The coolant may vaporize in the centrifugal pump to cause cavitation in pool-type nuclear heating reactor. Installing a jetting device at the pump suction port is an effective means of applying jetting technology to solve the problem of preventing cavitation in centrifugal pumps. In this paper, an annular multi-nozzles ejector was designed and an experimental system was constructed to test the actual supercharging performance of the device. When the high-energy fluid at the pump outlet flowed through the device, it was first mixed uniformly in the annular chamber, and then injected through the nozzles to mix with the main flow to increase the pressure of the main flow. The static pressure at the suction port of the pump increased. Accordingly, the available Net Positive Suction Head (NPSHa) of the pump increased. The test was constructed around the total flow flux through the pump invariable and the main loop flow flux invariable two schemes. The results show that when the proportion of the return flow flux was same, the greater the total flow flux through the pump, the higher the pressure increment at the pump suction port; when the proportion of the return flow flux was larger, the difference in the pressure increment corresponding to different total flow fluxes was larger. When the flow flux through the main circuit of the system was same, the pressure increment increased nonlinearly with the increase of the return flow flux. Increasing the return flow flux was beneficial to the supercharging performance of the jetting device.
{"title":"Research on the Supercharging Performance of the Annular Multi-Nozzles Ejector at the Suction Port of a Centrifugal Pump","authors":"Fubing Ma, Guangming Fan, Junxiu Xu, Changqi Yan, Shuai Hao, Yuning Zhou","doi":"10.1115/icone29-93123","DOIUrl":"https://doi.org/10.1115/icone29-93123","url":null,"abstract":"\u0000 The coolant may vaporize in the centrifugal pump to cause cavitation in pool-type nuclear heating reactor. Installing a jetting device at the pump suction port is an effective means of applying jetting technology to solve the problem of preventing cavitation in centrifugal pumps. In this paper, an annular multi-nozzles ejector was designed and an experimental system was constructed to test the actual supercharging performance of the device. When the high-energy fluid at the pump outlet flowed through the device, it was first mixed uniformly in the annular chamber, and then injected through the nozzles to mix with the main flow to increase the pressure of the main flow. The static pressure at the suction port of the pump increased. Accordingly, the available Net Positive Suction Head (NPSHa) of the pump increased. The test was constructed around the total flow flux through the pump invariable and the main loop flow flux invariable two schemes. The results show that when the proportion of the return flow flux was same, the greater the total flow flux through the pump, the higher the pressure increment at the pump suction port; when the proportion of the return flow flux was larger, the difference in the pressure increment corresponding to different total flow fluxes was larger. When the flow flux through the main circuit of the system was same, the pressure increment increased nonlinearly with the increase of the return flow flux. Increasing the return flow flux was beneficial to the supercharging performance of the jetting device.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"38 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":"128378242","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}
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}
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}
Guangliang Yang, Weixiang Wang, Tao Ding, Hongli Chen
Thermal migration phenomena in the fast reactor can affect the temperature distribution and in-pile behaviors heavily through changing the local properties of nuclear fuels. In this research, the classical thermal diffusion equations for the oxygen diffusion, plutonium migration, Joint Oxide Gain (JOG) formation, and porosity migration are solved and integrated into the fuel rod performance analysis code KMC-Fueltra as thermal migration analysis module. Validations of these models have been performed by comparing with the experimental data or simulation results. Comparisons have proved the correctness of the thermal migration module in KMC-Fueltra. Effects of these phenomena to the fuel rod performance are analyzed and discussed under the steady-state operating conditions in the 1000MWth Medium-size Modular Lead-cooled Fast Reactor (M2LFR-1000) using multi-physics simulation of coupled thermal analysis, thermal migration analysis, fission gas release analysis and mechanical analysis. Simulation results show that the influence of thermal migration mainly reflects in the fuel pellet other than the cladding. It can result in large changes in some parameters during the evaluation of the fuel rod performance, compared with simulations that do not account for thermal migration phenomena.
快堆热迁移现象通过改变核燃料的局部性质，对堆内温度分布和堆内行为产生重大影响。在本研究中，求解了氧扩散、钚迁移、联合氧化增益(Joint Oxide Gain, JOG)形成和孔隙度迁移等经典热扩散方程，并将其作为热迁移分析模块集成到燃料棒性能分析程序KMC-Fueltra中。通过与实验数据或仿真结果的比较，对模型进行了验证。通过对比验证了KMC-Fueltra热迁移模块的正确性。采用耦合热分析、热迁移分析、裂变气体释放分析和力学分析等多物理场模拟方法，对1000mwm中型模块化铅冷快堆(M2LFR-1000)稳态工况下这些现象对燃料棒性能的影响进行了分析和讨论。模拟结果表明，热迁移的影响主要体现在燃料球团内部，而非包壳内部。与不考虑热迁移现象的模拟相比，在评估燃料棒性能时，它可能导致某些参数发生较大变化。
{"title":"Analysis on the Effects of Thermal Migration Phenomena to the Fuel Performance in the Fast Reactor","authors":"Guangliang Yang, Weixiang Wang, Tao Ding, Hongli Chen","doi":"10.1115/icone29-90561","DOIUrl":"https://doi.org/10.1115/icone29-90561","url":null,"abstract":"\u0000 Thermal migration phenomena in the fast reactor can affect the temperature distribution and in-pile behaviors heavily through changing the local properties of nuclear fuels. In this research, the classical thermal diffusion equations for the oxygen diffusion, plutonium migration, Joint Oxide Gain (JOG) formation, and porosity migration are solved and integrated into the fuel rod performance analysis code KMC-Fueltra as thermal migration analysis module. Validations of these models have been performed by comparing with the experimental data or simulation results. Comparisons have proved the correctness of the thermal migration module in KMC-Fueltra. Effects of these phenomena to the fuel rod performance are analyzed and discussed under the steady-state operating conditions in the 1000MWth Medium-size Modular Lead-cooled Fast Reactor (M2LFR-1000) using multi-physics simulation of coupled thermal analysis, thermal migration analysis, fission gas release analysis and mechanical analysis. Simulation results show that the influence of thermal migration mainly reflects in the fuel pellet other than the cladding. It can result in large changes in some parameters during the evaluation of the fuel rod performance, compared with simulations that do not account for thermal migration phenomena.","PeriodicalId":302303,"journal":{"name":"Volume 15: Student Paper Competition","volume":"72 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":"127334232","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}
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}
Flow boiling in vertical pipes widely exists in nuclear reactors. The bubble motion and behavior attract more and more attention due to their influence on the heat transfer capacity. However, the most used two-phase flow model in numerical simulation, called Eulerian two-fluid model, is not able to obtain parameters of phase interfaces and provide an observed image of bubble movements. Therefore, the present study aims to simulate the bubble behavior and trajectory in the saturated flow boiling in the vertical pipe using VOF model which can treat the deformation of interfaces. Firstly, the bubble parameters were calculated based on existing bubble dynamic models. Then, the random generation of bubbles was simulated by directly adding mass and momentum sources into the flow region by the User Defined Function (UDF). Finally, the deformation, collapse, and coalescence of bubbles were simulated and predicted in bubbly flow. The feasibility of the newly proposed model is proved by comparing with experimental data and other simulation results. The present study provides a new idea for simulating the movement of a large number of bubbles in the saturated flow boiling in vertical pipes, which adopts bubble parameters as boundary conditions directly, instead of heat and mass transfer models. In comparison, the present model can greatly improve the calculation efficiency.
{"title":"Bubble Behaviors in Saturated Flow Boiling Based on the VOF Model","authors":"Deyang Gao, Wen He, H. Bo","doi":"10.1115/icone29-92489","DOIUrl":"https://doi.org/10.1115/icone29-92489","url":null,"abstract":"\u0000 Flow boiling in vertical pipes widely exists in nuclear reactors. The bubble motion and behavior attract more and more attention due to their influence on the heat transfer capacity. However, the most used two-phase flow model in numerical simulation, called Eulerian two-fluid model, is not able to obtain parameters of phase interfaces and provide an observed image of bubble movements. Therefore, the present study aims to simulate the bubble behavior and trajectory in the saturated flow boiling in the vertical pipe using VOF model which can treat the deformation of interfaces. Firstly, the bubble parameters were calculated based on existing bubble dynamic models. Then, the random generation of bubbles was simulated by directly adding mass and momentum sources into the flow region by the User Defined Function (UDF). Finally, the deformation, collapse, and coalescence of bubbles were simulated and predicted in bubbly flow. The feasibility of the newly proposed model is proved by comparing with experimental data and other simulation results. The present study provides a new idea for simulating the movement of a large number of bubbles in the saturated flow boiling in vertical pipes, which adopts bubble parameters as boundary conditions directly, instead of heat and mass transfer models. In comparison, the present model can greatly improve the calculation efficiency.","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":"129388109","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.
{"title":"Design and Evaluation of a Prototype Portable Panel PET Imaging System","authors":"Jing Wen, C. Pei, Meng Niu, Yingguo Li, Yurong Li, Qinghua Zhang, Chuan Huang, Y. Yin, Lixia He","doi":"10.1115/icone29-92229","DOIUrl":"https://doi.org/10.1115/icone29-92229","url":null,"abstract":"\u0000 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.","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":"128518987","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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