The flow field calculation plays a crucial role in thermal-hydraulic calculation of High Temperature Gas-cooled Reactor (HTGR). While using the thermal-hydraulic program for HTGR to calculate the low-flow condition, the calculation of the helium pressure field distribution in the reactor core is difficult to converge, which may lead to the non-physical pressure oscillation. The analysis and improvement of flow field calculation to alleviate this non-physical oscillation is of great significance for HTGR thermal-hydraulic design. In this work, the factors affecting the flow field calculation are analyzed. The approximation assumptions of horizontal cavity modeling and the using of Gauss-Seidel (GS) partition point iteration method leading to the flow field calculation is sensitive to round-off error. For the reason of GS partition point iterative method suffers from the slow convergence rate, and may even non-convergence in some conditions, a global direct method is developed in this paper to solve the whole flow field directly to pursue strong stability and high convergence rate. Compared with original method, the numerical results show that the newly developed algorithm achieves faster convergence rate and stricter convergence results.
{"title":"Analysis and Improvement of Flow Field Calculation in Thermal Hydraulic Program for High Temperature Gas-Cooled Reactor","authors":"Dou Haoming, Lang Minggang, Z. Han, She Ding","doi":"10.1115/icone29-92090","DOIUrl":"https://doi.org/10.1115/icone29-92090","url":null,"abstract":"\u0000 The flow field calculation plays a crucial role in thermal-hydraulic calculation of High Temperature Gas-cooled Reactor (HTGR). While using the thermal-hydraulic program for HTGR to calculate the low-flow condition, the calculation of the helium pressure field distribution in the reactor core is difficult to converge, which may lead to the non-physical pressure oscillation. The analysis and improvement of flow field calculation to alleviate this non-physical oscillation is of great significance for HTGR thermal-hydraulic design. In this work, the factors affecting the flow field calculation are analyzed. The approximation assumptions of horizontal cavity modeling and the using of Gauss-Seidel (GS) partition point iteration method leading to the flow field calculation is sensitive to round-off error. For the reason of GS partition point iterative method suffers from the slow convergence rate, and may even non-convergence in some conditions, a global direct method is developed in this paper to solve the whole flow field directly to pursue strong stability and high convergence rate. Compared with original method, the numerical results show that the newly developed algorithm achieves faster convergence rate and stricter convergence results.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"31 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":"131175172","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}
Compared with offline simulation based on software completely, Hardware-in-the-loop Simulation (HILS) is a simulation method based on software and hardware coupling, which can not only verify the principle of the model studied, but also feedback hardware response for comparison, shorten product test cycle, improve research and development efficiency and accuracy. Taking the marine nuclear reactor as the background, this paper modelled the main circuit of energy power and the part of propulsion power output, simulated the energy power module offline based on Modelica language, and coupled Arduino MCU with LEGO parts to simulate the hardware response of propulsion power output. This study used OpenModelica to construct the steady-state and transient simulation operation of the off-line simulation model, realized the interaction between the hardware signal input and the offline simulation model, processed the mechanical response of the simulation output and communicated with the external hardware. Finally, the feedback action response was compared with the key parameters in the existing literature. The results show that the simulation results of the model and the hardware response feedback results are consistent with the literature parameters, and based on the coupling of Modelica language with Arduino MCU can carry out the HILS for the marine nuclear power system in steady state and transient state.
{"title":"Propulsion Control of Marine Nuclear Reactor by Hardware-in-the-Loop Simulation (HILS)","authors":"Ao Zhang, Xiang Wang","doi":"10.1115/icone29-91544","DOIUrl":"https://doi.org/10.1115/icone29-91544","url":null,"abstract":"\u0000 Compared with offline simulation based on software completely, Hardware-in-the-loop Simulation (HILS) is a simulation method based on software and hardware coupling, which can not only verify the principle of the model studied, but also feedback hardware response for comparison, shorten product test cycle, improve research and development efficiency and accuracy. Taking the marine nuclear reactor as the background, this paper modelled the main circuit of energy power and the part of propulsion power output, simulated the energy power module offline based on Modelica language, and coupled Arduino MCU with LEGO parts to simulate the hardware response of propulsion power output. This study used OpenModelica to construct the steady-state and transient simulation operation of the off-line simulation model, realized the interaction between the hardware signal input and the offline simulation model, processed the mechanical response of the simulation output and communicated with the external hardware. Finally, the feedback action response was compared with the key parameters in the existing literature. The results show that the simulation results of the model and the hardware response feedback results are consistent with the literature parameters, and based on the coupling of Modelica language with Arduino MCU can carry out the HILS for the marine nuclear power system in steady state and transient state.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"39 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":"132578791","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}
A three-dimensional (3D) computational fluid dynamics (CFD) investigation of steam flow distribution of a cross-flow X-type steam superheater in a small modular reactor (SMR) has been carried out, and different flow distributors have been compared. As a non-baffle shell and tube heat exchanger, the secondary steam flow of the superheater flows across the tube bundles and is superheated in the shell side. The flow distributor is arranged between the shell side inlet and the tube bundles, devices compared are the impingement plate and orifice plate. The diameter and the geometry distribution of the holes on the orifice plate have also been researched. The software used is ANSYS FLUENT, applying standard k-epsilon turbulence flow model. Distribution of velocity and pressure drop of the shell-side steam is obtained. As the analysis of the flow-field distribution contributes to optimizing the heat exchange performance, the analysis solutions can provide helpful information for the superheater design.
{"title":"CFD Analysis of the Steam Side in a Cross-Flow X-Type Steam Superheater","authors":"S. Zhao, Weihua Li, Wentao Hao, Wenwen Zhang","doi":"10.1115/icone29-91387","DOIUrl":"https://doi.org/10.1115/icone29-91387","url":null,"abstract":"\u0000 A three-dimensional (3D) computational fluid dynamics (CFD) investigation of steam flow distribution of a cross-flow X-type steam superheater in a small modular reactor (SMR) has been carried out, and different flow distributors have been compared. As a non-baffle shell and tube heat exchanger, the secondary steam flow of the superheater flows across the tube bundles and is superheated in the shell side. The flow distributor is arranged between the shell side inlet and the tube bundles, devices compared are the impingement plate and orifice plate. The diameter and the geometry distribution of the holes on the orifice plate have also been researched. The software used is ANSYS FLUENT, applying standard k-epsilon turbulence flow model. Distribution of velocity and pressure drop of the shell-side steam is obtained. As the analysis of the flow-field distribution contributes to optimizing the heat exchange performance, the analysis solutions can provide helpful information for the superheater design.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"13 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":"132750564","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}
Raka Firman Baskara Permana, Junpei Tabuchi, T. Okawa, Yuki Narushima, Hajime Furuichi, K. Katono
Study on the droplet entrainment in annular two-phase flow has attracted many researchers in connection with the liquid film dryout in the annular two-phase flow. However, the knowledge on the entrainment due to nucleate boiling is still insufficient to predict the droplet entrainment rate accurately. In this study, measurements were made of the droplet entrainment rate with falling liquid films on the locally heated test section. The visualization using a high-speed camera to clarify the accuracy of the measurement results also carried out in this experiment. For the first step in this study, the measurement of the droplet entrainment rate was performed after getting a stable or steady state conditions. Then, we investigated the influence of the separator position on the reproducibility of the droplet entrainment rate to get the droplet entrainment rate – separator position map. As a result, the reproducibility of the droplet entrainment rate increases with decreasing separation distance from the liquid film. In additions, we also investigated the influence of the heat flux and liquid film flow rate on the reproducibility of the droplet entrainment rate. As a result, the reproducibility of the droplet entrainment rate increases with increasing the heat flux and liquid film flow rate. In the future, we expect to investigate the influence of gas flow rate, and degree of subcooling on the reproducibility of the droplet entrainment rate and some correlation models are developed.
{"title":"Experimental Study on Measurement of Boiling Entrainment Rate From Falling Liquid Film With Gas Sheared Flow","authors":"Raka Firman Baskara Permana, Junpei Tabuchi, T. Okawa, Yuki Narushima, Hajime Furuichi, K. Katono","doi":"10.1115/icone29-90420","DOIUrl":"https://doi.org/10.1115/icone29-90420","url":null,"abstract":"\u0000 Study on the droplet entrainment in annular two-phase flow has attracted many researchers in connection with the liquid film dryout in the annular two-phase flow. However, the knowledge on the entrainment due to nucleate boiling is still insufficient to predict the droplet entrainment rate accurately. In this study, measurements were made of the droplet entrainment rate with falling liquid films on the locally heated test section. The visualization using a high-speed camera to clarify the accuracy of the measurement results also carried out in this experiment. For the first step in this study, the measurement of the droplet entrainment rate was performed after getting a stable or steady state conditions. Then, we investigated the influence of the separator position on the reproducibility of the droplet entrainment rate to get the droplet entrainment rate – separator position map. As a result, the reproducibility of the droplet entrainment rate increases with decreasing separation distance from the liquid film. In additions, we also investigated the influence of the heat flux and liquid film flow rate on the reproducibility of the droplet entrainment rate. As a result, the reproducibility of the droplet entrainment rate increases with increasing the heat flux and liquid film flow rate. In the future, we expect to investigate the influence of gas flow rate, and degree of subcooling on the reproducibility of the droplet entrainment rate and some correlation models are developed.","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":"132041254","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 irradiation mechanism of iron-based alloys has proven to be related to dislocation movement and interaction between dislocation and irradiation defect. Fe is an important element of the iron-based alloys. The single crystal iron is selected as the material of the indenter and the substrate when molecular dynamics (MD) simulation is launched. This article studies the effect of the different temperature and potential functions on the dislocation evolution and mechanical properties of single crystal iron in the nanoindentation process. Results show that temperature affects the load-displacement curve; the potential has no effect on the trend of the load-displacement curve, but it has an impact on the value of the load; the dislocation behavior of the substrate after compression results in a jagged load-displacement curve (pop-in event). These results are of great significance for understanding the dislocation behavior of the typical body centered cubic (BCC) metal during nanoindentation process.
{"title":"Effect of Temperature and Potential on BCC-Fe Nanoindentation Process","authors":"Dexing Wang, P. Lin, Libin Sun, Z. Cai","doi":"10.1115/icone29-91251","DOIUrl":"https://doi.org/10.1115/icone29-91251","url":null,"abstract":"\u0000 The irradiation mechanism of iron-based alloys has proven to be related to dislocation movement and interaction between dislocation and irradiation defect. Fe is an important element of the iron-based alloys. The single crystal iron is selected as the material of the indenter and the substrate when molecular dynamics (MD) simulation is launched. This article studies the effect of the different temperature and potential functions on the dislocation evolution and mechanical properties of single crystal iron in the nanoindentation process.\u0000 Results show that temperature affects the load-displacement curve; the potential has no effect on the trend of the load-displacement curve, but it has an impact on the value of the load; the dislocation behavior of the substrate after compression results in a jagged load-displacement curve (pop-in event). These results are of great significance for understanding the dislocation behavior of the typical body centered cubic (BCC) metal during nanoindentation process.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"14 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":"131383428","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}
Safety is the biggest concern of nuclear power plant and research reactors.As one of the three primary thermal design criteria for rectors, the critical heat flux (CHF) guarantee the reactor’s safety and economics. The bubble dynamics in narrow rectangular channel is didderent from that in conventional channels. Therefore the CHF characteristics obtained in the conventional channel may not be suitable in the narrow rectangular channel. To analyze CHF characteristics in the narrow rectangular channel, a visual experiment study on CHF was carried out in one side heated narrow rectangular channel under upflow condition condition. The experiments were performed at pressures ranging from 1 to 4 MPa, with inlet subcooling ranging from 65 to 120 K and mass flux ranging from 350–200 kg/(m2s). The deionized water was used as the working medium. The relevant thermal-hydraulic parameters and visualization results were collected synchronously. Then compare the CHF experimental values with the predicted values of the W-3 correlation,Mishima correlation, and Chang H correlation. The result shows the predicted values of W-3 correlation and Mishima correlation are always larger than the experimental values. Among these corrrelations, we found that the errors of Chang H correlation is within 30% in 2mm gap size.
{"title":"An Evaluation of Critical Heat Flux Prediction in Single-Side Heated Narrow Rectangular Channel Under Upflow Condition","authors":"Meiyue Yan, Zaiyong Ma, Liangming Pan, Qingche He, Wangtao Xv, Xiang Li","doi":"10.1115/icone29-89378","DOIUrl":"https://doi.org/10.1115/icone29-89378","url":null,"abstract":"\u0000 Safety is the biggest concern of nuclear power plant and research reactors.As one of the three primary thermal design criteria for rectors, the critical heat flux (CHF) guarantee the reactor’s safety and economics. The bubble dynamics in narrow rectangular channel is didderent from that in conventional channels. Therefore the CHF characteristics obtained in the conventional channel may not be suitable in the narrow rectangular channel. To analyze CHF characteristics in the narrow rectangular channel, a visual experiment study on CHF was carried out in one side heated narrow rectangular channel under upflow condition condition. The experiments were performed at pressures ranging from 1 to 4 MPa, with inlet subcooling ranging from 65 to 120 K and mass flux ranging from 350–200 kg/(m2s). The deionized water was used as the working medium. The relevant thermal-hydraulic parameters and visualization results were collected synchronously. Then compare the CHF experimental values with the predicted values of the W-3 correlation,Mishima correlation, and Chang H correlation. The result shows the predicted values of W-3 correlation and Mishima correlation are always larger than the experimental values. Among these corrrelations, we found that the errors of Chang H correlation is within 30% in 2mm gap size.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"215 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":"114624664","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}
Heng Zhang, Xue Lyu, Qin Hang, Yulu Du, Bo Liu, Qun Liu, Guo-Zhen Wang, Jinchao Liu
An accurate measurement for the modality and motion parameters of bubbles is of great significance. In the existing bubble measurement methods, there are some problems that are desirable to be solved, such as system complexity, poor real-time performance, and the deviation due to two-dimensional measurement. To overcome these challenges, we developed a novel three-dimensional analysis method based on light field imaging diagnosis and deep learning algorithm. Different from traditional two-dimensional reconstruction, the bubble depth can be computed from light field images directly through digital refocusing technology. After calibrating, the conversion between the camera coordinate system and the real-world coordinate system is achieved through the sharpness evaluation algorithm. According to the corresponding relationship, the refocused image could be calibrated to the actual position in real world. Combined with the Multi-input Residual Convolution Neural Network, (MRCNN), the bubble depth could be computed fully automated from given images at high accuracy. Based on the above works, the three-dimensional reconstruction model for bubble flow can be established by coupling the depth and the parameters extracted through bounding boxes. The proposed method solves the problem that conventional imaging can only perform the two-dimensional measurement, which contributes to the error during the measurement process. Results show a promising performance on the three-dimensional reconstruction of bubble flow, validating the feasibility of the three-dimensional measurement method for bubbles in gas-liquid two-phase flow based on light field imaging diagnosis and deep learning algorithm.
{"title":"Deep-Learning Based Three-Dimensional Analysis of Bubble Flows From Light Field Images","authors":"Heng Zhang, Xue Lyu, Qin Hang, Yulu Du, Bo Liu, Qun Liu, Guo-Zhen Wang, Jinchao Liu","doi":"10.1115/icone29-91353","DOIUrl":"https://doi.org/10.1115/icone29-91353","url":null,"abstract":"\u0000 An accurate measurement for the modality and motion parameters of bubbles is of great significance. In the existing bubble measurement methods, there are some problems that are desirable to be solved, such as system complexity, poor real-time performance, and the deviation due to two-dimensional measurement. To overcome these challenges, we developed a novel three-dimensional analysis method based on light field imaging diagnosis and deep learning algorithm. Different from traditional two-dimensional reconstruction, the bubble depth can be computed from light field images directly through digital refocusing technology. After calibrating, the conversion between the camera coordinate system and the real-world coordinate system is achieved through the sharpness evaluation algorithm. According to the corresponding relationship, the refocused image could be calibrated to the actual position in real world. Combined with the Multi-input Residual Convolution Neural Network, (MRCNN), the bubble depth could be computed fully automated from given images at high accuracy. Based on the above works, the three-dimensional reconstruction model for bubble flow can be established by coupling the depth and the parameters extracted through bounding boxes. The proposed method solves the problem that conventional imaging can only perform the two-dimensional measurement, which contributes to the error during the measurement process. Results show a promising performance on the three-dimensional reconstruction of bubble flow, validating the feasibility of the three-dimensional measurement method for bubbles in gas-liquid two-phase flow based on light field imaging diagnosis and deep learning algorithm.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"12 2 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":"124377276","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}
Konstantinos Gkouliaras, Jake Marr, Vasileios Theos, S. Chatzidakis
Recent and future advancements in the upcoming digital era of Nuclear Industry would rely heavily on real-time, remote, and unattended monitoring, as well as continuous data collection. Advanced reactor designs (e.g., Microreactors, SMR, etc.) intended for installation in remote and possibly inaccessible locations would require robust, compact, passive, low-cost, radiation-tolerant, and energy efficient sensor systems that could be remotely interrogated and provide real-time information of operating and safety-related parameters (temperature, flux, etc.). In addition, to ensure economic competitiveness and minimize sensor costs, it is equally important to guarantee a simple, streamlined, and cost-efficient manufacturing procedure. To achieve this, we explore the development of low-cost 3D-printed Surface Acoustic Wave (SAW) sensors optimized for remote monitoring of advanced reactors. SAW sensors are passive devices that can convert an electromagnetic wave into a surface acoustic wave propagating along a piezoelectric substrate. The mechanical wave is then reflected and eventually converted back into an electrical signal which can be broadcasted. These characteristics offer unique advantages including sensor simplicity, power-free operation, and radiation tolerance since no integrated circuits are needed. To develop customized SAW sensors, we used a state-of-the-art aerosol jet printer that enables precise fabrication of sensors with features as small as 10 μm. In this work, LiNbO3, LiTaO3 and Quartz substrates are used to demonstrate the feasibility of the proposed approach by 3D-printing two-port SAW structures using conductive silver nanoink. A parametric analysis is performed in order to optimize the printing procedure and investigate optimization of printing line resolution using optical and Scanning Electron Microscopy.
{"title":"3D-Printed SAW Sensor Development for Enabling Remote Monitoring of Advanced Reactors","authors":"Konstantinos Gkouliaras, Jake Marr, Vasileios Theos, S. Chatzidakis","doi":"10.1115/icone29-92008","DOIUrl":"https://doi.org/10.1115/icone29-92008","url":null,"abstract":"\u0000 Recent and future advancements in the upcoming digital era of Nuclear Industry would rely heavily on real-time, remote, and unattended monitoring, as well as continuous data collection. Advanced reactor designs (e.g., Microreactors, SMR, etc.) intended for installation in remote and possibly inaccessible locations would require robust, compact, passive, low-cost, radiation-tolerant, and energy efficient sensor systems that could be remotely interrogated and provide real-time information of operating and safety-related parameters (temperature, flux, etc.). In addition, to ensure economic competitiveness and minimize sensor costs, it is equally important to guarantee a simple, streamlined, and cost-efficient manufacturing procedure. To achieve this, we explore the development of low-cost 3D-printed Surface Acoustic Wave (SAW) sensors optimized for remote monitoring of advanced reactors.\u0000 SAW sensors are passive devices that can convert an electromagnetic wave into a surface acoustic wave propagating along a piezoelectric substrate. The mechanical wave is then reflected and eventually converted back into an electrical signal which can be broadcasted. These characteristics offer unique advantages including sensor simplicity, power-free operation, and radiation tolerance since no integrated circuits are needed. To develop customized SAW sensors, we used a state-of-the-art aerosol jet printer that enables precise fabrication of sensors with features as small as 10 μm. In this work, LiNbO3, LiTaO3 and Quartz substrates are used to demonstrate the feasibility of the proposed approach by 3D-printing two-port SAW structures using conductive silver nanoink. A parametric analysis is performed in order to optimize the printing procedure and investigate optimization of printing line resolution using optical and Scanning Electron Microscopy.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"7 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":"126175779","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}
Air dispersion modeling is an important tool for emergency response following a nuclear accident, such as the Fukushima accident. Current researches mainly focus on global- and regional-scale modeling with wind field data derived from different methodological models and observations. However, the capability of the local-scale atmospheric dispersion model hasn’t been discussed in detail for the Fukushima accident. In this paper, the local-scale modeling of radionuclides following the Fukushima accident was investigated with the combination of the wind diagnosed model SWIFT and the radionuclide transport model RIMPUFF. The coarse input wind field of SWIFT is prepared with WRF using the European Centre for Medium-Range Weather Forecasts (ECMWF) Meteorological data. The SWIFT-diagnosed wind field was used to drive RIMPUFF for calculating the dispersion of radionuclides and gamma dose rates around the Fukushima Daiichi Nuclear Power Plant (FDNPP) site. The diagnostic wind fields were validated to the on-site meteorological observations, whereas the dispersion and gamma dose rates were validated the onsite gamma dose rate monitoring data and the observations of suspended particulate m? near the FDNPP. The plume patterns were also analyzed to help understand the transport behaviour of the radionuclides. The validation demonstrates that, with the 1km-resolved ECMWF meteorological data, SWIFT fairly reproduces the wind field. The speed is slightly overestimated, with a Normalized Mean Squared Error (NMSE) below 6. The wind direction is well simulated at some specific moments, which is critical for reproducing some peaks of the dose rates. However, RIMPUFF underestimates the dose rates around the FDNPP, partly because of the overestimated wind speed. The concentration simulations better agree with observations in the Naraha station than Futaba station, with the Fractional Bias (FB) under 0.3 and NMSE under 6 at the Naraha station.
{"title":"Local-Scale Atmospheric Dispersion Modelling of Radionuclides Following the Fukushima Daiichi Nuclear Accident Using SWIFT-RIMPUFF","authors":"Shuhan Zhuang, Shengjiang Fang, Xinwen Dong","doi":"10.1115/icone29-90748","DOIUrl":"https://doi.org/10.1115/icone29-90748","url":null,"abstract":"\u0000 Air dispersion modeling is an important tool for emergency response following a nuclear accident, such as the Fukushima accident. Current researches mainly focus on global- and regional-scale modeling with wind field data derived from different methodological models and observations. However, the capability of the local-scale atmospheric dispersion model hasn’t been discussed in detail for the Fukushima accident. In this paper, the local-scale modeling of radionuclides following the Fukushima accident was investigated with the combination of the wind diagnosed model SWIFT and the radionuclide transport model RIMPUFF. The coarse input wind field of SWIFT is prepared with WRF using the European Centre for Medium-Range Weather Forecasts (ECMWF) Meteorological data. The SWIFT-diagnosed wind field was used to drive RIMPUFF for calculating the dispersion of radionuclides and gamma dose rates around the Fukushima Daiichi Nuclear Power Plant (FDNPP) site. The diagnostic wind fields were validated to the on-site meteorological observations, whereas the dispersion and gamma dose rates were validated the onsite gamma dose rate monitoring data and the observations of suspended particulate m? near the FDNPP. The plume patterns were also analyzed to help understand the transport behaviour of the radionuclides. The validation demonstrates that, with the 1km-resolved ECMWF meteorological data, SWIFT fairly reproduces the wind field. The speed is slightly overestimated, with a Normalized Mean Squared Error (NMSE) below 6. The wind direction is well simulated at some specific moments, which is critical for reproducing some peaks of the dose rates. However, RIMPUFF underestimates the dose rates around the FDNPP, partly because of the overestimated wind speed. The concentration simulations better agree with observations in the Naraha station than Futaba station, with the Fractional Bias (FB) under 0.3 and NMSE under 6 at the Naraha station.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"22 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":"127439024","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}
In order to study the influence of the water level of the water tank on the flow instability and heat transfer character istics,which is of the low-pressure two-phase open natural circulation system. The open natural circulation system was numerically simulated and experimentally verified. Numerical simulations are calculated by using a homogeneous flow model in this study, The flow rate and heat removal power of the system under different water level conditions were calculated and recorded, and the trend of changing with the water level was obtained. The results were then compared with the experimental results. It shows that the calculated open natural circulation flow and heat removal power results are consistent with the experimental. As the liquid level decreases, the flow state of the system gradually changes from the periodic flashing state inside the adiabatic section to the stable flashing operating state, and the heat exchange power also increases gradually. times. Therefore, in the low-pressure system, reducing the liquid level of the water tank can achieve a good effect of enhancing the flow stability of the low-pressure two-phase open natural circulation, and also has a good effect on the improvement of the heat removal power of the system.
{"title":"Research on the Influence of Water Tank Liquid Level on Low Pressure Two-Phase Open Natural Circulation Flow and Heat Exchange","authors":"Shengnan Zhang, Zhong-ning Sun, N. Zhang","doi":"10.1115/icone29-92041","DOIUrl":"https://doi.org/10.1115/icone29-92041","url":null,"abstract":"\u0000 In order to study the influence of the water level of the water tank on the flow instability and heat transfer character istics,which is of the low-pressure two-phase open natural circulation system. The open natural circulation system was numerically simulated and experimentally verified. Numerical simulations are calculated by using a homogeneous flow model in this study, The flow rate and heat removal power of the system under different water level conditions were calculated and recorded, and the trend of changing with the water level was obtained. The results were then compared with the experimental results. It shows that the calculated open natural circulation flow and heat removal power results are consistent with the experimental. As the liquid level decreases, the flow state of the system gradually changes from the periodic flashing state inside the adiabatic section to the stable flashing operating state, and the heat exchange power also increases gradually. times. Therefore, in the low-pressure system, reducing the liquid level of the water tank can achieve a good effect of enhancing the flow stability of the low-pressure two-phase open natural circulation, and also has a good effect on the improvement of the heat removal power of the system.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"16 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":"133471702","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}
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