bluuebunny/crossref_metadata_2025_split huggingface dataset:
Models of the Temperature Dependence and Scatter in J-R and J0.1 for Ferritic Reactor Pressure Vessel Steels
Authors: Kirk Mark , Erickson Marjorie , Stevens Gary 
Published: November 2015

At the 2014 ASME Pressure Vessel and Piping Conference, these authors and others presented a paper that drew together a number of models describing the fracture toughness of ferritic reactor pressure vessel (RPV) steels. That paper summarized models of both the temperature dependence and scatter in a number of fracture toughness metrics (i.e., KJc, KIa, JIc, and J0.1). That paper also provided equations that quantify the interrelationships between these toughness metrics, and how these interrelationships are affected by hardening. Significantly, all of these models and interrelationships are linked via a single parameter: the Master Curve index temperature, To, which can be measured as described in ASTM Standard Test Method E1921. Work is currently underway within the ASME Section XI Working Group on Flaw Evaluation (WGFE) to develop a revision to Code Case N-830 that incorporates all of these models, and provides information on how to apply them in a flaw evaluation. As part of that work, an effort was initiated to augment these models by the addition of a model that can be used to predict the temperature variation of, and the scatter in, J-R curve behavior. A J-R curve model is also expected to support on-going WGFE efforts to in development of acceptance criteria for flaws in ferritic components operating in the upper shelf temperature range.
The work presented in this paper provides a model of the J-R behavior of ferritic RPV steels. When combined with other fracture toughness models to be published in Code Case N-830-1, this model allows prediction of the mean J-R curve, confidence bounds on the mean, and the temperature dependence of J-R all based only on input of To. The J-R model described herein has equivalent or better accuracy to other models described in the literature, and generally has fewer fitting parameters than those other models. Because the full J-R curve is predicted, this model is also useful for prediction of J0.1.
Applicability of Fracture Toughness Curves Developed for Japanese Pressure Vessel Steels to Structural Integrity Evaluation
Authors: Yoshimoto Kentaro , Hirota Takatoshi , Sakamoto Hiroyuki 
Published: November 2015

Surveillance tests have been conducted on Japanese Pressurized Water Reactor (PWR) plants for more than 40 years to monitor irradiation embrittlement of reactor pressure vessel (RPV) beltline materials. Fracture toughness specimens are contained as well as tensile and Charpy impact specimens in a surveillance capsule and utilized for structural integrity evaluation. Therefore, a lot of fracture toughness data have been obtained by fracture toughness tests using such as Compact Tension (CT) and Wedge Opening Loading (WOL) specimens. More than one thousand data have been accumulated for both unirradiated and irradiated materials until 2013. Additionally, in terms of fracture toughness, Master Curve (MC) concept has been widely used for fracture toughness transition curve expression of ferritic steels. Considering such a situation, the new fracture toughness curves using Tr30, which denotes Charpy V-notch 30ft-lb transition temperature, as an indexing parameter were developed based on MC concept depending on product form for Japanese RPV steels in 2014.
In this study, applicability of the newly developed curves of Japanese RPV steels to structural integrity evaluation is investigated. Especially, this paper focused on conservatism of the curves and the adequate margin to be added in evaluation of RPV integrity employing statistical methodology.
Master Curve Testing of Reactor Pressure Vessel Multilayer Welding Seams
Authors: Viehrig Hans-Werner , Houska Mario , Altstadt Eberhard 
Published: November 2015

Reactor pressure vessel (RPV) multilayer welding seams show an inhomogeneous structure. It raises concerns that the evaluation of non-uniform material might not be amenable to the statistical analysis methods on which the Master Curve approach is based. In particular with regard to weld metals, it can be expected that the cleavage fracture toughness is strongly influenced by the orientation of the Charpy size SE(B) specimen. The T-L oriented SE(B) specimen (axis axial and crack propagation in circumferential direction) comprises of various welding beads along the crack front whereas in a L-S specimen (axis axial and crack propagation through the thickness) the crack tip is located in one welding bead with an approximately uniform structure.
The paper summarises fracture toughness results measured on welding seams of decommissioned and non-commissioned RPVs of WWER type nuclear reactors and the non-commissioned Biblis-C RPV. Specimens of T-L and T-S orientation were tested. The results show, that in general the cleavage fracture toughness values, KJc-1T, follow the Master Curve description. However, the number of KJc-1T data outside the 2% and 98% tolerance bounds is larger than predicted by the underlying model, which indicates non-uniform material.
There is a large variation in the evaluated through thickness T0 values of the investigated multilayer beltline welding seams. Within the sampling range of the surveillance specimens, T0 values vary with a span of 30 to about 60 K depending on the applied welding technology. The fracture toughness strongly depends on the intrinsic weld bead structure. Hence, the position of the fatigue crack tip of the pre-cracked SE(B) specimen at the multilayer welding seam is crucial and defines the cleavage fracture toughness. Modified Master Curve based evaluation procedures like the MC based approach of the SINTAP procedure were applied to get fracture toughness values which are representative for the most brittle fraction the test series.
Despite of the pronounced non-homogeneity of the micro-structure along the crack front of T-L specimens, crack initiation sites are randomly distributed along the crack front. This means that one of the basic assumptions in ASTM E1921, i.e. the uniform distribution of initiation sites, is fulfilled also for the T-L specimens from the multilayer weld metal.
The Influence of Creep Strain on Crack Length Measurements Using the Potential Drop
Authors: Tarnowski K. M. , Davies C. M. , Nikbin K. M. , Dean D. W. 
Published: November 2015

One of the most common methods for estimating crack extension in the laboratory is electrical potential drop (PD). A key limitation of this technique is that it is sensitive to strains at the crack tip as well as crack extension. When producing J-R curves the onset of crack growth may be identified from a point of inflection on a plot of PD vs. CMOD. For creep crack growth (CCG) tests however, the effects of strain are often ignored. This paper investigates whether a similar method may be applied to CCG testing.
A single CCG test was performed on type 316H stainless steel and a point of inflection, similar to that observed during J-R curve testing was identified. A finite element (FE) based approach was used to investigate this phenomenon further. A 3D sequentially-coupled structural-electrical FE model was used to reproduce the experimental PD vs. CMOD plot up to the point of inflection. The model was capable of predicting the general relationship between strain and PD. It predicted the magnitude of the change in PD to within 30%. A simplified 2D FE model was then used to perform a parametric study to investigate whether a similar trend may be expected for a range of materials. Power law tensile and creep properties were investigated with stress exponents of 1, 3 and 10. The results confirm that a point of inflection should be observable for the range of material properties considered.
A Study of the Effects of Scaling on Structural Integrity Assessment
Authors: Orrock Paulo , Smith David J. , Truman Christopher E. 
Published: November 2015

For nuclear welded components the complex nature of the residual stresses involved means it is often advantageous to produce mock-ups in order that the structural integrity and performance may be assessed. The weight and size of these components can make the production of mock-ups prohibitively expensive, and so the use of scaled models is considered here. Numerical analysis and finite element simulations have been carried out to investigate the scaling laws encountered affecting the applied loads, stress fields and crack driving forces that are of interest in the full sized component.
To illustrate the effects of scaling we consider the introduction of a residual stress through prior plastic deformation in rectangular beams of different sizes. A simple scaling law provides the loads required to introduce the same magnitude and distribution of residual stresses in different sized specimens. This is pertinent to uncracked beams. In contrast, if a crack is introduced this scaling law is no longer applicable and the stress intensity factor associated with residual and applied stresses differ for different sized specimens. Alternatively, to create the same crack driving force in different sized specimens different initial residual stress fields are required. The implications of these findings are discussed in the context of future work.
Comparison Between the ASME Code NB-3600 Piping Design Branch Connection Stress Analyses and Finite Element Analyses
Authors: Faraz Umar , Gurdal Robert 
Published: November 2015

Stresses in Class 1 branch connections that consist of large bore run pipe with a reinforced branch nozzle should rarely be limited by the run–branch interface stresses. The end of the “branch nozzle – branch pipe” interface is the location on the branch nozzle one would expect to see the limiting stress. Therefore, it is important that reasonable Design Rules are maintained in the ASME Code Section III for the stress analyses of the Class 1 Piping branch connections to avoid over-predicting the “run pipe - branch nozzle” interface stresses. This will allow the analysts to concentrate on load reductions needed in a logical manner.
In Class 1 Piping Design, the calculation of the branch total stress due to the moments is the result of the sum of the stresses from the run moment and of the stresses from the branch moment with these branch moment stresses being calculated using either the branch pipe cross-section or the branch nozzle cross-section. This in itself is already severe, when compared with other Piping Design Rules for branch connections. In addition, starting with the ASME Code year 2002, the branch-side moment stress is based exclusively on the branch pipe cross-section, which leads to a higher moment stress, and this higher moment stress is still absolutely added to the run-side moment stress. As indicated in that ASME Code year 2002 and beyond, this addition is independent of the length of the branch nozzle reinforcement. This leads to total moment stresses that are the sums of moment stresses that do not occur at all at the same location.
The purpose of this technical paper is to compare a) the stresses calculated with the earlier more correct Class 1 Piping methodology from 2001 and before 2001; b) the stresses calculated with the more recent and more severe Class 1 Piping methodology; and c) the stresses from finite-element analyses.
Conclusions are provided on what should be done for the future Class 1 Piping Design methodology of branch connections.
Influence of Specimen Geometry and Strain Rate on Ductile-Brittle Transition Characterisation of Reactor Pressure Vessel Steels Using the Small Punch Technique
Authors: Adams Jack , Hurst Roger C. , Borradaile J. Bryan , Bache Martin R. 
Published: November 2015

The small punch (SP) tensile test, originally developed for assessing the integrity of nuclear containments, has seen a renaissance in recent years with the introduction of a Code of Practice and a standardisation proposal. For nuclear applications, the extremely low volumes of material that are required allows specimens to be manufactured from quasi-destructive scoop samples, surveillance specimens or even previously tested Charpy specimens. The low volume of material also alleviates the health and safety requirements and the cost associated with testing active materials. By assessing the energy absorbed before fracture, it is possible to build an entire SP ductile-brittle transition curve using less material than is required for a single Charpy test.
Small punch testing has been performed on SA 508-3 NESC-1 spinning cylinder material to establish ductile-brittle transition data, for comparison to that obtained by conventional Charpy impact test techniques. Multiple SP ductile-brittle transition curves have been constructed, building upon the framework of the existing Code of Practice. Novel geometries and associated machining techniques employed to incorporate notches into the surface of the SP specimen, and also the application of relatively high strain rates have been investigated. Post-test fractography illustrates the influence of both stress raising features and strain rate on small punch fracture behaviour.
Lessons From an Operational Small Leakage at Tsuruga Nuclear Power Station
Authors: Kobayashi Hiroyuki , Urabe Osamu , Fujino Takushi 
Published: November 2015

Operational small leakage is occasionally observed in a nuclear power plant, and the leak forces an operator to decide whether to shut down the plant or not. Even if the leakage is just a little, it might draw the considerable attention in the society, so that the operator sometimes gets into the situation to judge more severely than technical judgment. Furthermore, at the time of plant restart and the system leak test just after maintenance, even the operator doesn’t accept any leakage considering the long management for the leakage up to the next outage.
On the other hand, once the operator shut down the plant, it sometimes takes long time to restart again because of the difficulty to obtain new pipes and valves in short time. The temporary repair techniques referred to the JSME code might be able to be applied to maintain the plant operation, however some difficulties exist in a practical process.
One of the authors has faced with many cases in which the operational small leakage had to be dealt at Tsuruga nuclear power station. This paper shows some cases of them and discusses lessons which are related to the codes and standards.
Direct Measurements of Acoustic Damping and Sound Amplification in Corrugated Pipes With Flow
Authors: Golliard Joachim , Belfroid Stefan , Vijlbrief Olav , Lunde Knud 
Published: November 2015

The flow-induced pulsations in corrugated pipes result from a feedback loop between an acoustic resonator and the noise amplification at each shear layer in the axisymmetric cavities forming the corrugations. The quality factor of the resonator is determined by the reflection coefficients at the ends of the corrugated pipe and by the damping in the pipe. In this work, the damping of acoustic waves in a set of smooth and corrugated pipes is measured by a direct method.
For these measurements, the tested pipes are placed between two measuring pipes equipped with flush-mounted pressure transducers to allow reconstruction of the acoustic waves with the two-microphone method. Loudspeakers are used to generate acoustic waves, and anechoic terminations allow near reflection-free conditions. The tests are done in air without flow and with flow velocities up to 60 m/s.
The results for the corrugated pipes allow to investigate the influence of the corrugations on the damping. Two cases are considered: Without flow, the visco-thermal damping is increased for the corrugated pipe compared to a smooth pipe of same diameter. When there is a flow in the pipe, the damping results depend strongly on the flow velocity. At certain frequencies which depend on the flow velocity, the damping increases or decreases. The regions of increase or decrease are shown to be at constant ranges of Strouhal numbers. The decrease of the damping can in some cases be such that acoustic waves are amplified through the corrugated pipe. This corresponds to the acoustic source behavior of the shear layers. The measured amplification is compared to the computed source term due to the axisymmetric cavities.
The Effect of Load Frequency on the Temperature Dependence of Fracture Life of Notched Specimens for 9-12Cr Steel Under Creep-Fatigue Conditions
Authors: Shirai Y. , Yokobori A. T. , Sugiura R. , Fukuda T. , Matsumoto D. , Ishikawa H. , Ito K. 
Published: November 2015

In order to operate a thermal power plant safely, it is necessary to establish the prediction methods of fracture life for heat-resistant steels which is used in thermal power plant. For the establishment of prediction methods, it is necessary to consider the effects of creep damage and creep-fatigue interaction on the fracture life.
Therefore, in this paper, creep-fatigue tests were conducted on notched specimens of W-added 9-12Cr steels for various temperatures and load frequencies. From these results, the influence of load frequency on temperature dependence of crack growth life for 9-12Cr steels was determined.
Applicability of Miniature C(T) Specimens for the Master Curve Evaluation of RPV Weld Metal
Authors: Yamamoto Masato , Miura Naoki 
Published: November 2015

The Master Curve approach for the fracture toughness evaluation is expected to be a powerful tool to ensure the reliability of long term used reactor pressure vessel (RPV) steels. In order to get sufficient number of data for the Master Curve approach coexistent with the present surveillance program for RPVs, the utilization of miniature specimens that can be taken from the broken halves of the surveillance Charpy specimens is important. CRIEPI has developed the test technique for the miniature C(T) specimens, whose dimensions are 4 × 10 × 9.6 mm, and has verified the basic applicability of the Master Curve approach by means of the miniature C(T) for the determination of the fracture toughness of typical Japanese RPV steel base metals [1]. A series of round robin tests on RPV steel base metals [2–4] demonstrated that the miniature C(T) specimen can be used for the determination of the reference temperature (To) with no specific difficulties in test techniques.
The present paper addresses the applicability of the fracture toughness evaluation by the miniature C(T) specimens on a RPV weld metal with multi-layer weld bead structure. The distribution of the fracture toughness and the trend in fracture toughness change with temperature were confirmed to show a good agreement with the assumption of the Master Curve method [5]. Fracture surface of the specimens were in cleavage fracture mode regardless of the difference in fracture toughness level. The relevance of the specimen size correction in the Master Curve method was confirmed. The difference of To values were only in a few degrees Celsius between the data obtained with 0.5 inch-thickness C(T) specimens and the miniature C(T) specimens. The effect of local loss of constraint nearby the specimen side surface was examined by comparing with the datasets from the specimens with and without side grooves. The difference of To was only 3 degree centigrade and no remarkable effect of side grooving could be seen. From overall examination results, it was concluded that the miniature C(T) specimen can be used for the Master Curve evaluation of tested PRV weld metal.
Friction Stir Seal Welding (FSSW) Tube-Tubesheet Joints Made of Steel
Authors: Shuaib Abdel Rahman , Al-Badour Fadi , Merah Nesar 
Published: November 2015

This paper demonstrates the feasibility of successful seal welding process of tube-tubesheet joints using the relatively new friction stir welding (FSW) process. The purpose of the reported study is to develop the process parameters and to test the feasibility of friction stir welding ASTM 179 seamless cold-drawn carbon steel tube into an ASTM A516 Grade 70 tubesheet. All welds were performed in position control on a fully instrumented experimental friction stir welder using a water-cooled tool holder and a shroud for argon shielding gas. A proprietary tungsten-rhenium pin tool with a 1.54 mm pin length and shoulder diameter of 4.9 mm was used to perform the seal weld between the roller expanded tube and tubesheet. A steel plug was employed during each weld in order to maintain support for the weld throughout the circumference of the weld.
Sound welds were achieved in the FSW of ASTM 179 seamless cold-drawn carbon steel tube into an ASTM A516 Grade 70 tubesheet. Welding was improved by avoiding tool contact with the tube plug or the flash of the previous weld. Though a root void has been observed, which is typical of partial penetration butt welds, it is believed that the weld would still achieve a hermetic seal. Tool wear features of the W-Re pin has also been documented.
Uncertainty Characterization of the CrCOD Circumferential Crack Opening Displacement Module for xLPR
Authors: Olson Richard , Scott Paul 
Published: November 2015

The US NRC/EPRI xLPR (eXtremely Low Probability of Rupture) probabilistic pipe fracture analysis program uses deterministic modules as the foundation for the calculation of the probability of pipe leak or rupture as a consequence of active degradation mechanisms, vibration or seismic loading. The circumferential crack opening displacement module, CrCOD, estimates crack opening displacement (COD) at the inside pipe surface, at the mid-wall thickness location, and at the outside pipe surface using a combined tension/crack face pressure/bending GE/EPRI-like solution. Each module has an uncertainty beyond the uncertainty of the xLPR data inputs. This paper documents the uncertainty for CrCOD.
Using 36 pipe fracture experiments, including: base metal, similar metal weld, and dissimilar metal weld experiments; bend only and pressure and bend loading; static and dynamic load histories; cracks that range from short to long, the uncertainty of the CrCOD methodology is characterized. Module uncertainty is presented in terms mean fit and standard deviation between prediction and experimental values.
Validation of Stress Intensity Factor Solutions in xLPR Version 2.0 Code
Authors: Shim Do-Jun , Wallace Jay , Kalyanam Sureshkumar , Benson Michael 
Published: November 2015

As part of the xLPR (Extremely Low Probability of Rupture) project, the stress intensity factor (SIF) solutions required for crack growth calculations were updated. This involved extension of existing solutions and development of new solutions as well. For surface cracks, the Universal Weight Function Method (UWFM) was implemented to handle complex stress distributions. In addition, a crack transition model was developed to more accurately capture the surface to through-wall crack transition. Finally, solutions for idealized through-wall cracks were extended to various pipe sizes and longer crack lengths.
In this paper, the SIF (K) solutions in xLPR Version 2.0 were validated against existing experimental data. The SIF modules in the xLPR code were used to simulate fatigue crack growth of circumferential cracks in pipes under bending up to wall penetration and to through-wall crack transition stage until idealized through-wall cracks were formed. The predicted fatigue crack growth results (mainly crack shape evolution) using the xLPR K-solutions provided good agreement with experimental data.