Steam generator tube rupture(SGTR) accident is an important scenario needed to be considered in the safety analysis of lead-based fast reactors. When the steam generator tube breaks close to the main pump, water vapor...Steam generator tube rupture(SGTR) accident is an important scenario needed to be considered in the safety analysis of lead-based fast reactors. When the steam generator tube breaks close to the main pump, water vapor will enter the reactor core, resulting in a two-phase flow of heavy liquid metal and water vapor in fuel assemblies. The thermal-hydraulic problems caused by the SGTR accident may seriously threaten reactor core's safety performance. In this paper, the open-source CFD calculation software OpenFOAM was used to encapsulate the improved Euler method into the self-developed solver LBEsteamEulerFoam. By changing different heating boundary conditions and inlet coolant types, the two-phase flow in the fuel assembly with different inlet gas content was simulated under various accident conditions. The calculation results show that the water vapor may accumulate in edge and corner channels. With the increase in inlet water vapor content, outlet coolant velocity increases gradually. When the inlet water vapor content is more than 15%, the outlet coolant temperature rises sharply with strong temperature fluctuation. When the inlet water vapor content is in the range of 5–20%, the upper part of the fuel assembly will gradually accumulate to form large bubbles. Compared with the VOF method, Euler method has higher computational efficiency. However, Euler method may cause an underestimation of the void fraction, so it still needs to be calibrated with future experimental data of the two-phase flow in fuel assembly.展开更多
The China initiative Accelerator Driven System,CiADS,physics design adopts 162.5 MHz,325 MHz,and 650 MHz cavities,which are driven by the corresponding radio frequency(RF)power system,requiring frequency translation f...The China initiative Accelerator Driven System,CiADS,physics design adopts 162.5 MHz,325 MHz,and 650 MHz cavities,which are driven by the corresponding radio frequency(RF)power system,requiring frequency translation front-end for the RF station.For that application,a general-purpose design front-end prototype has been developed to evaluate the multi-frequency point supported design feasibility.The difficult parts to achieve the requirements of the general-purpose design are reasonable device selection and balanced design.With a carefully selected low-noise wide-band RF mixer and amplifier to balance the performance of multi-frequency supported down-conversion,specially designed LO distribution net to increase isolation between adjacent channels,and external band-pass filter to realize expected up-conversion frequencies,high maintenance and modular front-end generalpurpose design has been implemented.Results of standard parameters show an R2 value of at least 99.991%in the range of-60-10 dBm for linearity,up to 18 dBm for P1dB,and up to 89 dBc for cross talk between adjacent channels.The phase noise spectrum is lower than 80 dBc in the range of 0-1 MHz;cumulative phase noise is 0.006°;and amplitude and phase stability are 0.022%and 0.034°,respectively.展开更多
A new RF system for a proton linear accelerator named as C-ADS at Institute of Modern Physics (IMP) hasbeen designed and developed to match its related RFQ cavity, which is a quadrilateral four-vane resonator withtwo ...A new RF system for a proton linear accelerator named as C-ADS at Institute of Modern Physics (IMP) hasbeen designed and developed to match its related RFQ cavity, which is a quadrilateral four-vane resonator withtwo separate coupling ports and 80 tuners. Its RF system design including mainly all simulation for coupler andtwo-port configuration have also calculated and analysed to be operated in continuous wave (CW) mode with 120kW forward power resulted from the simulated shunt impedance of 45.62 kΩ and accelerating voltage of 65 kV forRFQ resonator, respectively. The design and measurements for the power source, transmission line, two identicalcouplers and power transmission system, even final two-port configuration were finished in the beginning of 2014.Some valuable experiences were accumulated in the original power conditioning and beam experiments on a previousprototype RFQ, which has 560 keV output energy and one-meter size operated by the end of 2013[1]. Until now,on the new RFQ, almost 120 kW CW power have already put into cavity to accelerate 10 mA proton beam, anoverview of the RF system design is to be given, including some specific simulation, even the two-port couplingconfiguration were analysed and evaluated in the paper.展开更多
基金supported partly by the Ministry of Science and Technology of the People's Republic of China (No. 2020YFB1902100)the Shanghai Municipal Commission of Economy and Informatization (No. GYQJ-2018-2-02)。
文摘Steam generator tube rupture(SGTR) accident is an important scenario needed to be considered in the safety analysis of lead-based fast reactors. When the steam generator tube breaks close to the main pump, water vapor will enter the reactor core, resulting in a two-phase flow of heavy liquid metal and water vapor in fuel assemblies. The thermal-hydraulic problems caused by the SGTR accident may seriously threaten reactor core's safety performance. In this paper, the open-source CFD calculation software OpenFOAM was used to encapsulate the improved Euler method into the self-developed solver LBEsteamEulerFoam. By changing different heating boundary conditions and inlet coolant types, the two-phase flow in the fuel assembly with different inlet gas content was simulated under various accident conditions. The calculation results show that the water vapor may accumulate in edge and corner channels. With the increase in inlet water vapor content, outlet coolant velocity increases gradually. When the inlet water vapor content is more than 15%, the outlet coolant temperature rises sharply with strong temperature fluctuation. When the inlet water vapor content is in the range of 5–20%, the upper part of the fuel assembly will gradually accumulate to form large bubbles. Compared with the VOF method, Euler method has higher computational efficiency. However, Euler method may cause an underestimation of the void fraction, so it still needs to be calibrated with future experimental data of the two-phase flow in fuel assembly.
文摘The China initiative Accelerator Driven System,CiADS,physics design adopts 162.5 MHz,325 MHz,and 650 MHz cavities,which are driven by the corresponding radio frequency(RF)power system,requiring frequency translation front-end for the RF station.For that application,a general-purpose design front-end prototype has been developed to evaluate the multi-frequency point supported design feasibility.The difficult parts to achieve the requirements of the general-purpose design are reasonable device selection and balanced design.With a carefully selected low-noise wide-band RF mixer and amplifier to balance the performance of multi-frequency supported down-conversion,specially designed LO distribution net to increase isolation between adjacent channels,and external band-pass filter to realize expected up-conversion frequencies,high maintenance and modular front-end generalpurpose design has been implemented.Results of standard parameters show an R2 value of at least 99.991%in the range of-60-10 dBm for linearity,up to 18 dBm for P1dB,and up to 89 dBc for cross talk between adjacent channels.The phase noise spectrum is lower than 80 dBc in the range of 0-1 MHz;cumulative phase noise is 0.006°;and amplitude and phase stability are 0.022%and 0.034°,respectively.
文摘A new RF system for a proton linear accelerator named as C-ADS at Institute of Modern Physics (IMP) hasbeen designed and developed to match its related RFQ cavity, which is a quadrilateral four-vane resonator withtwo separate coupling ports and 80 tuners. Its RF system design including mainly all simulation for coupler andtwo-port configuration have also calculated and analysed to be operated in continuous wave (CW) mode with 120kW forward power resulted from the simulated shunt impedance of 45.62 kΩ and accelerating voltage of 65 kV forRFQ resonator, respectively. The design and measurements for the power source, transmission line, two identicalcouplers and power transmission system, even final two-port configuration were finished in the beginning of 2014.Some valuable experiences were accumulated in the original power conditioning and beam experiments on a previousprototype RFQ, which has 560 keV output energy and one-meter size operated by the end of 2013[1]. Until now,on the new RFQ, almost 120 kW CW power have already put into cavity to accelerate 10 mA proton beam, anoverview of the RF system design is to be given, including some specific simulation, even the two-port couplingconfiguration were analysed and evaluated in the paper.
