Search Results (152)

The global transition to clean energy necessitates integrated solutions that ensure both environmental sustainability and energy security. This paper proposes a scenario-based modeling framework for urban hybrid energy systems combining small modular reactors (SMRs), photovoltaic (PV) generation, and battery storage within a smart grid architecture. SMRs offer compact, low-carbon, and reliable baseload power suitable for urban environments, while PV and storage enhance system flexibility and renewable integration. Six energy mix scenarios are evaluated using a lifecycle-based cost model that incorporates both capital expenditures (CAPEX) and cumulative carbon costs over a 25-year horizon. The modeling results demonstrate that hybrid SMR–renewable systems—particularly those with high nuclear shares—can reduce lifecycle CO₂ emissions by over 90%, while maintaining long-term economic viability under carbon pricing assumptions. Scenario C, which combines 50% SMR, 40% PV, and 10% battery, emerges as a balanced configuration offering deep decarbonization with moderate investment levels. The proposed framework highlights key trade-offs between emissions and capital cost and seeking resilient and scalable pathways to support the global clean energy transition and net-zero commitments. Full article

The ongoing efforts to convert High-Performance Research Reactors (HPRRs) using Highly Enriched Uranium (HEU) to Low-Enriched Uranium (LEU) fuel require reliable thermal–hydraulic assessments of modified core designs. The involute-shaped fuel plates used in several major HPRRs present unique modeling challenges due to their compact core geometries and high heat flux conditions. This study evaluates the capability of three commercial CFD tools, STAR-CCM+, COMSOL, and ANSYS CFX, to predict cladding-to-coolant heat transfer using Reynolds-Averaged Navier–Stokes (RANS) methods within the thermal–hydraulic regimes of involute-shaped plate reactors. Broad sensitivity analysis was conducted across a range of reactor-relevant parameters using two turbulence models ($k-ϵ$ and $k-\omega$ SST) and different near-wall treatment strategies. The results were benchmarked against the Sieder–Tate correlation and experimental data from historic studies. The codes produced consistent results, showing good agreement with the empirical correlation of Sieder–Tate and the experimental measurements. The findings support the use of these commercial CFD codes as effective tools for assessing the thermal–hydraulic performance of involute-shaped plate HPRRs and guide future LEU core development. Full article

Compact toroid (CT) injection, with its characteristics of high plasma density and extremely high injection velocity, is considered a highly promising method for core fueling in fusion reactors. Previous studies have lacked investigation into the transport process of CT within drift tubes. To investigate the dynamic processes of CT in drift tubes, this study developed a compressible magnetohydrodynamics (MHD) solver and a magnetic diffusion solver based on the OpenFOAM platform. They were integrated into a multi-region coupling framework to create a multi-region coupled MHD solver, mhdMRF, for simulating the dynamic behavior of CT in drift tubes and its interaction with finite-resistivity walls. The solver demonstrated excellent performance in simulations of the Orszag–Tang MHD vortex problem, the Brio–Wu shock tube problem, analytical verification of magnetic diffusion, and validation of internal coupling boundary conditions. Additionally, this work innovatively explored the effects of the geometric structure at the end of the inner electrode and finite-resistivity walls on the transport processes of CT. The results indicate that optimizing the geometric structure at the end of the inner electrode can significantly enhance the confinement performance and stability of CT transport. The resistivity of the wall profoundly influences the magnetic field structure and density distribution of CT. Full article

Lead–bismuth eutectic alloy (LBE, Pb_44.5Bi_55.5) has emerged as a promising candidate for use in advanced nuclear and solar energy systems due to its favorable thermophysical characteristics and radiation shielding capabilities. The aim of this research is to assess the applicability of the induction melting technique to synthesize LBE. This paper presents a comprehensive evaluation of the structural, thermophysical, and radiation shielding properties of the obtained LBE sample. Various techniques were employed to investigate the solid-to-liquid eutectic transformation, phase composition, morphology, and homogeneity of the obtained material. Experimental and theoretical determinations on density, void, molar volume, thermal conductivity, heat capacity, thermal diffusivity, and electrical conductivity were performed. Radiation shielding performance over photon energies ranging from 0.015 to 15 MeV was simulated using the Phy-X/PSD program. The results revealed the eutectic structure comprising Pb₇Bi₃ and Bi phases with near-ideal stoichiometry and a melting point of 127.6 °C. The alloy demonstrated a small void that corresponds to a high degree of sample compaction, high specific heat capacity, moderate thermal conductivity, low thermal diffusivity, and effective radiation shielding. These findings confirm that LBE obtained by the induction melting technique possesses the necessary structural stability and functional properties for integration into nuclear reactor and solar thermal technologies. Full article

Microbially induced calcite precipitation (MICP) has attracted attention as an environmentally friendly soil stabilization method, with Sporosarcina pasteurii being a key ureolytic bacterium in this process. However, its behavior in oxygen-limited environments remains poorly understood, limiting the predictability of MICP outcomes in natural soils. This study investigated the population dynamics of Sporosarcina in compacted soil reactors operated under aerobic and anaerobic conditions, including saturated environments. Quantitative PCR and 16S rRNA gene sequencing revealed that Sporosarcina thrived and became dominant under aerobic, unsaturated conditions, but failed to maintain a high abundance under anaerobic or saturated conditions. These findings indicate that gas-phase oxygen—not merely its presence in the overlying atmosphere—is essential for effective Sporosarcina-driven MICP. The results highlight a critical environmental constraint that limits the application of biostimulation strategies relying on indigenous Sporosarcina in oxygen-poor soils. This study provides the first in situ evidence linking oxygen availability and microbial dominance in MICP systems, with implications for optimizing microbial soil stabilization in real-world conditions. Full article

The continuous change in the entrance cross-section of a parallel-plate flow channel generally affects the mass and heat transfer on the walls of the channel. In this paper, an electrochemical parallel-plate flow channel equipped with a selenoid pulse generator has been developed to enhance the convective mass transfer on the walls of a mass transfer flow system such as an electrodeposition cell, absorption column, flow reactor, etc. A number of experimental studies have been conducted to determine the distribution of the mass transfer coefficients on the bottom wall of a parallel-plate channel for the flow conditions with/without a pulse in the research. Here, the distribution of the convective mass transfer coefficients has been determined by the electrochemical limiting diffusion current technique (ELDCT) using nickel local cathodes arranged on the bottom surface of the flow channel. The experimental results show the effects of the parameters used, which are the flow Reynolds number, opened/closed (OP/CL) ratio, and pulse number, on the distribution of mass transfer coefficients. The results have revealed that the pulse generator altered the flow structure and increased the turbulent intensity at Re < 2860 flow conditions. Within the range of Reynolds number 950 < Re < 2860, the mass transfer correlation was given as $Sh=67.02{Re}^{0.897}{\left({\displaystyle \frac{Op}{Cl}}\right)}^{-0.059}S{c}^{1/3}$. According to the research findings, the highest k_M values were obtained at Re = 2860 with an (OP/CL) ratio of 1/2. If a parallel-plate flow reactor with a pulse generator is designed using these flow conditions, it will yield a reactor that is both more efficient and more compact than a reactor without a pulse generator. Full article

Liquid fuels obtained from CO₂ and green hydrogen (i.e., e-fuels) are powerful tools for decarbonizing economy. Improvements provided by Process Intensification in the existing conventional reactors aim to decrease energy consumption, increase yield, and ensure more compact and safe processes. This review describes the advances in the production of methanol, dimethyl ether, and hydrocarbons by Fischer–Tropsch using different Process Intensification tools, mainly membrane reactors, sorption-enhanced reactors, and structured reactors. Due to the environmental interest, this review article focused on discussing methanol and dimethyl ether synthesis from CO₂ + H₂, which also represented the most innovative approach. The use of syngas (CO + H₂) is generally preferred for the Fischer–Tropsch process; hence, studies examining this process were included in the present review. Both mathematical models and experimental results are discussed. Achievements in the improvement of catalytic reactor performance are described. Experimental results in membrane reactors show increased performance in e-fuels production compared to the conventional packed bed reactor. The combination of sorption and reaction also increases the single-pass conversion and yield, although this improvement is limited by the saturation capacity of the sorbent in most cases. Full article

The power conversion system of a small micro-reactor has strict requirements on the compactness of the rotating mechanical support. Although the active magnetic bearing is an ideal choice, the thermally induced vibration caused by it may destroy the stability of the system. As such, this study proposes a multi-physics coupling simulation framework, which integrates electromagnetic, thermal, and mechanical multi-physics coupling mechanisms and quantifies the stability of the system under thermal-induced vibration in the frequency domain. Firstly, the equivalent magnetic circuit and electromagnetic finite element modeling and calculation of the compressor rotor are carried out. In the case of the maximum AC current of 10 A, the equivalent stiffness of the magnetic pole is 4.21 × 10⁸ N/m and 2.1 × 10⁸ N/m, and the eddy current loss of the rotor is 4.17496 W. Based on the eddy current loss, a magneto-thermal coupling model is established to reveal the temperature gradient distribution and the thermal sensitivity coefficient of the journal is 0.006. Subsequently, the thermal stress and equivalent stiffness are coupled to the rotor dynamics equation, and the maximum amplitude of the rotor is obtained at a value of 0.001 mm. Finally, the critical stability threshold of the system is determined by a Nyquist diagram, and the results show that the system is stable as a whole. In this paper, the quantitative analysis of the cross-scale coupling mechanism of electromagnetic, thermal, and mechanical multi-physical fields is realized, which provides a systematic analysis method for the thermally induced vibration of magnetically suspended rotors and has important engineering significance for high power density rotating mechanical systems in small micro-reactors. Full article

This study explored the effectiveness of plasma-activated water (PAW), generated by a newly developed compact generator, for decontaminating foodborne bacteria in oyster meats. The generator effectively produced PAW with antibacterial activity when the water passed through the plasma reactor in a single cycle. The temperature of the PAW produced by the developed device did not exceed 40 °C, enabling its direct application to biological tissues immediately after production and discharge from the plasma reactor. The effects of flow rates and post-discharge times on key reactive species—including hydrogen peroxide, nitrite, and nitrate—were analyzed, along with pH and temperature. Freshly produced PAW can completely inhibit both E. coli and S. aureus in vitro, with a 5-log reduction within 5 min of treatment. Application to oyster meats led to an 86.6% and 87.9% inactivation of V. cholerae and V. parahaemolyticus, respectively. These research findings indicate that PAW generated using the developed compact flow-through generator holds promise as a food safety solution for households. The fact that complete foodborne pathogen elimination was not achieved emphasizes the need for further optimization. Full article

A thermodynamic analysis of a compact hydrogen generation system for mobile fuel cell applications is presented. The system consists of a miniature autothermal steam reformer (ATR) and a water–gas shift (WGS) reactor, designed to produce hydrogen from hydrocarbon fuels for a 1 kW proton exchange membrane (PEM) fuel cell. Methane is used as the model fuel, and the study focuses on optimizing feed compositions and operational conditions to maximize hydrogen yield and purity. Feed compositions and operational conditions are optimized. In total, 0.7 Nm³ h⁻¹ H₂ is generated from 0.25 Nm³ h⁻¹ CH₄ with properly adjusted steam and air feeding. Issues with product purity and start-up procedures have been identified and discussed, along with feasible solutions. The system is suitable for remote and mobile applications. Full article

Discharging oil-contaminated wastewater into the environment without adequate treatment can have a negative impact on water resources, public water and wastewater treatment systems, and even human health. In this sense, it is essential to develop compact, easily automated, low-cost, and highly efficient unitary treatment processes in order to comply with legal requirements regarding effluent emission standards for water bodies. Therefore, the present study consisted of the development of two treatment processes aimed at the separation of oil emulsions stabilised by anionic surfactants: a sorption column using polyurethane/graphene foam composites as sorbent material and a continuous flow AC electroflotation reactor. Initially, composites with 0.5% and 1% w/w graphene (based on polyol mass) were developed using a dispersing agent (1-methyl-2-pyrrolidone). The foams were characterised in terms of morphology and mechanical and sorption properties. In the fixed bed column, the foams retained up to 77.15% of the emulsified oil and 52.36% of the anionic surfactants. In the continuous flow electroflotation reactor, emulsified oil removal efficiencies above 90% were achieved at all electrical currents tested, and up to 88.6% of anionic surfactants were removed at an electrical current of 150 A. Given the advantages and disadvantages of the two oily effluent treatment processes, their combined use in the same system proved promising. Full article

This article discusses the problem of numerically solving the Navier–Stokes equations, the heat conduction equation, and the transport equation in the orthogonal coordinates of a free curve. Since the numerical solution domain is complex, the curvilinear mesh method was used. To do so, first, a boundary value problem was posed for the elliptic equation to automate the creation of orthogonal curved meshes. By numerically solving this problem, the program code for the curvilinear mesh generator was created. The motion of a liquid or gas through a porous medium was described by numerically solving the Navier–Stokes equations in freely curvilinear orthogonal coordinates. The transformation of the Navier–Stokes equation system, written in the stream function, vorticity variables, and cylindrical coordinates, into arbitrary curvilinear coordinates, was considered in detail by introducing metric coefficients. To solve these equations, the coefficients of which vary rapidly, a three-layer differential scheme was developed. The approximation, stability, and compactness of the differential scheme were previously studied. The considered problem was considered to be the mathematical model of a car catalytic converter, and computational experiments were conducted. Calculations were performed with the developed program code in different geometries of the computational domain and different values of grid size. The Reynolds number was changed from 100 to 10,000, and its effect on the size of the backflow in front of the porous medium was discussed. The software code, which is based on the differential equation of the Navier–Stokes equations written in the orthogonal coordinates of a curved line, and its calculation algorithm can be used for the mathematical and computer modeling of automobile catalytic converters and chemical reactors. Full article

In this paper, a numerical study of two-phase flow instability in parallel rectangular channels is presented. Using the homogeneous flow model, marginal stability boundaries (MSBs) are derived in the parameter space defined by the phase change number (N_pch) and subcooling number (N_sub) under various operating conditions. Comparison with experimental data shows that the model predicts stability trends with a deviation of ±12.5%. The study reveals that, under constant mass flux conditions, stability decreases as the equivalent diameter (De) of the channels increases. Additionally, the exit area ratio of the two parallel tubes has minimal effect on the MSB, indicating that exit geometry does not significantly influence system stability. However, an increase in the inlet area ratio, from 0.1 to 1, reduces system stability, suggesting that larger inlet areas relative to tube cross-sectional areas may lead to greater flow disturbances, thereby decreasing stability. Moreover, increasing the length of the tubes enhances system stability, which may be attributed to the extended development length allowing for dissipation of flow disturbances. The study further demonstrates that higher flow rates, between 0.15 kg/s and 0.25 kg/s, enhance stability, while increasing the outlet flow resistance coefficient reduces stability. Conversely, increasing the inlet flow resistance coefficient improves stability. At system pressures of 3 MPa, 6 MPa, and 9 MPa, it is observed that higher pressures shift the boundary of complete vaporization (X_e = 1) to the left on the N_pch and N_sub graph, reducing the region susceptible to instability. The study also employs Fast Fourier Transform (FFT) analysis to identify peak frequencies across different parameter ranges. By examining the stability map and frequency spectra, the study provides deeper insights into two-phase flow instabilities in parallel channels. Full article

Neutron beams, being electrically neutral and highly penetrating, offer unique advantages for the irradiation of biological species such as plants, seeds, and microorganisms. We comprehensively investigated the potential of neutron irradiation for inducing genetic mutations by using simulations of spallation, reactor, and compact neutron sources based on J-PARC BL10, the JRR-3 TNRF, and KUANS. We analyzed neutron flux, energy deposition rates, and Linear Energy Transfer (LET) distributions. The KUANS simulation demonstrated the highest dose rate of 17 Gy/h, significantly surpassing that obtained at BL10, due to the large solid angle achieved with optimal sample placement. The findings highlight KUANS’s suitability for efficiently inducing specific genetic mutations and neutron breeding, particularly for inducing targeted mutations in biological samples, also on account of its LET range of 20–70 keV/μm. Our results emphasize the importance of choosing neutron sources based on LET requirements to maximize mutation induction efficiency. This research study shows the potential of compact neutron sources such as KUANS for effective biological irradiation and neutron breeding, offering a viable alternative to larger facilities. The neutron filters used at BL10 and the TNRF effectively exclude low-energy neutrons while keeping the high-LET component. The neutron capture reaction, ¹⁴N(n,p)¹⁴C, was found to be the main dose contributor under thermal neutron-dominated conditions. Full article

Small Modular Reactors (SMRs) are gaining significant attention as nuclear power sources due to their advantages, such as compact design, enhanced safety features compared to large nuclear plants, and scalability for varying power output needs. To successfully consider this emerging technology, understanding SMR designs and their readiness levels is essential for informed decision making and effective planning. This technical review provides insights into the potential, development, and application of SMR technology. Various SMR designs were investigated to identify those in deployment, commercial operation, or nearing deployment stages. Key technical parameters of advanced-stage SMRs, with some local insights, were analyzed to establish a comprehensive set of criteria for future technical and economic assessments in the context of local applications. Additionally, this study outlines potential phases for SMR project implementation in the Philippines, referencing the IAEA Milestone Approach for nuclear power infrastructure development. Relevant policies, issues, and activities are also discussed, highlighting the status of the country’s nuclear power infrastructure, as well as its legislative and regulatory framework for supporting nuclear energy. While certain SMR technologies show technical readiness, it is important to consider that many are still under development, requiring a careful evaluation of factors such as the 19 Infrastructure Issues to ensure a successful SMR deployment in the Philippines. Full article