scholarly journals PERFORMANCE OF PRESSURE TUBES IN CANDU REACTORS

2016 ◽  
Vol 5 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Douglas Rodgers ◽  
Malcolm Griffiths ◽  
Grant Bickel ◽  
Andrew Buyers ◽  
Christopher Coleman ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Material Properties ◽  
Corrosion Behaviour ◽  
Alpha Phase ◽  
Operating Conditions ◽  
Grain Structure ◽  
Candu Reactors ◽  
Hexagonal Close Packed ◽  
Pressure Tubes

The pressure tubes in CANDU reactors typically operate for times up to about 30 years prior to refurbishment. The in-reactor performance of Zr-2.5Nb pressure tubes has been evaluated by sampling and periodic inspection. This paper describes the behavior and discusses the factors controlling the behaviour of these components. The Zr–2.5Nb pressure tubes are nominally extruded at 815 °C, cold worked nominally 27%, and stress relieved at 400 °C for 24 hours, resulting in a structure consisting of elongated grains of hexagonal close-packed alpha-Zr, partially surrounded by a thin network of filaments of body-centred-cubic beta-Zr. These beta-Zr filaments are meta-stable and contain about 20% Nb after extrusion. The stress-relief treatment results in partial decomposition of the beta-Zr filaments with the formation of hexagonal close-packed alpha-phase particles that are low in Nb, surrounded by a Nb-enriched beta-Zr matrix. The material properties of pressure tubes are determined by variations in alpha-phase texture, alpha-phase grain structure, network dislocation density, beta-phase decomposition, and impurity concentration that are a function of manufacturing variables. The pressure tubes operate at temperatures between 250 °C and 310 °C with coolant pressures up to about 11 MPa in fast neutron fluxes up to 4 × 1017 n·m−2·s−1 (E > 1 MeV) and the properties are modified by these conditions. The properties of the pressure tubes in an operating reactor are therefore a function of both manufacturing and operating condition variables. The ultimate tensile strength, fracture toughness, and delayed hydride-cracking properties (velocity (V) and threshold stress intensity factor (KIH)) change with irradiation, but all reach a nearly limiting value at a fluence of less than 1025 n·m−2 (E > 1 MeV). At this point the ultimate tensile strength is raised about 200 MPa, toughness is reduced by about 50%, V increases by about a factor of 6, while KIH is only slightly reduced. The role of microstructure and trace elements in these behaviours is described. Pressure tubes exhibit elongation, diametral expansion, and sag. The deformation behaviour is a function of operating conditions and the material properties that vary from tube-to-tube and as a function of axial location. Semi-empirical predictive models have been developed to describe the deformation response of average tubes as a function of operating conditions. The effect of material variability on corrosion behaviour is less well defined compared with other properties but there are instances where tube orientation and ingot source can be identified as factors that have an effect on hydrogen pick-up.

Effects of Electromagnetic Stirring Plus Single Pulse on the Microstructures and Properties of High Strength Al-Cu Alloy Welds

2011 ◽  
Vol 391-392 ◽  
pp. 1225-1229
Author(s):  
Cheng Gang Yang ◽  
Ge Ping Liu ◽  
Yu Hua Chen ◽  
Wei Ping Xu
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Weld Joint ◽  
High Strength ◽  
Single Pulse ◽  
Elongation Rate ◽  
Electromagnetic Stirring ◽  
Grain Structure ◽  
Cu Alloy ◽  
Columnar Grains

The effect of single pulse, electromagnetic stirring plus single pulse on the microstructures and properties of high strength Al-Cu alloy welds is investigated. The results show that the grain structure of weld under conventional MIG welding are coarse, oriented columnar grains, the ultimate tensile strength of weld joint is 286.5 MPa, the elongation rate of joint is 2.4%. The thermal gradient at the solid-liquid interface in the welding pool is decreased and the density of heterogeneous nucleation is enhanced by electromagnetical stirring plus single pulse, which resulted in the coarse and oriented columnar grains transforming to fine equiaxed grains; morphology and distribution of α(Al)-CuAl2 eutectic along the grain boundaries are improved, so it significantly improves the mechanical property of weld joint, the ultimate tensile strength of weld joint is up to 326.0 MPa, the elongation rate of joint reaches 7.8%.

Correlation of quantitative ultrasound measurements with material properties and bone mineral density in the equine metacarpus

2004 ◽  
Vol 1 (1) ◽  
pp. 61-69
Author(s):  
G Whan ◽  
J Runciman ◽  
M Hurtig
Keyword(s):  
Bone Mineral Density ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Bone Mineral ◽  
Quantitative Ultrasound ◽  
Material Properties ◽  
Modulus Of Elasticity ◽  
Bone Development ◽  
Mineral Density ◽  
Metacarpal Bones

AbstractThis study explored the relationship between speed-of-sound (SOS) measurements and the material properties of metacarpal bones in order to validate a device that uses linear unicortical transmission of ultrasound. SOS, ultimate tensile strength and modulus of elasticity were determined at nine experimental sites. Measurements of SOS and bone mineral density were collected at three of the nine experimental sites. Twenty-five equine metacarpal (MC3) bones were used. Micro-computerized tomography was used to validate testing protocols. SOS measurements were highly site- and horse-dependent. One or more statistically significant correlations were found with ultimate tensile strength, modulus of elasticity and bone mineral density in four of the nine experimental sites. A previously described pattern of high lateral and medial cortical stiffness and SOS was found in the mid-diaphysis that correlated with bone mineral density (r2=0.25, P<0.01) and modulus of elasticity (r2=0.14, P<0.05). SOS and ultimate tensile strength correlated strongly in the distal dorsal metacarpus (r2=0.47, P<0.001). Lateral and medial distal-level sites just above the fetlock joint had a variable amount of cancellous bone, reducing the ultimate strength of these sites. The study indicates that quantitative ultrasound is sensitive to differences in the quality of equine metacarpal bone, so this technique may be useful for monitoring adaptation to exercise and bone development.

scholarly journals Stress Corrosion Cracking of Steel and Aluminum in Sodium Hydroxide: Field Failure and Laboratory Test

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Y. Prawoto ◽  
K. Sumeru ◽  
W. B. Wan Nik
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Laboratory Test ◽  
Stress Corrosion ◽  
Sodium Hydroxide ◽  
Stress Corrosion Cracking ◽  
Crack Depth ◽  
Corrosion Cracking ◽  
Operating Conditions ◽  
Field Failure

Through an investigation of the field failure analysis and laboratory experiment, a study on (stress corrosion cracking) SCC behavior of steel and aluminum was performed. All samples were extracted from known operating conditions from the field failures. Similar but accelerated laboratory test was subsequently conducted in such a way as to mimic the field failures. The crack depth and behavior of the SCC were then analyzed after the laboratory test and the mechanism of stress corrosion cracking was studied. The results show that for the same given stress relative to ultimate tensile strength, the susceptibility to SCC is greatly influenced by heat treatment. Furthermore, it was also concluded that when expressed relative to the (ultimate tensile strength) UTS, aluminum has similar level of SCC susceptibility to that of steel, although with respect to the same absolute value of applied stress, aluminum is more susceptible to SCC in sodium hydroxide environment than steel.

scholarly journals Improvement of Mechanical Properties of Aluminium 6061 based Metal Matrix Composite with Addition of Granite Particulate

2020 ◽  
Vol 9 (7) ◽  
pp. 296-298
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Material Properties ◽  
Metal Matrix ◽  
Vortex Method ◽  
Stir Casting ◽  
Automotive Sector ◽  
Al6061 Alloy ◽  
Novel Applications

Aluminium is considered as one of the material of future. Aluminium based metal matrix comes with a fascinating set of material properties which combines strength with less weight. Due to this these Al-base metal matrix finds their application in aerospace and automotive sector. Many types of reinforcements are done with Aluminium since last many years to check the improvement in its performance. Therefore many reinforcements are found suitable to form the composite which finds variety of novel applications. In this present investigation MMCs are fabricated with Al 6061 alloy and reinforced with granite particulate of 2-3 microns size in different compositions are used to see their effect on the mechanical properties of Al6061 alloy. The vortex method of stir casting is used to from the metal matrix wherein reinforcements are forced into the vortex created by the molten metal by means of mechanical stirrer. The castings prepared by above method are machined with turning operation on lathe. Improvement in Ultimate tensile strength, Yield strength, % Elongation and Hardness are found with increasing the percentage of granite particulates..

scholarly journals Effects of Welded Mechanical Heterogeneity on Interface Crack Propagation in Dissimilar Weld Joints

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Fu-qiang Yang ◽  
He Xue ◽  
Ling-yan Zhao ◽  
Xiu-rong Fang
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Ultimate Tensile Strength ◽  
Crack Propagation ◽  
Interface Crack ◽  
Material Properties ◽  
Crack Extension ◽  
Stress And Strain ◽  
Mechanical Heterogeneity ◽  
Weld Joints

The stress and strain status associated with the material properties is one of the main factors affecting stress corrosion cracking (SCC) of structural components in nuclear power plants (NPPs). In many SCC prediction models, the stress intensity factor calculated with homogeneous materials is used to characterize the crack tip stress state. However, the mechanical and material properties in weld joints are heterogeneous, which will produce the discontinuous distribution of stress and strain nearby crack tip and affect the crack propagation. To understand the material mechanical heterogeneity effects on interface crack propagation, the specimens with ultimate tensile strength mismatch and elastic modulus mismatch were studied by using an extended finite element method (XFEM). The results indicate that the interface crack extension is easy to occur in the specimens with larger ultimate tensile strength mismatch, while the elastic modulus mismatch has little effects on crack extension. The different interface cracks in the dissimilar metal weld joints of the reactor pressure vessel used in NPPs tend to deviate from the initial direction into alloy 182, and the interface crack propagation path fluctuation is small.

Effect of the Cyclic Extrusion and Compression Processing on Microstructure and Mechanical Properties of Al-1%Cu Alloy

2018 ◽  
Vol 780 ◽  
pp. 93-97
Author(s):  
Walaa Abdelaziem ◽  
Atef Hamada ◽  
Mohsen Abdel-Naeim Hassan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Cast Alloy ◽  
Surface Hardness ◽  
Grain Structure ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Microstructure And Mechanical Properties ◽  
Elongation To Failure

The Simple Cyclic extrusion compression (SCEC) has been developed for producing Al-1%Cu alloys with fine microstructures and superior properties. SCEC method was applied for only two-passess.It was found that the grain structure was significantly reduced from 1500 μm to 100 μm after two passes of cyclic extrusion. The ultimate tensile strength and elongation to failure of as-cast alloy were 110 MPa and 12 %, respectively. However, the corresponding mechanical properties of the two pass CEC deformed alloy are 275 MPa and 35%, respectively. These findings ensure that a significant improvement in the grain structure has been achieved. In addition, cyclic extrusion deformation increased the surface hardness of the alloy by 50 % after two passes.

scholarly journals Конструкционные прочностные параметры и разрушение ультрамелкозернистого титана Grade 4, полученного методом равноканального углового прессования РКУП-К

2019 ◽  
Vol 89 (4) ◽  
pp. 541
Author(s):  
И.В. Смирнов
Keyword(s):  
Plastic Deformation ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Experimental Studies ◽  
Tensile Tests ◽  
Grain Structure ◽  
Angular Pressing ◽  
Pure Grade ◽  
Localized Plastic Deformation ◽  
Titanium Structure

AbstractProcessing of metals and alloys by severe plastic deformation (SPD) is accompanied by refinement of the material grain structure, which can increase their physicomechanical properties, for instance, unique tensile strength. However, studies of mechanical properties of materials after SPD are usually limited by tensile tests and other properties of strength and fracture are not sufficiently considered. This article presents experimental studies of ultimate tensile strength, impact toughness, fracture toughness, as well as respective surfaces of fracture of initial and ultrafine-grained pure Grade 4 titanium fabricated by continuous equal channel angular pressing. The results demonstrated that upon high ultimate tensile strength after SPD the material demonstrates decreased resistance against initiation and propagation of cracks upon single loading. The fracture surface of both states of titanium structure reveals mainly localized plastic deformation.

Improvement of the Evaluation Accuracy for the Diameter Prediction of the CANDU Pressure Tubes

2020 ◽  
Author(s):  
Jong Yeob Jung
Keyword(s):  
Measured Data ◽  
Operating Conditions ◽  
Tube Diameter ◽  
Pressure Tube ◽  
Dramatic Improvement ◽  
Irradiation Creep ◽  
Candu Reactors ◽  
Irradiation Growth ◽  
Pressure Tubes ◽  
Dry Out

Abstract Measurements of the inside diameter of the pressure tubes in CANDU reactors have shown that the diameter has been increasing over time, and this phenomena has been explained as a creep phenomenon which is a kind of aging process of the pressure tube owing to the operating conditions of irradiation by neutron flux, high pressure, and high temperature over the plant life. The diameter expansion of the pressure tube has been regarded as a principle aging mechanism governing the heat transfer and hydraulic degradation within the primary heat transport system of the CANDU reactor. Diametrical expansion results in a reduction of the fuel cooling owing to the increased bypass flow, which increases the possibility of a fuel dry-out and thus limits the operating power of the reactor. In order to explain the mechanism of the creep phenomena of the pressure tube, traditionally the creep deformation has been modeled as a combination of thermal creep, irradiation creep and irradiation growth. However, this modeling approach is too complex to determine all parameters and constants which are relevant to the equation. In this research, we proposed a very simple approach for modeling the pressure tube diameter deformation in which the pressure tube diameter was modeled based on the measured data, flux distribution of each fuel channel and temperature variation inside the pressure tube. New rules were derived to determine the effect of flux and temperature distribution on the diameter expansion based on the measured data of pressure tube diameter. Results from applying the methodology show a dramatic improvement of the prediction accuracy of pressure tube diameter compared to the previous modeling results.

scholarly journals Effect of Tool Profile Influence in Dissimilar Friction Stir Welding of Aluminium Alloys (AA5083 and AA7068)

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
S. Jayaprakash ◽  
S. Siva Chandran ◽  
T. Sathish ◽  
Bhiksha Gugulothu ◽  
R. Ramesh ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Ultimate Tensile Strength ◽  
Aluminium Alloys ◽  
Plate Thickness ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Grain Structure ◽  
Friction Stir ◽  
Process Factors

Friction stir welding is an innovative welding process for similar and dissimilar joining of the materials effectively. FSW simply modified the grain structure and also improved the strength of the joints for any type of alloying elements. This experimental study planned to carry out the joining process for dissimilar materials such as aluminium alloys 5083 and 7068. Three different types of tools are involved to find the ultimate tensile strength and Vickers hardness. The tool types are straight cylindrical tool, taper cylindrical tool, and triangular tool. The process factors for this investigation are a rotational speed of 800, 1000, 1200, and 1400 rpm, welding speed of 30, 40, 50, and 60 mm/min, axial force of 3, 4, 5, and 6 kN, and plate thickness of 5, 6, 7, and 8 mm. The hardness value and the ultimate tensile strength were increased in the welding zone, which proves the effects of tool profiles are efficiently utilized.

Dynamic Tensile Characteristics of TRIP-Type and DP-Type Sheets for an Auto-Body

2007 ◽  
Vol 340-341 ◽  
pp. 255-262
Author(s):  
Seok Bong Kim ◽  
Hoon Huh ◽  
Sung Ho Park ◽  
Ji Ho Lim
Keyword(s):  
Tensile Strength ◽  
Flow Stress ◽  
Ultimate Tensile Strength ◽  
Strain Rate ◽  
Material Properties ◽  
High Strain ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Strain Effect ◽  
Dynamic Tensile Tests

This paper investigates the dynamic tensile characteristics of TRIP600, TRIP800, DP600 and DP800 at the range of strain rate from 0.003 to 200/s. The tensile test acquires stress−strain curves and the strain rate sensitivity of each material. Experimental results show two important aspects for TRIP-type and DP-type sheets quantitatively: the flow stress increases as the strain rate increases; the elongation is not a monotonic function of the strain rate and increases at the same level of the strain rate even when the strain rate increases. In order to investigate the pre-strain effect for two types of metals at the high strain rate, TRIP600 and DP600 were elongated with the pre-strain of 5 and 10% at the strain rate of 0.003/s. Then, dynamic tensile tests were carried out at the strain rate of 0.003, 1, 10 and 100/s. The results demonstrate that the material properties of TRIP600 and DP600 are noticeably influenced by the pre-strain when the strain rate was over 1/s. The ultimate tensile strength as well as the yield stress increases due to the pre-strain effect.

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