Effect of Long-Term Irradiation on the Fracture Properties of Zr-2.5Nb Pressure Tubes

2008 ◽  
pp. 122-122-17 ◽  
Author(s):  
RR Hosbons ◽  
PH Davies ◽  
M Griffiths ◽  
S Sagat ◽  
CE Coleman
Keyword(s):  
Fracture Properties ◽  
Pressure Tubes

Regulatory Perspectives on Fitness for Service Assessments of CANDU Pressure Boundary Components

2017 ◽  
Author(s):  
John C. Jin ◽  
Blair Carroll
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Management Program ◽  
Steam Generators ◽  
Operating Life ◽  
Term Operation ◽  
Pressure Tubes ◽  
Extended Operation ◽  
Condition Assessments

Major pressure boundary components such as pressure tubes, feeder pipes and steam generators at some Canadian CANDU nuclear power plants are entering periods of extended operation beyond their initially assumed operating life. The Canadian Nuclear Safety Commission (CNSC) has approved their long term operations based on the assurance of fitness for service of those components which was composed of condition assessments and aging management programs carried out and implemented by the Canadian licensees. The condition assessments were conducted to demonstrate that components would be within their design basis for the period of intended long term operation and the aging management program was implemented to ensure that the conditions of the components would be maintained as evaluated in the condition assessments and to monitor if new degradation mechanisms would become active. This paper presents the CNSC regulatory practice adopted in the course of technical reviews of fitness for service assessments of major pressure boundary components conducted by Canadian nuclear licensees to demonstrate the safe long term operation of major components can be achieved.

Modeling Two-Phase Flowback of Multifractured Horizontal Wells Completed in Shale

SPE Journal ◽  
2013 ◽  
Vol 18 (04) ◽  
pp. 795-812 ◽  
Author(s):  
C.R.. R. Clarkson ◽  
J.D.. D. Williams-Kovacs
Keyword(s):  
Shale Gas ◽  
Transient Analysis ◽  
Horizontal Wells ◽  
Production Data ◽  
Two Phase ◽  
Fracture Properties ◽  
Rate Transient Analysis ◽  
Wellbore Storage ◽  
Fluid Production

Summary Early fluid production and flowing pressure data gathered immediately after fracture stimulation of multifractured horizontal wells may provide an early opportunity to generate long-term forecasts in shale-gas (and other hydraulically fractured) reservoirs. These early data, which often consist of hourly (if not more frequent) monitoring of fracture/formation fluid rates, volumes, and flowing pressures, are gathered on nearly every well that is completed. Additionally, fluid compositions may be monitored to determine the extent of load fluid recovery, and chemical tracers added during stage treatments to evaluate inflow from each of the stages. There is currently debate within the industry of the usefulness of these data for determining the long-term production performance of the wells. “Rules of thumb” derived from the percentage of load-fluid recovery are often used by the industry to provide a directional indication of well performance. More-quantitative analysis of the data is rarely performed; it is likely that the multiphase-flow nature of flowback and the possibility of early data being dominated by wellbore-storage effects have deterred many analysts. In this work, the use of short-term flowback data for quantitative analysis of induced-hydraulic-fracture properties is critically evaluated. For the first time, a method for analyzing water and gas production and flowing pressures associated with the flowback of shale-gas wells, to obtain hydraulic-fracture properties, is presented. Previous attempts have focused on single-phase analysis. Examples from the Marcellus shale are analyzed. The short (less than 48 hours) flowback periods were followed by long-term pressure buildups (approximately 1 month). Gas + water production data were analyzed with analytical simulation and rate-transient analysis methods designed for analyzing multiphase coalbed-methane (CBM) data. This analogy is used because two-phase flowback is assumed to be similar to simultaneous flow of gas and water during long-term production through the fracture system of coal. One interpretation is that the early flowback data correspond to wellbore + fracture volume depletion (storage). It is assumed that fracture-storage volume is much greater than wellbore storage. This flow regime appears consistent with what is interpreted from the long-term pressure-buildup data, and from the rate-transient analysis of flowback data. Assuming further that the complex fracture network created during stimulation is confined to a region around perforation clusters in each stage, one can see that fluid-production data can be analyzed with a two-phase tank-model simulator to determine fracture permeability and drainage area, the latter being interpreted to obtain an effective (producing) fracture half-length given geometrical considerations. Total fracture half-length, derived from rate-transient analysis of online (post-cleanup) data, verifies the flowback estimates. An analytical forecasting tool that accounts for multiple sequences of post-storage linear flow, followed by late-stage boundary flow, was developed to forecast production with flowback-derived parameters, volumetric inputs, matrix permeability, completion data, and operating constraints. The preliminary forecasts are in very good agreement with online production data after several months of production. The use of flowback data to generate early production forecasts is therefore encouraging, but needs to be tested for a greater data set for this shale play and for other plays, and should not be used for reserves forecasting.

Influence of loading direction on the static and fatigue fracture properties of the long term operated metallic materials

2019 ◽  
Vol 96 ◽  
pp. 409-425 ◽  
Author(s):  
G. Lesiuk ◽  
B. Rymsza ◽  
J. Rabiega ◽  
José A.F.O. Correia ◽  
A.M.P. De Jesus ◽  
...  
Keyword(s):  
Fatigue Fracture ◽  
Metallic Materials ◽  
Fracture Properties ◽  
Loading Direction

scholarly journals Influence of Laboratory Long-Term Aging on Selected Fracture Parameters of Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 811
Author(s):  
Pavla Vacková ◽  
Jan Valentin ◽  
Majda Belhaj
Keyword(s):  
Asphalt Mixtures ◽  
Bending Test ◽  
Cracking Behavior ◽  
Reclaimed Asphalt ◽  
Fracture Properties ◽  
Three Point Bending ◽  
Complex Information ◽  
Scb Test ◽  
Fracture Work

The paper presents the influence of laboratory aging simulation on fracture properties determined on 150 variants of asphalt mixtures. The fracture properties were determined by two different test approaches—semi-circular bending test (SCB test) and three-point bending test on beam specimens (3-PB test). The aging was simulated according to one of the methods defined in EN 12697-52 (storage of test specimens in chamber at temperature of 85 °C for 5 days). The evaluated group of variants covered asphalt mixtures for all road layers. The group was further divided according to used bituminous binder (unmodified vs. modified) and reclaimed asphalt content. The results showed that strength parameters (flexural strength and fracture toughness) increase with aging. It further shows that fracture work provides more complex information about the cracking behavior. For the aging indexes, it was found that for mixtures with modified binders and mixtures which did not contain reclaimed asphalt (RA), the values were higher. The aging indexes for fracture work showed different results for both performed tests.

Evaluation of Viscoelastic and Fracture Properties of Asphalt Mixtures with Long-Term Laboratory Conditioning

2018 ◽  
Vol 2672 (28) ◽  
pp. 503-513 ◽  
Author(s):  
Reyhaneh Rahbar-Rastegar ◽  
Jo Sias Daniel ◽  
Eshan V. Dave
Keyword(s):  
Viscoelastic Properties ◽  
Complex Modulus ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Maximum Aggregate Size ◽  
Cracking Behavior ◽  
Fracture Properties ◽  
Fracture Parameters

Aging affects the properties of asphalt mixtures in different ways; increase of stiffness, decrease of relaxation capability, and the increase of brittleness, resulting in changes in cracking behavior of asphalt mixtures. In this study, ten plant-produced, lab-compacted mixtures with various compositions (recycled materials, binder grades, binder source, and nominal maximum aggregate size) are evaluated at different long-term aging levels (24 hours at 135°C, 5 days at 95°C, and 12 days at 95°C on loose mix and 5 days at 85°C on compacted specimens). The asphalt mixture linear viscoelastic properties (|E*| and δ) and master curve shape parameters measured from complex modulus testing and fracture properties (measured from disc-shaped compact tension and semi-circular bending fracture testing) are compared at different levels of aging. The results indicate that the mixture exposure time to aging is proportional to the dynamic modulus and phase angle changes. Generally, the fracture parameters of mixtures become worse when aging level changes from 5 to 12 days aging. In spite of the similar viscoelastic properties, the mixtures with 24 hours at 135°C and 12 days at 95°C aging do not show similar fracture parameters.

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