Small modular reactors(SMRs) are beneficial in providing electricity power safely and viable for specific applications such as seawater desalination and heat production. Due to its inherent safety feature, the modular...Small modular reactors(SMRs) are beneficial in providing electricity power safely and viable for specific applications such as seawater desalination and heat production. Due to its inherent safety feature, the modular high temperature gas-cooled reactor(MHTGR) is considered as one of the best candidates for SMR-based nuclear power plants. Since its dynamics presents high nonlinearity and parameter uncertainty, it is necessary to develop adaptive power-level control, which is beneficial to safe, stable, and efficient operation of MHTGR and is easy to be implemented. In this paper, based on the physically-based control design approach, an adaptive outputfeedback power-level control is proposed for MHTGRs. This control can guarantee globally bounded closedloop stability and has a simple form. Numerical simulation results show the correctness of the theoretical analysis and satisfactory regulation performance of this control.展开更多
The following design features which satisfy fundamental safety design objectives of an MHTGR are analyzed: (i) inherent safety features to reactivity effect: (ii) passive decay heat removal: and (iii) multiple barrier...The following design features which satisfy fundamental safety design objectives of an MHTGR are analyzed: (i) inherent safety features to reactivity effect: (ii) passive decay heat removal: and (iii) multiple barriers.Several events have been identified to be the bounding. hypothetical accidents for the MHTGR. The important accident sequences leading to severe accidents are ingress of a large amount of water or air into the core. The analyses of severe accident scenarios have shown that even the harm of fuel element predicted to occur by chmeical reaction after a hypothetical large amount of water ingress into the core or air ingress into the core will not result in major impact on the environment due to the nitegrity of fuel particles remained. Therefore, it would not be necessary to require an emergency plan to evacuate nearby inhabitants.展开更多
Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The gra...Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The graphite balls consist of proper mix-ratio of natural graphite, electrographite and phenolic resin were manufactured and characterized by thermal conductivity, anisotropy of thermal expansion, crush strength, and drop strength. Results show that some types of graphite powders possess very high purity, degree of graphitization, and sound size distribution and apparent density, which can serve for matrix graphite of HTR-PM. The graphite balls manufactured with reasonable mix-ratio of graphite powders and process method show very good properties. It is indicated that the properties of graphite balls can meet the design criterion of HTR-PM. We can provide a powerful candidate material for the future manufacture of HTR-PM fuel elements.展开更多
Due to its inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR) has been seen as one of the best candidates in building next generation nuclear plants (NGNPs). Since the MHTGR dynamics has ...Due to its inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR) has been seen as one of the best candidates in building next generation nuclear plants (NGNPs). Since the MHTGR dynamics has high nonlinearity, it is necessary to develop nonlinear power-level controller which is not only beneficial to the safe, stable, efficient and autonomous operation of the MHTGR but also easy to be implemented practically. In this paper, based on the concept of shiftedectropy and the physically-based control design approach, it is proved theoretically that the simple proportional-differential (PD) output-feedback power-level control can provide globally asymptotic closed-loop stability. Numerical simulation results verify the theoretical results and show the influence of the controller parameters to the dynamic response.展开更多
High Temperature Gas-cooled Reactors are recognized as a representative advanced nuclear system for the future owing to the excellent safety performance,high efficiency,multipurpose uses and hydrogen production.These ...High Temperature Gas-cooled Reactors are recognized as a representative advanced nuclear system for the future owing to the excellent safety performance,high efficiency,multipurpose uses and hydrogen production.These type reactors are characterized by ceramic coated particle fuel,inert helium as coolant,and graphite used as moderator and reflector in core,which makes the outlet temperature of coolant reaching 950℃ even more.Under the National High Technology Program,the HTR-10 project has been successfully implemented and achieved full power operation in connection with the grid in January of 2003.HTR-10,which is the first module HTR with inherent safety feature around world,has carried out safety demonstration tests simulating the severe accident conditions in 2004.Based on the proven technologies and experience feedback during HTR-10 design,manufacture,construction and operation,a HTR-PM demonstration power plant with 200MWe power capacity sited at Rongcheng of Shandong province has been initiated.展开更多
The resuspension of graphite dust is an important phenomenon in the release of radioactivity and the safety of nuclear reactors during severe accidents.In this study,a visualization experimental platform is constructe...The resuspension of graphite dust is an important phenomenon in the release of radioactivity and the safety of nuclear reactors during severe accidents.In this study,a visualization experimental platform is constructed to study effects of particle size,flow velocity,and wall roughness on the resuspension characteristics of graphite particles.A statistical model of particle resuspension applicable to monolayer dispersed particles is developed based on the moment equilibrium of the particles and the flow field characteristics,as calculated by the large-eddy simulation framework.The results show that particle resuspension can be divided into short-and long-term resuspension stages.Most particle resuspension occurs during the short-term stage.With increases in flow velocity and particle diameter,the aerodynamic or adhesion force acting on the particles increases,and corresponding particle resuspension fraction increases.The influence of rough walls on particle resuspension is related to both the force on the particles and the arm ratio between the wall morphology and the particle diameter.A comparison with the experimental results demonstrates that the particle resuspension model developed in this study accurately predicts the impact of flow velocity,particle size,and wall roughness on particle resuspension.展开更多
The 10MW high temperature gas-cooled test reactor (HTR-10) under construction at INET uses whole ceramic fuel elements. The main barrier which prevents fission product release is the SiC layer of the coated fuel parti...The 10MW high temperature gas-cooled test reactor (HTR-10) under construction at INET uses whole ceramic fuel elements. The main barrier which prevents fission product release is the SiC layer of the coated fuel particles. Fabrication of high quality SiC layers is one of the key R&D tasks for the HTR-10 fuel element. The SiClayer was deposited on the fuel particles in a 50 mm conical fluidized bed using the CVD (chemical vapour deposition) technique. The density, thickness, strength and elastic modulus of the SiC layer were measured. The microstructure was observed using SEM (scanning electron microscope ). Parameters were established for manufacturing the SiC layer of the coated fuel particles to be used in the HTR-10. It was found that the traditional density measurement by the sink-float method is questionable in the low density region and that the SiC layer may be contaminated by uranium under certain conditions.展开更多
A very promising technology to achieve a carbon free energy system is to produce hydrogen from water, rather than from fossil fuels. Iodine-sulfur (IS) thermochemical water decomposition is one promising process. Th...A very promising technology to achieve a carbon free energy system is to produce hydrogen from water, rather than from fossil fuels. Iodine-sulfur (IS) thermochemical water decomposition is one promising process. The IS process can be used to efficiently produce hydrogen using the high temperature gas-cooled reactor (HTGR) as the energy source supplying gas at 1000℃. This paper describes that dem- onstration experiment for hydrogen production was carried out by an IS process at a laboratory scale. The results confirmed the feasibility of the closed-loop operation for recycling all the reactants besides the water, H2, and O2. Then the membrane technology was developed to enhance the decomposition efficiency. The maximum attainable one-pass conversion rate of HI exceeds 90% by membrane technology, whereas the equilibrium rate is about 20%.展开更多
The oxidation resistance of the matrix materials is vital to the normal operation of HTGR and is also an important parameter for evaluating the safety response under accidental air or water ingress conditions. The oxi...The oxidation resistance of the matrix materials is vital to the normal operation of HTGR and is also an important parameter for evaluating the safety response under accidental air or water ingress conditions. The oxidation kinetics of the three matrix material components: natural graphite, artificial graphite and resin carbon. was studied in a flowing gas mixture of oxygen and nitrogen using an auto thermogravimetric system. The results indicate that the artificial graphite has the slowest oxidation rate followed by the natural graphite and then the resin carbon with the highest oxidation rate. Vacuum heat treatment of the natural graphite at 1950℃ decreases the impurities and increases the oxidation activation energy. Differences between the activation energy and the oxidation rate of the resin carbon heat treated at 1950℃ and 1600℃ resulted from changes in the micro-pore texture. and the reduction of impurities.展开更多
The Modular High Temperature Gas-Cooled Reactor (HTR) can be used to burn plutonium fuel to reduce Pu stockpiles because of its inherent safety characteristics and ability to burn a variety of fuel mixtures. The equil...The Modular High Temperature Gas-Cooled Reactor (HTR) can be used to burn plutonium fuel to reduce Pu stockpiles because of its inherent safety characteristics and ability to burn a variety of fuel mixtures. The equilibrium core is calculated and analyzed for Pu enriched fuel. Fuel spheres with 7g heavy metal including the civilian grade Pu and thorium are loaded into the reactor. An enrichment of 11% is chosen to provide the desired equilibrium core reactivity. The fuel and moderator temperature coefficients are both negative. The maximum fuel element temperature during normal operation and during a loss of coolant accident is less than 1500℃. 92% of 239 Pu will be burnt during nomal operation. Therefore, a thorium fuel cycle in the modular HTR is an effective method for burning civilian grade plutonium.展开更多
文摘Small modular reactors(SMRs) are beneficial in providing electricity power safely and viable for specific applications such as seawater desalination and heat production. Due to its inherent safety feature, the modular high temperature gas-cooled reactor(MHTGR) is considered as one of the best candidates for SMR-based nuclear power plants. Since its dynamics presents high nonlinearity and parameter uncertainty, it is necessary to develop adaptive power-level control, which is beneficial to safe, stable, and efficient operation of MHTGR and is easy to be implemented. In this paper, based on the physically-based control design approach, an adaptive outputfeedback power-level control is proposed for MHTGRs. This control can guarantee globally bounded closedloop stability and has a simple form. Numerical simulation results show the correctness of the theoretical analysis and satisfactory regulation performance of this control.
文摘The following design features which satisfy fundamental safety design objectives of an MHTGR are analyzed: (i) inherent safety features to reactivity effect: (ii) passive decay heat removal: and (iii) multiple barriers.Several events have been identified to be the bounding. hypothetical accidents for the MHTGR. The important accident sequences leading to severe accidents are ingress of a large amount of water or air into the core. The analyses of severe accident scenarios have shown that even the harm of fuel element predicted to occur by chmeical reaction after a hypothetical large amount of water ingress into the core or air ingress into the core will not result in major impact on the environment due to the nitegrity of fuel particles remained. Therefore, it would not be necessary to require an emergency plan to evacuate nearby inhabitants.
文摘Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The graphite balls consist of proper mix-ratio of natural graphite, electrographite and phenolic resin were manufactured and characterized by thermal conductivity, anisotropy of thermal expansion, crush strength, and drop strength. Results show that some types of graphite powders possess very high purity, degree of graphitization, and sound size distribution and apparent density, which can serve for matrix graphite of HTR-PM. The graphite balls manufactured with reasonable mix-ratio of graphite powders and process method show very good properties. It is indicated that the properties of graphite balls can meet the design criterion of HTR-PM. We can provide a powerful candidate material for the future manufacture of HTR-PM fuel elements.
文摘Due to its inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR) has been seen as one of the best candidates in building next generation nuclear plants (NGNPs). Since the MHTGR dynamics has high nonlinearity, it is necessary to develop nonlinear power-level controller which is not only beneficial to the safe, stable, efficient and autonomous operation of the MHTGR but also easy to be implemented practically. In this paper, based on the concept of shiftedectropy and the physically-based control design approach, it is proved theoretically that the simple proportional-differential (PD) output-feedback power-level control can provide globally asymptotic closed-loop stability. Numerical simulation results verify the theoretical results and show the influence of the controller parameters to the dynamic response.
文摘High Temperature Gas-cooled Reactors are recognized as a representative advanced nuclear system for the future owing to the excellent safety performance,high efficiency,multipurpose uses and hydrogen production.These type reactors are characterized by ceramic coated particle fuel,inert helium as coolant,and graphite used as moderator and reflector in core,which makes the outlet temperature of coolant reaching 950℃ even more.Under the National High Technology Program,the HTR-10 project has been successfully implemented and achieved full power operation in connection with the grid in January of 2003.HTR-10,which is the first module HTR with inherent safety feature around world,has carried out safety demonstration tests simulating the severe accident conditions in 2004.Based on the proven technologies and experience feedback during HTR-10 design,manufacture,construction and operation,a HTR-PM demonstration power plant with 200MWe power capacity sited at Rongcheng of Shandong province has been initiated.
基金This project was supported by the Beijing Natural Science Foundation(No.JQ21009)the National Natural Science Foundation of China(NSFC)(No.52176158)+1 种基金the National Key R&D Program of China(No.2020YFB1901401)the Youth Talent Project of China National Nuclear Corporation.
文摘The resuspension of graphite dust is an important phenomenon in the release of radioactivity and the safety of nuclear reactors during severe accidents.In this study,a visualization experimental platform is constructed to study effects of particle size,flow velocity,and wall roughness on the resuspension characteristics of graphite particles.A statistical model of particle resuspension applicable to monolayer dispersed particles is developed based on the moment equilibrium of the particles and the flow field characteristics,as calculated by the large-eddy simulation framework.The results show that particle resuspension can be divided into short-and long-term resuspension stages.Most particle resuspension occurs during the short-term stage.With increases in flow velocity and particle diameter,the aerodynamic or adhesion force acting on the particles increases,and corresponding particle resuspension fraction increases.The influence of rough walls on particle resuspension is related to both the force on the particles and the arm ratio between the wall morphology and the particle diameter.A comparison with the experimental results demonstrates that the particle resuspension model developed in this study accurately predicts the impact of flow velocity,particle size,and wall roughness on particle resuspension.
文摘The 10MW high temperature gas-cooled test reactor (HTR-10) under construction at INET uses whole ceramic fuel elements. The main barrier which prevents fission product release is the SiC layer of the coated fuel particles. Fabrication of high quality SiC layers is one of the key R&D tasks for the HTR-10 fuel element. The SiClayer was deposited on the fuel particles in a 50 mm conical fluidized bed using the CVD (chemical vapour deposition) technique. The density, thickness, strength and elastic modulus of the SiC layer were measured. The microstructure was observed using SEM (scanning electron microscope ). Parameters were established for manufacturing the SiC layer of the coated fuel particles to be used in the HTR-10. It was found that the traditional density measurement by the sink-float method is questionable in the low density region and that the SiC layer may be contaminated by uranium under certain conditions.
基金Supported by the Ministry of Culture,Sport,Science, and Technology of the Japanese Government
文摘A very promising technology to achieve a carbon free energy system is to produce hydrogen from water, rather than from fossil fuels. Iodine-sulfur (IS) thermochemical water decomposition is one promising process. The IS process can be used to efficiently produce hydrogen using the high temperature gas-cooled reactor (HTGR) as the energy source supplying gas at 1000℃. This paper describes that dem- onstration experiment for hydrogen production was carried out by an IS process at a laboratory scale. The results confirmed the feasibility of the closed-loop operation for recycling all the reactants besides the water, H2, and O2. Then the membrane technology was developed to enhance the decomposition efficiency. The maximum attainable one-pass conversion rate of HI exceeds 90% by membrane technology, whereas the equilibrium rate is about 20%.
文摘The oxidation resistance of the matrix materials is vital to the normal operation of HTGR and is also an important parameter for evaluating the safety response under accidental air or water ingress conditions. The oxidation kinetics of the three matrix material components: natural graphite, artificial graphite and resin carbon. was studied in a flowing gas mixture of oxygen and nitrogen using an auto thermogravimetric system. The results indicate that the artificial graphite has the slowest oxidation rate followed by the natural graphite and then the resin carbon with the highest oxidation rate. Vacuum heat treatment of the natural graphite at 1950℃ decreases the impurities and increases the oxidation activation energy. Differences between the activation energy and the oxidation rate of the resin carbon heat treated at 1950℃ and 1600℃ resulted from changes in the micro-pore texture. and the reduction of impurities.
基金IAEA CRP on the Potential of Th- basedFuel Cycles to Constrain Pu and to Reduce the L ong- L ived Waste Toxicit
文摘The Modular High Temperature Gas-Cooled Reactor (HTR) can be used to burn plutonium fuel to reduce Pu stockpiles because of its inherent safety characteristics and ability to burn a variety of fuel mixtures. The equilibrium core is calculated and analyzed for Pu enriched fuel. Fuel spheres with 7g heavy metal including the civilian grade Pu and thorium are loaded into the reactor. An enrichment of 11% is chosen to provide the desired equilibrium core reactivity. The fuel and moderator temperature coefficients are both negative. The maximum fuel element temperature during normal operation and during a loss of coolant accident is less than 1500℃. 92% of 239 Pu will be burnt during nomal operation. Therefore, a thorium fuel cycle in the modular HTR is an effective method for burning civilian grade plutonium.
