Nonlinear vibrations of a single fuel rod in nuclear heating reactor with fixed-fixed ends and subjected to various excitation levels are comprehensively analyzed using explicit dynamics. The responses of empty, pellet-filled, and water-submerged rod are investigated. Pellet-cladding and pellet-pellet interactions are addressed by a penalty-based contact treatment, meanwhile the fluid-structure interactions (FSI) between the vibrating fuel rod and surrounding coolants are simulated by the Arbitrary Lagrangian-Eulerian (ALE) method, wherein the water is modeled as Eulerian elements. The results reveal that both empty and pellet-filled rods exhibit frequency hardening phenomena, where eigenfrequencies increase with vibration amplitude due to geometric nonlinearity. The damping decay resulting from fuel pellet motions is found to be positively correlated with vibration amplitude, thereby enhancing the reactor safety. For submerged rod, the frequency decreases due to added mass effects, and the overall system damping increases despite structural damping from dry friction and impacts is reduced.
{"title":"Nonlinear vibrations analysis of a fuel rod in nuclear heating reactor","authors":"Musen Lin, Dingqu Wang, Junzheng Zheng, Yueyuan Jiang","doi":"10.1016/j.pnucene.2024.105531","DOIUrl":"10.1016/j.pnucene.2024.105531","url":null,"abstract":"<div><div>Nonlinear vibrations of a single fuel rod in nuclear heating reactor with fixed-fixed ends and subjected to various excitation levels are comprehensively analyzed using explicit dynamics. The responses of empty, pellet-filled, and water-submerged rod are investigated. Pellet-cladding and pellet-pellet interactions are addressed by a penalty-based contact treatment, meanwhile the fluid-structure interactions (FSI) between the vibrating fuel rod and surrounding coolants are simulated by the Arbitrary Lagrangian-Eulerian (ALE) method, wherein the water is modeled as Eulerian elements. The results reveal that both empty and pellet-filled rods exhibit frequency hardening phenomena, where eigenfrequencies increase with vibration amplitude due to geometric nonlinearity. The damping decay resulting from fuel pellet motions is found to be positively correlated with vibration amplitude, thereby enhancing the reactor safety. For submerged rod, the frequency decreases due to added mass effects, and the overall system damping increases despite structural damping from dry friction and impacts is reduced.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105531"},"PeriodicalIF":3.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-29DOI: 10.1016/j.pnucene.2024.105540
Yuan Lanfei, Li Ziang, Wang Chenglong, Qiu Suizheng
Lead-bismuth fast reactor may solidify under accident conditions due to overcooling in components such as steam generators, waste heat exhaust heat exchangers, etc. In order to investigate the impact of the solidified layer adhering to the wall surface on the transient flow heat transfer and pressure drop characteristics of lead-bismuth eutectic, an experimental study of lead-bismuth eutectic solidification phenomenon flowing in a vertical circular tube was conducted. Moreover, a rapid prediction model for lead-bismuth eutectic solidification phenomenon was developed and verified with experimental results. The experimental results demonstrate that the formation of solidification layer results in a reduction in time-averaged Nu by approximately 43%, while concurrently exhibiting a sustained increase in pressure drop of the fluid flow. Additionally, the maximum thickness of the solidification layer on one side is 6.4 mm (inner diameter of the round tube is 20 mm), while the average thickness is 1.97 mm. The findings demonstrate that the formation of the solidification layer not only markedly diminishes the heat transfer efficiency between the lead-bismuth eutectic fluid and the wall but also augments the flow resistance.
{"title":"Experimental and model development of lead-bismuth eutectic solidification phenomenon flowing inside the tube","authors":"Yuan Lanfei, Li Ziang, Wang Chenglong, Qiu Suizheng","doi":"10.1016/j.pnucene.2024.105540","DOIUrl":"10.1016/j.pnucene.2024.105540","url":null,"abstract":"<div><div>Lead-bismuth fast reactor may solidify under accident conditions due to overcooling in components such as steam generators, waste heat exhaust heat exchangers, etc. In order to investigate the impact of the solidified layer adhering to the wall surface on the transient flow heat transfer and pressure drop characteristics of lead-bismuth eutectic, an experimental study of lead-bismuth eutectic solidification phenomenon flowing in a vertical circular tube was conducted. Moreover, a rapid prediction model for lead-bismuth eutectic solidification phenomenon was developed and verified with experimental results. The experimental results demonstrate that the formation of solidification layer results in a reduction in time-averaged Nu by approximately 43%, while concurrently exhibiting a sustained increase in pressure drop of the fluid flow. Additionally, the maximum thickness of the solidification layer on one side is 6.4 mm (inner diameter of the round tube is 20 mm), while the average thickness is 1.97 mm. The findings demonstrate that the formation of the solidification layer not only markedly diminishes the heat transfer efficiency between the lead-bismuth eutectic fluid and the wall but also augments the flow resistance.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105540"},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-28DOI: 10.1016/j.pnucene.2024.105535
Siwei Qi , Bin Han , Xiaoliang Zhu , Bao-Wen Yang , Tianyang Xing , Aiguo Liu , Shenghui Liu
Accurate prediction and assessment of Critical Heat Flux(CHF) events are essential for reducing Departure From Nucleate Boiling ratio(DNBr), thereby ensuring reactor safety and enhancing the economic efficiency of nuclear power plants. The application of Machine Learning(ML) models for predicting CHF has garnered significant attention in recent research. These models are not only more accessible but also provide a broader applicability and greater accuracy than traditional empirical CHF correlations, making them a hot topic in this field. To disseminate the latest advancements in the application of ML techniques for predicting CHF and to refine these models for superior predictive performance. This paper reviews recent advancements in the application of ML techniques to CHF predicting, categorizing the research into CHF value prediction and CHF event identification. The synthesis covers the performance of various ML models under different conditions, examining input feature selection, model training, performance evaluation, addressing current deficiencies in data generation and model performance assessment. Additionally, the paper in CHF event identification summarizes the strengths and weaknesses of approaches. Finally, the perspectives of challenges and future directions in CHF studies are proposed. The review emphasizing the potential significance of these advancements for further exploration and application of ML in CHF research.
{"title":"Machine learning in critical heat flux studies in nuclear systems: A detailed review","authors":"Siwei Qi , Bin Han , Xiaoliang Zhu , Bao-Wen Yang , Tianyang Xing , Aiguo Liu , Shenghui Liu","doi":"10.1016/j.pnucene.2024.105535","DOIUrl":"10.1016/j.pnucene.2024.105535","url":null,"abstract":"<div><div>Accurate prediction and assessment of Critical Heat Flux(CHF) events are essential for reducing Departure From Nucleate Boiling ratio(DNBr), thereby ensuring reactor safety and enhancing the economic efficiency of nuclear power plants. The application of Machine Learning(ML) models for predicting CHF has garnered significant attention in recent research. These models are not only more accessible but also provide a broader applicability and greater accuracy than traditional empirical CHF correlations, making them a hot topic in this field. To disseminate the latest advancements in the application of ML techniques for predicting CHF and to refine these models for superior predictive performance. This paper reviews recent advancements in the application of ML techniques to CHF predicting, categorizing the research into CHF value prediction and CHF event identification. The synthesis covers the performance of various ML models under different conditions, examining input feature selection, model training, performance evaluation, addressing current deficiencies in data generation and model performance assessment. Additionally, the paper in CHF event identification summarizes the strengths and weaknesses of approaches. Finally, the perspectives of challenges and future directions in CHF studies are proposed. The review emphasizing the potential significance of these advancements for further exploration and application of ML in CHF research.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105535"},"PeriodicalIF":3.3,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.pnucene.2024.105537
Longxiang Zhu , Li Liu , Luteng Zhang , Qiang Lian , Simiao Tang , Zaiyong Ma , Wan Sun , Liangming Pan
Understanding the bubble motion characteristics in the two-phase flow is crucial for mass, momentum, and heat transfer processes between gas and liquid phases in various engineering systems. Despite decades of studying the phenomenon of bubbles rising in quiescent water, there is no unified conclusion regarding the three-dimensional motion characteristics of bubbles larger than 3 mm, where bubbles exhibit zigzag or spiral trajectories with shape oscillations. Meanwhile, the zigzag and spiral motions are sustained by the induced additional lift caused by the wake vortices acting on the bubbles, however, the evolution of forces acting on the bubbles during the stable rising phase has not been further studied by considering the combined effects of forces. This paper presents experimental research on the three-dimensional motion characteristics of bubbles during the stable rising phase. The results show that the bubbles transition from ellipsoidal shape to irregular shapes as the diameter increases, and the trajectory of the bubbles changes from regular spiral motion to random motion coupled with straight lines, zigzags, and spiral. The motion of bubbles during the stable rising phase is influenced by the combined effects of buoyancy, drag, and induced lift by the wake vortex. Additionally, the aspect ratio and terminal velocity of the bubbles were investigated using empirical relationships and dimensionless numbers, Eotvos, Weber, and Tadaki number. It was found that using the Tadaki number to predict the aspect ratio yielded the most accurate results, with the experimental values well predicted by an empirical correlation.
{"title":"Experimental study of three-dimensional trajectory and dynamic characteristics of rising bubbles","authors":"Longxiang Zhu , Li Liu , Luteng Zhang , Qiang Lian , Simiao Tang , Zaiyong Ma , Wan Sun , Liangming Pan","doi":"10.1016/j.pnucene.2024.105537","DOIUrl":"10.1016/j.pnucene.2024.105537","url":null,"abstract":"<div><div>Understanding the bubble motion characteristics in the two-phase flow is crucial for mass, momentum, and heat transfer processes between gas and liquid phases in various engineering systems. Despite decades of studying the phenomenon of bubbles rising in quiescent water, there is no unified conclusion regarding the three-dimensional motion characteristics of bubbles larger than 3 mm, where bubbles exhibit zigzag or spiral trajectories with shape oscillations. Meanwhile, the zigzag and spiral motions are sustained by the induced additional lift caused by the wake vortices acting on the bubbles, however, the evolution of forces acting on the bubbles during the stable rising phase has not been further studied by considering the combined effects of forces. This paper presents experimental research on the three-dimensional motion characteristics of bubbles during the stable rising phase. The results show that the bubbles transition from ellipsoidal shape to irregular shapes as the diameter increases, and the trajectory of the bubbles changes from regular spiral motion to random motion coupled with straight lines, zigzags, and spiral. The motion of bubbles during the stable rising phase is influenced by the combined effects of buoyancy, drag, and induced lift by the wake vortex. Additionally, the aspect ratio and terminal velocity of the bubbles were investigated using empirical relationships and dimensionless numbers, Eotvos, Weber, and Tadaki number. It was found that using the Tadaki number to predict the aspect ratio yielded the most accurate results, with the experimental values well predicted by an empirical correlation.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105537"},"PeriodicalIF":3.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-26DOI: 10.1016/j.pnucene.2024.105538
Qiuwen Wang
The maritime industry's critical role in global greenhouse gas emissions necessitates innovative solutions for decarbonization. The adoption of nuclear energy in maritime and offshore applications holds the potential to align it with low-carbon emission objectives. China has recognized the urgency of emissions reduction and harnessed its nuclear expertise to lead the way in applying nuclear technology for maritime decarbonization. This research conducts an in-depth examination of China's law and policy initiatives aimed at promoting nuclear energy adoption in maritime and offshore contexts, employing a policy analysis approach to assess their effectiveness while unveiling inherent challenges and problems. This study also delves into the extensive international implications of China's foray into nuclear marine propulsion programs and highlights the imperative for collaborative efforts, comprehensive regulatory frameworks, and adaptive international governance structures to ensure the responsible development and operation of nuclear marine propulsion equipment while minimizing risks and conflicts on the global stage.
{"title":"China's law and policy initiatives for integrating nuclear energy in maritime applications: A critical review","authors":"Qiuwen Wang","doi":"10.1016/j.pnucene.2024.105538","DOIUrl":"10.1016/j.pnucene.2024.105538","url":null,"abstract":"<div><div>The maritime industry's critical role in global greenhouse gas emissions necessitates innovative solutions for decarbonization. The adoption of nuclear energy in maritime and offshore applications holds the potential to align it with low-carbon emission objectives. China has recognized the urgency of emissions reduction and harnessed its nuclear expertise to lead the way in applying nuclear technology for maritime decarbonization. This research conducts an in-depth examination of China's law and policy initiatives aimed at promoting nuclear energy adoption in maritime and offshore contexts, employing a policy analysis approach to assess their effectiveness while unveiling inherent challenges and problems. This study also delves into the extensive international implications of China's foray into nuclear marine propulsion programs and highlights the imperative for collaborative efforts, comprehensive regulatory frameworks, and adaptive international governance structures to ensure the responsible development and operation of nuclear marine propulsion equipment while minimizing risks and conflicts on the global stage.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105538"},"PeriodicalIF":3.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.pnucene.2024.105534
Xiangyuan Meng , Mei Huang , Jianghao Yang , Xiaoping Ouyang , Boxue Wang , Yanping Huang , Hiroshi Matsuda , Bo Cao
The inverse problems of the convection-diffusion equation (ICDE) have received extensive attention in incomplete boundary conditions and uncertain source terms. They can be applied in thermally stratified pipe elbows and so on. Many algorithms need to combine with optimization algorithms to repeatedly calculate the direct problem in the solution process. To solve such problems, this paper employs a boundary-type algorithm named the half-boundary method (HBM). The HBM does not require additional repeated optimization of the direct problem. To test the performance of the method, the numerical simulations of some problems have been carried out, including the inverse problems of heat convection, river pollution and air pollution. The results show that the HBM has the desired accuracy by comparing with the exact solution. If there are errors in the measurement process, the solution doesn't generate a large deviation from the result. It is worth noting that the placement of internal measurement points minimally impacts the numerical results within the solution domain. And the method is also able to handle with discontinuous problems. Because the Gaussian plume model verifies the accuracy of HBM, the HBM can quickly calculate the atmospheric diffusion of the non-Gaussian plume model.
{"title":"Application of a boundary-type algorithm to the inverse problems of convective heat and mass transfer","authors":"Xiangyuan Meng , Mei Huang , Jianghao Yang , Xiaoping Ouyang , Boxue Wang , Yanping Huang , Hiroshi Matsuda , Bo Cao","doi":"10.1016/j.pnucene.2024.105534","DOIUrl":"10.1016/j.pnucene.2024.105534","url":null,"abstract":"<div><div>The inverse problems of the convection-diffusion equation (ICDE) have received extensive attention in incomplete boundary conditions and uncertain source terms. They can be applied in thermally stratified pipe elbows and so on. Many algorithms need to combine with optimization algorithms to repeatedly calculate the direct problem in the solution process. To solve such problems, this paper employs a boundary-type algorithm named the half-boundary method (HBM). The HBM does not require additional repeated optimization of the direct problem. To test the performance of the method, the numerical simulations of some problems have been carried out, including the inverse problems of heat convection, river pollution and air pollution. The results show that the HBM has the desired accuracy by comparing with the exact solution. If there are errors in the measurement process, the solution doesn't generate a large deviation from the result. It is worth noting that the placement of internal measurement points minimally impacts the numerical results within the solution domain. And the method is also able to handle with discontinuous problems. Because the Gaussian plume model verifies the accuracy of HBM, the HBM can quickly calculate the atmospheric diffusion of the non-Gaussian plume model.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105534"},"PeriodicalIF":3.3,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.pnucene.2024.105533
Hao Ding , Daogang Lu , Danting Sui , Xiao Luo , Kunjun Han
The combination of supercritical carbon dioxide (SCO2) Brayton cycle and microreactor is a promising technology. SCO2 direct-cooled microreactor system takes advantages of compact system design and high efficiency, which can be applied in various scenes. Although the design SCO2 Brayton cycle system is already compact, the control rods in reactor core still results in relatively large design size of the reactor. Considering relatively high negative temperature coefficient of reactor core and fast response characteristics of SCO2 Brayton cycle, simplified control strategies are proposed in this paper to reduce the number of control rods in the reactor, thus decreasing the diameter of the reactor. Aimed towards the design of SCO2 cooled floating nuclear power plant (SCFNP),the simplified control strategies are proposed. Then, adjustment ranges of system key parameters with different control strategies are simulated, and comparisons between them in various aspects are performed. According to the results, inventory control, shaft speed control and bypass valve control are proved to be able to adjust reactor power effectively instead of control rods. When applied shaft speed control and bypass valve control, system maximum temperature obviously exceeds the design temperature, which is about 12% and 20% respectively. What's more, inventory control and shaft speed control take about six times longer than bypass control to stabilized the system parameters. Besides, advantages and disadvantages are concluded of the three different control strategies, which can be used as reference of the control system design for SCO2 direct-cooled microreactor system.
{"title":"Transient characteristics and adjustment ranges of key parameters in supercritical CO2 direct-cooled microreactor system with simplified control strategies","authors":"Hao Ding , Daogang Lu , Danting Sui , Xiao Luo , Kunjun Han","doi":"10.1016/j.pnucene.2024.105533","DOIUrl":"10.1016/j.pnucene.2024.105533","url":null,"abstract":"<div><div>The combination of supercritical carbon dioxide (SCO<sub>2</sub>) Brayton cycle and microreactor is a promising technology. SCO<sub>2</sub> direct-cooled microreactor system takes advantages of compact system design and high efficiency, which can be applied in various scenes. Although the design SCO<sub>2</sub> Brayton cycle system is already compact, the control rods in reactor core still results in relatively large design size of the reactor. Considering relatively high negative temperature coefficient of reactor core and fast response characteristics of SCO<sub>2</sub> Brayton cycle, simplified control strategies are proposed in this paper to reduce the number of control rods in the reactor, thus decreasing the diameter of the reactor. Aimed towards the design of SCO<sub>2</sub> cooled floating nuclear power plant (SCFNP),the simplified control strategies are proposed. Then, adjustment ranges of system key parameters with different control strategies are simulated, and comparisons between them in various aspects are performed. According to the results, inventory control, shaft speed control and bypass valve control are proved to be able to adjust reactor power effectively instead of control rods. When applied shaft speed control and bypass valve control, system maximum temperature obviously exceeds the design temperature, which is about 12% and 20% respectively. What's more, inventory control and shaft speed control take about six times longer than bypass control to stabilized the system parameters. Besides, advantages and disadvantages are concluded of the three different control strategies, which can be used as reference of the control system design for SCO<sub>2</sub> direct-cooled microreactor system.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105533"},"PeriodicalIF":3.3,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.pnucene.2024.105527
Xuyao Geng, Wenkui Ma, Jie Wang
Microreactors coupled with closed helium Brayton cycle (MR-CBC) can be used as mobile nuclear power source and have a wide range of application prospects. The power regulation methods and accident control measures are the key to safe and efficient operation of MR-CBC system. In this paper, the dynamic model of MR-CBC system is established, the characteristics of MR-CBC under bypass valve regulation method and load rejection event are analyzed. The results indicate that bypass valve is a fast regulating device. The power distribution of MR-CBC can be changed significantly and quickly with little change in core power. This regulation method changes the flow rate and operating performance of compressor and turbine, resulting in an increase in the proportion of compressor power consumption, a rapid reduction in generator power, and a significant drop in system efficiency. After losing the generator load, if no protection measures are taken, the shaft speed will increase rapidly and exceed the designed limit value in a short time. Due to the short time left for the protection system to act, it is necessary to prepare responsive control methods, such as bypass valve regulation. Finally, the transient characteristics of load rejection under the control of bypass valve are analyzed. Opening the bypass valve can avoid overspeed of the shaft. When the valve opening action is assumed to be completed in 0.25s, at least 1.37 kg/s of bypass flow rate is required to keep the rotational speed below designed limit value. The simulation results demonstrate the basic characteristics of power regulation and mitigation measures, and provide a reference for the design and operation of MR-CBC.
{"title":"Study on transient characteristics for bypass valve regulation and load rejection of microreactor with helium Brayton cycle","authors":"Xuyao Geng, Wenkui Ma, Jie Wang","doi":"10.1016/j.pnucene.2024.105527","DOIUrl":"10.1016/j.pnucene.2024.105527","url":null,"abstract":"<div><div>Microreactors coupled with closed helium Brayton cycle (MR-CBC) can be used as mobile nuclear power source and have a wide range of application prospects. The power regulation methods and accident control measures are the key to safe and efficient operation of MR-CBC system. In this paper, the dynamic model of MR-CBC system is established, the characteristics of MR-CBC under bypass valve regulation method and load rejection event are analyzed. The results indicate that bypass valve is a fast regulating device. The power distribution of MR-CBC can be changed significantly and quickly with little change in core power. This regulation method changes the flow rate and operating performance of compressor and turbine, resulting in an increase in the proportion of compressor power consumption, a rapid reduction in generator power, and a significant drop in system efficiency. After losing the generator load, if no protection measures are taken, the shaft speed will increase rapidly and exceed the designed limit value in a short time. Due to the short time left for the protection system to act, it is necessary to prepare responsive control methods, such as bypass valve regulation. Finally, the transient characteristics of load rejection under the control of bypass valve are analyzed. Opening the bypass valve can avoid overspeed of the shaft. When the valve opening action is assumed to be completed in 0.25s, at least 1.37 kg/s of bypass flow rate is required to keep the rotational speed below designed limit value. The simulation results demonstrate the basic characteristics of power regulation and mitigation measures, and provide a reference for the design and operation of MR-CBC.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105527"},"PeriodicalIF":3.3,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.pnucene.2024.105532
Boxue Wang , Mei Huang , Xiangyuan Meng , Xiaoping Ouyang , Yanping Huang , Hiroshi Matsuda , Chihiro Morita
The use of annular fuel in nuclear power plants has been developed to improve their efficiency, safety, and economic viability. Therefore, studying the thermal hydraulic issues of annular fuel is crucial. The melting of annular fuel under accident conditions is equally important. This study uses a novel numerical technique called the Half Boundary Method (HBM) to tackle this issue. With new variables introduced, this method avoids the need for additional continuity equations at the boundary when solving multi-layer composite problems. First, the HBM is used to model a multi-layer composite ring and solve its transient thermal problems, which are then verified. Next, the temperature distribution of annular fuel under operational conditions is calculated, and the results are compared to validate HBM's accuracy. Based on these findings, simulations are conducted to model the melting phase transitions of annular fuel during Loss of Coolant Accidents (LOCAs) and Reactivity Insertion Accidents (RIAs).
{"title":"Numerical study on the melting behavior of annular fuel under accident conditions","authors":"Boxue Wang , Mei Huang , Xiangyuan Meng , Xiaoping Ouyang , Yanping Huang , Hiroshi Matsuda , Chihiro Morita","doi":"10.1016/j.pnucene.2024.105532","DOIUrl":"10.1016/j.pnucene.2024.105532","url":null,"abstract":"<div><div>The use of annular fuel in nuclear power plants has been developed to improve their efficiency, safety, and economic viability. Therefore, studying the thermal hydraulic issues of annular fuel is crucial. The melting of annular fuel under accident conditions is equally important. This study uses a novel numerical technique called the Half Boundary Method (HBM) to tackle this issue. With new variables introduced, this method avoids the need for additional continuity equations at the boundary when solving multi-layer composite problems. First, the HBM is used to model a multi-layer composite ring and solve its transient thermal problems, which are then verified. Next, the temperature distribution of annular fuel under operational conditions is calculated, and the results are compared to validate HBM's accuracy. Based on these findings, simulations are conducted to model the melting phase transitions of annular fuel during Loss of Coolant Accidents (LOCAs) and Reactivity Insertion Accidents (RIAs).</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105532"},"PeriodicalIF":3.3,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.pnucene.2024.105519
V. Zeman, Z. Hlaváč, Š. Dyk
The paper presents a comprehensive method for modelling contact interactions between two different types of fuel assemblies within a mixed core. Particular emphasis is placed on the hexagonal fuel assemblies commonly found in VVER reactors. The presence of bowed fuel assemblies may induce mutual contact, resulting in temporary or permanent contact conditions. This interaction, in conjunction with the vibration of core components, can lead to fretting wear of the load-bearing skeletons of fuel assemblies. By using the proposed computational model and experimentally estimated fretting wear parameters, the method allows detailed analysis of fretting wear as a function of various factors. These factors include operating conditions, distribution of fuel assembly types within the mixed core, burn-up state of contacting assemblies and the shape of their static deformation.
{"title":"Contact phenomena between load-bearing skeletons of bowed fuel assemblies in PWRs with mixed cores","authors":"V. Zeman, Z. Hlaváč, Š. Dyk","doi":"10.1016/j.pnucene.2024.105519","DOIUrl":"10.1016/j.pnucene.2024.105519","url":null,"abstract":"<div><div>The paper presents a comprehensive method for modelling contact interactions between two different types of fuel assemblies within a mixed core. Particular emphasis is placed on the hexagonal fuel assemblies commonly found in VVER reactors. The presence of bowed fuel assemblies may induce mutual contact, resulting in temporary or permanent contact conditions. This interaction, in conjunction with the vibration of core components, can lead to fretting wear of the load-bearing skeletons of fuel assemblies. By using the proposed computational model and experimentally estimated fretting wear parameters, the method allows detailed analysis of fretting wear as a function of various factors. These factors include operating conditions, distribution of fuel assembly types within the mixed core, burn-up state of contacting assemblies and the shape of their static deformation.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"178 ","pages":"Article 105519"},"PeriodicalIF":3.3,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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