[en] Highlights: •Dynamic characteristics of the nuclear containment structure are obtained from finite element analysis. •The effects of material properties variations on seismic responses is investigated. •Ambient temperature, aging and scragging were taken into consideration. •Various isolated period along with influence factor are employed in the analysis. •The results are compared the influence degree of each factors. -- Abstract: The mechanical properties of rubber bearing continuously change with the aging and environmental conditions. To evaluate the effects of deteriorating factors during the lifecycle of the base-isolated nuclear containment structure, a series of nonlinear time history analyses was performed. Computations were performed for three representative periods (2, 2.5, and 3 s), four types of deteriorating factors (aging, scragging, ambient temperature and multi-factor coupling), and actual ground motion. The influences of the deteriorating factors on acceleration and displacement of the superstructure have been discussed, as well as the shear force and deformation of the rubber bearing, and their response ratio. The results show that the changes in the mechanical properties of the rubber bearing had a significantly influence on the seismic responses of the base-isolated nuclear containment structure.

[en] Because of the design and construction requirements, the nuclear structures need to maintain the structural integrity under both design state and extreme earthquake shaking. The base-isolation technology can significantly reduce the damages of structures under extreme earthquake events, and effectively protect the safeties of structures and internal equipment. This study proposes a base-isolation design for the AP1000 nuclear shield building on considering the performance requirements of the seismic isolation systems and devices of shield building. The seismic responses of isolated and nonisolated shield buildings subjected to design basis earthquake (DBE) shaking and beyond-design basis earthquake (BDBE) shaking are analyzed, and three different strategies for controlling the displacements subjected to BDBE shaking are performed. By comparing with nonisolated shield buildings, the floor acceleration spectra of isolated shield buildings, relative displacement, and base shear force are significantly reduced in high-frequency region. The results demonstrate that the base-isolation technology is an effective approach to maintain the structural integrity which subjected to both DBE and BDBE shaking. A displacement control design for isolation layers subjected to BDBE shaking, which adopts fluid dampers for controlling the horizontal displacement of isolation layer is developed. The effectiveness of this simple method is verified through numerical analysis

[en] Seismic safety is considered to be one of the key design objectives of AP1000 nuclear power plant (NPP) in strong earthquakes. Dynamic behavior, damage development and aggravation effect are studied in this study for the three main components of AP1000 NPP, namely reinforced concrete shield building (RCSB), steel vessel containment (SVC) and reinforced concrete auxiliary building (RCAB). Characteristics including nonlinear concrete tension and compressive constitutions with plastic damage are employed to establish the numerical model, which is further validated by existing studies. The author investigates three earthquakes and eight input levels with the maximum magnitude of 2.4 g and the results show that the concrete material of both RCSB and RCAB have suffered serious damage in intense earthquakes. Considering RCAB in the whole NPP, significant damage aggravation effect can be detected, which is mainly concentrated at the upper intersection between RCSB and RCAB. SVC and reinforcing bar demonstrate excellent seismic performance with no obvious damage

[en] To be able to deduce water holdup from the mixture conductivity measured by conductance sensors in water continuous oil–gas–water three-phase flow, the water conductivity must be known in advance. As water conductivity depends on water salinity and temperature, variation in water salinity or temperature changes the water conductivity, which seriously affects water holdup measurement. In this study, we propose a novel online technique to detect the conductivity of water in vertical upward oil–gas–water flows in 20 mm inner diameter pipe via the conductance method. A water conductivity sensor (WCS) is designed and the geometry of the electrodes in its water trapping cavity is optimized using finite element methodology. After this, the relationship between sensor response and water conductivity is investigated. WCS performance is experimentally evaluated and the results show that the WCS can effectively detect the water conductivity in a three-phase mixture online. By correcting the water conductivity in the expression for the normalized conductivity of a rotating electric field conductance sensor, water salinity and temperature independent water holdup measurement can be realized. Based on the relationship between the calculated water holdup and water cut, the superficial velocity of water is accurately predicted despite differences in water conductivity. (paper)

[en] Three types of rotating electric field conductance sensors (REFCSs) with four, six, and eight electrodes are designed and optimized in this paper to measure the water holdup of oil–gas–water three-phase flow in vertical upward 20 mm inner diameter pipe. The geometric parameters of the REFCSs are optimized using finite element method to access highly sensitive and homogeneous detection fields. The performance of the REFCSs in the water holdup measurement of three-phase flows is experimentally evaluated by generalizing the Maxwell equation. Based on the measured water holdup from the REFCSs, the slippage behaviors in oil–gas–water are uncovered and the superficial velocity of the water phase is determined. The results show that the REFCSs present a high resolution in the water holdup measurement. The REFCS with eight electrodes has better performance than those with four- and six-electrodes, which indicates that its configuration and geometric parameters are more suitable for vertical oil–gas–water three-phase flow measurement in 20 mm inner diameter pipe. (paper)