In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R...In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R＆D have been completed. The divertor is designed in an up-down symmetric configuration to accommodate both double null and single null plasma operation. Passive plates are used for plasma movement control. In-vessel coils are used for the active control of plasma vertical movements. Each cryo-pump can provide an approximately 45 m^3/s pumping rate at a pressure of 10^-1 Pa for particle exhaust. Analysis shows that, when a plasma current of 1 MA disrupts in 3 ms, the EM loads caused by the eddy current and the halo current in a vertical displacement event （VDE） will not generate an unacceptable stress on the divertor structure. The bolted divertor thermal structure with an active cooling system can sustain a load of 2 MW/m^2 up to a 60 s operation if the plasma facing surface temperature is limited to 1500 ℃. Thermal testing and structural optimization testing were conducted to demonstrate the analysis results.展开更多
For safe operation with active water cooling plasma facing components （PFCs） to handle a large input power over a long pulse discharge, some design optimization, R＆D and maintenance were accomplished to improve the...For safe operation with active water cooling plasma facing components （PFCs） to handle a large input power over a long pulse discharge, some design optimization, R＆D and maintenance were accomplished to improve the in-vessel components. For the purpose of large plasma current （1 MA） operation, the previous separated top and bottom passive stabilizers in the low field were electrical connected to stabilize plasma in the case of vertical displace events （VDEs）. The design and experiments are described in this paper展开更多
The aims of this study are to determine the effect of Sabah ragi on food waste and dry leaves composting as well as to compare the composting performance from a previous study that had no addition of Sabah ragi.The co...The aims of this study are to determine the effect of Sabah ragi on food waste and dry leaves composting as well as to compare the composting performance from a previous study that had no addition of Sabah ragi.The composting process was conducted using an in-vessel passive aerated bioreactor with turning every 3 days for 40 days.Based on the physiochemical analysis,the stability and maturity of the compost were evaluated.Parameters such as temperature,total organic carbon,moisture content,pH,conductivity,and C/N were monitored.During the composting process,the highest temperature of 54.2℃ and the highest heat generation rate per initial mass of compost dry matter of 4098 kJ kg^(-1) day^(-1) was achieved on day 7.Furthermore,when compared to previous studies,this study achieved a faster thermophilic phase(≥45℃),a longer thermophilic period(4 days),and a higher cumulative temperature.Elementary kinetic analysis was performed based on the TOC profile and evaluated using coefficient correlation(R^(2)).In this study,application of the second-order model resulted in good responses.Low pathogen levels and higher nitrogen content were detected in the final compost,while some of the nutrients were not in the recommended range.An estimated ragi cost of RM 1.22 was required for every 1 kg of compost with a selling price of RM 6.00/kg of compost.展开更多
A historical review of in-vessel melt retention （IVR） is given, which is a severe accident mitigation mea- sure extensively applied in Generation III pressurized water reactors （PWRs）. The idea of IVR actually ori...A historical review of in-vessel melt retention （IVR） is given, which is a severe accident mitigation mea- sure extensively applied in Generation III pressurized water reactors （PWRs）. The idea of IVR actually originated from the back-fitting of the Generation 11 reactor Loviisa WER-440 in order to cope with the core-melt risk. It was then employed in the new deigns such as Westinghouse APIO00, the Korean APR1400 as well as Chinese advanced PWR designs HPRIO00 and CAP1400. The most influential phe- nomena on the IVR strategy are in-vessel core melt evolution, the heat fluxes imposed on the vessel by the molten core, and the external cooling of the reactor pressure vessel （RPV）. For in-vessel melt evolution, past focus has only been placed on the melt pool convection in the lower plenum of the RPV; however, through our review and analysis, we believe that other in-vessel phenomena, including core degradation and relocation, debris formation, and coolability and melt pool formation, may all contrib- ute to the final state of the melt pool and its thermal loads on the lower head. By looking into previous research on relevant topics, we aim to identify the missing pieces in the picture. Based on the state of the art, we conclude by proposing future research needs.展开更多
Magneto-mechanical coupling vibration arises in the in-vessel components of Tokamak devices especially during the plasma disruption. Strong electromagnetic forces cause the structures to vibrate while the motion in tu...Magneto-mechanical coupling vibration arises in the in-vessel components of Tokamak devices especially during the plasma disruption. Strong electromagnetic forces cause the structures to vibrate while the motion in turn changes the distribution of the electromagnetic field. To ensure the Tokamak devices operating in a designed state, numerical analysis on the coupling vibration is of great importance. This paper introduces two numerical methods for the magneto-mechanical coupling problems. The coupling term of velocity and magnetic flux density is manipulated in both Eulerian and Lagrangian description, which brings much simplification in numerical implementation. Corresponding numerical codes have been developed and applied to the dynamic simulation of a test module in J-TEXT and the vacuum vessel of HL-2M during plasma disruptions. The results reveal the evident influence of the magnetic stiffness and magnetic damping effects on the vibration behavior of the in-vessel structures. Finally, to deal with the halo current injection problem, a numerical scheme is described and validated which can simulate the distribution of the halo current without complicated manipulations.展开更多
CH-HCSB TBM is designed to test the feasibility of DEMO fusion reactor on ITER. A safety assessment has to demonstrate that the TBM with its own cooling system does not impede the safe operation of ITER under normal a...CH-HCSB TBM is designed to test the feasibility of DEMO fusion reactor on ITER. A safety assessment has to demonstrate that the TBM with its own cooling system does not impede the safe operation of ITER under normal and accidental conditions. For analysis of the highly transient accident sequences, a RELAP5 model has been developed for the HCS and TBM system. The steady-state, In-Vessel LOCA, Ex-Vessel LOCA and In-Box LOCA have been analyzed and the designed TBM steady-state inlet/outlet temperatures have been obtained. In all LOCA accidents, the Ex-Vessel LOCA is the most dangerous accident because of the melting of the First Wall. Based on the results, the design of TBM could be modified further in order to improve the safety of TBM and ITER.展开更多
In international thermonuclear experimental reactor （ITER）, one of major concerns is an in-vessel tritium inventory from a point of safety. It is believed that the carbon-tritium co-deposited film produced by the er...In international thermonuclear experimental reactor （ITER）, one of major concerns is an in-vessel tritium inventory from a point of safety. It is believed that the carbon-tritium co-deposited film produced by the erosion of carbon diverter walls has a high tritium concentration. However, no systematic evaluation for the tritium concentration has been conducted yet. In the present study, the carbon-hydrogen co-deposited films were prepared at the wall of pumping duct in Local Island Divertor experiments of LHD, in order to evaluate the tritium concentration of the co-deposited films produced in ITER. The hydrogen concentration was obtained by measuring the amount of retained hydrogen in the film and the mass density of the film. The hydrogen concentration of the co-deposited carbon film at the wall not facing to the plasma with a low temperature was extremely high, 1.3 in the atomic ratio of H/C. This value is triple times higher than the previous value obtained so far. The crystal structure of the co-deposited carbon film observed by Raman spectroscopy showed very unique structure （polymeric aC：H）, which is well consistent with the high hydrogen concentration. The present study suggests that the tritium concentration of the co-deposited film in ITER depends on the wall position and becomes quite high as high as T/C-0.65. The results obtained contribute to evaluate the in-vessel tritium inventory owing to the co-deposited carbon films.展开更多
The lower head of reactor pressure vessel （RPV） will endure a great temperature gradient above the phase transition temperature, and the creep and fracture will be the primary failure mode for the RPV material in su...The lower head of reactor pressure vessel （RPV） will endure a great temperature gradient above the phase transition temperature, and the creep and fracture will be the primary failure mode for the RPV material in such a situation. The interrupted creep tests were performed on a typical RPV material, SA508 Gr3 steel, at 800 ℃. The microstructure of different creep stages was examined by scanning electron microscopy and transmission electron microscopy. The results showed that the microscopic damage is mainly induced by creep cavities and coarse second-phase particles. Furthermore, the volume fractions of creep cavities and coarse second-phase particles show a linear relationship with the extended creep time. The second-phase particles are determined to be MoC in the second creep stage and Mo2C in the third creep stage, according to the results of selected-area electron diffraction pattern. Combined with energy-dispersive spectrum analysis, the segregation of precipitates caused by the migration of atoms is finally unveiled, which leads to the coarsening of the particles.展开更多
基金JSPS-CAS Core-University Program on Basic Research of Nuclear Fusion Reactor Engineering in 2007
文摘In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R＆D have been completed. The divertor is designed in an up-down symmetric configuration to accommodate both double null and single null plasma operation. Passive plates are used for plasma movement control. In-vessel coils are used for the active control of plasma vertical movements. Each cryo-pump can provide an approximately 45 m^3/s pumping rate at a pressure of 10^-1 Pa for particle exhaust. Analysis shows that, when a plasma current of 1 MA disrupts in 3 ms, the EM loads caused by the eddy current and the halo current in a vertical displacement event （VDE） will not generate an unacceptable stress on the divertor structure. The bolted divertor thermal structure with an active cooling system can sustain a load of 2 MW/m^2 up to a 60 s operation if the plasma facing surface temperature is limited to 1500 ℃. Thermal testing and structural optimization testing were conducted to demonstrate the analysis results.
文摘For safe operation with active water cooling plasma facing components （PFCs） to handle a large input power over a long pulse discharge, some design optimization, R＆D and maintenance were accomplished to improve the in-vessel components. For the purpose of large plasma current （1 MA） operation, the previous separated top and bottom passive stabilizers in the low field were electrical connected to stabilize plasma in the case of vertical displace events （VDEs）. The design and experiments are described in this paper
基金The authors acknowledge University Malaysia Sabah for the financial aid(SDG03-2020)Dana Inovasi Sekolah(DIS0005-2020)postdoctoral awarded to Dr.Junidah Lamaming.
文摘The aims of this study are to determine the effect of Sabah ragi on food waste and dry leaves composting as well as to compare the composting performance from a previous study that had no addition of Sabah ragi.The composting process was conducted using an in-vessel passive aerated bioreactor with turning every 3 days for 40 days.Based on the physiochemical analysis,the stability and maturity of the compost were evaluated.Parameters such as temperature,total organic carbon,moisture content,pH,conductivity,and C/N were monitored.During the composting process,the highest temperature of 54.2℃ and the highest heat generation rate per initial mass of compost dry matter of 4098 kJ kg^(-1) day^(-1) was achieved on day 7.Furthermore,when compared to previous studies,this study achieved a faster thermophilic phase(≥45℃),a longer thermophilic period(4 days),and a higher cumulative temperature.Elementary kinetic analysis was performed based on the TOC profile and evaluated using coefficient correlation(R^(2)).In this study,application of the second-order model resulted in good responses.Low pathogen levels and higher nitrogen content were detected in the final compost,while some of the nutrients were not in the recommended range.An estimated ragi cost of RM 1.22 was required for every 1 kg of compost with a selling price of RM 6.00/kg of compost.
文摘A historical review of in-vessel melt retention （IVR） is given, which is a severe accident mitigation mea- sure extensively applied in Generation III pressurized water reactors （PWRs）. The idea of IVR actually originated from the back-fitting of the Generation 11 reactor Loviisa WER-440 in order to cope with the core-melt risk. It was then employed in the new deigns such as Westinghouse APIO00, the Korean APR1400 as well as Chinese advanced PWR designs HPRIO00 and CAP1400. The most influential phe- nomena on the IVR strategy are in-vessel core melt evolution, the heat fluxes imposed on the vessel by the molten core, and the external cooling of the reactor pressure vessel （RPV）. For in-vessel melt evolution, past focus has only been placed on the melt pool convection in the lower plenum of the RPV; however, through our review and analysis, we believe that other in-vessel phenomena, including core degradation and relocation, debris formation, and coolability and melt pool formation, may all contrib- ute to the final state of the melt pool and its thermal loads on the lower head. By looking into previous research on relevant topics, we aim to identify the missing pieces in the picture. Based on the state of the art, we conclude by proposing future research needs.
基金the National Magnetic Confinement Fusion Program of China(Grant 2013GB113005)the National Natural Science Foundation of China(Grants51577139 and 51407132)for funding in part
文摘Magneto-mechanical coupling vibration arises in the in-vessel components of Tokamak devices especially during the plasma disruption. Strong electromagnetic forces cause the structures to vibrate while the motion in turn changes the distribution of the electromagnetic field. To ensure the Tokamak devices operating in a designed state, numerical analysis on the coupling vibration is of great importance. This paper introduces two numerical methods for the magneto-mechanical coupling problems. The coupling term of velocity and magnetic flux density is manipulated in both Eulerian and Lagrangian description, which brings much simplification in numerical implementation. Corresponding numerical codes have been developed and applied to the dynamic simulation of a test module in J-TEXT and the vacuum vessel of HL-2M during plasma disruptions. The results reveal the evident influence of the magnetic stiffness and magnetic damping effects on the vibration behavior of the in-vessel structures. Finally, to deal with the halo current injection problem, a numerical scheme is described and validated which can simulate the distribution of the halo current without complicated manipulations.
文摘CH-HCSB TBM is designed to test the feasibility of DEMO fusion reactor on ITER. A safety assessment has to demonstrate that the TBM with its own cooling system does not impede the safe operation of ITER under normal and accidental conditions. For analysis of the highly transient accident sequences, a RELAP5 model has been developed for the HCS and TBM system. The steady-state, In-Vessel LOCA, Ex-Vessel LOCA and In-Box LOCA have been analyzed and the designed TBM steady-state inlet/outlet temperatures have been obtained. In all LOCA accidents, the Ex-Vessel LOCA is the most dangerous accident because of the melting of the First Wall. Based on the results, the design of TBM could be modified further in order to improve the safety of TBM and ITER.
文摘In international thermonuclear experimental reactor （ITER）, one of major concerns is an in-vessel tritium inventory from a point of safety. It is believed that the carbon-tritium co-deposited film produced by the erosion of carbon diverter walls has a high tritium concentration. However, no systematic evaluation for the tritium concentration has been conducted yet. In the present study, the carbon-hydrogen co-deposited films were prepared at the wall of pumping duct in Local Island Divertor experiments of LHD, in order to evaluate the tritium concentration of the co-deposited films produced in ITER. The hydrogen concentration was obtained by measuring the amount of retained hydrogen in the film and the mass density of the film. The hydrogen concentration of the co-deposited carbon film at the wall not facing to the plasma with a low temperature was extremely high, 1.3 in the atomic ratio of H/C. This value is triple times higher than the previous value obtained so far. The crystal structure of the co-deposited carbon film observed by Raman spectroscopy showed very unique structure （polymeric aC：H）, which is well consistent with the high hydrogen concentration. The present study suggests that the tritium concentration of the co-deposited film in ITER depends on the wall position and becomes quite high as high as T/C-0.65. The results obtained contribute to evaluate the in-vessel tritium inventory owing to the co-deposited carbon films.
基金This research was supported by the National Natural Science Foundation of China （51575489） and National 13th Five-Year Key Technologies R＆D Program （No. 2016YFC0801902）.
文摘The lower head of reactor pressure vessel （RPV） will endure a great temperature gradient above the phase transition temperature, and the creep and fracture will be the primary failure mode for the RPV material in such a situation. The interrupted creep tests were performed on a typical RPV material, SA508 Gr3 steel, at 800 ℃. The microstructure of different creep stages was examined by scanning electron microscopy and transmission electron microscopy. The results showed that the microscopic damage is mainly induced by creep cavities and coarse second-phase particles. Furthermore, the volume fractions of creep cavities and coarse second-phase particles show a linear relationship with the extended creep time. The second-phase particles are determined to be MoC in the second creep stage and Mo2C in the third creep stage, according to the results of selected-area electron diffraction pattern. Combined with energy-dispersive spectrum analysis, the segregation of precipitates caused by the migration of atoms is finally unveiled, which leads to the coarsening of the particles.
