Coupling aerosol gravity sedimentation mechanism and aggregation effect, considering the correction of submicron particle free path and gas dynamic viscosity in thermal environment, a gravitational sedimentation model suitable for submicron aerosol accompanied by coalescence effect under high temperature and high humidity conditions is established, and the established model is verified by the results of thermal experiments. The aerosol aggregation model is established using the discretization method. By controlling whether the aggregation mechanism occurs in the established model, the influence of aggregation on gravitational settling when steam fraction and ambient pressure are changed is studied. In the study, it was found that the aggregation effect has a nearly 1-fold acceleration effect on the decay constant of the number concentration of submicron aerosols during gravitational sedimentation, and the acceleration effect on the decay constant of the mass concentration can be ignored, but there is an acceleration trend. When submicron aerosols settle under high temperature and high humidity conditions, the number median particle size tends to increase, that is, the increase of the number median particle size by the aggregation effect is greater than the decrease of the number median particle size by gravity sedimentation. After considering the aggregation effect, the number concentration decay constant and the mass concentration decay constant when the submicron aerosol undergoes gravitational sedimentation will decrease with the increase of the ambient pressure, and increase with the increase of the steam fraction. However, the number concentration decay constant changes larger, the mass concentration decay constant has a trend of change, and the change range is relatively weak. In addition, in the sensitivity analysis of the aerosol coalescence and gravitational sedimentation models, it is found that the molecular free path has a greater impact on the calculation results of aerosol coalescence and deposition in a thermal environment than the dynamic viscosity. Moreover, the influence of Brownian coalescence on the aerosol particle size spectrum is much greater than that caused by gravitational coalescence.
{"title":"Effects of Aggregation on Gravity Settlement of Submicron Aerosols Under High Temperature and High Humidity Conditions","authors":"Jun Yan Chen, Pu Zhen Gao, Haifeng Gu, Hui Yu Yu","doi":"10.1115/icone29-92065","DOIUrl":"https://doi.org/10.1115/icone29-92065","url":null,"abstract":"\u0000 Coupling aerosol gravity sedimentation mechanism and aggregation effect, considering the correction of submicron particle free path and gas dynamic viscosity in thermal environment, a gravitational sedimentation model suitable for submicron aerosol accompanied by coalescence effect under high temperature and high humidity conditions is established, and the established model is verified by the results of thermal experiments. The aerosol aggregation model is established using the discretization method. By controlling whether the aggregation mechanism occurs in the established model, the influence of aggregation on gravitational settling when steam fraction and ambient pressure are changed is studied. In the study, it was found that the aggregation effect has a nearly 1-fold acceleration effect on the decay constant of the number concentration of submicron aerosols during gravitational sedimentation, and the acceleration effect on the decay constant of the mass concentration can be ignored, but there is an acceleration trend. When submicron aerosols settle under high temperature and high humidity conditions, the number median particle size tends to increase, that is, the increase of the number median particle size by the aggregation effect is greater than the decrease of the number median particle size by gravity sedimentation. After considering the aggregation effect, the number concentration decay constant and the mass concentration decay constant when the submicron aerosol undergoes gravitational sedimentation will decrease with the increase of the ambient pressure, and increase with the increase of the steam fraction. However, the number concentration decay constant changes larger, the mass concentration decay constant has a trend of change, and the change range is relatively weak. In addition, in the sensitivity analysis of the aerosol coalescence and gravitational sedimentation models, it is found that the molecular free path has a greater impact on the calculation results of aerosol coalescence and deposition in a thermal environment than the dynamic viscosity. Moreover, the influence of Brownian coalescence on the aerosol particle size spectrum is much greater than that caused by gravitational coalescence.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"1 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":"131282327","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}
There has been growing interest in nuclear hydrogen cogeneration recently since hydrogen has been considered one of the prospective substitutes to fossil fuels in the future, and nuclear energy can supply the energy required for hydrogen production efficiently and cleanly. The multi-modular high-temperature gas-cooled reactor (MHTGR) is a small modular reactor with the advantage of inherent safety, and its nuclear steam supply system (NSSS) can provide steam at around 570°C. Methane Steam Reforming (MSR) is currently the most widely used hydrogen production method, and if it is combined with a carbon capture and storage system, the greenhouse gas emissions can be minimized. This paper presents the design for a nuclear hydrogen cogeneration plant that has six-module MHTGRs coupled with MSR.
{"title":"Dynamic Modeling of Nuclear Hydrogen Generation Plant Based on Multi-Modular High-Temperature Gas-Cooled Reactor","authors":"Junyi Li, Z. Dong, Bowen Li, Xiaojin Huang","doi":"10.1115/icone29-88899","DOIUrl":"https://doi.org/10.1115/icone29-88899","url":null,"abstract":"\u0000 There has been growing interest in nuclear hydrogen cogeneration recently since hydrogen has been considered one of the prospective substitutes to fossil fuels in the future, and nuclear energy can supply the energy required for hydrogen production efficiently and cleanly. The multi-modular high-temperature gas-cooled reactor (MHTGR) is a small modular reactor with the advantage of inherent safety, and its nuclear steam supply system (NSSS) can provide steam at around 570°C. Methane Steam Reforming (MSR) is currently the most widely used hydrogen production method, and if it is combined with a carbon capture and storage system, the greenhouse gas emissions can be minimized. This paper presents the design for a nuclear hydrogen cogeneration plant that has six-module MHTGRs coupled with MSR.","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":"130773176","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}
The bond graph can be used to simulate and model conservation processes in different energy domains. In this paper, based on bond graph, the pressurizer was modeled and diagnosed at full power. Two parameters of pressure and mass flow were selected. Firstly, the bond graph of pressurizer was established. The pressurizer was divided into three zones: the fluctuating zone, the saturated liquid zone and the gaseous zone. The conservation equations of mass and energy were given respectively for these three regions. Secondly, the conservation equations of mass and energy were combined with the conservation of volume, and the model was constructed according to the combination rules. Then, according to the established bond graph model, the time causality diagram was established to determine the influence relationship between the coefficients and listed the fault characteristic matrix. Meanwhile, the reasoning structure between the coefficient was realized by the expert system G2. Finally, the fault data simulated by simulator was imported into the bond graph model. The failure of the safety valve, the spray valve and the immersion type heater were introduced to verify the modeling and diagnosis effect. It concludes that the diagnosis effect is consistent with the imported fault. Compared with the data-driven method, the bond graph method is more reliable, and compared with the expert knowledge method, the bond graph method can diagnose unknown faults and has a wide range of applications. In addition, a new method for nuclear power plant simulation modeling was provided. This was a new attempt to model bond graphs outside the research of mechanic, electronic and hydraulic.
{"title":"Modeling and Fault Diagnosis of Pressurizer Based on Bond Graph","authors":"Zhuoran Zhou, M. Peng, Hang Wang, Yingying Jiang","doi":"10.1115/icone29-93053","DOIUrl":"https://doi.org/10.1115/icone29-93053","url":null,"abstract":"\u0000 The bond graph can be used to simulate and model conservation processes in different energy domains. In this paper, based on bond graph, the pressurizer was modeled and diagnosed at full power. Two parameters of pressure and mass flow were selected. Firstly, the bond graph of pressurizer was established. The pressurizer was divided into three zones: the fluctuating zone, the saturated liquid zone and the gaseous zone. The conservation equations of mass and energy were given respectively for these three regions. Secondly, the conservation equations of mass and energy were combined with the conservation of volume, and the model was constructed according to the combination rules. Then, according to the established bond graph model, the time causality diagram was established to determine the influence relationship between the coefficients and listed the fault characteristic matrix. Meanwhile, the reasoning structure between the coefficient was realized by the expert system G2. Finally, the fault data simulated by simulator was imported into the bond graph model. The failure of the safety valve, the spray valve and the immersion type heater were introduced to verify the modeling and diagnosis effect. It concludes that the diagnosis effect is consistent with the imported fault. Compared with the data-driven method, the bond graph method is more reliable, and compared with the expert knowledge method, the bond graph method can diagnose unknown faults and has a wide range of applications. In addition, a new method for nuclear power plant simulation modeling was provided. This was a new attempt to model bond graphs outside the research of mechanic, electronic and hydraulic.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"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":"129331193","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}
Wangtao Xu, Qingche He, Tao Huang, Shuhua Ding, Meiyue Yan, Luteng Zhang, Liangming Pan
As a common heat transfer structure, the vertical round pipe is widely used in nuclear energy systems. The phase distribution characteristics of two-phase flow in a vertical round pipe is an important issue. For two-phase flow, combined with the local typical flow phenomenon, the analysis of the phase distribution characteristics such as the void fraction and the interfacial area concentration is helpful to research the two-fluid model and interfacial area transport equation. Based on the completed flow pattern experiment, an air-water two-phase flow characteristic experiment is carried out for the visualized experimental section of 10 mm ID vertical round pipe. In addition, the 5 × 7 total 35 measuring points of bubbly to slug flow transition region are selected, including 5 superficial liquid velocities (0.5, 1.0, 1.5, 2.0, 2.5 m/s) and 7 superficial gas velocities (0.08, 0.11, 0.13, 0.17, 0.21, 0.28, 0.35 m/s). High-speed camera is used to capture the flow patterns of bubbly to slug flow transition region. Four-sensor conductivity probe is used to measure the interfacial parameters such as void fraction and interfacial area concentration. Thus, the phase distribution characteristics of bubbly to slug flow transition region in the round pipe is analyzed. The obtained two-phase flow parameter data can provide data support for the development of two-fluid model and interfacial area transport equation.
{"title":"Phase Distribution Characteristics of Bubbly to Slug Flow Transition Region in a 10mm ID Vertical Round Pipe","authors":"Wangtao Xu, Qingche He, Tao Huang, Shuhua Ding, Meiyue Yan, Luteng Zhang, Liangming Pan","doi":"10.1115/icone29-93313","DOIUrl":"https://doi.org/10.1115/icone29-93313","url":null,"abstract":"\u0000 As a common heat transfer structure, the vertical round pipe is widely used in nuclear energy systems. The phase distribution characteristics of two-phase flow in a vertical round pipe is an important issue. For two-phase flow, combined with the local typical flow phenomenon, the analysis of the phase distribution characteristics such as the void fraction and the interfacial area concentration is helpful to research the two-fluid model and interfacial area transport equation. Based on the completed flow pattern experiment, an air-water two-phase flow characteristic experiment is carried out for the visualized experimental section of 10 mm ID vertical round pipe. In addition, the 5 × 7 total 35 measuring points of bubbly to slug flow transition region are selected, including 5 superficial liquid velocities (0.5, 1.0, 1.5, 2.0, 2.5 m/s) and 7 superficial gas velocities (0.08, 0.11, 0.13, 0.17, 0.21, 0.28, 0.35 m/s). High-speed camera is used to capture the flow patterns of bubbly to slug flow transition region. Four-sensor conductivity probe is used to measure the interfacial parameters such as void fraction and interfacial area concentration. Thus, the phase distribution characteristics of bubbly to slug flow transition region in the round pipe is analyzed. The obtained two-phase flow parameter data can provide data support for the development of two-fluid model and interfacial area transport equation.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"1 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":"129379594","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}
Additive manufacturing (AM) is a transformational digital manufacturing technology featured with rapidity, customizability, precision, and economy, which is fundamentally altering the way components are designed and manufactured. AM enables the freedom of design, and makes full use of complexity of geometry which “comes for free”. Applying AM technology to nuclear industry can yield advanced reactor designs with function and structure matched for the best thermal, hydraulic and mechanical performance. In this work, an AM-informed reactor core design with silicon carbide (SiC) matrix and tri-structural isotropic (TRISO) particle fuel is proposed and analyzed. The core is an integrated 3D-printing SiC bulk with helical cruciform coolant channels, and the UO2-bearing TRISO fuel particles are dispersed in the bulk. A multi-physics analysis framework for irregular geometry is developed to analyze and further optimize the reactor design. The TRISO particle positions are generated with discrete element method (DEM). The Reactor Monte Carlo code (RMC) and the commercial CFD software STAR-CCM+ are used for the neutronic and thermal-hydraulic analyses, respectively. RMC simulates the neutron transport to predict the effective multiplication factor and power distribution. STAR-CCM+ calculates the flow and heat transfer in coolant channels and heat conduction in solid matrix with the power distribution as the heat source. Preliminary results show that the power peaking factor FQ decreases below 1.65, the heat transfer area increases by 30.3% and the fuel peaking temperature decreases by 25 K. The optimized AM-informed design enjoys better neutronic and thermal-hydraulic performance than those with regular geometry.
{"title":"Neutronic and Thermal-Hydraulic Analyses for an Additive Manufacturing Reactor Core With SiC Matrix and TRISO Particle Fuel","authors":"Wenbin Han, Jian Deng, Qi Lu, Chong Chen, Youyou Xu, Zhang Tao, Shanfang Huang","doi":"10.1115/icone29-92655","DOIUrl":"https://doi.org/10.1115/icone29-92655","url":null,"abstract":"\u0000 Additive manufacturing (AM) is a transformational digital manufacturing technology featured with rapidity, customizability, precision, and economy, which is fundamentally altering the way components are designed and manufactured. AM enables the freedom of design, and makes full use of complexity of geometry which “comes for free”. Applying AM technology to nuclear industry can yield advanced reactor designs with function and structure matched for the best thermal, hydraulic and mechanical performance. In this work, an AM-informed reactor core design with silicon carbide (SiC) matrix and tri-structural isotropic (TRISO) particle fuel is proposed and analyzed. The core is an integrated 3D-printing SiC bulk with helical cruciform coolant channels, and the UO2-bearing TRISO fuel particles are dispersed in the bulk. A multi-physics analysis framework for irregular geometry is developed to analyze and further optimize the reactor design. The TRISO particle positions are generated with discrete element method (DEM). The Reactor Monte Carlo code (RMC) and the commercial CFD software STAR-CCM+ are used for the neutronic and thermal-hydraulic analyses, respectively. RMC simulates the neutron transport to predict the effective multiplication factor and power distribution. STAR-CCM+ calculates the flow and heat transfer in coolant channels and heat conduction in solid matrix with the power distribution as the heat source. Preliminary results show that the power peaking factor FQ decreases below 1.65, the heat transfer area increases by 30.3% and the fuel peaking temperature decreases by 25 K. The optimized AM-informed design enjoys better neutronic and thermal-hydraulic performance than those with regular geometry.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"199 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":"133878728","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 the conventional power system, the space nuclear reactor power system can provide a more stable and longer-life electricity supply, which can better meet the requirements of deep space exploration. For space gas-cooled reactors, the impact of the submerged accidents after a launch abort situation must be considered. In such an accident, the core void is filled with seawater and wet sand, the neutron spectrum in the reactor is thermalized, and the reactivity increases significantly and probably making the reactor supercritical. In this paper, the research focuses on a novel control system named the control ring. Two different neutron-absorption materials are doped in the control ring, and the reactivity control effect of the control ring in submerged accidents is analyzed with different enrichments of fuel. Also, the burnup and neutron spectrum of these two materials are also studied. The result shows that the performance of the reactivity control effect of gadolinium in the submerged accidents is equal to boron-10, and the control effect of the control drums will slightly increase when gadolinium is doped in the control ring. In addition, the reactivity penalty of gadolinium is smaller than boron-10. These results can provide a reference for the design of space gas-cooled nuclear reactors.
{"title":"Research on In-Core Reactivity Control Method and Neutron Characteristic Analysis of a Space Gas-Cooled Reactor","authors":"Zhiqi Chen, Jiejin Cai, Xuezhong Li","doi":"10.1115/icone29-92383","DOIUrl":"https://doi.org/10.1115/icone29-92383","url":null,"abstract":"\u0000 Compared with the conventional power system, the space nuclear reactor power system can provide a more stable and longer-life electricity supply, which can better meet the requirements of deep space exploration. For space gas-cooled reactors, the impact of the submerged accidents after a launch abort situation must be considered. In such an accident, the core void is filled with seawater and wet sand, the neutron spectrum in the reactor is thermalized, and the reactivity increases significantly and probably making the reactor supercritical. In this paper, the research focuses on a novel control system named the control ring. Two different neutron-absorption materials are doped in the control ring, and the reactivity control effect of the control ring in submerged accidents is analyzed with different enrichments of fuel. Also, the burnup and neutron spectrum of these two materials are also studied. The result shows that the performance of the reactivity control effect of gadolinium in the submerged accidents is equal to boron-10, and the control effect of the control drums will slightly increase when gadolinium is doped in the control ring. In addition, the reactivity penalty of gadolinium is smaller than boron-10. These results can provide a reference for the design of space gas-cooled nuclear reactors.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"50 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":"132171252","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}
Yang Ming, Yang Jin, Yanlong Qiao, F. Zhao, Ruifeng Tian
In this paper, a dynamic model of a 5MW small modular supercritical CO2 Brayton-cycle reactor system is established based on Modelica language, and the control rod ejection accident simulation with different reactivity is carried out. This paper takes a 5MW small modular supercritical CO2 Brayton cycle reactor system as the research object. Based on the modular modeling idea, the dynamic model of the system including reactor, turbine, compressor, regenerator, cooler, and other main equipment is built, and the reactor power control system is based on the PID control principle is designed. The results show that the system has certain inherent safety, and the designed control system can coordinate the main equipment under accident conditions, maintain the important parameters such as reactor core fuel temperature, coolant temperature, and reactor pressure within the limit, and control the system flow, permeability and compressor rotor speed within a reasonable range. The work of this paper provides a certain reference for the selection of control strategy and safety system design of the new supercritical CO2 reactor system.
{"title":"Reactivity Introduction Accident and Control Strategy Analysis of Small Modular Supercritical CO2 Brayton-Cycle Reactor System","authors":"Yang Ming, Yang Jin, Yanlong Qiao, F. Zhao, Ruifeng Tian","doi":"10.1115/icone29-92122","DOIUrl":"https://doi.org/10.1115/icone29-92122","url":null,"abstract":"\u0000 In this paper, a dynamic model of a 5MW small modular supercritical CO2 Brayton-cycle reactor system is established based on Modelica language, and the control rod ejection accident simulation with different reactivity is carried out. This paper takes a 5MW small modular supercritical CO2 Brayton cycle reactor system as the research object. Based on the modular modeling idea, the dynamic model of the system including reactor, turbine, compressor, regenerator, cooler, and other main equipment is built, and the reactor power control system is based on the PID control principle is designed. The results show that the system has certain inherent safety, and the designed control system can coordinate the main equipment under accident conditions, maintain the important parameters such as reactor core fuel temperature, coolant temperature, and reactor pressure within the limit, and control the system flow, permeability and compressor rotor speed within a reasonable range. The work of this paper provides a certain reference for the selection of control strategy and safety system design of the new supercritical CO2 reactor system.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"27 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":"116690762","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}
Jing Wen, C. Pei, Meng Niu, Yingguo Li, Yurong Li, Qinghua Zhang, Chuan Huang, Y. Yin, Lixia He
Positron Emission Tomography (PET) is a nuclear imaging modality used in clinical diagnostics and biomedical research to show metabolic processes in an organism. Movable PET has great significance for the practical application of tumor diagnosis. In this paper, we propose a panel PET imaging system with high portability, and further evaluate a virtual-pinhole PET (VP-PET) system with higher spatial resolution. To evaluate the resolution of the PET prototype, we build a rotation stage coupled with two PET detector modules. PET detectors are composed of 12 × 12 LYSO crystals and Position Sensitive Photomultiplier Tubes (PSPMT). The central position of the two coincidence detectors is consistent with the rotation center, where a 22Na point source with a 3 mm diameter and an activity of 1 μCi is placed. The stage rotates several times on the horizontal plane, which enables signal acquisition within the range of 360°. A TCA DAQ system from Natuq is used for signal waveform acquisition, and FPGA algorithm programming is performed. After removing the coincidence detection data of repeated angles, the filtered back-projection (FBP) algorithm is used to reconstruct the 22Na point source image. Since the pixel size of the LYSO crystal directly affects the spatial resolution of the PET system, we set experiments of five types of LYSO crystals with pixels from 0.9mm to 2.0mm on VP-PET geometry. Meanwhile, the relationship between the spatial resolution of VP-PET with the pixel size of LYSO crystal is compared and analyzed in the experiments. In addition, in the Geant4 simulation, the two-dimensional image reconstruction of MRI glioma phantom is carried out by the panel PET system, which further proves that the VP-PET system has accurate spatial resolution and high sensitivity.
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