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
Large stockpiles of civil-grade as well as weapons-grade plutonium have been accumulated in the world from nuclear power or other programs of different countries. One alternative for the management of the plutonium is...Large stockpiles of civil-grade as well as weapons-grade plutonium have been accumulated in the world from nuclear power or other programs of different countries. One alternative for the management of the plutonium is to incinerate it in the high temperature reactor （HTR）. The thorium-based fuel cycle was studied in the modular HTR to reduce weapons-grade plutonium stockpiles, while producing no additional plutonium or other transuranic elements. Three thorium-uranium fuel cycles were also investigated. The thorium absorption cross sections of the resolved and unresolved resonances were generated using the ZUTDGL code based on existing resonance data. The equilibrium core of the modular HTR was calculated and analyzed by means of the code VSOP＇94. The results show that the modular HTR can incinerate most of the initially loaded plutonium amounting to about 95.3% net 239pu for weapons-grade plutonium and can effectively utilize the uranium and thorium in the thorium-uranium fuel cycles.展开更多
In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transfor...In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transformer(CT)saturation and outliers.In this paper,a current trajectory image-based protection algorithm is proposed for AC lines connected to MMC-HVDC stations using a convolution neural network improved by a channel attention mechanism(CA-CNN).Taking the dual differential currents as two-dimensional coordinates of the moving point,the moving-point trajectories formed by differential currents have significant differences under internal and external faults.Therefore,internal faults can be identified using image recognition based on CA-CNN.This is improved by a channel attention mechanism,data augmentation,and adaptive learning rate.In comparison with other machine learning algorithms,the feature extraction ability and accuracy of CA-CNN are greatly improved.Various fault conditions like different net-work structures,operation modes,fault resistances,outliers,and current transformer saturation,are fully considered to verify the superiority of the proposed protection algorithm.The results confirm that the proposed current trajectory image-based protection algorithm has strong learning and generalizability,and can identify internal faults reliably.展开更多
The coolant thermal mixing performance in the hot gas plenum (HGP) in the core bottom reflector of the 10MW high temperature gas-cooled reactor test module (HTR-10) was experimentally investigated on a 1:1.5 scale tes...The coolant thermal mixing performance in the hot gas plenum (HGP) in the core bottom reflector of the 10MW high temperature gas-cooled reactor test module (HTR-10) was experimentally investigated on a 1:1.5 scale test model. The experimental results show that the HGP installed with a radial partition static mixer results in excellent thermal mixing of the coolant with a nondimensional temperature mixing degree (ε) value of 94%. Within the Re range from 1. 4 ×105～5. 8×105, the ε value reaches 94% at the outlet of the HGP and 99% at the outlet of the hot gas duct (HGD). There is little influence of the inlet flow rate ratio. Gh/Ge. on the thermal mixing performance in the Gh/Ge range from 0.5～2.0.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Large stockpiles of civil-grade as well as weapons-grade plutonium have been accumulated in the world from nuclear power or other programs of different countries. One alternative for the management of the plutonium is to incinerate it in the high temperature reactor （HTR）. The thorium-based fuel cycle was studied in the modular HTR to reduce weapons-grade plutonium stockpiles, while producing no additional plutonium or other transuranic elements. Three thorium-uranium fuel cycles were also investigated. The thorium absorption cross sections of the resolved and unresolved resonances were generated using the ZUTDGL code based on existing resonance data. The equilibrium core of the modular HTR was calculated and analyzed by means of the code VSOP＇94. The results show that the modular HTR can incinerate most of the initially loaded plutonium amounting to about 95.3% net 239pu for weapons-grade plutonium and can effectively utilize the uranium and thorium in the thorium-uranium fuel cycles.
基金supported in part by the Fundamental Research Funds for the Central Universities under Grant 2022JCCXJD01in part by Training Program of Innovation and Entrepreneurship for Undergraduates of China University of Mining and Technology(Beijing)under Grant 202204009.
文摘In the presence of an MMC-HVDC system,current differential protection(CDP)has the risk of failure in operation under an internal fault.In addition,CDP may also incur security issues in the presence of current transformer(CT)saturation and outliers.In this paper,a current trajectory image-based protection algorithm is proposed for AC lines connected to MMC-HVDC stations using a convolution neural network improved by a channel attention mechanism(CA-CNN).Taking the dual differential currents as two-dimensional coordinates of the moving point,the moving-point trajectories formed by differential currents have significant differences under internal and external faults.Therefore,internal faults can be identified using image recognition based on CA-CNN.This is improved by a channel attention mechanism,data augmentation,and adaptive learning rate.In comparison with other machine learning algorithms,the feature extraction ability and accuracy of CA-CNN are greatly improved.Various fault conditions like different net-work structures,operation modes,fault resistances,outliers,and current transformer saturation,are fully considered to verify the superiority of the proposed protection algorithm.The results confirm that the proposed current trajectory image-based protection algorithm has strong learning and generalizability,and can identify internal faults reliably.
文摘The coolant thermal mixing performance in the hot gas plenum (HGP) in the core bottom reflector of the 10MW high temperature gas-cooled reactor test module (HTR-10) was experimentally investigated on a 1:1.5 scale test model. The experimental results show that the HGP installed with a radial partition static mixer results in excellent thermal mixing of the coolant with a nondimensional temperature mixing degree (ε) value of 94%. Within the Re range from 1. 4 ×105～5. 8×105, the ε value reaches 94% at the outlet of the HGP and 99% at the outlet of the hot gas duct (HGD). There is little influence of the inlet flow rate ratio. Gh/Ge. on the thermal mixing performance in the Gh/Ge range from 0.5～2.0.
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.
