Articles de revues : « Chemical reactor safety »

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Athar, Muhammad, Nor Ayuni Binti Zaidi, Azmi Mohd Shariff, Azizul Buang et Muhammad Ishaq Khan. « Chemical reactor inherent safety index at preliminary design stage ». IOP Conference Series : Materials Science and Engineering 458 (24 décembre 2018) : 012048. http://dx.doi.org/10.1088/1757-899x/458/1/012048.

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Chen, Junjie, et Baofang Liu. « CFD Modeling and Operation Strategies for Hetero-/Homogeneous Combustion of Methane-Air Mixtures in Catalytic Microreactors Using Detailed Chemical Kinetics ». Chemical Product and Process Modeling 11, n^o 4 (1 décembre 2016) : 291–304. http://dx.doi.org/10.1515/cppm-2015-0053.

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Abstract The hetero-/homogeneous combustion of methane-air mixtures in platinum-coated microreactors was investigated by means of two-dimensional CFD (computational fluid dynamics) simulations with detailed chemical reaction schemes, detailed species transport, and heat transfer mechanisms in the solid wall. Detailed homogeneous and heterogeneous chemical kinetic mechanisms are employed to describe the chemistry. The effects of the reactor size, inlet velocity and feed composition were elucidated. Operation strategies for controlling the heterogeneous and homogeneous chemistry in heterogeneous-homogeneous microreactors were developed. Simulations using these mechanisms suggested that homogeneous chemistry can be sustained for gaps well below the quenching distance because of enhanced catalyst-induced heating. This finding has very important ramifications for catalyst safety and lifetime, as well as can be used to produce chemicals, e. g. in oxidative coupling and oxidative dehydrogenation reactions. The proportion of heterogeneous and homogeneous contributions depends strongly upon the reactor operating conditions. Reactor size plays a vital role in the homogeneous chemistry contribution. Smaller reactors result in reduced homogeneous chemistry contribution. Pure heterogeneous chemistry can occur under certain proper conditions, such as heat loss/heat exchange rates, feed compositions, and flow rates. The competition or synergism between homogeneous and heterogeneous chemistry was delineated.

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Muscalu, Constantin, Gheorghe Maria et Daniel Dinculescu. « The Reactor Size Influence on the Optimal Operating Setpoint Choice for a Fixed-Bed Multi-Tubular Catalytic Reactor ». Revista de Chimie 69, n^o 8 (15 septembre 2018) : 2012–18. http://dx.doi.org/10.37358/rc.18.8.6464.

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Optimal operation of chemical reactors of high thermal sensitivity is a central engineering problem of very high current interest. One elegant alternative to choose the optimal setpoint when at least two contrary (opposite) objectives are considered is based on the so-called Pareto-optimal front technique. This paper exemplifies how to generate Pareto optimal operating policies when reactor productivity and safety objectives (expressed in probabilistic terms) are simultaneously considered in the presence of technological constraints, uncertainty in safety boundaries, and random fluctuations in control variables. Beside the operating control variables, one important design variable is the reactor pipe diameter because it is directly related to the reaction heat removal. This paper exemplifies the influence of this design variable on the setpoint choice when applying the Pareto-optimal front method with computing the runaway-boundaries by using the generalized sensitivity criterion of Morbidelli and Varma (MV-criterion). An example is provided for an industrial fixed-bed tubular reactor used for the catalytic oxidation of benzene to maleic anhydride (MA) in vapour phase.

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Li, Zhi Hua, et Ning Chen. « Study on Pressure Detection and Relief Device of Bio Chemical Equipment ». Applied Mechanics and Materials 484-485 (janvier 2014) : 373–77. http://dx.doi.org/10.4028/www.scientific.net/amm.484-485.373.

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This paper describes the chemical equipment and design overpressure conditions. Analysis of the different setting conditions on the discharge area of influence drawn: set a smaller discharge pressure tends to reduce the discharge area; reaction should be increased to increase the quality of the material discharge area; For gas system, increasing large volume of the reactor or the design pressure discharge area required can be reduced, when designing the reactor discharge area is too large can not meet the case of volume of the reactor can be increased and thus meet the requirements of the design pressure. By analyzing the results, in the design of the discharge system, can effectively reduce the discharge area, to meet safety and economy.

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MITROPETROS, K., P. FOMIN et H. HIERONYMUS. « Safety aspects of a bubbly medium inside a chemical reactor ». Chemical Engineering Journal 107, n^o 1-3 (15 mars 2005) : 27–32. http://dx.doi.org/10.1016/j.cej.2004.12.006.

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Azmi, A., S. A. Sata, F. S. Rohman et N. Aziz. « Dynamic optimization of low-density polyethylene production in tubular reactor under thermal safety constraint ». Chemical Industry and Chemical Engineering Quarterly, n^o 00 (2020) : 27. http://dx.doi.org/10.2298/ciceq190108027a.

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A commercial low-density polyethylene (LDPE) which is produced by the polymerization process of ethylene in the presence of initiators in a long tubular reactor is the most widely used in polymer industry. The highly exothermic nature of the LDPE polymerization process and the heating-cooling prerequisite in tubular reactor can lead to various problems particularly safety in term of thermal runaway and productivity, i.e. decreasing monomer conversion. Therefore, model based optimization of an industrial LDPE tubular reactor under thermal safety consideration is required to be implemented. A first principle model for this process is developed and validated using industrial data. Mass and energy balances have been derived from kinetics of LDPE polymerization. Thereafter, an expression of reactor temperature under critical condition is developed and incorporated in the reference model for the thermal safety study. In order to ensure the process is thermally safe and meet the desired product grade, the constrained dynamic optimization is proposed to maximize the conversion of monomer using orthogonal collocation (OC). The dynamic optimization result shows that the maximum reaction temperature under critical condition constraint can be satisfied by optimizing reactor jacket. Moreover, it is achieved without jeopardizing the monomer conversion and the product grade.

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Erwin, S., K. Schulz, H. U. Moritz, C. Schwede et H. Kerber. « Increased Reactor Performance versus Reactor Safety Aspects in Acrylate Copolymerization ». Chemical Engineering & ; Technology 24, n^o 3 (mars 2001) : 305–11. http://dx.doi.org/10.1002/1521-4125(200103)24:3<305 ::aid-ceat305>3.0.co;2-o.

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Bibhab Kumar, Lodh. « The transformative role of Computational Fluid Dynamics (CFD) in chemical engineering ». Open Journal of Chemistry 10, n^o 1 (12 mars 2024) : 001–3. http://dx.doi.org/10.17352/ojc.000033.

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Chemical engineering is a discipline intrinsically linked to fluid behavior. From reaction kinetics to reactor design, understanding how fluids flow, mix, and transfer heat is paramount. Traditionally, this relied heavily on experimentation, a time-consuming and resource-intensive process. The emergence of Computational Fluid Dynamics (CFD) has revolutionized the field, offering a powerful in-silico approach to analyze fluid dynamics in chemical engineering processes. This review paper explores the transformative role of CFD, examining its impact on various aspects of chemical engineering, including reactor design, optimization, process intensification, scale-up, and safety analysis. The paper also discusses the challenges associated with CFD simulations, ongoing advancements in the field, and potential future directions.

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Mcintosh, A. C., B. F. Gray, G. C. Wake et R. Ball. « The stability of a near-adiabatic Endex batch CSTR reactor ». ANZIAM Journal 43, n^o 1 (juillet 2001) : 59–75. http://dx.doi.org/10.1017/s1446181100011421.

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AbstractMany tens of serious incidents involving reactors occur in the developed countries each year. The disaster at the chemical plant in Bhopal, India in 1984 was particularly notable where a thermal runaway process led to more than 3000 tragic fatalities from the cloud of extremely toxic methyl isocyanate that boiled out of a storage tank. This signalled the design of special types of chemical reactors to reduce the risk of thermal runaway by planning (at the design stage) integral safety and thermal stabilization mechanisms. The Endex CSTR (continuously stirred tank reactor) proposed by Gray and Ball [3] involves a reactor in two parts with heat exchange allowed between them. The two parts of the reactor operate side by side in tandem, such that the thermal runaway of one part is offset by an endothermic reaction in the other reactor—hence the term ‘endex’.It is found that the adiabatic endex system has a large region of parameter space where the operation can be made safe. However adiabatic conditions rely on the continuous supply of reactants to the endothermic side of the reactor, for operation of the system. The risks involved are such that it is always safer to operate batch reactors in a non-adiabatic mode. Thus we consider the limiting case of the approach to adiabatic conditions where although the mathematics produces no oscillatory causes for instability, yet there is a narrow but significant area where the stable solution branch is lost and consequently a persistent and unexpected region of instability in what otherwise appears to be a simple CSTR system.

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Marchix, Anthony, et Manon Dieuaide. « Molten salt fast reactor SAMOFAR : Safety issues of the chemical plant ». EPJ Web of Conferences 239 (2020) : 22004. http://dx.doi.org/10.1051/epjconf/202023922004.

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The concept of Molten Salt Fast Reactor (MSFR) has been selecting by the Generation IV International forum as it presents interesting features in terms of safety, sustainability and economics. SAMOFAR project aims to provide the safety assessment of the MSFR concept based on the Thorium fuel cycle. This document provides the radiological assessments for the chemical plant, including shielding requirements and decay heat evaluations.

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Podofillini, L., et V. N. Dang. « Conventional and dynamic safety analysis : Comparison on a chemical batch reactor ». Reliability Engineering & ; System Safety 106 (octobre 2012) : 146–59. http://dx.doi.org/10.1016/j.ress.2012.04.010.

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Rashmi Pradhan, Swaraj, Ramón Fernando Colmenares-Quintero et Juan Carlos Colmenares Quintero. « Designing Microflowreactors for Photocatalysis Using Sonochemistry : A Systematic Review Article ». Molecules 24, n^o 18 (12 septembre 2019) : 3315. http://dx.doi.org/10.3390/molecules24183315.

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Use of sonication for designing and fabricating reactors, especially the deposition of catalysts inside a microreactor, is a modern approach. There are many reports that prove that a microreactor is a better setup compared with batch reactors for carrying out catalytic reactions. Microreactors have better energy efficiency, reaction rate, safety, a much finer degree of process control, better molecular diffusion, and heat-transfer properties compared with the conventional batch reactor. The use of microreactors for photocatalytic reactions is also being considered to be the appropriate reactor configuration because of its improved irradiation profile, better light penetration through the entire reactor depth, and higher spatial illumination homogeneity. Ultrasound has been used efficiently for the synthesis of materials, degradation of organic compounds, and fuel production, among other applications. The recent increase in energy demands, as well as the stringent environmental stress due to pollution, have resulted in the need to develop green chemistry-based processes to generate and remove contaminants in a more environmentally friendly and cost-effective manner. It is possible to carry out the synthesis and deposition of catalysts inside the reactor using the ultrasound-promoted method in the microfluidic system. In addition, the synergistic effect generated by photocatalysis and sonochemistry in a microreactor can be used for the production of different chemicals, which have high value in the pharmaceutical and chemical industries. The current review highlights the use of both photocatalysis and sonochemistry for developing microreactors and their applications.

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Mahmoud Aboelkheir, Ibrahim Mohamed. « An Optimized Chemical and Mechanical Engineering Design of an Ammonia Reactor ». Cognizance Journal of Multidisciplinary Studies 2, n^o 1 (30 janvier 2022) : 10–37. http://dx.doi.org/10.47760/cognizance.2022.v02i01.002.

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Design of an ammonia reactor was conceived as part of a series of item designs for an ammonia plant in Cyprus. The Chemical and Mechanical aspects of the design were considered. Optimization of these designs was studied, worked on, & discussed. The safety, environmental and legal regulations of relevant reactor regulations were followed in the design concerned.

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Leal, Alexandre Soares, João Gabriel Oliveira Marques, Amir Zacarias Mesquita, Daniel Almeida Magalhães Campolina, Denise Das Merces Camarano et Jefferson Jose Vilela. « Water quality management program for IPR-R1 TRIGA® research reactor ». Brazilian Journal of Radiation Sciences 11, n^o 4 (20 décembre 2023) : 01–16. http://dx.doi.org/10.15392/2319-0612.2023.2389.

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The IPR-R1 Triga nuclear research reactor of the Nuclear Technology Development Center (CDTN) is one of the oldest reactors in operation in the world. It is a compact and inherently safe reactor that operates at a continuous power level of 100 kW with a solid homogeneous General Atomic (GA) fuel element of zirconium hydride moderator homogeneously combined with 20% enriched uranium. The reactor core is at the bottom of a tank under approximately 6.0 meters of shielding water. The long operation time of the reactor, 63 years, and the contact of the water with the core, can induce corrosive processes in the IPR-R1 reactor and affect its safe operation. To keep the water quality according to the chemical-physical recommended standards, a quality management program, as recommended by the International Atomic Energy Agency (IAEA), was implemented. The water quality management program is a guideline of good practices applied to nuclear reactors, targeting to keep their water coolants at specified physical-chemical standard. The main aim of the present work is to introduce IPR-R1 Triga’s water chemistry program results from the second half of 2022 till the first half of 2023, when the installation returned to its regular activities after the Covid-19 pandemic. The physical-chemical parameters evaluated (e.g.: pH, alpha and beta radiation, electrical conductivity and gamma emitters) shows that the IPR-R1 reactor operates within recommended safety standards.

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Vernières-Hassimi, L., M. A. Abdelghani-Idrissi et D. Seguin. « Experimental and Theoretical Steady State Maximum Temperature Localization along an Exothermic Tubular Chemical Reactor ». Open Chemical Engineering Journal 2, n^o 1 (7 avril 2008) : 57–65. http://dx.doi.org/10.2174/1874123100802010057.

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This article deals with the experimental and theoretical localization of steady state maximum temperature along an exothermic tubular reactor in counter current flow configuration; which represents a key parameter for safety in the chemical engineering processes. The fluid flowing in the inner tube is a mixture of sodium thiosulfate solution in reaction with hydrogen peroxide. To control the reactive fluid temperature, the inner tube is cooled with a refrigerant fluid flowing through the annular space. The steady state is obtained from the resolution of the nonlinear partial differential equations with the McCormack numerical method. The steady state temperature of the reactive fluid along the tubular reactor presents a maximum value due to the exothermic chemical reaction. The maximum temperature value which represents the critical point of the reactor is investigated. In particular its localization is studied for the first time according to various parameters such as flow rates, reactant concentrations and inlet temperatures.

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Chen, Fang, Xi-Lin Dong, Yan Tang, An-Chi Huang, Mei-Lin Zhang, Qing-Chun Kang, Zhong-Jun Shu et Zhi-Xiang Xing. « Thermal Characteristic Analysis of Sodium in Diluted Oxygen via Thermogravimetric Approach ». Processes 10, n^o 4 (5 avril 2022) : 704. http://dx.doi.org/10.3390/pr10040704.

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As the main reactor type of the fourth-generation nuclear power systems, sodium-cooled fast reactors are now designed and built worldwide. A sodium pool cooling circulation process is indispensable in a sodium-cooled fast reactor. However, the sodium pool fire design is the basis of accidents in sodium-cooled fast reactors. The fire hazard caused by the sodium–oxygen reaction and fast reactor safety have attracted extensive attention. Dry powder is widely used as an effective fire-extinguishing agent to control sodium fire. The sodium will burn in an oxygen-depleted atmosphere when using dry powder to cover fire. In this study, the change law of thermogravimetry of melted sodium is studied by thermogravimetric analysis (TGA) and the apparent activation energy (Ea) is obtained, which has a linear relationship with the oxygen concentration. The results can provide a reference for improving the engineering design standards of sodium fire suppression systems and can also be incorporated into simulation software to improve the accuracy of fire suppression simulations.

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Selinsek, Manuel, Manfred Kraut et Roland Dittmeyer. « Experimental Evaluation of a Membrane Micro Channel Reactor for Liquid Phase Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Nafion® Membranes for Safe Utilization of Undiluted Reactants ». Catalysts 8, n^o 11 (17 novembre 2018) : 556. http://dx.doi.org/10.3390/catal8110556.

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In recent years, various modular micro channel reactors have been developed to overcome limitations in challenging chemical reactions. Direct synthesis of hydrogen peroxide from hydrogen and oxygen is a very interesting process in this regard. However, the complex triphasic process (gaseous reactants, reaction in liquid solvent, solid catalyst) still holds challenges regarding safety, selectivity and productivity. The membrane micro reactor system for continuous liquid phase H2O2 direct synthesis was designed to reduce safety issues by separate dosing of the gaseous reactants via a membrane into a liquid-flow channel filled with a catalyst. Productivity is increased by enhanced mass transport, attainable in micro channels and by multiple re-saturation of the liquid with the reactants over the length of the reaction channel. Lastly, selectivity is optimized by controlling the reactant distribution. The influence of crucial technical features of the design, such as micro channel geometry, were studied experimentally in relationship with varying reaction conditions such as residence time, pressure, reactant ratio and solvent flow rate. Successful continuous operation of the reactor at pressures up to 50 bars showed the feasibility of this system. During the experiments, control over the reactant ratio was found to be crucial in order to maximize product yield. Thereby, yields above 80% were achieved. The results obtained are the key elements for future development and optimization of this reactor system, which will hopefully lead to a breakthrough in decentralized H2O2 production.

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Mateiu, Horia, Traian Fleşer et Alin Constantin Murariu. « The Assessment of Remaining Life of Chemical Reactor Exposed to Creep and Fatigue ». Key Engineering Materials 399 (octobre 2008) : 51–59. http://dx.doi.org/10.4028/www.scientific.net/kem.399.51.

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The paper presents an application according the reliability and remining life assessment of the reactor (coxing box) from a petrochemical plant, after failure in welding joint of plated shell from W1.5423 (16Mo5) steel with 25 mm thickness, plated with W1.4002 stainless steel with 3 mm thickness. The reactor failure it has associated with initial flaws from welding process, which have accelerated remaining life exhaustion. The assessment made in two steps. It has used VII section of ASME code specifications and iRiS-Thermo expert system for preliminary remaining life assessment. Concomitantly, it was performed the experimental creep and thermal fatigue testing. The program results have defined creep and thermal fatigue exhaustion and its remaining life at common creep-fatigue action, in condition of safety exploitation. It was emphasized the possibility of use an extra 40,000 hours of rehabilitated reactor in the safety condition of normal parameters.

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Horváth, Ákos, Attila R. Imre et György Jákli. « Investigation of Corrosion Resistance of Alloys with Potential Application in Supercritical Water-cooled Nuclear Reactors ». Periodica Polytechnica Chemical Engineering 63, n^o 2 (25 février 2019) : 328–32. http://dx.doi.org/10.3311/ppch.12923.

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The Supercritical Water Cooled Reactor (SCWR) is one of the Generation IV reactor types, which has improved safety and economics, compared to the present fleet of pressurized water reactors. For nuclear applications, most of the traditional materials used for power plants are not applicable, therefore new types of materials have to be developed. For this purpose corrosion tests were designed and performed in a supercritical pressure autoclave in order to get data for the design of an in-pile high temperature and high-pressure corrosion loop. Here, we are presenting some results, related to corrosion resistance of some potential structural and fuel cladding materials.

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Burkholder, Michael, Stanley Gilliland, Adam Luxon, Christina Tang et B. Gupton. « Improving Productivity of Multiphase Flow Aerobic Oxidation Using a Tube-in-Tube Membrane Contactor ». Catalysts 9, n^o 1 (17 janvier 2019) : 95. http://dx.doi.org/10.3390/catal9010095.

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The application of flow reactors in multiphase catalytic reactions represents a promising approach for enhancing the efficiency of this important class of chemical reactions. We developed a simple approach to improve the reactor productivity of multiphase catalytic reactions performed using a flow chemistry unit with a packed bed reactor. Specifically, a tube-in-tube membrane contactor (sparger) integrated in-line with the flow reactor has been successfully applied to the aerobic oxidation of benzyl alcohol to benzaldehyde utilizing a heterogeneous palladium catalyst in the packed bed. We examined the effect of sparger hydrodynamics on reactor productivity quantified by space time yield (STY). Implementation of the sparger, versus segmented flow achieved with the built in gas dosing module (1) increased reactor productivity 4-fold quantified by space time yield while maintaining high selectivity and (2) improved process safety as demonstrated by lower effective operating pressures.

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Mikuš, Vladimír, Martina Ridzoňová et Pavol Steltenpohl. « Fuel additives production : ethyl-t-butyl ether, a case study ». Acta Chimica Slovaca 6, n^o 2 (1 octobre 2013) : 211–26. http://dx.doi.org/10.2478/acs-2013-0034.

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Abstract The students frequenting the program Chemical Engineering at the Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology of the Slovak University of Technology in Bratislava are taught to be able to combine and develop their knowledge acquired in the area of chemical, energetic, environmental, and safety engineering. Prior to completing their study, they are obliged to develop a report regarding engineering, economic, and safety analysis of important chemical technology. This paper presents the most valuable outputs of the student’s Technology project aimed on simulation and optimization of the fuel additives production technology. 2-Ethoxy-2-methylpropane (ethyl-t-butyl ether, ETBE) production based on liquid-phase etherification of 2-methylpropene with ethanol in the presence of heterogeneous catalyst was studied. Different patented technologies were investigated in terms of their profitability and safeness. The first technology was an isothermal reactor with the product separation via distillation (Kochar & Marcell, 1981). The next ETBE production design assumed was a modification of the previous one; the product separation was carried out using liquid-phase extraction (Pucci et al., 1992). The last design considered in this study was a reactive distillation column with a pre-reactor (Bakshi et al., 1992). In all three technologies, etherification reaction was carried out using Amberlyst ion-exchange resin in its H+ form as the catalyst. Selected ETBE production designs were simulated using Aspen+ program. Their profitability was compared on basis of the investment and operation costs assessment taking into account both the produced ETBE yield and purity. Further, basic safety analysis of all chosen technologies was performed in order to identify possible hazards. Finally, individual and social risk connected with the plant operation was computed. Taking into account these economic and safety criteria, the best alternative for ETBE production was the reactive distillation.

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Gaydamaka, Sergey, Marina Gladchenko, Olga Maslova, Olga Senko, Alla Kornilova et Igor’ Kornilov. « Application of the Hybrid Chemical-Biocatalytic Approach for Conversion of Nitrocellulose-Containing Sewage Sludge ». Processes 11, n^o 7 (6 juillet 2023) : 2017. http://dx.doi.org/10.3390/pr11072017.

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Waste containing explosive chemicals are hazardous to the environment. We suggested and implemented a hybrid approach for the destruction of nitrocellulose-containing sewage sludge (NCS) from a real chemical industrial complex. Combining chemical alkaline hydrolysis and mesophilic anaerobic digestion in a up-flow anaerobic sludge blanket (UASB) reactor allowed us to successfully achieve the balance between the environmental safety and economic efficiency of the stages of the treatment. After the alkaline treatment of waste at 50 °C with 1.5 M KOH, the solid residue contained mostly just sand and no nitrocellulose (NC). The liquid phase accumulated 2869 ± 24 mg N-NO2−/L and 1698 ± 51 mg N-NO3−/L. Bioconversion of the liquid phase neutralized with acetic acid and diluted with water by a factor of 50 in a 1 L UASB reactor ensured 99% efficiency of extracting N(NO2− + NO3−) and chemical oxygen demand (COD). Further, biogas with high methane content (>70%) was obtained. The establishment of the operational regime in the UASB reactor was achieved in two stages. The suggested hybrid approach to denitrification and methanogenesis is aimed at implementing the sustainable development concept in industrial chemical cycles. The results of this study are significant for researchers and technologists interested in developing hybrid processes for waste treatment that involve chemical catalysis as the first stage.

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Jurtz, Nico, Steffen Flaischlen, Sören C. Scherf, Matthias Kraume et Gregor D. Wehinger. « Enhancing the Thermal Performance of Slender Packed Beds through Internal Heat Fins ». Processes 8, n^o 12 (24 novembre 2020) : 1528. http://dx.doi.org/10.3390/pr8121528.

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Slender packed beds are widely used in the chemical and process industry for heterogeneous catalytic reactions in tube-bundle reactors. Under safety and reaction engineering aspects, good radial heat transfer is of outstanding importance. However, because of local wall effects, the radial heat transport in the vicinity of the reactor wall is hindered. Particle-resolved computational fluid dynamics (CFD) is used to investigate the impact of internal heat fins on the near wall radial heat transport in slender packed beds filled with spherical particles. The simulation results are validated against experimental measurements in terms of particle count and pressure drop. The simulation results show that internal heat fins increase the conductive portion of the radial heat transport close to the reactor wall, leading to an overall increased thermal performance of the system. In a wide flow range (100<Rep<1000), an increase of up to 35% in wall heat transfer coefficient and almost 90% in effective radial thermal conductivity is observed, respectively.

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DeSalvo, Riccardo. « The Micro Modular Reactors MMR^® ». EPJ Web of Conferences 310 (2024) : 00011. http://dx.doi.org/10.1051/epjconf/202431000011.

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The Micro Modular Reactor (MMR) represents a new paradigm of Ultra Safe Nuclear power with intrinsic safety. The safety starts from its revolutionary ceramic fuel, that cannot melt and makes it impossible to release radioactive elements in the environment. The elimination of water as a heat transport fluid eliminates the possibility of chemical explosions. Uranium 238, that absorbs more neutrons at higher temperatures shuts down the chain reaction without damage even in case of coolant loss at full power. These characteristics make MMR ideal to provide heat process directly inside factories, to replace natural gas, and to provide power to small communities.

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Simon, Levente L., Marina Introvigne, Ulrich Fischer et Konrad Hungerbühler. « Batch reactor optimization under liquid swelling safety constraint ». Chemical Engineering Science 63, n^o 3 (février 2008) : 770–81. http://dx.doi.org/10.1016/j.ces.2007.08.076.

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Gijiu, Cristiana Luminita, Daniel Dinculescu et Mara Crisan. « Anniversary Professor dr.ing. Gheorghe MARIA at 65 years old - teacher and scientist ». Revista de Chimie 71, n^o 4 (5 mai 2020) : 1–18. http://dx.doi.org/10.37358/rc.20.4.8038.

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Prof. Dr. Ing. Gheorghe Maria from University Politehnica of Bucharest (UPBuc.), Department of Chemical and Biochemical Engineering is a valuable scientist in Romania, being the successor and continuer of the Romanian school of (bio)chemical reactors and reaction engineering, but also the creator of novel courses in the (bio)chemical engineer curricula at UPBuc. His research interests include a wide range of classic but also modern border fields, namely (bio)chemical reactors, kinetic modelling, bioinformatics, chemical reactors risk analysis, modelling dynamics of cell metabolic processes, of gene regulatory circuits, and of controlled drug release. Following the large number of international cooperations (20), its scientific productivity is impressive, including over 230 papers in ISI journals and intl. Conferences, 11 ISBN books (RO,USA), 5 teaching books (UPBuc., RO), and 6 ISBN book chapters abroad. Their practical realizations include the design and putting into operation of an industrial plant in Romania (at Petrochemical works /Refinery Brazi-Ploiesti, Romania, PWBP,1985), of a lab-scale pilot plant in Switzerland (Paul Scherer Inst., 1992-1998), or a safety-based optimization of a semi-batch (SBR) reactor (at CIBA-Novartis, Basel, 1994-1996). Based on these multiple contributions, it can be stated that Prof. Maria has had a significant impact on the science and the practice of Chemical and Biochemical Reaction Engineering in Romania and world-wide, his publications being well cited (Hirsch index 20, I10 index 49, more than 1400 citations). In 2019 he joined (unanimously by votes) the Romanian Academy. as a correspondent member.

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Razzaq, Ghassan Hassan Abdul, Khaleel I. Hamad et Jasim Ibrahim Humadi. « Silver Nanoparticles for Ultrasonic Assisted Synthesis of Oxidant Agents in Micro-Reactor : Kinetic Analysis and Process Intensification ». Materials Science Forum 1083 (6 avril 2023) : 23–32. http://dx.doi.org/10.4028/p-0brrx7.

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Chemical engineering frequently uses "process intensification" to consciously combine various phenomena or procedures. By treating the molecules in such a system in a way that every single molecule experiences the same processing, the selectivity is raised, enhancing productivity. For mass transfer limited reactions, the enhancement of the transport rates & the specific interfacial area are the typical approaches. These enable the reduction of diffusion path length, reduce hold-up and improve the controlling on temperature control, even for highly exothermic reactions. Micro reactor technology (MRT) is a subset of process intensification that aims to reduce the size of equipment, energy consumption, and waste generation. The research of peracetic acid (PAA) and perform acid (PFA) preparation is the focus of the current investigation. Amberlite IR-120H catalyst was used to study the synthesis of PAA and PFA in batch and micro-structured reactors while ultrasonic irradiations were present.. The current research describes a method for synthesizing both compounds in a batch and micro-structured reactors, with and without ultrasonic irradiation. Such a technology might be crucial in the online synthesis of these chemicals as it eliminates the need for harmful components to be transported and stored, assuring safety among other benefits. For these substances, various safety characteristics could be improved.

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Shan, Yilian, Jiye Sun, Xianglong Zhu, Yanhui Tian, Junyao Zhou, Yuzhe Ding, Benjie Ding, Jianke Du et Minghua Zhang. « Fatigue Life Analysis of Cyclone Separator Group Structure in a Reactor Device ». Materials 18, n^o 6 (9 mars 2025) : 1214. https://doi.org/10.3390/ma18061214.

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In the chlorination industry, the reactor is a crucial equipment in which the chlorination reaction takes place. However, when the reactor is subjected to complex conditions such as high temperatures (e.g., >200 °C) and high pressures (e.g., >10 MPa), its structural integrity is significantly compromised, leading to severe safety issues. In this study, the fatigue life of a reactor is analyzed, with particular focus on the fatigue behavior of the cyclone separator under varying working conditions, such as changes in the temperature, pressure, and chemical environment. Using finite element simulations under steady-state conditions and the S-N curve from fatigue testing, the fatigue life and potential weak points of the reactor under different amplitudes and vibration frequencies are analyzed and predicted. This analysis is conducted using a combined simulation approach with ABAQUS and Fe-Safe software, v 6.14. This work also considers the periodic vibrations at the base of the cyclone separator within the reactor. Fatigue simulations under different vibration conditions are performed to further assess the fatigue life of the reactor, providing a theoretical basis for the optimization of design and ensuring operational safety. In addition, the influence of welding zones on the fatigue life is discussed. The results indicate that the welding defects and stress concentration may cause the welded joint to become a critical weak point for fatigue failure. Therefore, the fatigue performance of the welding zone should be carefully considered during the design phase.

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Kiegiel, Katarzyna, Dagmara Chmielewska-Śmietanko, Irena Herdzik-Koniecko, Agnieszka Miśkiewicz, Tomasz Smoliński, Marcin Rogowski, Albert Ntang, Nelson Kiprono Rotich, Krzysztof Madaj et Andrzej G. Chmielewski. « The Future of Nuclear Energy : Key Chemical Aspects of Systems for Developing Generation III+, Generation IV, and Small Modular Reactors ». Energies 18, n^o 3 (29 janvier 2025) : 622. https://doi.org/10.3390/en18030622.

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Nuclear power plants have the lowest life-cycle greenhouse gas emissions intensity and produce more electricity with less land use compared to any other low-carbon-emission-based energy source. There is growing global interest in Generation IV reactors and, at the same time, there is great interest in using small modular reactors. However, the development of new reactors introduces new engineering and chemical challenges critical to advancing nuclear energy safety, efficiency, and sustainability. For Generation III+ reactors, water chemistry control is essential to mitigate corrosion processes and manage radiolysis in the reactor’s primary circuit. Generation IV reactors, such as molten salt reactors (MSRs), face the challenge of handling and processing chemically aggressive coolants. Small modular reactor (SMR) technologies will have to address several drawbacks before the technology can reach technology readiness level 9 (TRL9). Issues related to the management of irradiated graphite from high-temperature reactors (HTR) must be addressed. Additionally, spent fuel processing, along with the disposal and storage of radioactive waste, should be integral to the development of new reactors. This paper presents the key chemical and engineering aspects related to the development of next-generation nuclear reactors and SMRs along with the challenges associated with them.

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Wu, Yao-Chang, Bin Laiwang et Chi-Min Shu. « Investigation of an Explosion at a Styrene Plant with Alkylation Reactor Feed Furnace ». Applied Sciences 9, n^o 3 (1 février 2019) : 503. http://dx.doi.org/10.3390/app9030503.

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To prevent and mitigate chemical risks in the petrochemical industry, such as fires and spillage, process safety management (PSM), is essential, especially where flammable, corrosive, explosive, toxic, or otherwise dangerous chemicals are used. We investigated process safety (PS) between man–machine (material equipment) and environmental interfaces by using process hazard analysis (PHA) and fault tree analysis (FTA). By analyzing the data obtained through machinery and mechanical integrity (MI), pre-startup safety review (PSSR), current operating modes, and areal locations of hazardous atmospheres (ALOHA) simulations of the disaster’s aftermath, the cause of the styrene plant accident was found to be the fuel furnace (F101) switching process. Although the furnace had been extinguished, fuel continued to enter the furnace, and it was exposed to a high-temperature surface, resulting in the flashing ignition of the C4 fuel. The plan-do-check-act (PDCA) management model can be used to forestall the system from accident, and it is used to improve the proposal and develop countermeasures that would increase PSM performance and substantially lessen the impact of the thermal hazard. Disasters are often attributable to the unsafe state of machinery, equipment, or the environment, dangerous behaviors of the operator, and the lack of a thorough management system. It is anticipated that the investigation and analysis of the accident would not only find the real cause of the disaster but also lead to the establishment of better effective solutions for common safety problems.

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Ramezani, Leila, Masoud Mansouri et Mohammad Rahgoshay. « Modeling the water side corrosion and hydrogen pickup of VVER 1000 fuel clad ». Nuclear Technology and Radiation Protection 33, n^o 4 (2018) : 334–40. http://dx.doi.org/10.2298/ntrp180606013r.

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Zirconium alloys, are usually used as fuel cladding materials in VVER (water-cooled, water-moderated energy reactor) type reactors, mainly, due to their low neutron absorption cross-section, desirable mechanical properties, and good corrosion resistance under reactor operating conditions. During exposure to water at high temperature, water reacts with zirconium alloys, which results in the production of an oxide layer. The entire area of corrosion along with the accompanying absorption of hydrogen in the zirconium metal matrix has attracted a lot of attention when the performance of the core components as well as the operation of the reactor is emphasized. The growth of the zirconium oxide layer plays a destructive role in decreasing thermal efficiency of the reactor by restricting the inlet temperature and chemical properties of the coolant. The present study aimed to develop a computer code to predict long-term water side corrosion weight gain, oxide thickness and determine the concentration of absorbed hydrogen in VVER-1000 reactors during normal operating conditions. The proposed model can be utilized to estimate the pre-transition and post-transition corrosion weight gain and the oxide thickness in operating conditions.

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Chiappetta, G., G. Clarizia et E. Drioli. « Analysis of safety aspects in a membrane reactor ». Desalination 193, n^o 1-3 (mai 2006) : 267–79. http://dx.doi.org/10.1016/j.desal.2005.06.064.

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Labovský, Juraj, Zuzana Švandová, Jozef Markoš et L’udovít Jelemenský. « Mathematical model of a chemical reactor—useful tool for its safety analysis and design ». Chemical Engineering Science 62, n^o 18-20 (septembre 2007) : 4915–19. http://dx.doi.org/10.1016/j.ces.2007.01.071.

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Sharaevsky, І. G., Т. S. Vlasenko, L. B. Zimin, А. V. Nоsоvskyi, N. М. Fіаlkо et G. І. Sharaevsky. « Current Physical Problems of the Dynamic Damage in Elements of the First Circuit of VVER Reactors ». Nuclear Power and the Environment 24, n^o 2 (2022) : 3–17. http://dx.doi.org/10.31717/2311-8253.22.2.1.

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In the context of the actual problems of the physics of operational damage of modern reactor steels produced in the leading countries of the world (USA, Russia, Western Europe) and used for the manufacture of nuclear reactor vessels and other equipment of the first circuit of nuclear power plants, the characteristic features of possible dynamic damage in the responsible elements of this are considered. The mentioned problems are systematized from the standpoint of analyzing the effects of radiation embrittlement, as well as physical and chemical processes that, under certain conditions, are capable of developing in the operating equipment of Ukrainian NPPs, which are already working out their design operational resource. The characteristic features of possible dynamic damage in the operating reactor equipment of Ukrainian and foreign nuclear power plants are considered. The problem is systematized, first of all, from the standpoint of analyzing the operational stability of domestic and foreign reactor steels in relation to their radiation embrittlement. The peculiarities of the course of this physical process have been analyzed, which should be taken into account when determining the maximum possible terms of extension of safe operation of nuclear power units with reactors of the VVER type at the NPP of Ukraine. The main metal-physical properties of reactor steels of various types and possible problems caused by neutron irradiation, physical and chemical processes, vibrational and thermomechanical fatigue, which threaten the unexpected sudden destruction of reactor vessels, are considered. Special attention is paid to mechanical damage and processes accompanying the operation of reactor housings under conditions of cyclic and dynamic loads. A warning has been given regarding the unjustified extension of the period of reactors safe operation. The significant technological lag of the former Soviet, and now Russian, metallurgy from the level of metallurgy of the leading Western countries was noted. Data are provided on the high operational properties of the latest American steels, from which modern reactors of the AR1000 type are manufactured in the USA, and the safety, technical, economic and environmental advantages of using these reactors in Ukraine in comparison with new models of reactors of the VVER-1000 and VVER-1200.

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Wishart, James F., Kazuhiro Iwamatsu, Bobby Layne et Philip Halstenberg. « Reactivity of Metal Ions with Excess Electrons in Molten MgCl₂-KCl Mixtures ». ECS Meeting Abstracts MA2022-02, n^o 55 (9 octobre 2022) : 2056. http://dx.doi.org/10.1149/ma2022-02552056mtgabs.

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Molten salts are proposed as liquid fuels or coolants in a new fleet of molten salt nuclear reactors that would have operational and safety advantages over present reactor systems. Under those conditions, the salt will be exposed to high radiation levels, and understanding the chemical effects of radiolysis on the molten salt fuel or coolant is essential to reliable, efficient and sustainable reactor operation. Building this understanding begins with identifying primary salt radiolysis products and characterizing their reactivities, for which we perform high-temperature pulse radiolysis transient absorption spectroscopy at the BNL Laser-Electron Accelerator Facility. Salt mixtures containing monovalent and divalent cations are of particular interest because of their tunable Lewis acidity-basicity that can be used to control the solubility of dissolved metal ions in the reactor. Changing the MgCl2:KCl mixing ratio alters the absorption spectra of radiolytically-produced excess electrons, with increasing blue shifts related to the probable number of Mg2+ ions close to the cavity electron. These strong blue shifts imply significant changes in the electron’s energetics and reactivity that we quantify by measuring reaction kinetics with metal ion electron acceptors. This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

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Ao, Rui, Ruihua Lu, Guanghui Leng, Youran Zhu, Fuwu Yan et Qinghua Yu. « A Review on Numerical Simulation of Hydrogen Production from Ammonia Decomposition ». Energies 16, n^o 2 (13 janvier 2023) : 921. http://dx.doi.org/10.3390/en16020921.

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Ammonia (NH3) is regarded as a promising medium of hydrogen storage, due to its large hydrogen storage density, decent performance on safety and moderate storage conditions. On the user side, NH3 is generally required to decompose into hydrogen for utilization in fuel cells, and therefore it is vital for the NH3-based hydrogen storage technology development to study NH3 decomposition processes and improve the decomposition efficiency. Numerical simulation has become a powerful tool for analyzing the NH3 decomposition processes since it can provide a revealing insight into the heat and mass transfer phenomena and substantial guidance on further improving the decomposition efficiency. This paper reviews the numerical simulations of NH3 decomposition in various application scenarios, including NH3 decomposition in microreactors, coupled combustion chemical reactors, solid oxide fuel cells, and membrane reactors. The models of NH3 decomposition reactions in various scenarios and the heat and mass transport in the reactor are elaborated. The effects of reactor structure and operating conditions on the performance of NH3 decomposition reactor are analyzed. It can be found that NH3 decomposition in microchannel reactors is not limited by heat and mass transfer, and NH3 conversion can be improved by using membrane reactors under the same conditions. Finally, research prospects and opportunities are proposed in terms of model development and reactor performance improvement for NH3 decomposition.

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Reátegui-Romero, Warren, Fredy Castillejo-Melgarejo et María E. King-Santos. « Industrial Manufacturing of Aqueous Solutions of Sodium Sulfhydrate (NaHS 43%) in a Multi-Phase Reactor ». Open Chemical Engineering Journal 13, n^o 1 (31 mai 2019) : 46–67. http://dx.doi.org/10.2174/1874123101913010046.

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Background: This research deals with the manufacture of sodium sulphides and sodium sulfhydrate in an isothermal multiphase chemical reactor to produce concentrated aqueous solutions of sodium sulfhydrate (greater than 43%) through Gas-Liquid-Solid reactions from hydrogen sulfide and hydroxide of sodium at 50%. Methods: A method is proposed that integrates the recovery of hydrogen sulfide from an industrial chemical process where the H2S gas is generated as a sub product, the strategy of the developed process was integrated into a manufacturing plant of dithiophosphoric acids (ADTF) where it was possible to recover the hydrogen sulfide in the form of an aqueous solution of NaHS with a concentration higher than 43%. Results: The experimental tests showed that the biphasic reaction mixture formed by Na2S, NaHS and H2O with global compositions of 13.3%; 26.9% and 59.7% respectively, is appropriate to obtain 43% sodium sulfhydrate in a stirred tank reactor, operated at temperatures ranging from 50°C to 55°C, where gaseous hydrogen sulfide is continually bubbled. Conclusion: Sodium sulfide (specifically Na2S.5H2O crystals) of the biphasic mixture is produced from a solution of sodium sulfhydrate (43% NaHS) and aqueous sodium hydroxide (50% NaOH). The environmental problem generated by the H2S was solved with a 90% recovery in the multiphase reactor and 5% in the safety absorber.

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Alhuzaymi, Thaqal M., Meshari M. ALQahtani, Thaar M. Aljuwaya et Ayodeji B. Alajo. « MCNP and CFD Modeling for Potential High-Power Configuration of Missouri S&T Reactor ». Processes 11, n^o 4 (30 mars 2023) : 1044. http://dx.doi.org/10.3390/pr11041044.

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Utilization of nuclear research reactors is of high importance for education and training, research and development, and many other applications. However, less effective utilization encountered in research reactors is mainly due to limitations in power levels and related experimental facilities. Such limitations, however, have led different global owners of research reactors to consider upgrading the power levels of their reactors to accommodate the increase in utilization demands. To consider upgrading the power levels of research reactors without replacing major components, a pair of essential analyses must be performed, namely the neutronic evaluation of nuclear fission and thermal-hydraulic evaluation for heat removal from the reactor core. In this work, a conceptual upgrade to the core design and configuration of MSTR, or Missouri University of Science and Technology Reactor (200 kilowatts (kW)), is demonstrated. The conceptual design of the MSTR high-power configuration (MSTR-HPC) aims to achieve high neutron flux and demonstrate the power level and core configuration with greater flexibility and adaptability while not exceeding safety limits. The conceptual design of the MSTR-HPC involves uprating the power level to 2 megawatts (MW), reconfiguring the core, changing the fuel meat type, inclusion of a flux trap (FT) facility, and others. In addition, the conceptual design of MSTR-HPC includes three in-core irradiation facilities, namely FT, bare rabbit tube (BRT), and cadmium rabbit tube (CRT). The neutronic evaluation of the MSTR-HPC was carried out using the Monte Carlo N-particle Code (MCNP), version 6. In addition, the thermal-hydraulic behavior of MSTR-HPCs’ hot-channel has been assessed by means of ANSYS Fluent to evaluate the satisfaction of thermal-hydraulic safety requirements of the conceptual design. The results obtained have shown that the conceptual MSTR-HPC has demonstrated a maximum neutron flux obtained higher than that obtained in the current MSTR core by two orders of magnitude. The conceptual design of MSTR-HPC with composite BeO/graphite reflector blocks was able to sustain critically and operate continuously at full power for 61 days. In regards to the hottest fuel plate of MSTR-HPC, the results have shown that the determined temperature for the fuel plate regions was below the safety limits. In addition, at full operation power of the MSTR-HPC, the mass flow rate of 39.86 kg/s (10.644 gallon/s) was sufficient for removing the generated heat. In conclusion, the conceptual design of the MSTR-HPC has demonstrated its flux enhancement capabilities while maintaining safety limits, which are of high importance in enhancing reactor utilization for a larger window of time.

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Vashchenko, Volodymyr M., Volodymyr I. Skalozubov, Iryna B. Korduba, Serhiy I. Kosenko et Olena H. Zhukova. « Criteria of thermochemical conditions of steam gas explosions in dynamic accident modes at nuclear power units with WWER reactors ». Environmental safety and natural resources 44, n^o 4 (29 décembre 2022) : 128–34. http://dx.doi.org/10.32347/2411-4049.2022.4.128-134.

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The main lessons of the major accident at the Fukushima-Daiichi NPP in 2011 for the nuclear power industry identify the need to model, analyze and develop emergency measures for relatively unlikely events with catastrophic environmental consequences, taking into account multiple failures of safety systems. Steam-gas explosions became one of the main causes of the catastrophic environmental consequences of the Chernobyl and Fukushima accidents. Criteria and conditions for the occurrence of steam-gas explosions in dynamic emergency modes in the "tight" reactor circuit of nuclear power reactor units (NPP) with water-water reactors (WWER) with failures of safety systems valves and emergency steam gas removal are determined by the rate of change of thermodynamic and physico-chemical parameters. A method for determining the criteria and conditions for the occurrence of steam-gas explosions in dynamic accident modes with a "tight" reactor circuit and failure of safety valves for modeling the initial emergency events – seismic effects, falling of massive objects, etc. is presented. The conditions for the occurrence of hydrogen explosions are determined by the maximum rate of increase in the temperature of fuel oil shells, and the conditions for steam explosions are determined by the maximum rate of pressure increase as a result of the intensification of vaporization processes. The criteria for the occurrence of steam explosions in dynamic emergency modes are determined by the maximum pressure amplitude and the propagation speed of acoustic disturbances in the steam volume. And the criteria for hydrogen detonation in dynamic emergency modes are determined by the maximum amplitude of the increase in the temperature of the fuel shells and the average flow rate of the coolant in the active zone of the reactor.

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Chetouani, Yahya, Nordine Mouhab, Jean-Marie Cosmao et Lionel Estel. « Dynamic model-based technique for detecting faults in a chemical reactor ». Process Safety Progress 22, n^o 3 (septembre 2003) : 183–90. http://dx.doi.org/10.1002/prs.680220308.

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Minteer, Shelley D. « Improving the Selectivity and Efficiency of Synthetic Organic Electrosynthesis ». ECS Meeting Abstracts MA2024-01, n^o 56 (9 août 2024) : 2972. http://dx.doi.org/10.1149/ma2024-01562972mtgabs.

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Although electrochemistry is a current focus area in improving the sustainability and safety of chemical manufacturing, electrochemical techniques for synthesis rarely have sufficient selectivity and frequently have low faradaic, product, and energy efficiencies. This paper will discuss the use of biocatalytic systems to improve the selectivity of electrosynthesis followed by a discussion of materials, reactor, and technique strategies to improve the faradaic, product, and energy efficiencies in these systems. Examples will be shown that range from commodity chemical synthesis to fine chemical synthesis to pharmaceutical synthesis with a comparison of the concerns and advantages of electrosynthesis for each chemical industry.

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Shimada, Taro, Yuki Nishimura et Seiji Takeda. « Sensitivity Analysis on Safety Functions of Engineered and Natural Barriers for Fuel Debris Disposal ». MRS Advances 2, n^o 12 (2017) : 687–92. http://dx.doi.org/10.1557/adv.2017.24.

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ABSTRACTA disposal measure for fuel debris generated at the accident in the Fukushima Daiichi Nuclear Power Station has been studied so far. However, physical and chemical properties of the fuel debris located in reactor containment vessels have not yet been obtained. In order to investigate the safety function of barriers required for disposal of fuel debris, sensitivity analysis for radionuclide migration was carried out, considering with uncertainty of the properties. As a result, it is indicated that it was important for evaluation of fuel debris disposal to obtain the physical and chemical properties of 14C and 129I during release to groundwater, in addition to 238U.

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Wishart, James F., Kazuhiro Iwamatsu, Bobby Layne, Ellie Kim, Phillip Halstenberg, Sheng Dai, Jay A. LaVerne et al. « Radiation-Driven Reactivity of Metal Ions in Molten Salts ». ECS Meeting Abstracts MA2024-02, n^o 57 (22 novembre 2024) : 3879. https://doi.org/10.1149/ma2024-02573879mtgabs.

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Molten salts are proposed as liquid fuels or coolants in a new fleet of molten salt nuclear reactors that would have operational and safety advantages over present reactor systems. Under those conditions, the salt will be exposed to high radiation levels, and understanding the chemical effects of radiolysis on the molten salt fuel or coolant is essential to reliable, efficient and sustainable reactor operation. Building this understanding begins with identifying primary salt radiolysis products (solvated electrons (esolv –) and Cl2 •–) and characterizing their reactivities, for which we conduct high-temperature pulse radiolysis transient absorption spectroscopy at the BNL Laser-Electron Accelerator Facility. Here we report on the reaction kinetics of reactions of metal ions with esolv – and Cl2 •– in different molten salt compositions. Salt mixtures containing mono- and divalent cations are particularly interesting because of their tunable Lewis acidity-basicity that can be used to control the solubility and redox poise of dissolved metal ions in the reactor. Previously we showed how varying the MgCl2:KCl mixing ratio alters the absorption spectra of radiolytically-produced excess electrons, with increasing blue shifts related to the likely number of Mg2+ ions adjacent to the cavity electron. The strong blue shifts indicate significant changes in the electron’s energetics and reactivity that we now have probed by measuring reaction kinetics with metal ion electron acceptors. We observed that reaction rates of the solvated electron depend strongly on the composition of the salt. Reactivity trends among first-row transition metals in eutectic LiCl-KCl will be discussed. This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

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Semmache, B., S. Kallel, H. El Omari, M. Lemiti et A. Laugier. « Dépôt chimique en phase vapeur et à basse pression de couches minces à base de silicium dans un réacteur à lampes halogène ». Canadian Journal of Physics 77, n^o 9 (1 février 2000) : 737–43. http://dx.doi.org/10.1139/p99-035.

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Low-pressure chemical vapor deposition (LPCVD) in halogen lamp-heated reactor (RTLPCVD: rapid thermal LPCVD) is a promising technique for silicon-based thin films deposition. Indeed, overall process time and gas consumption reduction in RTP reactors allows to project new device fabrication technologies (microsensors, solar cells) in order to reach a higher environmental safety with respect to classical technologies.Various gases available on our RTP installation (SiH4, NH3, N2O, O2, PH3, B2H6) enable several silicon-based thin films RTLPCVD deposition: intrinsic polycrystalline silicon (poly-Si) films or in situ doped poly-Si, silicon nitride (Si-N) and oxynitride (Si-O-N). In this paper, we discuss our results on deposition kinetics and physical properties of these thin films. It appeared that RTLPCVD silicon-based thin films with interesting structural, electrical, and optical properties can be synthesized in our lamp-heated reactor with a tight control of process parameters such as temperature, pressure, and gas flow ratios.

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Nikitenko, Evgeniy, Nikolay Romadov et Mariya Pyshkina. « Determination of Radiation Exposure to Iodine-131 Emissions During Normal Operation of the Industrial Reactor Installation at Fsue “PO Mayak” Taking into Account Physical and Chemical Forms ». ANRI, n^o 4 (3 décembre 2020) : 46–54. http://dx.doi.org/10.37414/2075-1338-2020-103-4-46-54.

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The determination of the physicochemical forms of radioiodine in the gas-air environment of an industrial nuclear reactor is necessary to solve related problems – technological control and radiation safety. In the technological context, the results obtained make it possible to adequately assess the efficiency of purification of emissions of radioactive iodine isotopes, the choice of instruments and methods for controlling emissions. In the context of radiation safety, research results make it possible to correctly assess the radiation effects on the environment and humans, substantiation of emission standards for the atmosphere and confirmation of the safety of operation of an industrial reactor installation. The research method is based on the difference in the deposition of radioiodine on a set of one AFA-RMP aerosol filter and six filters of the AFA-SI type, which makes it possible to separately determine the 131I aerosol, easily and hardly sorbed form. It has been shown that the non-purified gas-aerosol mixture mainly contains radioactive iodine in the form of gaseous hardly adsorbed compounds. For 131I, the most probable percentage in volumetric activity of hardly adsorbed, easily adsorbed compounds and iodine aerosols was obtained. Based on the data obtained, an assessment of dose loads was carried out taking into account the annual emissions of the reactor installation and weather conditions. A conservative approach to assessing the radiation exposure of 131I emissions is 47 times higher than the assessment taking into account its physicochemical forms.

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Dell’Armi, Edoardo, Marta Maria Rossi, Lucia Taverna, Marco Petrangeli Papini et Marco Zeppilli. « Evaluation of the Bioelectrochemical Approach and Different Electron Donors for Biological Trichloroethylene Reductive Dechlorination ». Toxics 10, n^o 1 (13 janvier 2022) : 37. http://dx.doi.org/10.3390/toxics10010037.

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Trichloroethylene (TCE) and more in general chlorinated aliphatic hydrocarbons (CAHs) can be removed from a contaminated matrix thanks to microorganisms able to perform the reductive dechlorination reaction (RD). Due to the lack of electron donors in the contaminated matrix, CAHs’ reductive dechlorination can be stimulated by fermentable organic substrates, which slowly release molecular hydrogen through their fermentation. In this paper, three different electron donors constituted by lactate, hydrogen, and a biocathode of a bioelectrochemical cell have been studied in TCE dechlorination batch experiments. The batch reactors evaluated in terms of reductive dechlorination rate and utilization efficiency of the electron donor reported that the bio-electrochemical system (BES) showed a lower RD rate with respect of lactate reactor (51 ± 9 µeq/d compared to 98 ± 4 µeq/d), while the direct utilization of molecular hydrogen gave a significantly lower RD rate (19 ± 8 µeq/d), due to hydrogen low solubility in liquid media. The study also gives a comparative evaluation of the different electron donors showing the capability of the bioelectrochemical system to reach comparable efficiencies with a fermentable substrate without the use of other chemicals, 10.7 ± 3.3% for BES with respect of 3.5 ± 0.2% for the lactate-fed batch reactor. This study shows the BES capability of being an alternative at classic remediation approaches.

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Yamashita, Yu, Hiromi Tanabe, Tomofumi Sakuragi, Ryota Takahashi et Michitaka Sasoh. « C-14 Release Behavior and Chemical Species from Irradiated Hull Waste under Geological Disposal Conditions ». MRS Proceedings 1665 (2014) : 187–94. http://dx.doi.org/10.1557/opl.2014.645.

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ABSTRACTC-14 contained in Hull waste is one of the most important radionuclides in the safety assessment of transuranic (TRU) waste disposal. For more realistic safety assessment, it is important to clarify the release mechanism and chemical species of C-14 from Hull waste. In this research, leaching tests were conducted using an irradiated Zry cladding tube from a boiling-water reactor (BWR) to obtain leaching data and to investigate the relationship between Zry metal corrosion and C-14 release behavior. Both organic and inorganic C-14 compounds existed in the the liquid phase, and some C-14 moved to the gaseous phase. The release rate of C-14 obtained from the BWR cladding tube after two-year leaching tests was lower than the release rate from a pressurize water reactor (PWR) cladding tube. It is considered that the BWR cladding tube used in this test did not easily corrode since it used a comparatively new material. The release rate of C-14 was slightly lower as compared with the corrosion rate of unirradiated Zry. This is thought to be the result of improved corrosion resistance conferred by neutron irradiation, which encouraged the dissolution of grain boundary precipitation elements, such as Fe, Cr, and Ni, into the crystal grains. The leaching tests will be continued for 10 years.

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Tae Kim, Seon, Junichi Ryu et Yukitaka Kato. « Reactivity enhancement of chemical materials used in packed bed reactor of chemical heat pump ». Progress in Nuclear Energy 53, n^o 7 (septembre 2011) : 1027–33. http://dx.doi.org/10.1016/j.pnucene.2011.05.013.

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Chetouani, Y. « Fault Detection in a Chemical Reactor by Using the Standardized Innovation ». Process Safety and Environmental Protection 84, n^o 1 (janvier 2006) : 27–32. http://dx.doi.org/10.1205/psep.04285.

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Zhou, Junfei, et Xiaoguang Wang. « Process Design of Isopropyl Alcohol Synthesis Section of 80,000 Tons/Yea ». Academic Journal of Science and Technology 1, n^o 3 (15 juin 2022) : 91–95. http://dx.doi.org/10.54097/ajst.v1i3.521.

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Isopropanol is a chemical product with great application value and can be used as a chemical raw material and organic solvent. This design is a synthesis section of 80,000 tons/year isopropanol, using acetone hydrogenation synthesis process. At a temperature of 180 °C, a pressure of 0.8 MPa, n (hydrogen)/n (acetone) = 1.5 : 1, performed in a column tubular fixed bed reactor. This design uses a 4-stage tubular fixed-bed reactor with an effective length of 8.5 m, a total length of 15.705 m, and a housing diameter of 2.9 m. The total number of 4-segment column tubes is 10,444, and the column tubes are made of seamless stainless steel pipes with a diameter of 38 mm and a thickness of 4 mm. The design improves production safety and reduces energy losses. The design results have certain guiding significance for actual production and application.

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