Analysis of Cracks on the Containment of Loop Nuclear Power Stations for 60 Days

2011 ◽  
Vol 105-107 ◽  
pp. 1056-1059
Author(s):  
Yu Zhuo Sun ◽  
An Hai Yi ◽  
Jie Lin ◽  
Peng Qiao
Keyword(s):  
Tensile Strength ◽  
Theoretical Calculation ◽  
Temperature Stress ◽  
Calculation Method ◽  
Nuclear Power ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Construction Methods ◽  
Power Stations ◽  
Heat Preservation

The relation of tensile strength ＆ temperature stress and concrete fissure was researched firstly , then it showed the causes of late cracks on concrete by theoretical calculation, the result provided a simple theoretical calculation method to avoid concrete fissure. The construction methods to control the fissure was proposed: early strengthening cooling, managing maximum temperature of concrete through lately heat preservation, and overtime to preserving concrete moisture for controlling the late strain on mass concrete. This research has a great significance for controlling the fissure.

The Arch Support Construction and Hydration Heat Analysis of the First Bridge over Yangtze River in Hejiang

2013 ◽  
Vol 291-294 ◽  
pp. 1122-1127
Author(s):  
Yan Feng Luo ◽  
Da Yan Qin ◽  
Yun Zhang
Keyword(s):  
Yangtze River ◽  
Casting Process ◽  
Hydration Heat ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Element Analysis ◽  
Early Hydration ◽  
Mix Proportion ◽  
Arch Support ◽  
Heat Preservation

The arch support of the First Bridge over Yangtze River in Hejiang used the stratified and graded casting process in mass concrete pouring process. By means of optimizing the concrete mix proportion design, using high mixing amount of fly ash concrete, reducing heat release rate of concrete early hydration heat, delaying the time of maximum temperature rise, and combining turn-over forms and water storage and other surface heat preservation measures, the temperature difference between inside and outside concrete was reduced and the cracking of mass concrete was avoided. Finite element analysis of hydration heat was done to verify the feasibility of the construction scheme.

An evaluation of the equipment tagging process in nuclear power stations

1983 ◽  
Author(s):  
Peter Doyle ◽  
Lothar Schroeder ◽  
Stephen Brewer
Keyword(s):  
Nuclear Power ◽  
Power Stations

Environmental Protection Meets Security of Electricity Supply

2021 ◽  
pp. 1-18
Author(s):  
Ilina Cenevska
Keyword(s):  
Environmental Protection ◽  
Nuclear Power ◽  
Habitats Directive ◽  
Electricity Supply ◽  
The European Union ◽  
Power Stations ◽  
Court Of Justice ◽  
National Energy Policy ◽  
The Relationship ◽  
Practical Implications

Abstract This case comment explores the relationship between two intertwined objectives – ensuring security of electricity supply and environmental protection – in the context of the judgment of the Court of Justice of the European Union in Inter-Environnement Wallonie ASBL and Bond Beter Leefmilieu Vlaanderen ASBL v. Conseil des ministres. The analysis focuses on the application of the Environmental Impact Assessment Directive and the Habitats Directive to the facts of the case, which concerns the extension by a ten-year period of the operation of two Belgian nuclear power stations (Doel 1 and Doel 2) as part of a national energy policy strategy to ensure the security of Belgium's electricity supply. The case comment also considers the legal and practical implications that arise as a result of employing the ‘security of electricity supply’ exemption to enable derogation from the requirements of the aforementioned Directives in circumstances where a Member State considers the security of its electricity supply to be under threat.

Evaluation of the residual stress in stainless steel 304L hydraulically expanded joints

2020 ◽  
pp. 095440892096401
Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
The Finite Element Method ◽  
Power Stations ◽  
Stainless Steel 304 ◽  
Initial Clearance

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.

scholarly journals Analysis of Seepage Characteristics of a Foundation Pit with Horizontal Waterproof Curtain in Highly Permeable Strata

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1303
Author(s):  
Chenghua Shi ◽  
Xiaohe Sun ◽  
Shengli Liu ◽  
Chengyong Cao ◽  
Linghui Liu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Design Method ◽  
Water Pressure ◽  
Water Inflow ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Seepage Characteristics

At present, jet-grouted horizontal waterproof curtain reinforcement has become an essential method for deep foundation pit groundwater control. However, there is still a lack of an effective theoretical calculation method for horizontal waterproof curtain reinforcement, and there is little research on the seepage laws of foundation pits under different horizontal waterproof curtain conditions. Based on Darcy’s seepage theory, theoretical analysis models of deep foundation pit seepage were established considering the effect of a horizontal curtain in a highly permeable formation. Through the established models, the calculation method of the water inflow and the water pressure under the condition of a horizontal curtain was derived. Then through indoor tests, the reliability of the theoretical calculation method was verified. Furthermore, the established theoretical calculation method is used to analyze the influence of various factors on the water inflow and the water pressure, such as the ratio of hydraulic conductivity of the horizontal curtain to surrounding soil, thickness, and reinforcement position of the horizontal curtain. It is found that the hydraulic conductivity ratio has the most significant influence on the seepage characteristics of the foundation pit. Finally, the design method was applied to an example of the horizontal waterproof curtain of the foundation pit, which is located at Juyuanzhou Station in Fuzhou (China). The water inflow per unit area is 0.36 m3/d in the foundation pit, and this implies that the design method of the horizontal waterproof curtain applied for the excavation case is good and meets the requirements of design and safety.

Establishing and Satisfying Thermal Requirements for Drilled Shaft Concrete Based on Durability Considerations

2021 ◽  
pp. 036119812199635
Author(s):  
Andrew Z. Boeckmann ◽  
Zakaria El-tayash ◽  
J. Erik Loehr
Keyword(s):  
Mechanical Response ◽  
Large Diameter ◽  
Thermal Cracking ◽  
Drilled Shafts ◽  
Maximum Temperature ◽  
Design Parameters ◽  
Mass Concrete ◽  
Temperature Differential ◽  
Thermal Requirements ◽  
Ettringite Formation

Some U.S. transportation agencies have recently applied mass concrete provisions to drilled shafts, imposing limits on maximum temperatures and maximum temperature differentials. On one hand, temperatures commonly observed in large-diameter drilled shafts have been observed to cause delayed ettringite formation (DEF) and thermal cracking in above-ground concrete elements. On the other, the reinforcement and confinement unique to drilled shafts should provide resistance to thermal cracking, and the provisions that have been applied are based on dated practices for above-ground concrete. This paper establishes a rational procedure for design of drilled shafts for durability requirements in response to hydration temperatures, which addresses both DEF and thermal cracking. DEF is addressed through maximum temperature differential limitations that are based on concrete mix design parameters. Thermal cracking is addressed through calculations that explicitly consider the thermo-mechanical response of concrete for predicted temperatures. Results from application of the procedure indicate consideration of DEF and thermal cracking potential for drilled shafts is prudent, but provisions that have been applied to date are overly restrictive in many circumstances, particularly the commonly adopted 35°F maximum temperature differential provision.

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