bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fretting-Wear Damage due to Vibration in Nuclear and Process Equipment
Authors: Pettigrew Michel J. , Yetisir Metin , Fisher Nigel J. , Smith Bruce A. W. , Taylor Colette E. , Janzen Victor P. 
Published: October 2017

The problem of fretting-wear damage between a vibrating structure and its supports is discussed in this paper. Typical components of concern are piping systems and pipe-supports, multispan heat exchanger tubes and tube supports, and nuclear fuel bundles and fuel channels.
Fretting-wear damage is related to the dynamic interaction between a structure and its supports. This interaction is conveniently formulated in terms of a parameter called “work rate” to predict fretting-wear damage. Work rate is simply the integral of contact force over sliding distance per unit time.
Fretting-wear damage may be investigated from an energy point of view. It is essentially the mechanical energy or power dissipated through contact forces and sliding that causes fretting-wear damage. Development of a simple formulation that relates tube vibration response and fretting-wear damage is reviewed in this paper. Some new practical examples and simple calculations are discussed.
Age 60+ — Applicability of Ageing Related Data Bases and Methodologies for Ensuring Safe Operation of LWR Beyond 60 Years
Authors: Ortner Susan , Brumovsky Milan 
Published: October 2017

The AGE60+ project aimed towards the application of ageing related data bases and methodologies to ensuring the safe operation of Light Water Reactors beyond 60 years, and the longer-term safe storage of waste. It acted by encouraging European researchers to share data in order to maximize its utility.
As an initial step, the AGE60+ consortium considered the development and utilization of a number of databases set up to collate data and derive information relevant to the management of nuclear power plant. This review was used to identify the factors which lead to a database successfully making a useful contribution.
The AGE60+ project has been a very fruitful collaboration. It has:
• Raised the concept of sharing data and setting up databases related to the ageing of concrete in waste disposal, and received a generally positive response to this first step.
• Identified an area in which a new database would provide the opportunity to advance predictive modeling of the degradation of internals.
• Collated and reviewed data on the thermal ageing of low alloy steels.
• Identified information gaps in the area of internals degradation and the thermal ageing of low alloy steel components.
• Produced an up-to-date database on WWER-440 RPV steel embrittlement.
• Produced a new embrittlement trend curve (ETC), relating the fracture toughness transition temperature to fluence and composition for WWER-440 weld and base metal.
• Expanded and utilized a database on MnMoNi steel embrittlement.
This AGE 60+ project was realized as a part of the NUGENIA+ Call and lasted 18 months with participating organizations: UJV Rez a.s., Czech Republic, AREVA GmbH, Germany, CIEMAT, Spain, MTA EK, Hungary and NNL, UK as a leading organization.
On Categorization of Seismic Load As Primary or Secondary
Authors: Labbé Pierre B. 
Published: October 2017

The concept of primary/secondary categorization is first recalled and generalized for its application to an elastic-plastic oscillator subjected to a seismic load. Categorizing the seismic load requires calculating the input level associated to the oscillator ultimate capacity and compare it to the level associated to the plastic yield. In order to resolve this non-linear dynamic problem, it is assumed that the non-linear oscillator behaves like a linear equivalent oscillator, with an effective stiffness (or frequency) and an effective damping. However, as it is not a priori possible to predict the equivalent stiffness and damping, a wide range of possibilities is systematically considered. The input motion is represented by its conventional response spectrum.
It turns out that key parameters for categorization are i) the “effective stiffness factor” (varying from 0 for perfect damage behaviour to 1 for elastic-perfectly plastic) and the slope of the response spectrum in the vicinity of the natural frequency of the oscillator. Effective damping and spectrum sensitivity to damping play a second order role. A formula is presented that enables to calculate the primary part of a seismically induced stress as a function of both the oscillator and input spectrum features. The formula is also presented in the form of an abacus.
The actual “effective stiffness factor” of different piping systems is derived from outputs of experimental research programs carried out in the past in USA and Japan and still ongoing in India. It appears that even when experiencing large plastic strains under beyond design input motions, the observed effective frequency of piping systems is very close to their natural frequency, decreasing only by a few percents. These observations enable to calculate an effective stiffness factor value around 0.9 and lead to the conclusion that the seismic load, or the seismically induced inertial seismic strains, should basically be regarded as secondary in the sense of the definition adopted here.
Investigation on Method of Elasto-Plastic Analysis for Piping System Made of Stainless Steel: Secondary Benchmark Analysis
Authors: Arai Masashi , Kojima Nobuyuki , Kabaya Takuro , Hirouchi Satoru , Bando Masatsugu 
Published: October 2017

This paper provides investigation on method of elasto-plastic analysis for practical seismic design of nuclear piping system made of austenitic stainless steel. Our policy for the evaluation is that material properties used in the benchmark analyses are based on Japanese standard in nuclear design. The result of the first phase of this benchmark analysis intended for carbon steel piping systems has been provided in ASME PVP2016-63186[1].
In secondary benchmark analysis, analytical investigations focused on austenitic stainless steel piping were conducted. These analysis objects are two vibrating tests (model 1: piping containing an elbow, model 2:piping containing a tee). The elasto-plastic characteristic based on bilinear plasticity model based on the draft code case of JSME (Japan Society of Mechanical Engineers) was used in analyses. Additionally, analyses using the elasto-plastic characteristic which made yield point and 2nd modulus as a parameter were also carried out.
For the model 1, the maximum strain estimated by elasto-plastic analysis using the elasto-plastic characteristics of stainless steel material determined as proposed by the draft code case of JSME agreed well, but on the safe side, with the experiment. However, this is not the case for the model 2: the maximum strain estimated using the same elasto-plastic characteristics was underestimated compared with the experiment. However, for both the models 1 and 2, the elasto-plastic behavior of the piping systems estimated by this analysis was approximately the same between the analysis with the material’s elasto-plastic characteristics approximated by bilinear plasticity modeling proposed by the draft code case of JSME and that approximated by the same bilinear plasticity modeling but with different setting of yield point and 2nd modulus values of the material.
A possible cause of the underestimate that occurred in the model 2 is, according to the shape data of the tee, that the wall thickness of the tee is so large that its connection with the main and branch pipes has a large, step-like change in thickness, as opposed to the model that was designed without referencing the shape data. Another possible cause of this underestimate is coarse meshes of elements of the model. In order to improve analytical accuracy, it is necessary to add a method for modeling tee joints to the draft code case. To this end, a database of the shape of tee joints should be developed in cooperation with the manufacturers so that an optimum modeling method can be developed.
As mentioned above, according to the result of elasto-plastic analyses for the model 1 (piping containing an elbow) and model 2 (piping containing a tee), it is necessary to develop a modeling method for tee joints. It is likely possible to directly use the elasto-plastic characteristics of carbon steel for the purpose of analyzing a piping of stainless steel.
Features Testing of Stud Material Under Low Constraint Ductile Tearing
Authors: James P. , Jackson M. , Birkett P. , Madew C. 
Published: October 2017

Defect tolerance assessments are carried out to support the demonstration of structural integrity for high integrity components such as nuclear reactor pressure vessels. These assessments often consider surface-breaking defects and assess Stress Intensity Factors (SIFs) at both the surface and deepest points. This can be problematic when there is a high stress at the surface, for example due to the stress concentration at the root of a screw thread. In the past this has led to the development of complex and costly 3D finite element analyses to calculate more accurate SIFs, and still resulting in small apparent limiting defect sizes based on initiation at the surface point.
Analysis has been carried out along with supporting materials testing, to demonstrate that the increased SIF at the surface point is offset by a reduction in crack-tip constraint, such that the material exhibits a higher apparent fracture toughness. This enables a more simplistic assessment which reduces the effective SIF at the surface such that only the SIF at the deepest point needs to be considered. This then leads to larger calculated limiting defect sizes. This in turn leads to a more robust demonstration of structural integrity, as the limiting defect sizes are consistent with the capability of non-destructive examination techniques.
The high SIF at the surface location, and the concomitant reduction in crack-tip constraint, meant that it was not possible to demonstrate the material response with conventional tests, such as those using shallow-notched bend specimens. Instead it was necessary to develop modified specimens in which semielliptical defects were introduced into a geometry which replicated the notch acuity at the root of a screw thread. These feature tests were used to demonstrate the principle, prior to testing with more conventional specimens to fit more accurately the parameters required to represent the material response in a defect tolerance assessment.
Margins in defect tolerance assessments are usually measured against the initiation of tearing, even though the final failure for the material may occur at a higher load following stable crack extension. This work measured and assessed the benefit of reduced crack-tip constraint on both the point of initiation and on the development of the tearing resistance curve. This demonstrated that the effect of constraint was valid with tearing for this material and that there was additional margin available beyond the onset of tearing. The feature test geometry also provided evidence of the tearing behaviour at the surface and deepest points of a surrogate component under representative loading.
This paper provides an overview of the range of tests performed and the post-test interpretation performed in order to provide the R6 α and k constraint parameters.
Fracture Mechanics at Elevated Loading Rates in the Ductile to Brittle Transition Region
Authors: Mayer Uwe , Reichert Thomas , Tlatlik Johannes 
Published: October 2017

The rate-dependent reference temperature T0,x characterizes the fracture toughness of ferritic steels at the onset of cleavage. Fracture toughness values KJc,d were determined according to the Annex A1 of ASTM E1921 [1] which refers to the high rate annexes A14 and A17 of ASTM E1820 [2].
Results of extensive dynamic fracture toughness experiments at various loading rates, temperatures, specimen types and sizes revealed shortcomings in the transferability of the shape of the Master Curve under quasi-static conditions to elevated loading rates. In particular, the quasi-static Master Curve predicts lower fracture toughness values towards higher temperatures than experimentally observed under dynamic loading causing a steeper Master Curve shape.
Fractographic examinations proved the relevance of local crack arrest under dynamic loading conditions, which is consistent with the view of the parallelism of dynamic fracture probability and probability of arrest.
Validation of Fatigue Models for ERW Seam Weld Cracking
Authors: Young Bruce A. , Olson Richard J. , O’Brian Jennifer M. 
Published: October 2017

In response to the National Transportation Safety Board (NTSB) Recommendation P-09-1, the Department of Transportation (DOT) Pipeline and Hazardous Material Safety Administration (PHMSA) initiated a comprehensive study to identify actions that could be implemented by pipeline operators to significantly reduce longitudinal seam failures in electric resistance weld (ERW) pipe. As part of the project, Task 4 in Phase II was designed to validate existing failure prediction models and, where gaps exist, refine or develop these models needed to assess and quantify defect severity for cold welds, hook cracks, and selective seam weld corrosion (SSWC) (the primary ERW/Flash Weld seam threats) for failure subject to loadings that develop both during hydrotests and in service. These models would then be used to develop software to support integrity management of seam welds with enough flexibility to benefit from the experience gained during this project.
The purpose of this paper is to review the models used for fatigue crack growth rate (FCGR) calculations. Both the Willenborg Model, which is used to incorporate the retardation of crack growth after an overload occurs (such as a hydrostatic test in a pipeline), and the Walker Model, which is used to account for variation in stress ratio during the operation of a structure (i.e. pressure cycles in a liquid pipeline), will be discussed. Laboratory fatigue crack growth rate test results on several grades of pipe will be used to generate the constants employed in these models.
The reports generated during the course of the project are publicly available and are located on the following PHMSA website: http://primis.phmsa.dot.gov/matrix/PriHome.rdm?pri=390.
An Assessment of the Safety Factors and Uncertainties in the Fatigue Rules of the RCC-M Code Through the Benchmark With the EN-13445-3 Standard
Authors: Métais Thomas , Courtin Stéphan , Triay Manuela , Billon François , Duranton Pascal , Briot Rudy , Bridier Florent , Gourdin Cédric , Luciani Jean-Pascal 
Published: October 2017

The RCC-M code [1] is a well recognized international code and provides rules for the design and the construction of mechanical equipment for pressurized water reactors. It is used today for the nuclear industry exclusively, in countries such as France, South Africa and China and it is the basis for the design of the UK EPR to be built in Hinkley Point. The RCC-M code’s fatigue rules emanate from the ASME Boiler and Pressure Vessel Code and are hence very similar, albeit they have evolved in their own way over time to include some R&D results and other evolutions. These rules are published by AFCEN which involves a wide range of international organizations from the nuclear industry such as Apave, Areva, Bureau Veritas, CEA, DCNS, EDF, EDF Energy, ONET-MHI, Rolls-Royce and Westinghouse.
The EN-13445-3 [2] is a European standard which is mostly in use today in the conventional industry. Its fatigue rules are a compilation of rules from various national European codes, such as the German AD-Merkblatt, the British Standards, the Eurocodes for civil works and the French CODAP. The rules for fatigue are compiled in Chapters 17 and 18 of EN-13445-3 and have been the result of the work of contributors from major European organizations from the nuclear, oil and gas, chemical and mechanical industries: these include, among others, Areva, the Linde Group, CETIM, TÜV, and the TWI (The Welding Institute).
Since the beginning of 2015, AFCEN has created a technical Working Group (WG) on the topic of fatigue with the objective of identifying the Safety Factors and Uncertainties in Fatigue analyses (SFUF) and of potentially proposing improvements in the existing fatigue rules of the code. Nevertheless, the explicit quantification of safety factors and uncertainties in fatigue is an extremely difficult task to perform for fatigue analyses without a comparison to the operating experience or in relation to another code or standard. Historically, the approach of the code in fatigue has indeed been to add conservatism at each step of the analyses which has resulted in a difficult quantification of the overall safety margin in the analyses.
To fulfill its mission, the working group has deemed necessary to lead a benchmark with the EN-13445-3 standard given its wide use through other industries. Two cases were identified: either the comparison with EN-13445-3 is possible and in this case, the identification of safety factors and uncertainties is performed in relation to this standard; either the comparison is not possible, in which case the overall conservatism of the RCC-M code is evaluated in relation with operating experience, test results, literature, etc...
This paper aims at describing the overall work of the group and focuses more specifically on the results obtained through the benchmark with the EN-13445-3 standard.
Bayesian Analysis of Expert Elicitation Responses for Life Cycle Management Replacement Probability Estimates
Authors: Cluever Joseph , Esselman Thomas , Harvey Sam 
Published: October 2017

In 2014, the Integrated Life Cycle Management (ILCM) computer code was developed through collaboration between the Electric Power Research Institute (EPRI) and Électricité de France (EDF) to provide a standard methodology to support effective decision making for the long-term management of selected station assets. In order for the ILCM program to become a standard tool in the industry, additional work was needed in the development of a Likelihood of Replacement (LoR) calculator. The LoR calculator estimates the likelihood that a component will have to be replaced due to failure or reasons other than failure, such as high maintenance cost, inability to maintain, obsolescence, and other similar reasons. Expert elicitation was chosen as the method of gathering data and opinions on component replacement probabilities.
The majority of expert elicitation techniques consist of experts giving opinions on the probability of replacement at various points in time, from which a reliability curve can be calculated. Furthermore, any failure or replacement data is subjectively incorporated in to the expert’s opinion.
The present work uses Bayesian analysis to provide an objective method for statistically combining expert opinion with failure and replacement data. This paper also describes the process of extracting a Weibull LoR curve from expert’s opinions and reported failures and replacements. The expert’s work history and answer confidence is used to assign uncertainty in their answers and calculate 5th, 50th, and 95th percentile credibility Weibull curves for the probability of replacement.
Assessment of the Influence of Central and Lateral Feed Injection Systems on the Remaining Life of Coke Drums
Authors: Vivas Gabriel A. , Moret Armando J. , Bello Roberto E. , Melian Luis M. , Carmona Jose R. 
Published: October 2017

Coke drums are thin walled pressure vessels that are subjected to severe thermal cyclic operation, which causes low cycle thermal fatigue. Because of that, they are considered as the vessels with the highest failure rate in a refinery according to API survey conducted in1996.
In the last decade, a new technology in bottom blocking valve systems for coke drums has been introduced which induces a change in the traditional center feeding system to lateral feeding system; basically with the main goal to increase operators safety. Taking into account the mechanical integrity and remaining life of coke drums, the central feeding system has traditionally been considered as the best option, however; this hypothesis has not been fully demonstrated.
Two central fed coke drums were heavily instrumented with strain gauges and thermocouples in bulged zones identified after performing a bulge severity analysis (BSA). Thermocouple arrays and several strain gauges were installed in eight specific locations of the drums. This instrumentation was installed three months before installing bottom blocking valves in the drums, and consequently, changing their feeding system to lateral. A statistical analysis was performed using 40 thermal cycles of the two coke drums with central feeding system and 120 thermal cycles of the same coke drums after changing to lateral feeding system. The usage factor was estimated for each cycle considering the axial stress amplitude and a fatigue strength reduction factor of 2 for the ASME S-N design curve Fig. KD-320.2. Finally, the remaining life was estimated for each instrumented zone taking into consideration that the coke drums would have the same cumulative damage in the future.
The results show that average remaining life at instrumented zones (considering all locations) of one coke drum increased when the lateral feeding system was introduced; while the average remaining life at instrumented zones for the second coke drum remained practically unchanged after the lateral feeding system was put in to service.
Determination of Target Bolt Tension for Flanges With Lens Gaskets
Authors: van Zyl Gys 
Published: October 2017

A lens gasket is a specific type of metallic ring gasket that is usually only deployed in high pressure gas applications where a high integrity bolted flange joint is required. Lens gaskets are not common in ASME design and there are no ASME rules that guide the design of flanges with lens gaskets, nor are there ASME standards to control lens gasket specifications.
Lens gaskets present a special challenge when determining target bolt tension values for flange assembly. For calculating target bolt tension, the gasket seating width is an important parameter. With lens gaskets, the gasket seating width depends on the applied bolt tension, therefore calculation of bolt tension is by nature an iterative process. In these flange joints, the lens gasket has spherical machined surfaces that are in contact with conical gasket seats in the flanges. At low bolt tensions, gasket contact is nearly equivalent to line contact. At high bolt tensions, finite contact widths are developed, sometimes involving plastic deformation of the gasket.
This paper will present a method that was developed to determine target bolt tension for a lens gasket bolted flange. Reference will be made to European standards that address lens gaskets, and the results of finite element analysis studies that were used to validate the calculation method will be presented. The successful deployment of the outcome of this work for all the lens gasket flange joints on a plant will be discussed.