Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in ...Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in SDG generated from chemical process. From the point of the inherent operability, the worst unsafe factor is the SDG having positive loops that means any disturbance occurring within the loop will propagate through the nodes one by one and are amplified gradually, so the system may lose control, which may lead to an accident. So finding the positive loops in a SDG and treating these unsafe factors in a proper manner can improve the inherent safety of a chemical process. This article proposed a method that can detect the above-mentioned unsafe factors in the proc- ess conceptual design stage automatically through the analysis of the SDG generated from the chemical process. A case study is illustrated to show the working of the algorithm, and then a complicated case from industry is studied to depict the effectiveness of the proposed algorithm.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
For the submerged high-pressure liquid hydrogen pump,a core piece of equipment of liquid hydrogen transportation,extensive analysis,and research were conducted on its components and structure during the development pr...For the submerged high-pressure liquid hydrogen pump,a core piece of equipment of liquid hydrogen transportation,extensive analysis,and research were conducted on its components and structure during the development process.By referencing typical failure probabilities in the energy industry and statistical data from prototype pump development and testing,a list of failure probabilities for each part of the liquid hydrogen pump was compiled,and the consequences of those failures were deduced.The nitrogen liquid test experiment verified the possibility of pump seal failure and identified the fault modes.It confirmed that the piston rod seal is one of the critical components prone to failure in the liquid hydrogen pump.Subsequently,six important technical optimization measures for the piston rod seal pair have been carried out,reducing the probability of failure.Moreover,based on the concept of inherent safety,the sealing structure of the piston rod was innovatively designed,transforming hidden failures into visible ones,facilitating timely detection and monitoring of failures,and greatly reducing the safety risks caused by piston rod seal failure.The improved liquid hydrogen pump successfully passed subsequent tests,ensuring its long-term safe operation.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
The research and development (R & D) of nuclear heating reactors (NHRs) have been conducted as one of the national key projects in science and technology in China since the 1980s. This paper presents the developme...The research and development (R & D) of nuclear heating reactors (NHRs) have been conducted as one of the national key projects in science and technology in China since the 1980s. This paper presents the development status. main design featur and safety concepts of the NHR.展开更多
文摘Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in SDG generated from chemical process. From the point of the inherent operability, the worst unsafe factor is the SDG having positive loops that means any disturbance occurring within the loop will propagate through the nodes one by one and are amplified gradually, so the system may lose control, which may lead to an accident. So finding the positive loops in a SDG and treating these unsafe factors in a proper manner can improve the inherent safety of a chemical process. This article proposed a method that can detect the above-mentioned unsafe factors in the proc- ess conceptual design stage automatically through the analysis of the SDG generated from the chemical process. A case study is illustrated to show the working of the algorithm, and then a complicated case from industry is studied to depict the effectiveness of the proposed algorithm.
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.
文摘For the submerged high-pressure liquid hydrogen pump,a core piece of equipment of liquid hydrogen transportation,extensive analysis,and research were conducted on its components and structure during the development process.By referencing typical failure probabilities in the energy industry and statistical data from prototype pump development and testing,a list of failure probabilities for each part of the liquid hydrogen pump was compiled,and the consequences of those failures were deduced.The nitrogen liquid test experiment verified the possibility of pump seal failure and identified the fault modes.It confirmed that the piston rod seal is one of the critical components prone to failure in the liquid hydrogen pump.Subsequently,six important technical optimization measures for the piston rod seal pair have been carried out,reducing the probability of failure.Moreover,based on the concept of inherent safety,the sealing structure of the piston rod was innovatively designed,transforming hidden failures into visible ones,facilitating timely detection and monitoring of failures,and greatly reducing the safety risks caused by piston rod seal failure.The improved liquid hydrogen pump successfully passed subsequent tests,ensuring its long-term safe operation.
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The research and development (R & D) of nuclear heating reactors (NHRs) have been conducted as one of the national key projects in science and technology in China since the 1980s. This paper presents the development status. main design featur and safety concepts of the NHR.
