bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probabilistic Risk Assessment of Aging Layered Pressure Vessels
Authors: Riha D. S. , Kirby M. L. , Cardinal J. W. , Domyancic L. C. , McFarland J. M. , Brust F. W. 
Published: November 2019

Abstract
The National Aeronautics and Space Administration (NASA) operates approximately 300 aging layered pressure vessels that were designed and manufactured prior to ASME Boiler and Pressure Vessel (B&PV) code requirements. In order to make decisions regarding the continued fitness-for-service of these non-code carbon steel vessels, it is necessary to perform a relative risk of failure assessment for each vessel. However, risk assessment of these vessels is confounded by uncertainties and variabilities related to the use of proprietary materials in fabrication, missing construction records, geometric discontinuities, weld residual stresses, and complex service stress gradients in and around the welds. Therefore, a probabilistic framework that can capture these uncertainties and variabilities has been developed to assess the fracture risk of flaws in regions of interest, such as longitudinal and circumferential welds, using the NESSUS® probabilistic modeling software and NASGRO® fracture mechanics software. In this study, the probabilistic framework was used to predict variability in the stress intensity factor associated with different reference flaws located in the head-to-shell circumferential welds of a 4-layer and 14-layer pressure vessel. The probabilistic studies predict variability in flaw behavior and the important uncertain parameters for each reference flaw location.
Analysis of EDS Vessel Clamping System and Door Seal
Authors: Stofleth Jerome H. , Tribble Megan K. , Ludwigsen John , Crocker Robert W. 
Published: November 2019

Abstract
The V26 containment vessel was procured by the Project Manager, Non-Stockpile Chemical Materiel (PMNSCM) for use on the Phase-2 Explosive Destruction Systems. The vessel was fabricated under Code Case 2564 of the ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels. The explosive rating for the vessel, based on the Code Case, is nine (9) pounds TNT-equivalent for up to 637 detonations, limited only by fatigue crack growth calculations initiated from a minimum detectable crack depth.
The vessel consists of a cylindrical cup, a flat cover or door, and clamps to secure the door. The vessel is sealed with a metal gasket. The body is a deep cylindrical cup machined from a 316 stainless steel forging. The door is also machined from a 316 stainless steel forging. The closure clamps are secured with four 17-4 PH steel threaded rods with 4140 alloy steel threadednuts on one end and hydraulic nuts on the other.
A flange with four high-voltage electrical feedthroughs is bolted to the door and sealed with a small metal gasket. These feedthroughs conduct the firing signals for the high-voltage Exploding Bridge-wire detonators. Small blast plates on the inside of the door protect fluidic components and electrical feedthroughs. A large blast plate provides additional protection.
Both vessel door and feedthrough flange employ O-ring seals outside the metal seals in order to provide a mechanism for helium leak checks of the volume just outside the metal seal surface before and after detonation.
In previous papers (References 2 and 3), the authors describe results from testing of the vessel body and ends under qualification loads, determining the effective TNT equivalency of Composition C4 (EDS Containment Vessel TNT Equivalence Testing) and analyzing the effects of distributed explosive charges versus unitary charges (EDS Containment Vessel Explosive Test and Analysis).
In addition to measurements made on the vessel body and ends as reported previously, bulk motion and deformation of the door and clamping system was made. Strain gauges were positioned at various locations on the inner and outer surface of the clamping system and on the vessel door surface. Digital Image Correlation was employed during both hydrostatic testing and dynamic testing under full-load explosive detonation to determine bulk and bending motion of the door relative to the vessel body and clamping system. Some limited hydrocode and finite element code analysis was performed on the clamping system for comparison.
The purpose of this analysis was to determine the likelihood of a change in the static sealing efficacy of the metal clamping system and to evaluate the possibility of dynamic burping of vessel contents during detonation. Those results will be reported in this paper.
A Simplified Large Thin Plate Model for Modeling Fracture Behavior of a Hydrided Irradiated Zr-2.5Nb Pressure Tube Specimen With an Axial Crack
Authors: Sung Shin-Jang , Pan Jwo , Liu Cheng , Scarth Douglas A. 
Published: November 2019

Abstract
The crack tip opening displacements (CTODs) and the effective plastic strains ahead of the crack front in a hydrided irradiated Zr-2.5Nb pressure tube specimen with an axial crack are investigated using two 3-D finite element models in this paper. The first model is a pressure tube with 80 split circumferential hydrides distributed through the thickness ahead of the crack front. The second model is a large thin plate with a central crack with four split circumferential hydrides under symmetry/symmetry, free/symmetry and free/free constraint conditions. The results for CTOD indicate that the CTOD of the pressure tube specimen with 80 hydrides is slightly smaller than that for the large thin plate with the free/symmetry constraint condition and larger than that for the large thin plate with the symmetry/symmetry constraint condition. The effective plastic strain of the pressure tube specimen with 80 hydrides is smaller than that for the large thin plate with the free/symmetry constraint condition and larger than that for the large thin plate with the symmetry/symmetry constraint condition at large normalized loads. The computational results show that instead of modeling a full 3-D pressure tube with a larger number of hydrides, a large thin plate model with a limited number of hydrides can be used to efficiently determine the upper and lower bounds of the CTODs and the effective plastic strains ahead of the crack front in a pressure tube specimen.
Fast Reactor Core Seismic Analysis for Verification of Assessment Model Considering Deformation of Core Elements
Authors: Matsubara Shinichiro , Iwasaki Akihisa , Kawamura Kazuteru , Harada Hidenori , Yamamoto Tomohiko 
Published: November 2019

Abstract
To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Thus, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacements (rising). The analysis code is verified by a series of vibration tests.
The evaluation model to simulate the influence of core element deformation due to heat and irradiation were developed and the analysis of the seismic test was performed. And the evaluation model was verified by comparing the seismic test and analysis results.
A fast reactor core consists of hundreds of core elements, which lengthen due to thermal expansion and swelling. So, the core elements are self-standing on the core support structure and not restrained in the axial direction. When the vertical seismic excitation surpasses gravitational acceleration, it is necessary to consider vertical displacements and horizontal displacements of the core elements simultaneously. This 3-D vibration behavior is affected by the fluid loads from ambient coolant and the interference of surrounding structures. To solve this, the influential factors to vibration behaviors due to the structure and fluid body, including fluid structure interaction, are extracted and the 3-D reactor core group vibration analysis code (REVIAN-3D) is developed.
Core elements are deformed due to thermal expansion and irradiation, and are interfered with surrounding elements each other. The interference increases the frictional force acting on the core element and reduce the vertical displacement (rising) of the core element during the earthquake. To evaluate this reduction of rising, the evaluation model simulating this deformation is incorporated in REVIAN-3D.
In this study, the analysis of the vibration test was carried out using the new incorporated evaluation model. As the deformation of mock-up increases, the vertical displacement (rising) decreases, and when the initial interference due to deformation exceeds the threshold, no rising occurs. This trend agreed well between the vibration test and analysis. It is verified that the new incorporated evaluation model simulates the test result enough.
Mechanical and Tribological Evaluation of Aluminum Metal Matrix Composite Pipes Fabricated by Gravity and Squeeze Stir Casting
Authors: Christy John Victor , I. Mourad Abdel-Hamid , Arunachalam Ramanathan 
Published: November 2019

Abstract
Aluminum metal matrix composites (MMC) find many industrial applications due to its high strength, zero corrosion, light weight and durability. In this work, gravity stir casting and squeeze stir casting were used to produce MMC solid rods of length 21cm. LM25 grade, from scrap alloy wheel of car, was used as matrix and Alumina was added as reinforcements to improve the composite properties. The performed microstructure analysis showed a greater percentage of porosity for gravity casted samples. Brinell hardness tests recorded 61 and 56 for squeeze and gravity stir casting respectively. The analysis was further strengthened by conducting tensile test, compression test, abrasion and erosive wear tests on the casted pipe sections. Optical Microscopy images of squeeze casted Al MMC’s shows a homogenous and a condensed LM25 matrix with alumina reinforcements even at high abrasion rates. Squeeze casted samples exhibited higher hardness, tensile and compression strengths and wear resistance by keeping stirring time, and stirring speed constant. Squeeze stir casting was suggested for the production of Aluminum MMC pipes.
Evaluation of the Crack Interaction and Failure Behavior of Components With Crack Fields Using a Damage Mechanical Approach
Authors: Swacek Christian , Gauder Patrick , Seidenfuss Michael 
Published: November 2019

Abstract
In 2012 non-destructive testing measurements (NDT) of the reactor pressure vessels (RPV) in the Belgian Nuclear Power Plants Doel 3 and Tihange 2 revealed a high quantity of indications in the upper and lower core shells. The most likely explanation is that the measured indications are hydrogen flakes positioned in segregated zones in the base material of the pressure vessels. These hydrogen flakes have a laminar and quasi-laminar orientation with an inclination up to 15° to the pressure retaining surface. Under internal pressure, the crack tips undergo predominantly mixed mode loading conditions, where the induced stress and strain fields of the single crack tips influence each other. The safety assessment of crack afflicted pressurized components is performed by fracture mechanical approaches. For the evaluation of multiple cracks in crack fields, state of the art codes and standards apply interaction criteria and grouping methods, to determine a representative crack, which has to be evaluated.
In this paper, the interaction of cracks in crack fields is numerically and experimentally evaluated. Damage mechanical models based on the Rousselier- and the Beremin model are used to investigate numerically the interaction of cracks in crack fields. Experimental data from ferritic flat tensile specimens afflicted with cracks are used to verify the numerical results.
The damage mechanical calculations reveal critical crack arrangements due to coalescence behavior and cleavage fracture probability. These results and ongoing research intends the derivation of interaction criteria for cracks in crack fields. The interaction criteria will be used for the definition of a representative flaw for a conservative integrity assessment of crack afflicted components.
Validation for External Tieback Connector Bending Capacity by Strain Measurement
Authors: Christopherson Adam , Han Young-Hoon 
Published: November 2019

Abstract
Strain gauges provide a convenient and affordable method to accurately measure the strain field for complex systems. Not only do they provide crucial information for predicting the fatigue life of components, but they can also determine the principle stresses which can be used to compare design factors with accepted industry standards. The use of electrical resistance strain gauges for load verification has become an ever-increasing practice in the design of subsea connectors as evidenced by the recent application in the industry guidance API 17TR7 [1]. The design is aided by the development of a Finite Element Analysis (FEA) which is used to predict the load capacities for normal, extreme, and survival conditions. The present work describes the experimental validation of a 18-3/4in 10,000 psi subsea collet connector model by applying linear pattern CEA-06-062UW-350 strain gauges at discrete points along the circumferentially spaced collet segments. The collet segments are the selected components for strain gauge placement because not only are they the primary connecting element between the subsea wellhead and the connector body, but they also only support axial loads. The axial strain of the collet segments in tension were compared at two combined loading cases: maximum bending capacity with and without internal working pressure and found to be in good correlation with the elastic-plastic FEA. The experimentally validated FEA is a crucial tool in determining the connector’s application to project or customer specific load and fatigue requirements and eliminates the need for unnecessary experimentation.
Introduction of CASS Pipe Flaw Evaluation of JSME Rules on Fitness for Service
Authors: Hojo Kiminobu 
Published: November 2019

Abstract
This paper summarizes the revised flaw evaluation procedures for cast austenitic stainless steel (CASS) pipe of the Japan Society of Mechanical Engineers (JSME) rules on fitness for service (FFS) in 2018 addenda. The revision includes the introduction of thermal aging degradation models for stressstrain curve and fracture resistance (J-R) curve, application of a screening criteria for the fracture evaluation procedure of cast stainless steel pipes, and introduction of a new critical stress parameter for the limit load evaluation method of a shallow flaw with a flaw depth to thickness ratio of less than or equal to 0.5. These revisions are based on a large database of specimen tests and several fracture tests of flat plate and large pipe models using thermally aged material, which have already been published.
Recent Operational Experience of Pressurized Water Reactor Safety Injection and Drain Line Cracking and Supporting Flaw Evaluations
Authors: Imbrogno Greg , Marlette Stephen , Carolan Alexandria , Udyawar Anees , Gray Mark 
Published: November 2019

Abstract
A recent increase in operating experience (OE) related to pipe cracking in non-isolable auxiliary piping systems has been realized in the Pressurized Water Reactor (PWR) nuclear power industry. The majority of PWR auxiliary piping systems are comprised of welded stainless steel pipe and piping components. The susceptible piping systems are Class 1 pressure boundary and typically non-isolable from the primary loop. Since they are non-isolable, when a pipe crack or crack indication is identified, an emergent flaw evaluation and/or repair is required.
Typically, the evaluations begin with an ASME Section XI IWB-3640 flaw evaluation to determine acceptability of the as-found flaw at the time of shutdown. Subsequent flaw evaluations are performed to demonstrate the possibility of continued operation of the piping component by leaving the flaw as-is without repair. The flaw tolerance evaluation considers the applicable piping geometry, materials, loadings, crack growth evaluations, and the detection capabilities of the non-destructive examination technique. If evaluation of the as-found indication does not produce acceptable results, then a repair/replacement activity per ASME Section XI is considered. Possible repair scenarios include replacement of the piping section or component, or structural weld overlay. The results of the flaw evaluations or repairs must ensure that the auxiliary piping system will continue to operate safely.
This paper will discuss the recent experiences of two different piping systems (boron injection tank line and drain line) that experienced cracking, the potential causes for the cracking in the absence of evidence, and the ASME Code flaw evaluations and/or repairs performed to support continued operation of the plant.
Correlation of Plain and Notched Bar Creep Behavior in Grade 91 Steel
Authors: Takahashi Yukio , Shigeyama Haruhisa , Siefert John 
Published: November 2019

Abstract
Axi-symmetrical notched bar specimens are often used as a means of evaluating the effect of stress multiaxiality on material behavior under various loading conditions in a relatively easy way. In order to understand the possible correlation existing between plain and notched bar creep behavior of various materials with different characteristics, creep tests were systematically performed at 625°C for plain and notched bar specimens made from 6 heats of Grade 91 steel. They showed a wide variety in terms of creep rupture strength as well as in ductility when tested in a form of plain bar but also in notched bar to a larger extent. Strong similarities were found between the heat-dependency of creep strength and ductility of plain bar and notched bar specimens. Possibility of estimating notched bar behavior from the information obtained by plain bar tests was shown.
Equivalent Theodorsen Function for Fluidelastic Excitation in a Normal Triangular Array
Authors: Alyaldin Loay , Mureithi Njuki 
Published: November 2019

Abstract
Fluidelastic instability (FEI) remains an important concern to designers of heat exchangers subjected to high flow velocities of gases, liquids or a combination of the two phases. In the present work, experimental tests are conducted to measure the quasi-steady fluid forces acting on a normal triangular tube array of P/D = 1.5 subjected to single-phase cross-flow. The quasi-steady forces together with previously measured unsteady fluid forces are used to estimate the time delay between the central tube motion and fluid forces on itself. The time delay effect for the quasi-steady fluidelastic instability model is derived in the frequency domain in the form of an equivalent Theodorsen function. The results are compared with the Theodorsen function previously obtained for the rotated triangular array. Using the time delay formulation, a stability analysis is carried out to predict the critical velocity for fluidelastic instability in a normal triangular array subjected to single-phase flow.
Crack Growth Rate Testing and Large Plate Demonstration Under Chloride-Induced Stress Corrosion Cracking Conditions in Stainless Steel Canisters for Storage of Spent Nuclear Fuel
Authors: Lam Poh-Sang , Duncan Andrew J. , Ward Lisa N. , Sindelar Robert L. , Kim Yun-Jae , Jeong Jae-Yoon , Lee Hyun-Jae , Lee Myeong Woo 
Published: November 2019

Abstract
Stress corrosion cracking may occur when chloride-bearing salts deposit and deliquesce on the external surface of stainless steel spent nuclear fuel storage canisters at weld regions with high residual stresses. Although it has not yet been observed, this phenomenon leads to a confinement concern for these canisters due to its potential for radioactive materials breaching through the containment system boundary provided by the canister wall during extended storage. The tests for crack growth rate have been conducted on bolt-load compact tension specimens in a setup designed to allow initially dried salt deposits to deliquesce and infuse to the crack front under conditions relevant to the canister storage environments (e.g., temperature and humidity). The test and characterization protocols are performed to provide bounding conditions in which cracking will occur. The results after 2- and 6-month exposure are examined in relation to previous studies in condensed brine and compared with other experimental data in the open literature. The knowledge gained from bolt-load compact tension testing is being applied to a large plate cut from a mockup commercial spent nuclear fuel canister to demonstrate the crack growth behavior induced from starter cracks machined in regions where the welding residual stress is expected. All these tests are conducted to support the technical basis for ASME Boiler and Pressure Vessel Section XI Code Case N-860.
A Framework for Estimating Burst Test Fracture Toughness for Zr-2.5Nb Pressure Tubes Using Data From Small Specimen Tests
Authors: Xu Steven X. , Wallin Kim , Cho David 
Published: November 2019

Abstract
Zr-2.5Nb pressure tubes are primary pressure boundaries in a CANDU2 reactor. Design of pressure tube dimensions allows testing of a pressure tube section at its full size in the laboratory. Burst tests, i.e., internally pressuring pressure tube sections containing axial through-wall cracks till burst, have been used to provide test data of fracture toughness for pressure tubes with axial flaws. The advantage of measuring fracture toughness from burst tests is that measured toughness values are directly applicable to operating pressure tubes. Burst tests, however, are costly and consume considerable amount of material. Only a small number of burst tests can be performed in practice. There is strong motivation to estimate burst test fracture toughness using data from small specimen tests. The estimated burst test fracture toughness can fill the gap in the measured burst test toughness data, as well as provide information on material variability and data scatter.
The technical challenge for estimating burst test toughness is that the estimated burst test toughness using data from low cost, small specimen tests must be reliable and representative of burst test specimen behavior with high confidence. A framework for accurately estimating burst test toughness using data from curved compact tests has been under development and is described in this paper. Aspects of technical basis and current status of developing analytical procedures for systematically estimating burst test toughness are presented.