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Uncertainty and sensitivity analysis of in-vessel phenomena under severe accident mitigation strategy based on ISAA-SAUP program

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Nuclear Science and Techniques 2024年第1期35卷 108-123页

作者： Hao Yang Ji-Shen Li Zhi-Ran Zhang Bin Zhang Jian-Qiang Shan School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The phenomenology involved in severe accidents in nuclear reactors is highly ***,integrated analysis programs used for severe accident analysis heavily rely on custom empirical parameters,which introduce considerable ***,in recent years,the field of severe accidents has shifted its focus toward applying uncertainty analysis methods to quantify uncertainty in safety assessment programs,known as“best estimate plus uncertainty(BEPU).”This approach aids in enhancing our comprehension of these programs and their further development and *** study concentrates on a third-generation pressurized water reactor equipped with advanced active and passive mitigation *** an Integrated Severe Accident Analysis Program(ISAA),numerical modeling and uncertainty analysis were conducted on severe accidents resulting from large break loss of coolant *** uncertainty parameters of the ISAA program were meticulously *** Wilks'formula,the developed uncertainty program code,SAUP,was employed to carry out Latin hypercube sampling,while ISAA was employed to execute batch *** analysis was then conducted on two figures of merit,namely hydrogen generation and the release of fission products within the pressure *** calculations revealed that hydrogen production and the fraction of fission product released exhibited a normal distribution,ranging from 182.784 to 330.664 kg and from 15.6 to 84.3%,*** ratio of hydrogen production to reactor thermal power fell within the range of 0.0578–0.105.A sensitivity analysis was performed for uncertain input parameters,revealing significant correlations between the failure temperature of the cladding oxide layer,maximum melt flow rate,size of the particulate debris,and porosity of the debris with both hydrogen generation and the release of fission products.

关键词： Gen-III PWR Severe accident mitigation Wilks’formula Hydrogen Fission products Uncertainty and sensitivity analysis

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Mxene-Derived Ni/Tio2-X/Ti3c2 Catalyst for Enhanced Photothermal Co2 Methanation: Unraveling the Roles of Photoexcited Carriers

SSRN

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SSRN 2025年

作者： Sun, Fan Xin, Yu Xing, Xueli Lou, Jiahui Wang, Qiliang Hong, Hui International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China School of Aeronautics and Astronautics University of Chinese Academy of Sciences Beijing100049 China Huaneng Clean Energy Research Institute Beijing102209 China Shandong Institute of Advanced Technology Jinan250100 China Department of Architecture and Built Environment University of Nottingham NottinghamNG7 2RD United Kingdom Institute of Engineering Thermophysics China

Photothermal catalysis has emerged as a promising approach for CO2 conversion, which combines photo and thermal energy to drive catalytic reactions efficiently. While light can lower activation barriers and enhance reaction rates, the interplay between light and heat within the catalytic framework remains largely unexplored. In this study, we investigate the critical role of photoexcited carriers in enhancing catalytic performance under solar irradiation, unraveling their contribution to the CO2-to-CH4 conversion process. A multilayer accordion-like Ni/TiO2-x/Ti3C2 catalyst, which exhibits excellent photothermal and photoelectric response characteristics was fabricated for efficient photothermal CO2 methanation. Experimental results demonstrated that introduction of light during thermal catalysis markedly enhanced the CO2 conversion rate, with a 55% increase achieved at 275 ºC. Furthermore, the required temperature for maximum CO2 conversion rate was reduced by 50 ºC compared to the thermal-driven process. Meanwhile, the effects of concentrated ratio and incident wavelength on CO2 conversion were also examined, revealing a synergistic effect between photogenerated carriers and thermal energy. Further characterizations, including steady-state and transient photoluminescence spectroscopy, in-situ XPS, in-situ EPR, in-situ DRITFs, were employed to elucidate the enhancement mechanisms of photogenerated carriers in the catalytic reaction. At the same time, an outdoor experimental prototype was developed to verify the feasibility of photogenerated carrier-thermal synergistically driven CO2 methanation. The findings provide valuable insights into the role of photo-generated carriers in photothermal CO2 methanation, offering new perspectives for the design of efficient photothermal catalysts and advancing solar catalytic CO2 conversion technologies. © 2025, The Authors. All rights reserved.

关键词： Methanation

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Void fraction measurement and calculation model of vertical upward co-current air-water slug flow

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Chinese Journal of Chemical engineering 2022年第11期51卷 178-198页

作者： Teng Wang Miao Gui Jinle Zhao Qincheng Bi Tao Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China

The focus of this paper is on the measurement and calculation model of void fraction for the vertical upward co-current air-water slug flow in a circular tube of 15 mm inner diameter. High-speed photography and optical probes were utilized, with water superficial velocity ranging from 0.089 to 0.65 m·s^(-1)and gas superficial velocity ranging from 0.049 to 0.65 m·s^(-1). A new void fraction model based on the local parameters was proposed, disposing the slug flow as a combination of Taylor bubbles and liquid slugs. In the Taylor bubble region, correction factors of liquid film thickness Cδand nose shape CZ*were proposed to calculate aTB. In the liquid slug region, the radial void fraction distribution profiles were obtained to calculate aLS, by employing the image processing technique based on supervised machine learning. Results showed that the void fraction proportion in Taylor bubbles occupied crucial contribution to the overall void fraction. Multiple types of void fraction predictive correlations were assessed using the present data. The performance of the Schmidt model was optimal, while some models for slug flow performed not outstanding. Additionally, a predictive correlation was correlated between the central local void fraction and the cross-sectional averaged void fraction, as a straightforward form of the void fraction calculation model. The predictive correlation showed a good agreement with the present experimental data, as well as the data of Olerni et al., indicating that the new model was effective and applicable under the slug flow conditions.

关键词： Slug flow Gas-liquid flow Void fraction Measurement Optical probe Model

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Research on control strategies for rapid load decrease events in fluoride salt reactor-supercritical CO2 Brayton cycle systems

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Nuclear engineering and Design 2025年 439卷

作者： Shichang, Yun Xinyu, Li Dalin, Zhang Ping, Song Wenxi, Tian Suizheng, Qiu Guanghui, Su State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Marine Thermal Power Technology Wuhan Second Ship Design and Research Institute Wuhan China

This study delves into the control strategies for the Fluoride-salt-cooled High-temperature Reactor-Supercritical CO2 (SCO2) Brayton cycle power generation system under rapid grid load reduction scenarios. By developing a dynamic simulation model, the system's dynamic response characteristics under rapid load changes were analyzed, and a combined control strategy emphasizing safety, speed, and economic efficiency was proposed. The research first compared the dynamic response characteristics and steady-state performance of different bypass configurations under load rejection conditions. The computational results indicate that all three bypass control systems exhibit excellent load-following capabilities, effectively responding to a 50 % load step change within 10 s. However, significant differences were observed in their steady-state thermodynamic performance: the upper cycle bypass control achieves the highest steady-state efficiency (η = 29.92 %), followed by the turbine bypass control (η = 27.50 %), with the heat source bypass control showing relatively lower efficiency (η = 26.49 %). Although the upper cycle bypass offers superior efficiency, it leads to a substantial increase in the working fluid flow through the compressor (ΔQ = 15 %) during operation, raising the risk of compressor blockage and necessitating additional flow restriction and anti-blocking interlock control systems. Considering system safety, control complexity, and engineering feasibility, the turbine bypass system, with its relative independence and lower operational risk, is deemed more suitable as the primary control strategy for load rejection conditions. Building on this, the study proposes a combined control strategy that leverages the strengths of both bypass control and inventory control. During the initial phase of rapid load reduction, the bypass control system quickly adjusts the turbine bypass valve opening to promptly respond to grid load changes, ensuring system frequency stability

关键词： Frequency stability

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Experimental research on dryout point of flow boiling in narrow annular channels

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Nuclear Science and Techniques 2006年第4期17卷 252-256页

作者： WU Ge-Ping QIU Sui-Zheng SU Guang-Hui JIA Dou-Nan LU Dong-Hua State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Reactor Engineering Research Division Nuclear Power Institute of China Chengdu 610041 China

An experimental research on the dryout point of flow boiling in narrow annular channels under low mass flux with 1.55 mm and 1.05 mm annular gap, respectively, is conducted. Distilled water is used as working fluid and the range of pressure is limited within 2.04.0 MPa and that of mass flux is 26.069.0 kg·m(?2)·s(?1). The relation of critical heat flux (CHF) and critical qualities with mass flux and pressure are revealed. It is found that the critical qualities decrease with the increasing mass flux and increase with the increasing inlet qualities in externally heated annuli. Under the same conditions, critical qualities in the outer tube are always larger than those in the inner tube. The appearance of dryout point in bilaterally heated narrow annuli can be judged according to the ratio of qo/qi. key words: Narrow annular channel; flow boiling; Dryout point

关键词：临界热通量流动沸腾干燥核沸腾狭窄环形通道

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Experimental Investigation of Transient Heat Transferin the Once-Through Boiler Water Separator

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Journal of Thermal Science 1997年第1期6卷 44-50页

作者： Yang Dong Chen Tingkuan Zheng Jianxu(National laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an,710049, China) National Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

The transient heat transfer between working fluid and inner wall of 600 MW supercritical pressureboiler's water separator model during start-up was experimentally explored. The test conditions forwater steam two-phase were as follows: pressure P = 3 ~ 11 MPa, mass now M = 0.2 ~ 0.35 kg/s,and mass quality x = O.2 ~ 0.8; for subcooled water P = 3 ~ 11 MPa, M = 0.2 ~ 0.35 kg/s, andsubcooled degree △θ = 10℃. By using an accurate and tractable inverse heat conduction solution,the correlations of single phase and twouphase transient heat transfer coefficients were obtained. Theexperimental results demonstrated the heat transfer enhanced for subcooled water and water steammixture compared with fully developed turbulent flow in tube. The increasing heat transfer effect maybe attributed to the deformation or destruction f the boundary layer.

关键词： experimental investigation water separator inverse heat conduction transient heat transfer

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Numerical Stability and Accuracy of Contact Angle Schemes in Pseudopotential Lattice Boltzmann Model for Simulating Static Wetting and Dynamic Wetting

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Computer Modeling in engineering & Sciences 2023年第10期137卷 299-318页

作者： Dongmin Wang Gaoshuai Lin Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai200093China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application Suzhou University of Science and TechnologySuzhou215009China

There are five most widely used contact angle schemes in the pseudopotential lattice Boltzmann(LB)model for simulating the wetting phenomenon:The pseudopotential-based scheme(PB scheme),the improved virtualdensity scheme(IVD scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the fluid layer density above the wall(MPB-C scheme),the modified pseudopotential-based scheme with a ghost fluid layer constructed by using the weighted average density of surrounding fluid nodes(MPB-W scheme)and the geometric formulation scheme(GF scheme).But the numerical stability and accuracy of the schemes for wetting simulation remain unclear in the *** this paper,the numerical stability and accuracy of these schemes are clarified for the first time,by applying the five widely used contact angle schemes to simulate a two-dimensional(2D)sessile droplet on wall and capillary imbibition in a 2D channel as the examples of static wetting and dynamic wetting simulations respectively.(i)It is shown that the simulated contact angles by the GF scheme are consistent at different density ratios for the same prescribed contact angle,but the simulated contact angles by the PB scheme,IVD scheme,MPB-C scheme and MPB-W scheme change with density ratios for the same fluid-solid interaction *** PB scheme is found to be the most unstable scheme for simulating static wetting at increased density ratios.(ii)Although the spurious velocity increases with the increased liquid/vapor density ratio for all the contact angle schemes,the magnitude of the spurious velocity in the PB scheme,IVD scheme and GF scheme are smaller than that in the MPB-C scheme and MPB-W scheme.(iii)The fluid density variation near the wall in the PB scheme is the most significant,and the variation can be diminished in the IVD scheme,MPB-C scheme *** variation totally disappeared in the GF scheme.(iv)For the simulation of capillary imbibition,the MPB-C scheme,MPB-Wschem

关键词： Pseudopotential lattice Boltzmann model contact angle scheme static wetting dynamic wetting capillary imbibition

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Synergistic effect of oxygen species and vacancy for enhanced electrochemical CO_(2) conversion to formate on indium oxide

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eScience 2024年第3期4卷 134-141页

作者： Tengfei Ma Zihao Jiao Haoran Qiu Feng Wang Ya Liu Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Indium-based oxides are promising electrocatalysts for producing formate via CO_(2) reduction reaction,in which*OCHO is considered the key ***,we identified that the*COOH pathway could be preferential to produce formate on In_(2)O_(3)of In/In_(2)O_(3) heterojunction due to the synergistic effect of oxygen species and ***,*CO_(2) and *COOH were observed on In_(2)O_(3) and related to formate production by in situ Raman *** theoretical calculations further demonstrated that the energy barrier of the*COOH formation on In_(2)O_(3) was decreased in the presence of oxygen vacancy,similar to or lower than that of the*OCHO formation on the In *** a result,a formate selectivity of over 90%was obtained on prepared In/In_(2)O_(3) heterojunction with 343±7mAcm^(-2) partial current ***,when using a Si-based photovoltaic as an energy supplier,10.11%solar-to-fuel energy efficiency was achieved.

关键词： Electrocatalytic CO_(2)reduction Formate In_(2)O_(3) Oxygen species Oxygen vacancy

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Single-Reheating or Double-Reheating, Which is Better for S-CO_2 Coal Fired power Generation System?

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Journal of Thermal Science 2019年第3期28卷 431-441页

作者： SUN Enhui XU Jinliang HU Han YAN Chenshuai LIU Chao Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education North China Electric Power University

The objective of this paper is to provide the optimal choice of single-reheating or double-reheating when considering residual flue gas heat in S-CO_2 coal fired power system. The cascade utilization of flue gas energy includes three temperature levels, with high and low temperature ranges of flue gas heat extracted by S-CO_2 cycle and air preheater, respectively. Two methods are proposed to absorb residual flue gas heat Qre in middle temperature range. Both methods shall decrease CO_2 temperature entering the boiler T4 and increase secondary air temperature Tsec air, whose maximum value is deduced based on energy conservation in air preheater. The system is analyzed incorporating thermodynamics, boiler pressure drop and energy distribution. It is shown that at a given main vapor temperature T5, the main vapor pressure P5 can be adjusted to a value so that Qre is completely eliminated, which is called the main vapor pressure adjustment method. For this method, single-reheating is only available for higher main vapor temperatures. The power generation efficiency for single-reheating is obviously higher than double-reheating. If residual flue gas heat does exist, a flue gas heater FGC is integrated with S-CO_2 cycle, which is called the FGC method. Both single-reheating and double-reheating share similar power generation efficiency, but single-reheating creates less residual flue gas heat. We conclude that single-reheating is preferable, and the pressure adjustment method achieves obviously higher power generation efficiency than the FGC method.

关键词： S-CO2 coal fired power system thermodynamics heat transfer reheating residual flue gas heat

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An investigation on heat transfer to supercritical water in inclined upward smooth tubes

An investigation on heat transfer to supercritical water in ...

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作者： Yin, Fei Chen, Ting-Kuan Li, Hui-Xiong National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Within the range of pressures from 23 to 30 MPa, mass velocities from 600 to 1200 kg/(m 2 s), and heat fluxes from 200 to 600 kW/m 2 , experiments have been performed for an investigation on heat transfer to supercritical water in inclined upward smooth tubes with an inner diameter of 26 mm and an inclined angle of 20° from the horizon. The results indicated that heat transfer characteristics of supercritical water are not uniform along the circumference of the inclined tube. An increase in the mass velocity of the working fluid can decrease and even eliminate the non-uniformity. Properties of supercritical fluid acutely vary with the temperature near the pseudocritical point. While the ratio of the mass velocity to the heat flux exceeded 2.16 kg/(kWs), heat transfer enhancement occurred near the pseudocritical point;conversely, heat transfer deterioration occurred while the ratio of the mass velocity to the heat flux was lower than 2.16 kg/(kWs). As the pressure increased far from the critical pressure, the amount of deterioration decreased. Correlations of heat transfer coefficients of the forced-convection heat transfer on the top and bottom of the tube have been provided, and can be used to predict heat transfer coefficient of spirally water wall in supercritical boilers.

关键词： Pipe flow

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