Non-equilibrium statistical mechanics models can be used to construct reduced order models from the time-dynamics data such as numerical or physical fluid mechanics experiments. One of the well-established statistical projection methods is the Kramers-Moyal expansion (KM) method. The first two terms of the KM expansion result can be used to construct a non-linear Langevin equation, which can serve as the statistically-trained reduced-order model. This non-linear Langevin equation can be approximated to the Fokker-Planck equation, which is similar to Advection-Diffusion equation, thereby preserving some characteristics of fluctuations associated with fluid mechanics. The KM method captures continuous-time dynamics, however, any data obtained through measurement is discrete. In order to accurately capture the time dynamics of the discrete data, the method for calculating the KM coefficients must be carefully chosen and implemented. To better represent the solution from discrete data, the drift and diffusion coefficients can be calculated at multiple time scales and then extrapolated to a time scale of zero, assuming a linear correlation. One challenge in using this method is that the calculated KM coefficients are only accurate for time scales greater than the Taylor microscale. This means that the extrapolation must use only the KM coefficients calculated for time scales greater than the Taylor microscale, however, this value is not always provided from the data nor simple to calculate. This work presents a method of approximating the Taylor microscale from the data through the relationship between the Markov property and the Taylor microscale and implementing this method to find the extrapolated KM coefficients. The KM method implementing the Taylor microscale estimation was applied to existing DNS turbulent channel flow data to model a time series. This generated time series was then compared to the DNS data using a statistical analysis including probability density function, autocorrelation, and power spectral density.
{"title":"A Statistical Approach to Quantify Taylor Microscale for Turbulent Flow Surrogate Model","authors":"M. Ross, J. Matulis, H. Bindra","doi":"10.1115/icone29-91452","DOIUrl":"https://doi.org/10.1115/icone29-91452","url":null,"abstract":"\u0000 Non-equilibrium statistical mechanics models can be used to construct reduced order models from the time-dynamics data such as numerical or physical fluid mechanics experiments. One of the well-established statistical projection methods is the Kramers-Moyal expansion (KM) method. The first two terms of the KM expansion result can be used to construct a non-linear Langevin equation, which can serve as the statistically-trained reduced-order model. This non-linear Langevin equation can be approximated to the Fokker-Planck equation, which is similar to Advection-Diffusion equation, thereby preserving some characteristics of fluctuations associated with fluid mechanics. The KM method captures continuous-time dynamics, however, any data obtained through measurement is discrete. In order to accurately capture the time dynamics of the discrete data, the method for calculating the KM coefficients must be carefully chosen and implemented. To better represent the solution from discrete data, the drift and diffusion coefficients can be calculated at multiple time scales and then extrapolated to a time scale of zero, assuming a linear correlation. One challenge in using this method is that the calculated KM coefficients are only accurate for time scales greater than the Taylor microscale. This means that the extrapolation must use only the KM coefficients calculated for time scales greater than the Taylor microscale, however, this value is not always provided from the data nor simple to calculate. This work presents a method of approximating the Taylor microscale from the data through the relationship between the Markov property and the Taylor microscale and implementing this method to find the extrapolated KM coefficients. The KM method implementing the Taylor microscale estimation was applied to existing DNS turbulent channel flow data to model a time series. This generated time series was then compared to the DNS data using a statistical analysis including probability density function, autocorrelation, and power spectral density.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133960100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crystal Plasticity Finite Element Model (CPFEM) is the powerful tool to bridge the meso-scale and marco-scale and study the mechanical properties of metals systematically. In this paper, crystal plasticity theory coupling with irradiation effect is proposed. Note that it is based on density of dislocation and irradiation-induced full-absorption and partial-absorption dislocation loop and their interaction between each other. Then the model is numerically implemented in UMAT on ABAQUS platform. Secondly, A508-3 steel, the typical BCC crystal material, has specific brittle-ductile transition. The cleavage failure probability theory model (CFPTM) which assumes that the failure probability of specimen depends on its Cauthy stress filed is presented. The tensile tests for A508-3 steel are simulated by CPFEM in a combination of CFPTM to obtain the brittle-ductile transition temperature (BDTT). Results show that failure probability for specimen increases with increasing strain and decreasing temperature. In terms of BDTT, the numerical and experimental result are in close agreement whether there is under irradiation condition or not. Furthermore, the obvious irradiation embrittlement phenomenon is observed.
{"title":"Modelling the Brittle-Ductile Transition Temperature of Irradiated A508-3 Steel With CPFEM","authors":"P. Lin, J. Nie, Meidan Liu","doi":"10.1115/icone29-90986","DOIUrl":"https://doi.org/10.1115/icone29-90986","url":null,"abstract":"\u0000 Crystal Plasticity Finite Element Model (CPFEM) is the powerful tool to bridge the meso-scale and marco-scale and study the mechanical properties of metals systematically. In this paper, crystal plasticity theory coupling with irradiation effect is proposed. Note that it is based on density of dislocation and irradiation-induced full-absorption and partial-absorption dislocation loop and their interaction between each other. Then the model is numerically implemented in UMAT on ABAQUS platform. Secondly, A508-3 steel, the typical BCC crystal material, has specific brittle-ductile transition. The cleavage failure probability theory model (CFPTM) which assumes that the failure probability of specimen depends on its Cauthy stress filed is presented. The tensile tests for A508-3 steel are simulated by CPFEM in a combination of CFPTM to obtain the brittle-ductile transition temperature (BDTT). Results show that failure probability for specimen increases with increasing strain and decreasing temperature. In terms of BDTT, the numerical and experimental result are in close agreement whether there is under irradiation condition or not. Furthermore, the obvious irradiation embrittlement phenomenon is observed.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131570658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sasuke Kadoma, Kota Fujiwara, Kohei Yoshida, A. Kaneko
Pool scrubbing is one of the severe accidents (SA) countermeasures in nuclear power plants. In pool scrubbing, gas containing Fission Products (FPs) generated in the reactor during SA is passed through the pool water in the suppression chamber to move FPs into the pool water and prevent them from being released into the surrounding environment. Since FPs have a significant negative effect on the surrounding environment, it is important to predict and evaluate how much FPs will be removed by pool scrubbing. Currently, SA analysis codes such as MELCOR are used to evaluate FPs removal in pool scrubbing. However, the removal mechanism is not fully understood because the phenomena occurring in pool scrubbing are very complicated. It has been shown that parameters such as pool water depth and FPs size affect FPs removal rate (DF: Decontamination Factor), but there have been few experimental evaluations of the interrelationship between two-phase flow behavior and FPs removal. Therefore, we focus on the gas-liquid interfacial area, which is one of the most important parameters in FPs transport between gas and liquid and in two-phase flow behavior, and the aim of our study is development of gas-liquid interfacial area concentration using a Wire Mesh Sensor (WMS) and clarification of relationship with DF. First, the void fraction of two-phase flow was measured using WMS, and the bubble interfaces were reconstructed to estimate the interfacial area concentration. The interfacial area concentration diffused to the surrounding as the relative distance from the nozzle increased as well as the void fraction. The overall interfacial area concentration increased with increasing the flow rate and the relative distance from the nozzle. Moreover, the results of DF measurements were compared with those of flow parameters. It was found that there was an inverse trend between the two parameters, indicating that it is necessary to consider not only the above flow parameters but also FPs transport between gas and liquid and decontamination by unsteady behavior of bubbles such as bubble breakup.
{"title":"Measurement of Gas-Liquid Interfacial Area Concentration and Its Effect on Aerosol Behavior in Pool Scrubbing","authors":"Sasuke Kadoma, Kota Fujiwara, Kohei Yoshida, A. Kaneko","doi":"10.1115/icone29-90448","DOIUrl":"https://doi.org/10.1115/icone29-90448","url":null,"abstract":"\u0000 Pool scrubbing is one of the severe accidents (SA) countermeasures in nuclear power plants. In pool scrubbing, gas containing Fission Products (FPs) generated in the reactor during SA is passed through the pool water in the suppression chamber to move FPs into the pool water and prevent them from being released into the surrounding environment. Since FPs have a significant negative effect on the surrounding environment, it is important to predict and evaluate how much FPs will be removed by pool scrubbing.\u0000 Currently, SA analysis codes such as MELCOR are used to evaluate FPs removal in pool scrubbing. However, the removal mechanism is not fully understood because the phenomena occurring in pool scrubbing are very complicated. It has been shown that parameters such as pool water depth and FPs size affect FPs removal rate (DF: Decontamination Factor), but there have been few experimental evaluations of the interrelationship between two-phase flow behavior and FPs removal.\u0000 Therefore, we focus on the gas-liquid interfacial area, which is one of the most important parameters in FPs transport between gas and liquid and in two-phase flow behavior, and the aim of our study is development of gas-liquid interfacial area concentration using a Wire Mesh Sensor (WMS) and clarification of relationship with DF. First, the void fraction of two-phase flow was measured using WMS, and the bubble interfaces were reconstructed to estimate the interfacial area concentration. The interfacial area concentration diffused to the surrounding as the relative distance from the nozzle increased as well as the void fraction. The overall interfacial area concentration increased with increasing the flow rate and the relative distance from the nozzle. Moreover, the results of DF measurements were compared with those of flow parameters. It was found that there was an inverse trend between the two parameters, indicating that it is necessary to consider not only the above flow parameters but also FPs transport between gas and liquid and decontamination by unsteady behavior of bubbles such as bubble breakup.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131710150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As one of the new advanced fuels proposed to improve the safety of nuclear reactors, fully ceramic microencapsulated (FCM) fuel consisting of TRistructural ISOtropic (TRISO) particles dispersed in a silicon carbide matrix has received a lot of attention at home and abroad because of its distinguished advantages such as high corrosion resistance and excellent fuel irradiation stability. For analyzing FCM fuel performance and optimizing FCM fuel design, it is necessary to assess complicated behaviors of TRISO particle fuel under irradiation. To investigate the multidimensional behavior of TRISO particle fuel with UN or UO2 kernel, a three-dimensional thermomechanical coupling model was developed based on multiphysics coupling finite element software COMSOL. Additionally, thermomechanical performance analysis of TRISO particle fuel with irradiation-dependent material properties and behavior models was conducted, and important phenomena were implemented such as fission gas release, production and diffusion of CO gas, as well as the evolution of particle radius due to the irradiation deformation, fission product swelling strain and irradiation creep. Moreover, on the basis of the preliminary thermomechanical analysis, the performance of TRISO particle fuel with UO2 and UN kernel were compared. This paper is intended as an exploratory investigation of TRISO fuel behavior, which will provide vital reference for further performance analysis and design optimization of subsequent FCM fuel.
{"title":"Simulation on the Multidimensional Behavior of TRISO Particle Fuel With UN/ UO2 Kernel","authors":"Changwei Wu, Junmei Wu, Ya-Kai He, Yingwei Wu","doi":"10.1115/icone29-90307","DOIUrl":"https://doi.org/10.1115/icone29-90307","url":null,"abstract":"\u0000 As one of the new advanced fuels proposed to improve the safety of nuclear reactors, fully ceramic microencapsulated (FCM) fuel consisting of TRistructural ISOtropic (TRISO) particles dispersed in a silicon carbide matrix has received a lot of attention at home and abroad because of its distinguished advantages such as high corrosion resistance and excellent fuel irradiation stability. For analyzing FCM fuel performance and optimizing FCM fuel design, it is necessary to assess complicated behaviors of TRISO particle fuel under irradiation. To investigate the multidimensional behavior of TRISO particle fuel with UN or UO2 kernel, a three-dimensional thermomechanical coupling model was developed based on multiphysics coupling finite element software COMSOL. Additionally, thermomechanical performance analysis of TRISO particle fuel with irradiation-dependent material properties and behavior models was conducted, and important phenomena were implemented such as fission gas release, production and diffusion of CO gas, as well as the evolution of particle radius due to the irradiation deformation, fission product swelling strain and irradiation creep. Moreover, on the basis of the preliminary thermomechanical analysis, the performance of TRISO particle fuel with UO2 and UN kernel were compared. This paper is intended as an exploratory investigation of TRISO fuel behavior, which will provide vital reference for further performance analysis and design optimization of subsequent FCM fuel.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132946741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianyu Tang, T. Zhou, Peng Xu, Huaichang Lu, Tianyu Gao
Mobile heat pipe reactor has a wide application prospect in many fields. In the event of a nuclear leak, the reactor will have adverse effects on the environment. So, mastering the circumstances of nuclide migration has great value to enhance the capacity and efficiency of nuclear accident emergency response. This research uses a programming method to describe the diffusion and deposition of nuclides in the atmosphere after a leakage accident. Subsequently, further study the deposition of nuclide diffusion in the unsaturated zone. Through these studies, we can make predictions and evaluate the consequences of accidents. The result shows that there is a certain relationship between the concentration of nuclide diffusion in the atmosphere and the distance downwind direction and there is a maximum value. The maximum diffusion distance of a nuclide is positively correlated with the amount of leakage nuclide when it diffuses over a short distance and near the ground. The deposition conditions of nuclides are different under different conditions. Dry deposition flux can be neglected in short-term calculations. Wet deposition flux is the main source of the diffusion of nuclides into the unsaturated zone. Soil has a good retention effect on radionuclide diffusion and the unsaturated zone can slow the migration velocity. However, rainfall will accelerate the migration of nuclides.
{"title":"Study on Radionuclide Migration Under Accident Conditions of Mobile Heat Pipe Small Module Reactor","authors":"Jianyu Tang, T. Zhou, Peng Xu, Huaichang Lu, Tianyu Gao","doi":"10.1115/icone29-89015","DOIUrl":"https://doi.org/10.1115/icone29-89015","url":null,"abstract":"Mobile heat pipe reactor has a wide application prospect in many fields. In the event of a nuclear leak, the reactor will have adverse effects on the environment. So, mastering the circumstances of nuclide migration has great value to enhance the capacity and efficiency of nuclear accident emergency response. This research uses a programming method to describe the diffusion and deposition of nuclides in the atmosphere after a leakage accident. Subsequently, further study the deposition of nuclide diffusion in the unsaturated zone. Through these studies, we can make predictions and evaluate the consequences of accidents. The result shows that there is a certain relationship between the concentration of nuclide diffusion in the atmosphere and the distance downwind direction and there is a maximum value. The maximum diffusion distance of a nuclide is positively correlated with the amount of leakage nuclide when it diffuses over a short distance and near the ground. The deposition conditions of nuclides are different under different conditions. Dry deposition flux can be neglected in short-term calculations. Wet deposition flux is the main source of the diffusion of nuclides into the unsaturated zone. Soil has a good retention effect on radionuclide diffusion and the unsaturated zone can slow the migration velocity. However, rainfall will accelerate the migration of nuclides.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128835186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shang Mao, T. Zhou, Wenbin Liu, Chunhui Xue, Yiyi Jiang
90° bends are widely used in industrial tubes such as supercritical CO2 reactors, which inevitably generate some particle matters during the operation of supercritical CO2 reactors. The particle deposition characteristics in the 90° bend is simulated based on the DPM (Discrete phase model) model. The results show that when the fluid enters the bend, the pressure of the outer wall increases and the pressure of the inner wall decreases due to the centrifugal effect, forming a secondary flow between the inner and outer walls, and forming an obvious low velocity region in the inner wall. As the particle size increases, the deposition rate gradually increases, reaching a maximum at a particle size of 60 μm. Increasing the inlet flow rate first results in a sharp increase in the deposition rate and then a slow increase. The deposition rate is significantly increases with the increasing of wall heat flux due to the thermophoresis effect. The conclusions of this paper can provide reference for the deposition motion characteristics of fine particles in supercritical CO2.
{"title":"Particle Deposition Characteristics of Supercritical CO2 in a 90° Bend","authors":"Shang Mao, T. Zhou, Wenbin Liu, Chunhui Xue, Yiyi Jiang","doi":"10.1115/icone29-88890","DOIUrl":"https://doi.org/10.1115/icone29-88890","url":null,"abstract":"\u0000 90° bends are widely used in industrial tubes such as supercritical CO2 reactors, which inevitably generate some particle matters during the operation of supercritical CO2 reactors. The particle deposition characteristics in the 90° bend is simulated based on the DPM (Discrete phase model) model. The results show that when the fluid enters the bend, the pressure of the outer wall increases and the pressure of the inner wall decreases due to the centrifugal effect, forming a secondary flow between the inner and outer walls, and forming an obvious low velocity region in the inner wall. As the particle size increases, the deposition rate gradually increases, reaching a maximum at a particle size of 60 μm. Increasing the inlet flow rate first results in a sharp increase in the deposition rate and then a slow increase. The deposition rate is significantly increases with the increasing of wall heat flux due to the thermophoresis effect. The conclusions of this paper can provide reference for the deposition motion characteristics of fine particles in supercritical CO2.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"270 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123448278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Winding wire, as an important part of electrical equipment such as motor coils, is vital to the stable operation of reactor electrical equipment. The insulation aging of winding wire in reactor environment is affected by multiple factors such as temperature, voltage and irradiation. Due to the complex aging mechanism under the effect of multi-factor coupling, it has become a research hotspot to explore the influence of single factor and multi-factor coupling on the insulation lifespan of winding wire, and give the insulation lifespan of winding wire under multiple factors. In this paper, design of experiment (DOE) method was used to test design and results analysis, and the corona resistance tests of winding wire were carried out to get the corona resistance lifespans, which were regarded as the insulation indicator of winding wire under multiples factors. Full factorial experimental design was planned by changing the temperature, irradiation dose, and voltage amplitude at two level. The corona resistance lifespans of the samples were obtained, and the data were processed by the two-parameter Weibull distribution. Finally, the effects of single-factor and multi-factor coupling on insulation lifespan were discussed, and a model for evaluating the insulation lifespan of winding wire under the combined effects of three parameters was developed.
{"title":"Three-Factor Winding Wire Insulation Aging Evaluation Based on Design of Experiment","authors":"Daofan Zhou, He Yan, Xingzhong Diao","doi":"10.1115/icone29-91590","DOIUrl":"https://doi.org/10.1115/icone29-91590","url":null,"abstract":"\u0000 Winding wire, as an important part of electrical equipment such as motor coils, is vital to the stable operation of reactor electrical equipment. The insulation aging of winding wire in reactor environment is affected by multiple factors such as temperature, voltage and irradiation. Due to the complex aging mechanism under the effect of multi-factor coupling, it has become a research hotspot to explore the influence of single factor and multi-factor coupling on the insulation lifespan of winding wire, and give the insulation lifespan of winding wire under multiple factors. In this paper, design of experiment (DOE) method was used to test design and results analysis, and the corona resistance tests of winding wire were carried out to get the corona resistance lifespans, which were regarded as the insulation indicator of winding wire under multiples factors. Full factorial experimental design was planned by changing the temperature, irradiation dose, and voltage amplitude at two level. The corona resistance lifespans of the samples were obtained, and the data were processed by the two-parameter Weibull distribution. Finally, the effects of single-factor and multi-factor coupling on insulation lifespan were discussed, and a model for evaluating the insulation lifespan of winding wire under the combined effects of three parameters was developed.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121995367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As the key device of the secondary circuit system, the main feed water regulating valve plays a significant role in controlling water level, whose reliability directly affects the safety of the nuclear power plant. During the use of the main feed water regulating valve, the movement and stress state of the valve core are affected by the hydraulic force and the hydraulic torque, which is related to the accuracy and stability of the valve. In this paper, a typical throttling window type of main feed water regulating valve was taken as the research object, the shape coefficient of the throttling window was defined, and the effect of the throttling window shape on the force characteristics of the valve core under variable opening was analyzed. The results show that as the valve opening increases, the direction of valve core axial hydraulic force changes. And with the increase of the shape coefficient of the throttling window, the maximum axial hydraulic force and the maximum lateral hydraulic force of valve core first decrease and then increase, and the maximum hydraulic torque increases gradually. This study can provide some references for the optimal design of similar main feed water regulating valves.
{"title":"Parametric Study of Throttling Window Shapes on Flow Force Characteristics in Main Feed Water Regulating Valve","authors":"Lei Zhao, Qiang Ru, Jia-yi Wu, J. Qian","doi":"10.1115/icone29-93483","DOIUrl":"https://doi.org/10.1115/icone29-93483","url":null,"abstract":"\u0000 As the key device of the secondary circuit system, the main feed water regulating valve plays a significant role in controlling water level, whose reliability directly affects the safety of the nuclear power plant. During the use of the main feed water regulating valve, the movement and stress state of the valve core are affected by the hydraulic force and the hydraulic torque, which is related to the accuracy and stability of the valve. In this paper, a typical throttling window type of main feed water regulating valve was taken as the research object, the shape coefficient of the throttling window was defined, and the effect of the throttling window shape on the force characteristics of the valve core under variable opening was analyzed. The results show that as the valve opening increases, the direction of valve core axial hydraulic force changes. And with the increase of the shape coefficient of the throttling window, the maximum axial hydraulic force and the maximum lateral hydraulic force of valve core first decrease and then increase, and the maximum hydraulic torque increases gradually. This study can provide some references for the optimal design of similar main feed water regulating valves.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116993987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The helical wire spacer of liquid lead-bismuth cooled fast reactor (LFR) fuel assembly plays a significant role in the strengthening of the flow and heat transfer. However, most LFRs have a fixed initial angle of wire-wrapped direction in rod bundles, and the optimization analysis of their angle in the subchannel is absent. More analysis of the impacts that the wire spacer has on the liquid lead-bismuth eutectic (LBE) coolant should be obtained. In this paper, three different turbulence viscosity models and two constant turbulent Prandtl numbers were applied in the open source Computational Fluid Dynamics (CFD) platform OpenFOAM. The numerical results, which were considered with an extensive mesh sensitivity study, were validated against a series of experiment data. The simulations about key thermal hydraulic parameters such as temperature, velocity distribution, pressure drop, local and average Nusselt number were carried out based on 7-pin wire-wrapped rod bundles whose wires winding from internal, edge and corner channel. The results show that the k-ε model with Prt = 2.0 can be used to predict the flow and heat transfer characteristics of LBE. The influence of wire-wrapped starting position indicates that an optimum point exists in the internal channel. This work is useful in future safety design of fuel assemblies in the LFR.
{"title":"Initial Wire-Wrapped Angle Optimization Analysis of a Liquid Lead-Bismuth Cooled Fuel Assembly Based on OpenFOAM","authors":"Jie Wu, Jiejin Cai","doi":"10.1115/icone29-92097","DOIUrl":"https://doi.org/10.1115/icone29-92097","url":null,"abstract":"\u0000 The helical wire spacer of liquid lead-bismuth cooled fast reactor (LFR) fuel assembly plays a significant role in the strengthening of the flow and heat transfer. However, most LFRs have a fixed initial angle of wire-wrapped direction in rod bundles, and the optimization analysis of their angle in the subchannel is absent. More analysis of the impacts that the wire spacer has on the liquid lead-bismuth eutectic (LBE) coolant should be obtained. In this paper, three different turbulence viscosity models and two constant turbulent Prandtl numbers were applied in the open source Computational Fluid Dynamics (CFD) platform OpenFOAM. The numerical results, which were considered with an extensive mesh sensitivity study, were validated against a series of experiment data. The simulations about key thermal hydraulic parameters such as temperature, velocity distribution, pressure drop, local and average Nusselt number were carried out based on 7-pin wire-wrapped rod bundles whose wires winding from internal, edge and corner channel. The results show that the k-ε model with Prt = 2.0 can be used to predict the flow and heat transfer characteristics of LBE. The influence of wire-wrapped starting position indicates that an optimum point exists in the internal channel. This work is useful in future safety design of fuel assemblies in the LFR.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124415592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shanpu Wang, Yuxiang Li, Liwen He, L. Tong, Xuewu Cao
Estimation of aerosol penetration through the cracked concrete wall with a submillimeter height has attracted more attention for radioactivity optimization evaluation of containment, which emphasizes the aerosol deposition inside the cracks without catastrophic destruction of containment. While, no deposition has been considered in current radiological assessments and the penetration of aerosol is simply assumed to be released as the leakage of gas. Therefore, the results of assessment are too conservation for the leakage of radioactive aerosol without considering any deposition. In this work, an experimental facility is set up to study the penetration of particles through cracked concrete walls with different geometric dimensions. Titanium dioxide powder is chosen due to its density and nontoxicity. A sampling system is designed for the measurement of aerosol concentration under high temperature and containing condensable steam. One regular concrete crack in the shape of a straight rectangular slot and one irregular concrete crack with different streamwise tortuosities, τ, which is defined as the radio of the actual length of a crack pathway and the thickness of concrete structure, have been used in the tests of gas leakage and aerosol exposure. The height of cracks can be calculated from the consequences of gas leakage characteristic, based on the Suzuki’s flow model. Research results of aerosol exposure tests indicate that increasing the flow rate, particle diameter and tortuosity all can enhance the aerosol penetration, and micron particles cannot penetrate concrete cracks, compared with submicron particles. The aerosol penetration through the straight concrete crack is in good agreement with the prediction by the correlation proposed by Van De Vate, but no agreement is reached for the irregular crack with some tortuosity. Meantime, the effect of steam condensation on aerosol penetration is also been discussed preliminarily.
气溶胶穿透亚毫米高度混凝土裂缝壁的估算在安全壳放射性优化评价中受到越来越多的关注，其强调的是气溶胶在裂缝内的沉积而不会对安全壳造成灾难性的破坏。然而，在目前的辐射评估中没有考虑到沉积，而气溶胶的渗透只是假设作为气体泄漏释放。因此，对于未考虑沉降的放射性气溶胶的泄漏，评价结果过于保守。在这项工作中，建立了一个实验装置来研究颗粒在不同几何尺寸的裂缝混凝土墙中的穿透作用。选择二氧化钛粉是因为它的密度大且无毒。设计了一种用于测量高温下含可冷凝蒸汽气溶胶浓度的采样系统。在气体泄漏和气溶胶暴露试验中，采用了一条矩形直槽形状的规则混凝土裂缝和一条具有不同流向弯曲度的不规则混凝土裂缝τ，其定义为裂缝路径的实际长度与混凝土结构厚度的比值。根据铃木的流动模型，从气体泄漏特性的结果可以计算出裂缝的高度。气溶胶暴露试验研究结果表明，增大流速、颗粒直径和弯曲度均能增强气溶胶的穿透能力，而微米颗粒与亚微米颗粒相比，不能穿透混凝土裂缝。直裂缝的气溶胶穿透量与Van De Vate的相关性预测吻合较好，而具有一定弯曲度的不规则裂缝的气溶胶穿透量与Van De Vate的相关性预测不符。同时，还初步探讨了蒸汽凝结对气溶胶穿透的影响。
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