibility of measurement results. The proposed changes to GOST 30244–94 (standardization of gas, holders, calibrations) do not solve the problem of the lack of correlation between the test parameters and the physico-chemistry of combustion. The “damage” indicator is uninformative. It is necessary to evaluate heat generation, flame propagation velocity, gas toxicity, and other fire hazard parameters. Current flammability indicators and fire hazard classes do not reflect the actual danger of materials and cannot be used for fire safety rationing or fire development forecasting. One of the first steps to overcome existing problems may be the development of a unified classification standard based on a comprehensive assessment of these parameters.

Conclusions. The lack of reproducibility of results in different accredited laboratories indicates the need to revise and improve the regulatory framework.

Introduction. Ion exchange resins are widely used at nuclear fuel cycle facilities. During the exploitation of resins in nitric acid solutions, its self-decomposition at high temperatures is not excluded, which can lead to accidental situations. It is known that anion exchange resins in nitrate form decompose with heat release with the value higher than 300 J/g at the temperatures above 220 °С, which may pose a potential danger to technologies of extraction, separation and purification of radionuclides.

Aims and objectives. In this study, the problem was set to assess boundary conditions of fire and explosion safe use of AV-17-8 anion exchange resins in a sorption column. The objectives included the following steps: investigation of thermal stability of the anionite by differential scanning calorimetry; assessment of the kinetic parameters of the ongoing oxidation reactions; modeling of the process of the heat release in a sorption column. Based on the data obtained, the assessment of the boundary condition for a thermal explosion occurrence in equipment with AV-17-8 was carried out.

Methodology. For the investigation of the samples under study thermal stability, the heating was conducted in synchronous thermal analyzer STA 449 F3 Jupiter. Subsequent data analysis was performed in the Arks specialized software CJSC “Khiminform”, the stages of which included primary processing (base line subtraction, deconvolution of the heat flow signal, determination of thermal effects values), and modeling of the heat release in the column filled with sorbent with certain geometric and thermophysical parameters.

Results and discussion. It was determined by differential scanning calorimetry that the AV-17-8 resin in nitrate form decomposes in two stages at the temperature ranges of 100–200 and 200–320 °С with the heat release values of 148 ± 13 and 425 ± 43 J/g respectively. For these two exothermic effects, the kinetic parameters of the anionite decomposition, with the use of which the boundary temperatures of a thermal explosion in the sorption column depending on its radius are determined.

Conclusion. The Arks software provides an opportunity to simulate conditions for a thermal explosion occurrence in technological equipment. Considering the estimated parameters, it is possible to predict the development of uncontrolled exothermic reactions which determine fire and explosion safety of anion exchange resins application.

Introduction. Determining the frequency of fires in industrial buildings and warehouses is an important integral part of fire risk analysis, which greatly impacts its ultimate result. However, the present-day method used to determine this fire frequency has several weaknesses.

Goals and objectives. The goal of the article is to generate real fire statistics for production and warehouse facilities in the Russian Federation on the basis of alternative fire frequency data depending on the area of such facilities. The main objectives include collecting and processing statistical data, and also analyzing and interpreting results with due regard for international experience.

Methods. Processes of collecting and processing fire statistics for production and warehouse facilities are described depending on their areas; fire statistics is analyzed. The authors identified empirical dependencies, describing with acceptable accuracy the relationship between the fire frequency and the floor area of buildings used as production and warehouse facilities in various industries.

Conclusions. Dependencies between the fire frequency and the building area are identified for various industries. These dependencies are based on statistics, which are collected, processed, and analyzed, also from the viewpoint of obtainability of acceptable fire risk values at facilities that fully comply with regulatory requirements. Methods are proposed to improve regulations applying to fire risk analysis. New fire frequency data, provided in this work, are recommended for use in fire risk analysis.

Introduction. The use of fire-resistant materials at industrial facilities located in the Arctic region requires a special approach to the study of their performance in conditions of low temperatures and aggressive environment. In this regard, the issue of assessing the fire-resistant capacity of fire-protection means appears to be in demand and relevant.

Aims and purposes. This work is aimed at the study of the preservation of fire-resistant properties of fire-­resistant material under the influence of climatic factors in the conditions of an open industrial environment. To achieve the purpose of the study, the following tasks were performed:

• artificial aging of fire-resistant coating specimens was carried out in accordance with the applied methods for 5, 15 and 25 years;
• the resistance to the influence of weather factors and the preservation of fire-resistant characteristics of materials during their use by thermal analysis methods has been investigated;
• the fire-retardant effectiveness of the specimens after accelerated artificial aging, simulating long-term operation, was evaluated.

Methods. The following methods were used to study the preservation of the fire-retardant properties of the analyzed coating specimens:

• the method of artificial climatic aging;
• the methods of synchronous thermal analysis;
• the method of assessing fire-retardant effectiveness.

Results. The results of testing the analyzed specimens of fire-resistant materials under artificial accelerated aging showed a slight deterioration in the fire-resistant properties of the coating as the number of cycles increased. It was concluded that the above methods can be used to qualitatively assess the preservation of the fire-resistant properties of the studied materials.

Conclusion. The conducted experimental studies confirm that the analyzed coatings retain their fire-resistant properties, provided that the requirements specified in the technical documentation are met. Therefore, the studied intumescent fire-resistant material can be recommended for industrial facilities located in regions with predominantly low temperatures.

Introduction. Upholstered furniture in hotel rooms has a fire hazard due to flammable components, such as upholstery fabrics, fillers, and frame elements. However, analysis of fire hazards and their development patterns in hotel buildings disregards flammability properties of upholstered furniture. This can involve an underestimation of toxicological hazards for people in the course of evacuation.
The mission of this work is to assess fire hazards in crowded hotels buildings using mathematical modeling of fire and experimentally obtained information about the thermal decomposition of upholstered furniture.

Research methods. Mathematical modeling was employed to simulate the development of fire hazards in a standard hotel section; fire load values were taken from the database and contributed to the simulation.

Research results and their discussion. Parameters of fire loads, extracted from the database, can cause an underestimation of the effect of toxic gases on humans during evacuation.
Unlike standard combustible loads, emission of a mixture of highly toxic gases, such as carbon monoxide, hydrogen cyanide and hydrogen chloride, accompanies the thermal decomposition of upholstered furniture elements. Hence, partial density of hydrogen cyanide can reach a critical value before humans can start leaving hotel premises that have no fire sources.
The authors demonstrate that safe evacuation of people is unfeasible, because almost each of the five scenarios involves fire hazards that block evacuation exits from a standard hotel section before humans can evacuate from rooms without fire sources.

Conclusion. It is necessary to obtain relevant data on flammability properties of advanced polymers used to make and take care of upholstered furniture, since the thermal decomposition of such polymers can create a toxicological environment.

The article addresses the Thermal runaway of various lithium-ion batteries (LIB) and related fire hazards. Information about the composition of gaseous products released during thermal destruction of LIB components was summarized with a focus on the extreme toxicity of carbon monoxide and hydrogen fluoride. Experimental concentrations of these substances were analyzed and matched against effective standards (Maximum Permissible Concentrations, IDLH, AEGL), taking into account the volume of premises. It is found that even one LIB cell can cause permissible levels of CO and HF to be exceeded if ventilation is insufficient. It is recommended to contribute specific scenarios, involving LIBs, to the fire risk analysis and conduct more research on combustion modeling.