Based on the practice and analysis of peer review in nuclear power plants, the models on the Pareto improvement of peer review, governance entropy decrease of peer review are set up and discussed. The result shows tha...Based on the practice and analysis of peer review in nuclear power plants, the models on the Pareto improvement of peer review, governance entropy decrease of peer review are set up and discussed. The result shows that the peer review of nuclear power is actually a process of Pareto improvement, and of governance entropy decrease. It’s a process of improvement of the enterprise operational efficiency accordingly.展开更多
Performance monitoring is the important part of the equipment reliability process description( AP913),and the system performance is the main content of monitoring. The purpose of system performance monitoring is to id...Performance monitoring is the important part of the equipment reliability process description( AP913),and the system performance is the main content of monitoring. The purpose of system performance monitoring is to identify early performance degradation of system and equipment in time,evaluate the overall health of system, and carry out corrective actions in a timely manner. Performance monitoring also has the corresponding experience feedback. The paper introduces the process of system monitoring program development. In the end,the paper takes an example of the turbine control fluid system( GFR) in a domestic nuclear power plant. The example shows the process is good for the analysis.展开更多
The maximum principal stress, von Mises equivalent stress, equivalent creep strain, stress triaxiality in dissimilar metal welded joints between austenitic（HR3C） and martensitic heat-resistant steel（T91） are simul...The maximum principal stress, von Mises equivalent stress, equivalent creep strain, stress triaxiality in dissimilar metal welded joints between austenitic（HR3C） and martensitic heat-resistant steel（T91） are simulated by FEM at 873 K and under inner pressure of 42.26 MPa. The results show that the maximum principal stress and von Mises equivalent stress are quite high in the vicinity of weld/T91 interface, creep cavities are easy to form and expand in the weld/T91 interface. There are two peaks of equivalent creep strains in welded joint, and the maximum equivalent creep strain is in the place 27-32 mm away from the weld/T91 interface, and there exists creep constrain region in the vicinity of weld/T91 interface. The high stress triaxiality peak is located exactly at the weld/T91 interface. Accordingly, the weld/T91 interface is the weakest site of welded joint. Therefore, using stress triaxiality to describe creep cavity nucleation and expansion and crack development is reasonable for the dissimilar metal welded joint between austenitic and martensitic steel.展开更多
Annular jet pumps that are used in hydraulic machinery have a very simple structure but very complex internal flow fields. Large eddy simulations were used to study the coherent structures in the turbulent flows in an...Annular jet pumps that are used in hydraulic machinery have a very simple structure but very complex internal flow fields. Large eddy simulations were used to study the coherent structures in the turbulent flows in annular jet pumps with various area ratios,m. The distribution, movement and evolution of the coherent structure in the annular jet pumps are described based on vorticity,pressure and Q criteria. All the criteria demonstrate that the vortexes are mainly distributed in the recirculation region and in the mixing and the boundary layers, which have large velocity gradients. The various characteristics of the coherent structures are shown by the different criteria with the vorticity criterion describing the distribution, movement and evolution of the vortexes,the pressure criterion describing the movement and the Q criterion describing the vortex movement and evolution. The vorticity variation in the spanwise direction is larger than the variation in the streamwise direction; however, the streamwise vortex is the main mechanism driving the entrainment of the secondary flow and the mixing. The annular jet pump with m=3.33 had a higher vortex shedding frequency(about 1000 Hz) than that with m=1.72(313–417 Hz). The azimuthal instability is the main reason for the generation of the streamwise vortex from the spanwise vortex. The vortex structures in the recirculation region are very strong,but small and disordered with no periodic vortex rings.展开更多
The large eddy simulation（LES） of the flow characteristics in an annular jet pump（AJP） is conducted, and the flow characteristics are systematically analyzed from both time-averaged and instantaneous aspects. The ...The large eddy simulation（LES） of the flow characteristics in an annular jet pump（AJP） is conducted, and the flow characteristics are systematically analyzed from both time-averaged and instantaneous aspects. The jet expansion, the velocity distribution and the energy are considered to analyze the time-averaged evolution of the flow field in the AJP. The transient flow characteristics can also be acquired from the analysis of the turbulence intensity and the Reynolds stress. The simulation demonstrates that in the time-averaged characteristics, the potential cores increase linearly with the increase of the flow ratio. With the flow development, the jet half-width gradually increases and the residual energy coefficient decreases. Compared with the distribution of the time-averaged axial velocity, that of the instantaneous velocity is more complex and disorderly. The high intensity of the axial turbulence mainly occurs in the mixing layer and the near-wall regions of the diffuser. The annular distribution of the Reynolds stress is mainly in the mixing layer and the recirculation region. There is a low-stress zone between the mixing layer and the high-stress region in the wall-boundary layer. The intensity of the spanwise vortexes is larger than that of the streamwise vortexes, and therefore, the former make greater contribution to the total vorticity. This research provides a better understanding of the flow characteristics in the AJP.展开更多
文摘Based on the practice and analysis of peer review in nuclear power plants, the models on the Pareto improvement of peer review, governance entropy decrease of peer review are set up and discussed. The result shows that the peer review of nuclear power is actually a process of Pareto improvement, and of governance entropy decrease. It’s a process of improvement of the enterprise operational efficiency accordingly.
文摘Performance monitoring is the important part of the equipment reliability process description( AP913),and the system performance is the main content of monitoring. The purpose of system performance monitoring is to identify early performance degradation of system and equipment in time,evaluate the overall health of system, and carry out corrective actions in a timely manner. Performance monitoring also has the corresponding experience feedback. The paper introduces the process of system monitoring program development. In the end,the paper takes an example of the turbine control fluid system( GFR) in a domestic nuclear power plant. The example shows the process is good for the analysis.
基金Funded by the National Natural Science Foundation of China(No.51374154)
文摘The maximum principal stress, von Mises equivalent stress, equivalent creep strain, stress triaxiality in dissimilar metal welded joints between austenitic（HR3C） and martensitic heat-resistant steel（T91） are simulated by FEM at 873 K and under inner pressure of 42.26 MPa. The results show that the maximum principal stress and von Mises equivalent stress are quite high in the vicinity of weld/T91 interface, creep cavities are easy to form and expand in the weld/T91 interface. There are two peaks of equivalent creep strains in welded joint, and the maximum equivalent creep strain is in the place 27-32 mm away from the weld/T91 interface, and there exists creep constrain region in the vicinity of weld/T91 interface. The high stress triaxiality peak is located exactly at the weld/T91 interface. Accordingly, the weld/T91 interface is the weakest site of welded joint. Therefore, using stress triaxiality to describe creep cavity nucleation and expansion and crack development is reasonable for the dissimilar metal welded joint between austenitic and martensitic steel.
基金supported by the National Natural Science Foundation of China(Grant Nos.51179134&11472197)
文摘Annular jet pumps that are used in hydraulic machinery have a very simple structure but very complex internal flow fields. Large eddy simulations were used to study the coherent structures in the turbulent flows in annular jet pumps with various area ratios,m. The distribution, movement and evolution of the coherent structure in the annular jet pumps are described based on vorticity,pressure and Q criteria. All the criteria demonstrate that the vortexes are mainly distributed in the recirculation region and in the mixing and the boundary layers, which have large velocity gradients. The various characteristics of the coherent structures are shown by the different criteria with the vorticity criterion describing the distribution, movement and evolution of the vortexes,the pressure criterion describing the movement and the Q criterion describing the vortex movement and evolution. The vorticity variation in the spanwise direction is larger than the variation in the streamwise direction; however, the streamwise vortex is the main mechanism driving the entrainment of the secondary flow and the mixing. The annular jet pump with m=3.33 had a higher vortex shedding frequency(about 1000 Hz) than that with m=1.72(313–417 Hz). The azimuthal instability is the main reason for the generation of the streamwise vortex from the spanwise vortex. The vortex structures in the recirculation region are very strong,but small and disordered with no periodic vortex rings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51179134,11472197)
文摘The large eddy simulation（LES） of the flow characteristics in an annular jet pump（AJP） is conducted, and the flow characteristics are systematically analyzed from both time-averaged and instantaneous aspects. The jet expansion, the velocity distribution and the energy are considered to analyze the time-averaged evolution of the flow field in the AJP. The transient flow characteristics can also be acquired from the analysis of the turbulence intensity and the Reynolds stress. The simulation demonstrates that in the time-averaged characteristics, the potential cores increase linearly with the increase of the flow ratio. With the flow development, the jet half-width gradually increases and the residual energy coefficient decreases. Compared with the distribution of the time-averaged axial velocity, that of the instantaneous velocity is more complex and disorderly. The high intensity of the axial turbulence mainly occurs in the mixing layer and the near-wall regions of the diffuser. The annular distribution of the Reynolds stress is mainly in the mixing layer and the recirculation region. There is a low-stress zone between the mixing layer and the high-stress region in the wall-boundary layer. The intensity of the spanwise vortexes is larger than that of the streamwise vortexes, and therefore, the former make greater contribution to the total vorticity. This research provides a better understanding of the flow characteristics in the AJP.
