Non-Linear Analysis Of A Nuclear Containment Structure Under High Internal Pressure

The main objective of the current study is to investigate the response of an internally pressurized nuclear power plant containment structure at pressure values higher than design pressure, and is focused on the response of prestressed concrete containment to ultimate global structural failure. The containment structure consists of a prestressed concrete cylindrical perimeter wall, with a prestressed concrete tori-spherical dome, prestressed concrete ring beam, and conventionally reinforced concrete base slab. The finite element program ANSYS is used to predict the non-liner behaviour of the containment structure. Different techniques available in ANSYS program to model steel reinforcements for reinforced concrete and prestressed concrete is estimated to define a more suitable approach to model prestressing system. The approach proposed here is capable of incorporating parameters such as variation in tendon layout and non-uniform prestress losses in comparison to those done by other researchers. It is concluded that the design criteria for the containment structure are fully satisfied. No through crack was observed at design pressure. The first through crack develops in the dome at a pressure of 2.1 times the design pressure. There is no damage to be expected to the reactor systems up to a pressure well above design pressure. It is observed that the containment structure subject of this study meets the design requirement of the current standards and behaves linearly in excess of 1.5 times the design pressure. The response of the internally pressurized containment structure including the major openings is investigated. It is concluded that presence of openings does not have a significant effect on the pressure capacity of the containment structure. The minor differences in the responses are at pressure values beyond the linear limit and are less than 5%. The response when openings are included are very similar to those without openings, except at the immediate neighboring of the equipment airlock opening. It is concluded that to predict the pressure response of containment structure, including the openings can be ignored. In case of need for a more exact response, only the equipment airlock can be included in the model

Non-Linear Analysis Of A Nuclear Containment Structure Under High Internal Pressure

The main objective of the current study is to investigate the response of an internally pressurized nuclear power plant containment structure at pressure values higher than design pressure, and is focused on the response of prestressed concrete containment to ultimate global structural failure. The containment structure consists of a prestressed concrete cylindrical perimeter wall, with a prestressed concrete tori-spherical dome, prestressed concrete ring beam, and conventionally reinforced concrete base slab. The finite element program ANSYS is used to predict the non-liner behaviour of the containment structure. Different techniques available in ANSYS program to model steel reinforcements for reinforced concrete and prestressed concrete is estimated to define a more suitable approach to model prestressing system. The approach proposed here is capable of incorporating parameters such as variation in tendon layout and non-uniform prestress losses in comparison to those done by other researchers. It is concluded that the design criteria for the containment structure are fully satisfied. No through crack was observed at design pressure. The first through crack develops in the dome at a pressure of 2.1 times the design pressure. There is no damage to be expected to the reactor systems up to a pressure well above design pressure. It is observed that the containment structure subject of this study meets the design requirement of the current standards and behaves linearly in excess of 1.5 times the design pressure. The response of the internally pressurized containment structure including the major openings is investigated. It is concluded that presence of openings does not have a significant effect on the pressure capacity of the containment structure. The minor differences in the responses are at pressure values beyond the linear limit and are less than 5%. The response when openings are included are very similar to those without openings, except at the immediate neighboring of the equipment airlock opening. It is concluded that to predict the pressure response of containment structure, including the openings can be ignored. In case of need for a more exact response, only the equipment airlock can be included in the model

Experimental Constraints on Homogenization of Plagioclase-Hosted Melt Inclusions From Plagioclase Ultraphyric Basalts

Study of melt inclusions (MIs) is a commonly applied method for defining the composition of magmas present at depth prior to mixing, fractionation, and degassing. Our ability to use data from MIs is complicated by post-entrapment processes (PEP) that can modify their composition during transport and eruption. Many of the PEP can be reversed by heating the MIs to temperatures near those at which the MI and its host were formed. However, the process of reversing PEP by homogenization may introduce changes in MI compositions, making interpretation difficult. We present a series of low and high pressure homogenization experiments on plagioclase-hosted MIs from Plagioclase Ultraphyric Basalts (PUBs) designed to develop a methodology for recovering the composition at the time of entrapment of plagioclase-hosted MIs. These experiments included low pressure (1 bar) homogenization experiments conducted as a time series for 30 min, 4 h, 1 day, 4 days, and 8 days), and at 7.5 kbar for 2 and 4 days. The 7.5 kbar pressure used for the high pressure experiments was based on the CO2-based entrapment pressures determined from MI from this sample. Experiments run at low pressure and run times of 4 and 8 days exhibited compositional drift, most notably in the form of increasing MgO in MIs. This drift was not observed at 7.5 kbars or for the shorter run time 1 atm experiments. These results are consistent with a model where drift in composition with time is caused by crystal relaxation driven by the high internal pressure within the MI (the pressure at which the MI formed), together with the lower confining pressure during homogenization (1 bar). Therefore, MI homogenization will produce the least amount of drift if runs are made for short time periods (∼30 min) or at the pressure of entrapment.

Influence of the Valve - Pull-down Equipment on the Area of High Pressure Peaks in Long Pipelines

The pipeline system is usually destroyed by the high internal pressure in the tubes due to development of water hammers. Also the possibility of continuous pressure oscillations causing vibration of external piping is dangerous, because it leads to loosening and destruction of the supports. One of the effective methods to protect a long pipeline is the possibility of removing liquid from the pipeline. The paper deals with the calculation of similar valve-pull-down unit by the numerical method of characteristics

Theoretical Modeling, Analysis, and Experimental Results of a Hydraulic Artificial Muscle Prototype

Fluidic braided artificial muscles have been studied for close to seventy years. Their high power-to-weight ratio and force-to-weight ratio make them a desirable actuation technology for compact and lightweight mobile manipulation. Use of hydraulics with fluidic artificial muscles has helped realize high actuation forces with new potential applications. To achieve large actuation forces produced from high internal pressure, artificial muscles operate near the limitations of their mechanical strength. Design improvements and future applications in mechanical systems will benefit from detailed theoretical analysis of the fluidic artificial muscle mechanics. This paper presents the theoretical modeling of a hydraulic artificial muscle, analysis of its mechanics, and experimental results that validate the model. A prototype is analyzed that operates at 14 MPa and can generate up to 6.3 kN of force and a displacement of 21.5 mm. This model promises to be useful for mechanical system design and model-based control.

Principles for enhancing virus capsid capacity and stability from a thermophilic virus capsid structure

The capsids of double-stranded DNA viruses protect the viral genome from the harsh extracellular environment, while maintaining stability against the high internal pressure of packaged DNA. To elucidate how capsids maintain stability in an extreme environment, we use cryoelectron microscopy to determine the capsid structure of thermostable phage P74-26 to 2.8-Å resolution. We find P74-26 capsids exhibit an overall architecture very similar to those of other tailed bacteriophages, allowing us to directly compare structures to derive the structural basis for enhanced stability. Our structure reveals lasso-like interactions that appear to function like catch bonds. This architecture allows the capsid to expand during genome packaging, yet maintain structural stability. The P74-26 capsid has T = 7 geometry despite being twice as large as mesophilic homologs. Capsid capacity is increased with a larger, flatter major capsid protein. Given these results, we predict decreased icosahedral complexity (i.e. T ≤ 7) leads to a more stable capsid assembly.

Fibre reinforced polymer for strengthening cylindrical metal shells against elephant’s foot buckling: An elasto-plastic analysis

This article describes the use of fibre reinforced polymer composites to increase the strength of an isotropic metallic cylindrical shell against elephant’s foot buckling. This form of buckling occurs when a cylindrical shell structure is subjected to high internal pressure together with an axial force, such as those that may occur in tanks and silos. It is particularly relevant to tanks under seismic action. Although fibre reinforced polymer composites have been widely applied to different types of structures under several loading conditions, its use to strengthen thin steel cylindrical shells has been very limited. Here, a non-linear elasto-plastic finite element idealisation is used to explore the strengthening effect of a fibre reinforced polymer strip on a thin cylinder. The optimum size and position of the fibre reinforced polymer sheet were obtained and empirically formulated. This study has shown that the strength after repair is sensitive to minor changes in the fibre reinforced polymer parameters so that a close adherence to the optimum parameter values is very desirable.