Based on the plant model of 600-MW PWR,the molten core-concrete interactions(MCCI) under different models are studied.Station blackout (SBO) with steam-driven auxiliary feed water pump failure is selected as the case ...Based on the plant model of 600-MW PWR,the molten core-concrete interactions(MCCI) under different models are studied.Station blackout (SBO) with steam-driven auxiliary feed water pump failure is selected as the case for the model comparisons analysis.The result shows that thermal resistance model between debris and concrete has much influence on the consequence of MCCI.The concrete erosion rate calculated with gas film model is much higher than that of slag film model.Some other model comparisons such as the chemical reaction heat and the configuration molten pool are also discussed.展开更多
Steam explosion is one of the crucial and poorly understood phenomena which may occur during severe accident scenario and may lead to containment failure. In spite of several experimental and analytical studies, the r...Steam explosion is one of the crucial and poorly understood phenomena which may occur during severe accident scenario and may lead to containment failure. In spite of several experimental and analytical studies, the root cause of steam explosion has not been understood. Recent claims in the literature suggest that the presence of fine fragmentation during steam explosion causes its occurrence. In order to investigate this and understand the root cause of steam explosion, series of experiments were performed with 50 g to 2500 g of CaO-B<sub>2</sub>O<sub>3</sub>, a corium simulant in 4.5 litre of water. It was observed that steam explosion may occur even in the absence of fine fragments, which is contrary to the claims in the literature. To investigate further, conversion efficiency analysis was performed. This suggested that the amount of thermal energy converted to mechanical energy is more important deciding factor in explaining the occurrence of steam explosion. The present study discusses the importance of conversion efficiency in deciding steam explosion and also gives a new perspective to look at steam explosion phenomenology.展开更多
The hydro-hammer sampler is a new type of sampler compared with traditional ones. An important part of this new offshore sampler is that the structure of the core cutter has a significant effect on penetration and cor...The hydro-hammer sampler is a new type of sampler compared with traditional ones. An important part of this new offshore sampler is that the structure of the core cutter has a significant effect on penetration and core recovery. In our experiments,a commercial finite element code with a capability of simulating large-strain frictional contact be-tween two or more solid bodies is used to simulate the core cutter-soil interaction. The effects of the cutting edge shape,the diameter and the edge angle on penetration are analyzed by non-liner transient dynamic analysis using a finite ele-ment method (FEM). Simulation results show that the cutter shape clearly has an effect on the penetration and core re-covery. In addition,the penetration of the sampler increases with an increase in the inside diameter of the cutter,but de-creases with an increase in the cutting angle. Based on these analyses,an optimum structure of the core cutter is de-signed and tested in the north margin of the Dalian gulf. Experiment results show that the penetration rate is about 16.5 m/h in silty clay and 15.4 m/h in cohesive clay,while the recovery is 68% and 83.3% respectively.展开更多
The wave functions,energy levels and matrix elements of Yb+ions are calculated using the relativistic configuration interaction plus core polarization(RCICP)method.The static and dynamic electric dipole polarizabiliti...The wave functions,energy levels and matrix elements of Yb+ions are calculated using the relativistic configuration interaction plus core polarization(RCICP)method.The static and dynamic electric dipole polarizabilities of the ground state and low-lying excited states are determined.Then,the magic wavelengths of the magnetic sublevel 6s_(1/2,m=1/2)→5d_(3/2,m=±3/2,±1/2)and 6s_(1/2,m=1/2)→5_(d5/2,m=±5/2,±3/2,±1/2)transitions in the linearly,right-handed,and left-handed polarized light are further determined.The dependence of the magic wavelengths upon the angle between the direction of magnetic field and the direction of laser polarization is analyzed.展开更多
文摘Based on the plant model of 600-MW PWR,the molten core-concrete interactions(MCCI) under different models are studied.Station blackout (SBO) with steam-driven auxiliary feed water pump failure is selected as the case for the model comparisons analysis.The result shows that thermal resistance model between debris and concrete has much influence on the consequence of MCCI.The concrete erosion rate calculated with gas film model is much higher than that of slag film model.Some other model comparisons such as the chemical reaction heat and the configuration molten pool are also discussed.
文摘Steam explosion is one of the crucial and poorly understood phenomena which may occur during severe accident scenario and may lead to containment failure. In spite of several experimental and analytical studies, the root cause of steam explosion has not been understood. Recent claims in the literature suggest that the presence of fine fragmentation during steam explosion causes its occurrence. In order to investigate this and understand the root cause of steam explosion, series of experiments were performed with 50 g to 2500 g of CaO-B<sub>2</sub>O<sub>3</sub>, a corium simulant in 4.5 litre of water. It was observed that steam explosion may occur even in the absence of fine fragments, which is contrary to the claims in the literature. To investigate further, conversion efficiency analysis was performed. This suggested that the amount of thermal energy converted to mechanical energy is more important deciding factor in explaining the occurrence of steam explosion. The present study discusses the importance of conversion efficiency in deciding steam explosion and also gives a new perspective to look at steam explosion phenomenology.
基金Project 20002070005126 supported by the China Geological Survey
文摘The hydro-hammer sampler is a new type of sampler compared with traditional ones. An important part of this new offshore sampler is that the structure of the core cutter has a significant effect on penetration and core recovery. In our experiments,a commercial finite element code with a capability of simulating large-strain frictional contact be-tween two or more solid bodies is used to simulate the core cutter-soil interaction. The effects of the cutting edge shape,the diameter and the edge angle on penetration are analyzed by non-liner transient dynamic analysis using a finite ele-ment method (FEM). Simulation results show that the cutter shape clearly has an effect on the penetration and core re-covery. In addition,the penetration of the sampler increases with an increase in the inside diameter of the cutter,but de-creases with an increase in the cutting angle. Based on these analyses,an optimum structure of the core cutter is de-signed and tested in the north margin of the Dalian gulf. Experiment results show that the penetration rate is about 16.5 m/h in silty clay and 15.4 m/h in cohesive clay,while the recovery is 68% and 83.3% respectively.
基金the National Key Research and Development Program of China(Grant No.2022YFA1602500)the National Natural Science Foundation of China(Grant Nos.12174316 and 12174268)+2 种基金the Young Teachers Scientific Research Ability Promotion Plan of Northwest Normal University(Grant No.NWNU-LKQN2020-10)the Innovative Fundamental Research Group Project of Gansu Province,China(Grant No.20JR5RA541)the Project of the Educational Commission of Guangdong Province of China(Grant No.2020KTSCX124)。
文摘The wave functions,energy levels and matrix elements of Yb+ions are calculated using the relativistic configuration interaction plus core polarization(RCICP)method.The static and dynamic electric dipole polarizabilities of the ground state and low-lying excited states are determined.Then,the magic wavelengths of the magnetic sublevel 6s_(1/2,m=1/2)→5d_(3/2,m=±3/2,±1/2)and 6s_(1/2,m=1/2)→5_(d5/2,m=±5/2,±3/2,±1/2)transitions in the linearly,right-handed,and left-handed polarized light are further determined.The dependence of the magic wavelengths upon the angle between the direction of magnetic field and the direction of laser polarization is analyzed.
