bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear Graphite Irradiated Material Property Normalization, Interpolation, and Extrapolation Approach
Authors: Walker Adam , Caldwell Kevin , Kellner Stuart , Schroeder Anthony
Published: November 2024

Nuclear grade graphite has several physical characteristics that are advantageous for its use in high temperature reactors, including a high scatter cross-section and a low absorption cross-section (high moderating ratio). In addition to the neutronics benefits of graphite as a moderator, nuclear grade graphite has high thermal conductivity combined with adequate structural strength at high temperatures. However, the material properties associated with graphite grades that are candidates for high temperature environments exhibit a strong dependance on fast neutron fluence (E > 0.1 MeV). The material properties of interest are typically available only at discrete temperature and fluence levels, which results in an expensive process to characterize the material properties across a wide range of operating conditions. In addition, this approach may limit the reactor design to operating conditions and parameters established early in the design process. The purpose of this paper is to outline a technique to interpolate available irradiated material property data, within the bounds of the parameters examined in applicable testing programs, and also extrapolate to irradiation temperatures beyond those provided in the available test reports. Implementing this approach would permit a smaller data set to characterize the irradiation induced material property changes than if tabulated test results are directly used to represent the full range of operation. Furthermore, this paper will outline an example of the application of this approach in which the graphite material is exposed to temperatures that may exceed the upper bound temperatures examined in the Advanced Graphite Creep (AGC) testing program.
Prediction Method for Acoustically Induced Vibration of Process Piping Generated by a Restriction Orifice
Authors: Hayashi Itsuro , Maeda Shun , Yamaguchi Kazuya , Izuchi Hisao
Published: November 2024

Acoustically Induced Vibration (AIV) of the piping system downstream of the restriction orifice (RO) could be a concern when a large amount of gas is released in the blowdown system through an RO. The severity of AIV generated by the pressure reducing devices can be evaluated by utilizing the noise prediction method specified in the IEC standard (IEC 60534-8-3), since it is known that the vibration stress caused by AIV is basically proportional to the sound pressure level at the piping surface. Also, it is expected that the sound pressure level generated by the RO would decrease as the number of holes increases under the same process conditions. However, to the best of the authors’ knowledge, the governing parameter to evaluate the sound pressure reduction effect by a multi-hole orifice plate which is applicable to the IEC standard has not been published.

In this study, experimental investigations were conducted to establish a prediction method for acoustic power generated by multi-hole orifices. As a result, the correlation between the number of holes and the valve correction factors for the acoustic efficiency defined in the IEC standard was obtained. It was confirmed that the sound pressure level at the pipe wall could be accurately predicted by using this method. Also, the comparison between the proposed method and the conventional AIV sound power level calculation method by Carucci and Mueller is presented.
Creep Properties of Gas Metal Arc Directed Energy Deposition Austenitic Stainless Steel
Authors: Jang Eun , DeNonno Olivia , Gonzales Juan , Tate Stephen , Klemm-Toole Jonah
Published: November 2024

Gas metal arc directed energy deposition (GMA-DED) has potential for the power generation industry to reduce both time and cost since larger and more complex part geometries can be constructed compared to the typical subtractive methods. The performance of GMA-DED builds can be influenced by the deposition method, resulting microstructure, and formation of defects or secondary phases in the final component. Previous work in the literature evaluated the mechanical properties of GMA-DED builds for a range of austenitic stainless steels, however there is limited data on the high temperature mechanical behavior. This work evaluated the high temperature creep properties of GMA-DED builds constructed with type 316H, 316L, 316LSi, and 16-8-2 stainless steels at 650 °C, 750 °C and 825 °C. The alloy with longest time to rupture for a given stress varied depending on test temperature. Creep damage accumulation at grain boundaries was observed along with grain boundary precipitates which likely aided in damage accumulation. Evaluating the creep properties with the Larson-Miller parameter showed the majority of results fell within the scatter band of creep performance for wrought 316 alloys, indicating the GMA-DED process may be suitable for use in advanced energy systems.
Predicting Pipe Wall Vibration in Frequency Bands With Low Acoustic and Vibration Modal Coincidence
Authors: Mann J. Adin , Eilers Daniel
Published: November 2024

Accurate predictions of pipe wall vibration from internal dynamic fluid excitations are critical for assessment of damage mechanisms such as acoustic induced vibration. A common method to relate the excitation of the pipe wall vibration to the internal acoustic excitation is through relationships between the modes in the fluid and modes in the pipe wall. At coincidence, the transfer of acoustic energy to the pipe structural vibration is most efficient. Because of variations in the pipe dimensions and the internal acoustic field, the methods to predict the transfer of energy from the internal acoustic field to the pipe wall vibration often uses a frequency band averaged relationship. These methods rely on having a sufficient number of modes and a known coupling behavior in the frequency band over which the average is calculated. However, at low frequencies, the modal density can be such that there are few internal acoustic or structural modes which causes fewer modal coincidences between them to define the coupling behavior. Further, with finite length pipe segments, the coincidence may not occur as with an infinite length duct. In such cases, the radiation efficiency in the mode-based approach does not include coincidence and is augmented with a mass law approach. This methodology was implemented in statistical energy analysis methods. The basic formulation along with an example will be given.
Effect of Friction and Gaps on Elastic-Plastic Piping Supports
Authors: Kobayashi Wataru , Otani Akihito , Kai Satoru
Published: November 2024

In this study, we conducted an elastic-plastic analysis of the piping support with the aim of investigating the effects of piping friction and gaps on the elastic-plastic support.

The shape under consideration is a general framework type piping support, with an aspect ratio of 1.2 or higher, where the effect of elastic-plastic behavior is expected, based on JEAC4601. The analysis model uses 3D shell elements and includes a mass element that simulates piping at the center of the supports. Friction on the pipes is considered only in the in-plane direction and is represented by a gap element with zero clearance. Horizontal gaps are represented by nonlinear springs.

The input is controlled by a triangular wave displacement, gradually increasing the displacement amplitude to perform analysis in the elastic-plastic region. The equivalent stiffness specified in JEAC4601 is calculated from the obtained load-displacement curve to determine the damping effect of the piping supports. The influence of these factors on elastic-plastic properties will be confirmed from the differences in the load displacement curve. The effect of reducing seismic response will be investigated based on the obtained damping effect. The reduction of damping effect is caused by the clearance between pipe and support.
A Comprehensive Discussion of Sonic Choking in Pipe Systems for Steady, Compressible Flow
Authors: Walters Trey W.
Published: November 2024

Understanding and predicting sonic choking in pipe network systems can be critically important. Among the reasons is to ensure safety and to improve the performance of the system. In some cases, sonic choking is the dominant aspect of the system behavior and there is no way to understand the system without understanding sonic choking and where it occurs. However, sonic choking is (in general) poorly understood and (at best) incompletely documented in the literature. The literature often provides misleading examples built on unstated (and unrealistic) assumptions. Some situations where sonic choking occurs are almost completely ignored in the literature. The purpose of this paper is to provide a comprehensive reference for practicing engineers for all possible sonic choking behavior in any generalized, pipe network system with superheated, steady-state, single-phase gas flow. Discussions include multiple choking points in series and in parallel, as well as in systems with real gas behavior experiencing heat transfer in non-horizontal pipes.
Fatigue Analysis of HPHT Subsea Equipment According to API 17TR8
Authors: Karpanan Kumarswamy , Skeels Brian
Published: November 2024

American Petroleum Institute API 17TR8 Technical Report (TR) provides guidelines for designing and validating High Pressure High Temperature (HPHT) subsea oil and gas production equipment. HPHT equipment in the oil and gas industry is defined as equipment with an operating pressure of greater than 15 ksi or an operating temperature greater than 350F. The API 17TR8 design verification procedures provide recommended methodology to analyze pressure containing equipment by addressing all relevant failure modes. Design by analysis is recommended by this report, which includes API 6X elastic and ASME Sec VIII-2 and VIII-3 elastic-plastic analysis methods. The failure modes addressed in API 17TR8 are plastic collapse, local strain limit, ratcheting, hydrostatic body test, extreme & survival events, serviceability criteria, fatigue, etc.

Subsea oil and gas production equipment are exposed to cyclic loads (pressure, temperature, external loads due to wave, current, etc.) during drilling, completion, installation, operation, workover, etc. To address the fatigue failure, two types of fatigue assessment are provided in API 17TR8 which are S-N (or e-N) design based and fracture mechanics based. Additionally, fatigue screening is allowed to determine if the full fatigue assessment is required. API 17TR8 has adopted fatigue assessment methodology from various codes and standards: ASME VIII-2, ASME VIII-3, DNV-RP-C203, BS 7608, BS 7910, API 579-1/ASME FFS-1, etc. These codes also provide fatigue curves and crack growth data in air, seawater with cathodic protection, free corrosion, etc. Additionally, API 17TR8, App D provides details about material testing in various subsea environments. This paper provides a comprehensive study of all the fatigue analysis methods that can be used for analyzing HPHT equipment.
Physical Twins for Lifetime Evaluation of Safety-Relevant Large Components Containing Crack Fields
Authors: Mally Linda , Seidenfuß Michael , Werz Martin , Weihe Stefan
Published: November 2024

The creation and testing of physical twins using additive manufacturing (AM) methods allow for the replication and investigation of internal defects in real-world components. Such technological advancements pave the way for new approaches to lifetime assessment and evaluation of failure behavior. In 2012, internal crack-like defects were discovered in the pressure vessels at Belgium’s Doel 3 and Tihange 2 nuclear reactors through NDT assessment. Critical internal crack fields are identified based on these defects. This work demonstrates the manufacturability of various crack fields (crack shape, dimensional precision, orientation, etc.) and their corresponding failure behavior is examined using tensile tests. Selected crack fields are integrated into a scaled physical twin of the vessels, utilizing Laser Powder Bed Fusion (L-PBF).

This paper focuses on the conceptual description of a physical twin, the approach, and the challenges in creating, testing, and transferring the results to real components.
Pipe Whip Analysis for High Energy Lines
Authors: Pease Derrick , Antaki George
Published: November 2024

Often, the largest loads for the design of nuclear power plant structures, systems, and components are the loads that result from postulated pipe ruptures. These loads include pipe whip, jet impingement, blowdown waterhammer, compartment pressure, and blast wave. This paper provides an overview of pipe rupture hazards analysis process, including regulatory requirements. Second, the paper presents the methods and criteria for the development of the thrust force in high energy line breaks, in a manner more precise than ANS 58.2, taking into consideration the various phases of blowdown, starting with break formation, initial metastable unbalanced pressure, development of fluid motion, transient period, and final steady state. The paper presents the two methods to predict the pipe whip motion and impact: The first method is based on energy balance and dynamics-based analytical solutions, and the second solution is based on elastic-plastic numerical simulation using explicit solver of the pipe whip.
Consequences of an Imperfectly Mounted Reinforcement Cage in a Generical Cylindrical Concrete Container During Mechanical Specimen Tests
Authors: Weber Mike , Völzke Holger , Nieslony Gregor
Published: November 2024

By highest court decision in 2007 the issued license for the Konrad repository (a former iron ore mine) for low and intermediate level radioactive waste was finally confirmed. Since then, the site is improved, prepared and equipped for the currently planned start of waste package emplacement by 2029. The Bundesanstalt fuer Materialforschung und -pruefung (BAM, Federal Institute for Materials Research and Testing) is regularly contracted by the Bundesgesellschaft für Endlagerung (BGE, Federal Company for Radioactive Waste Disposal) as the responsible authority for waste product control, waste container design testing, and waste package acceptance. In this context BAM is mainly responsible for design testing of various container types including the evaluation quality assurance measures for container manufacturing.

In the written Konrad disposal requirements [1] [2], all acceptance criteria for potential final disposal containers are defined. In addition to general requirements concerning container design, materials, dimensions and others, specific mechanical load scenarios the casks have to withstand are derived from an analysis of the on-site handling and emplacement procedures. Drop tests from different heights under consideration of the most damaging drop orientation and a stacking test are two examples for safety demonstrations that have to be performed during the container design testing procedure to qualify the respective container type.

The containers, whether cubic or cylindrical containers, can be made from different materials like ductile cast iron, reinforced concrete or as welded construction from steel plates and profiles. In case of concrete containers the reinforcement has the function to absorb tensile forces the concrete is not able to withstand by its own. Because of manufacturing imperfections of cylindrical concrete waste containers manufactured already decades ago, the reinforcement cages are not always exactly, axisymmetrically positioned when they were poured. This inspired BAM to perform various ABAQUS® finite-element (FE) simulations [3] by using the example of a simplified cylindrical container design with generic dimensions and pure elastic material properties. As outcome the stress conditions in the container during the drop test impact under different drop positions and during the stacking test were investigated and are explained and illustrated in this contribution. Different reinforcement cage positions were calculated and compared. On the basis of the calculated tensile and compressive stress distributions suggestions are derived on how a cylindrical concrete container with an imperfectly placed reinforcement cage has to be oriented for a drop or stacking test to ensure the most damaging test scenario.
Comparison of Measured and Predicted Vessel Hoop Strains and Door Displacements for the Explosive Destructive System V31 Vessel
Authors: Ludwigsen John S. , Stofleth Jerome H. , Tribble Megan K. , Crocker Robert W.
Published: November 2024

The Explosive Destruction System (EDS) V31 containment vessel was procured by the US Army Recovered Chemical Materiel Directorate (RCMD) as a third-generation system used to destroy chemical munitions. It is the fifth individual EDS vessel to be fabricated under Code Case 2564 of the 2019 ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels. The explosive rating for this vessel, based on the code case, is twenty-four (24) pounds TNT-equivalent for up to 1092 detonations. This report documents the results of explosive tests that were performed on the vessel at Sandia National Laboratories in Albuquerque, New Mexico to qualify the vessel for field operations use. There were three design basis configurations for qualification testing. Qualification test (1) consisted of a simulated M55 rocket motor and warhead assembly of 24lbs of Composition C-4 (30 lb TNT equivalent). This test was considered the maximum load case, based on modeling and simulation methods performed by Sandia prior to the vessel design phase. Qualification test (2) consisted of a regular, right circular cylinder, unitary charge, located central to the vessel interior of 19.2 lb of Composition C-4 (24 lb TNT equivalent). Qualification test (3) consisted of a 12-pack of regular, right circular cylinders, distributed evenly inside the vessel (totaling 19.2 lb of C-4, or 24 lb TNT equivalent). The ASME certification was based exclusively on the analytical predictions because the data required for certification cannot be obtained through testing. Strains through the thickness of the wall and on the inside surface of the cylinder were required and could only be obtained through analysis. Strain gages were placed on the outside of the vessel in three locations and the displacement of the door was measured using a Photonic Doppler Velocimetry (PDV) system. These measured values are compared to analytical predictions to help ensure the accuracy of the predicted strains and displacements throughout the rest of the model.
Evaluation of Common Thermoplastic Polymers in High-Pressure Cycling Hydrogen Under Ambient and Cold Environments as Applicable to the Hydrogen Infrastructure
Authors: Menon Nalini C. , Nissen April , McArthur Keri , Mills Bernice , Ryan Fitzjames , Simmons Kevin
Published: November 2024

Thermoplastic polymers are required to perform consistently without failing under stringent conditions of changing pressures (35 MPa to 70 MPa) and temperatures (−40°C to +85°C) in storage and fueling operations. Although diffusivity in glassy polymers appears to be an order of magnitude lower than elastomers, polymer microstructural attributes such as degree of crystallinity and presence of polar and non-polar groups on the main chain with and without branching can play a substantial role in influencing their behaviors in hydrogen environments. The work described here addresses the effect of high-pressure hydrogen cycling on PEEK, PTFE, PA11, HDPE, and POM (and different commercial grades of these polymers) under ambient and cold (−40°C) conditions. Ex-situ characterization for polymer changes included density measurements for the impact of hydrogen retention, hardness changes using nanoindentation, storage modulus, and glass transition changes using dynamic mechanical and thermal analysis (DMTA), degree of crystallization with Differential Scanning Calorimetry (DSC) and tensile testing following ASTM D1708-18. In other evaluations, where possible, solid-state nuclear magnetic resonance (NMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and X-ray CT results are presented. The overall impact of these evaluations is to establish a technical basis for the behaviors of common thermoplastics in cycling hydrogen environments under ambient and cold temperatures while establishing the relationship between polymer structure-based properties and hydrogen transport effects.
A Mathematical Iterative Method to Validate Probabilistic Integrity Codes With Deterministic Experimental Data
Authors: Guo Lingyun , Liang Qionglin
Published: November 2024

A number of probabilistic integrity codes (PICs) have emerged for assessing the operational safety of pressure components, such as ProLOCA, PROST, xLPR, etc. These codes can calculate the failure probability of pressure components directly based on probability theory and structural calculations. However, despite rigorous analysis, the credibility of their calculation results is still questionable due to a lack of verifiability, which hinders their wide acceptance. Therefore, the validation of failure probabilities calculated by PICs is a state-of-the-art challenge currently.

In response to this issue, this paper proposes a mathematical iterative method to make the PCI validation achievable. The method establishes a mathematical iterative method based on the secant method to indicate the credibility of PIC. It is grounded in the principle that the failure probability Pr should be 50 % if the load L follows a symmetric distribution with a symmetry axis of Lr, and the other parameters remain deterministic in the structure’s critical failure state, characterized by parameters [Lr, ar1, ar2, ar3, ..., arn]. The validity of the method will be assessed by applying it to the calculation PIACACP. And its prediction outcomes and iteration procedure were analyzed to determine the method’s applicability and rationality.
A Simple Method for Calculating Accurate Gasket Stresses for Octagonal Ring Joints
Authors: Clover David
Published: November 2024

The goal of this paper is to serve as a guide to end-users who are developing torque guidelines for use with octagonal ring joint gaskets. Surprisingly, there is no readily available resource to guide end-users in determining the gasket seating stress on octagonal ring joint gaskets. To fill this void, this paper describes the trigonometric relationships that determine the gasket seating stress on the sloped sealing surfaces of octagonal ring joints using a simplified cross-sectional model of the rings. Furthermore, it describes a basic conceptual model that simplifies the formulae, reducing them to a load/area relationship. Finally, it shows that the simplified cross-sectional model used in this study — and also used by major refining organizations — induces a significant error. We show the formulaic corrections that eliminate this error — resulting in improved seating stress modeling.

The greater accuracy of these results leads to meaningful questions — raised in the concluding discussion. In light of this data, what reasonable limits are needed to prevent over-compression of the ring at assembly, ensure minimum stud stress, prevent flange rotation, and seal robustly at MAWP? While some tentative answers are offered, further discussion with industry stakeholders will undoubtedly be needed before such guidance can be included in PCC-1.
A Calculation Method of Pipeline Bending Strain Based on IMU Data of Pipeline Internal Detection
Authors: Xie Dong , Shuai Yi , Shuai Jian , Ren Fei , Chen Cuicui , Jiang Yuanliang , Liu Haipeng
Published: November 2024

In the process of service, long-distance oil and gas pipelines are located in a complex and changing environment, and the pipelines are prone to bending and deformation under the action of various factors, and in serious cases, wall rupture will occur, which will lead to major pipeline failure accidents. Therefore, accurately calculating the bending strain of the pipeline allows us to grasp the actual bending state of the pipeline, thus maximizing the prevention of pipeline failure due to bending deformation. In this paper, a method for calculating pipeline bending strain based on the attitude angle data of inertial measurement unit is proposed and verified with the inspection data of a pipeline. The results show that the proposed method has a certain degree of practicality and can effectively distinguish between structures such as bending deformation, elbows and bends. When there are bending deformations, elbows or bends in the pipeline, the calculated bending strains of the pipeline can be divided into three parts, including the transition section that gradually increases in the upstream, the transition section that gradually decreases in the downstream and the intermediate section that tends to be stabilized. However, when the structure for the elbow or bend and other structures, its bending strain calculation results relative to the bending deformation, with smaller fluctuations, the transition section is also more stable, and has a better symmetry, so that the elbow, bend and bending deformation can be effectively distinguished.
Flange Deformations Induced by Ring Joints: An FEA and Experimental Approach
Authors: de la Roca Leonardo R. , Girão Carlos D. , Veiga Jose C.
Published: November 2024

In the petrochemical and offshore industry, ring joints are crucial for their ability to handle high-pressure and temperature demands. Nonetheless, the tightening forces combined with direct metal-to-metal contact might cause flange sealing surfaces damage. The present study investigates the deformations in flanges sealing surfaces due to ring joints, with a particular focus on different ring geometries, materials and hardnesses. Leveraging finite element analysis (FEA) and a series of laboratory tests, this research evaluates how these variables impact the integrity and performance of ring joint-flange assemblies. Two novel types of rings were introduced: the first is a hollowed ring, inspired by a topology optimization study that identified unnecessary interior regions of a standard ring. The second employs metal 3D-printing techniques, specifically Selective Laser Sintering (SLS) and Metal Fused Filament Fabrication (MFFF), utilizing stainless steel grade 316L. Both designs underwent testing and were compared with standard oval & octagonal ASME B16.20 R-16 rings in terms of deformation and sealability. The study also addressed a common claim regarding a hardness difference of 30 HB (Brinell hardness) between the ring and flange, exploring the theoretical hardness gap necessary to avoid permanent flange deformation. The research, while facing challenges in material data and measurement techniques, offers novel ring design approaches and an in-depth understanding of the plasticity effects on ring joint assemblies.
Modelling the Effect of Residual Stresses on Damage Accumulation Using a Coupled Crystal Plasticity Phase Field Fracture Approach
Authors: Salvini Michael , Grilli Nicolò , Knowles David , Mostafavi Mahmoud , Esmati Parsa , Yankova Maria S. , Flint Thomas F. , Smith Mike C. , Vasileiou Anastasia N. , Larrosa Nicolas O. , Truman Christopher E.
Published: November 2024

Residual stresses are a crucial factor in assessing the integrity of welded joints. These stresses are known to influence the joint’s strength under additional loading, with the altered grain structure at and near the joint a complicating factor. Consequently, a mesoscale model is essential to understand the accumulation of damage in components subjected to external loading, as well as the impact of prior loads on failure. This study addresses the interplay between loading direction and grain morphology, explicitly investigating damage accumulation. The mesoscale model includes a coupled crystal plasticity and a phase field fracture model to estimate the deformation induced during a laser beam weld of 316H stainless steel. The displacement boundary condition was derived from a mechanical model of the weld, with the application of a Chaboche model. The temperature field required for the grain growth and mechanical models were obtained through a thermal fluid dynamics framework. Investigation of crack initiation and propagation was carried using a phase-field fracture model, which allowed the consideration of prior loading. This study indicated that the direction of loading plays an important role in damage susceptibility. The modified grain structure based on the welding simulation showed a different strain at failure compared to the 316H stainless steel parent material. The achieved strain at failure was found to be lower in normal loading compared to the transverse direction. Presently, the crystal plasticity model fails to estimate the macroscopic residual stresses, illustrated by damage propagation resulting in earlier than expected ductile failure upon reloading. The potential causes are addressed and discussed in detail.
Investigation and Modelling of Static O-Ring Sealing Performance After Ageing
Authors: Péta Oscar , Le Saux Vincent , Marco Yann , Omnès Benoît , Lejeune Hubert
Published: November 2024

Monitoring and predicting the ageing of industrial systems equipped with sealing products implies the necessity to ensure tightness. This functional performance is difficult to control due to the combined effects of the viscoelastic nature of the materials of interest and the heterogeneous material evolution due to ageing. Interfacial leakage may appear during ageing, causing an increase in leakage rate. However, leakage tests provide both interfacial and permeation leakage. Permeation must be predicted to evaluate the interfacial leak and eventually be able to predict it. Diffusion analytical models cannot be used with complex geometries such as a compressed O-ring in a groove. Therefore, a numerical model for diffusion has to be developed. The material studied is a peroxide crosslinked EPDM manufactured using a known standard industrial formula. Transport parameters of helium at room temperature are evaluated analytically on membranes using the time lag method. Mechanical properties are evaluated using an anhysteretic compression test on an O-ring. A model based on the equivalence between diffusion and heat transfer is evaluated and compared to experimental results. Satisfying results from numerical simulation on membranes and their comparison to an analytical model enabled the validation of the method. Then, mechanical and diffusion analyses were performed on an O-ring mounted in a groove. Close results were obtained between experimental and numerical leakage curves. However, an underestimation of the time lag is observed. First investigations show great sensitivity to the initial geometry of the seal. The developed model is considered sufficient for the prediction of steady-state leakage. Future work will focus on the comparison of aged and unaged O-rings and better identification of the seal cross-section.
Development and Application of Dynamic Monitoring System for Large Volume Winding Cylinder Tube Trailers
Authors: Yang Chao , Zhang Laiming , Luo Hui , Li Tong , Yu Yue , Chai Sen , Li Xiang
Published: November 2024

Large volume winding cylinder tube trailer as a typical mobile pressure special equipment in China is increasing rapidly, more than 500 new each year. Its transport medium is mostly flammable, explosive, corrosive and toxic compressed gas, with high safety hazards and potential dangers. The experimental research shows that fatigue times and fire accidents have an important impact on the safety performance of large-volume wound cylinders, resulting in liner cracking, wound layer failure, media leakage, explosion and other accidents. This paper intends to develop a monitoring system for the operation status of a large-volume winding cylinder long-tube trailer. By using pressure, temperature, medium concentration sensors, microprocessor, 4G communication, GPS and other technologies, a pressure monitoring and early warning system for a large-volume winding cylinder long-tube trailer is designed to realize remote real-time monitoring of the pressure of the long-tube trailer, and to give timely warning when the pressure of the cylinder is too high. Through the system simulation operation test, the normal operation of the system function is verified, which has certain feasibility and reliability to prevent the overpressure failure of the long-tube trailer gas cylinder, so as to realize the real-time monitoring of pressure and temperature, real-time alarm of media leakage, overtemperature and overpressure, and fatigue statistics of the long-tube trailer of large-volume winding gas cylinder as well as the variation law of defects with fatigue frequency is summarized.
A Multiple-Criteria Decision Application for Evaluating the Probabilistic Integrity Codes
Authors: Hanyi Niu , Guo Lingyun
Published: November 2024

To ensure the accuracy of probabilistic integrity in design, management and research, various codes have been established to assess safety and reliability of pipelines such as ProLOCA, PROST, xLPR, etc. They are refined and improved through benchmark projects (BPs), obtaining well-recognized research outcomes. However, BPs only compare the relative errors of the same calculation conditions and ignore the usability of the codes. Therefore, in further refining overall performance of probabilistic integrity codes (PICs), it is necessary to improve the usability.

This paper presents a novel application for evaluating the PICs, which is mainly divided into four main steps. Firstly, a multi-layer evaluation index system (EIS) is established which contains 3 layers and comprises three main aspects: Prediction Performance (PP), Software Usability (SU) and Option Diversity (OD). In the second step, we use the multi-layer best-worst method (MBWM) to determine the weights of different evaluation criteria. In the third step, a set of wv* experimental data is used to quantitatively mine the PP decision matrix, while the SU and OD decision matrixes are determined based on experience and expert knowledge. Finally, we adopt the sum weight method (SWM) to assess the overall performance of codes and provide suggestions for user selection and software optimization.
The Use of Tuned Mass Dampers in Mitigating Small-Bore Piping Vibration
Authors: Cheong Ian Ty
Published: November 2024

Vibration measurements of several small-bore pipework attached to a screw compressor package at an operating asset showed vibration levels more than the Energy Institute Guidelines “Problem” limit.

This presented a significant integrity threat to the operating asset. The piping vibration was primarily driven by pocket-pass frequency pulsations harmonics in the higher frequency range of 100–500 Hz.

Initial efforts to brace the pipework were not successful, likely due to the bracings inability to provide sufficient stiffness at higher frequencies. Following initial bracing attempts, a detailed vibration study and experimental modal analysis were carried out. The measurements were used to calibrate a dynamic finite element (FE) model of the small-bore piping. The predicted fatigue life of the worst affected pipework was 5.5 years.

The results of the FE model were used in the design of a tuned mass damper (TMD) to mitigate the vibration levels. During the design phase, the influence of the TMD on the dynamic response of the piping system was evaluated, however, this is not the primary focus of the paper.

Upon installation of the TMD, the vibration of the worst affected pipework showed a significant reduction of 73% and was no longer in the fatigue damage zone, which proved the effectiveness of the solution. This paper is intended to provide an overview of the concept of the solution, advantages of using TMDs and to share the results of this technique in mitigating piping vibration concerns where traditional methods (e.g: supports or bracing) may not be effective.
Technical Basis for Proposed ASME Section XI Code Case on Evaluation Requirements for a Static Over-Pressure Event in Class 2 or 3 Piping System
Authors: Xu Steven X. , Moenssens Mark , Antaki George , Pace Raymond
Published: November 2024

This paper presents the technical basis for a proposed ASME Section XI Code Case for assessing the structural integrity of a Class 2 or 3 metallic piping system after a static over-pressure event. Compliance with the required actions and acceptance criteria assures the piping system has adequate structural integrity to return to service.

ASME Code Section III NCD-3600 currently provides overpressure allowances for Service Levels C and D events that exceed the allowable working pressure calculated by ASME Section III NCD-3640 Eq. (5). NCA-2142.4, Design, Service, and Test Limits, defines the level of damage caused by Service Levels C and D events as possibly causing: “large deformations in areas of structural discontinuity” for a service Level C event, and “gross general deformations with some consequent loss of dimensional stability and damage” for a Service Level D event. However, NCA-2142.4, or Section III and Section XI in general, does not address the actions to be taken if these permitted Service Level C or D over-pressure allowances occur, or if the pressure exceeds the Service Level C and D limits. The proposed Code Case specifies the actions required in case of a static overpressure event that exceeds the allowable working pressure but remains within the bounds currently permitted for a Service Level C event, or an event that exceeds the over-pressure allowance currently permitted for a Service Level C event but remain lower than the Service Level D limit. Over-pressure events that exceed the ASME Section III Level D limit are not addressed in the proposed Code Case but are planned for a future revision to the Code Case.
CMC Components for HTR Design and Qualification Testing
Authors: Geringer Josina W. , Windes William
Published: November 2024

Ceramic Matrix Composites (CMCs) which include silicon-carbide silicon-carbide (SiC-SiC) and carbon-carbon (C-C) composite materials, for the use of core components for high temperature reactors in the American Society of Mechanical Engineers (ASME) Boiler Pressure Vessel Code (BPVC) Section III Division 5, were introduced due to their light weight, strength in extreme conditions and in some instances great neutron irradiation resistance. The code relies heavily on industry to align itself in the nuclear environment by using best practices adopted from others.

Over the years there has been a lot of emphasis on graphite qualification and component design, which is still a significant undertaking, but there is very little discussion on what it entails to follow a CMC component design and qualification process. According to Sec III-5-HHB, CMC’s only follows a Simple Assessment Method, as appose to graphite that has the option to follow either a Simple or Full Assessment Method. In addition, several test standards under the leadership of ASTM C28, have been developed to guide test methods. This paper focus on the optimization areas that have been identified since the first publication of ASME Sec III-5-HHB and it provides a roadmap to perform CMC materials qualification.
Exploration of the Effects of Response Spectrum Matching on Power Spectral Density Functions
Authors: Nie Jinsuo R.
Published: November 2024

Section 3.7.1, Revision 4, “Seismic Design Parameters,” issued December 2014, of the U.S. Nuclear Regulatory Commission document NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition” (SRP), provides acceptance criteria for seismic design acceleration time histories, which establish two sets of criteria: (1) the calculated response spectra (RS) from the time histories envelop the design response spectra (DRS), and (2) as a secondary check, the power spectral density (PSD) functions envelop the minimum target PSD functions that are compatible with the DRS. SRP section 3.7.1 also indicates that the PSD functions of closely RS-enveloped (or RS-matched) time histories fluctuate significantly and randomly as a function of frequency, and the fluctuations may lead to unconservative results for the response of structures, systems, and components. This explains the previous difficulties in meeting both RS and PSD enveloping criteria during the development of seismic design acceleration time histories. Such difficulties can potentially be relieved by a recently published wavelet-based time-domain RS-matching algorithm in Nuclear Engineering and Design, 410(112384), because that algorithm uses a minimal number of wavelets to achieve RS convergence and so allows a well-separated treatment of power assurance and RS matching. This paper explores, through examples, how that algorithm affects the PSD functions of the time histories and, more importantly, how it can help achieve both power sufficiency and the RS-matching criteria.
Verification of Earthquake Simulation Capabilities for Small Modular Reactor (SMR) Floating Seismic Isolation Systems
Authors: Tabbakhha Maryam , McCallen David , Miah Mamun , Nie Jinsuo , Wang Weijun , Graizer Vladimir , Pires Jose , Bauer Laurel
Published: November 2024

The ability to ensure robust seismic resilience is a critical requirement for all nuclear power plants (NPPs). There have been a number of innovative technologies considered for seismic response modification for NPPs, including application of traditional seismic base isolation technologies to ensure adequate earthquake performance. A unique response modification concept based on the utilization of a floating plant has recently been proposed. The underlying principle includes exploitation of the fact that shear waves cannot propagate through water, and floating a reactor building on a reservoir of water can isolate the reactor building from incoming earthquake-induced shear waves. The proposed system would also reduce seismic demand in the vertical direction by utilizing air cavities and orifices for enhanced damping. To explore the seismic performance of such a system, it is essential to have computational simulation models that can accurately represent the dynamic response of such complex systems. The objective of this work is to provide the U.S. Nuclear Regulatory Commission with the technical knowledge to appropriately evaluate the seismic performance of this type of innovative isolation system. In this article, existing finite element software programs are critically evaluated in terms of their ability to estimate the transient response of the floating isolation systems. A suite of numerical tests aimed at verifying the ability to appropriately represent gravity initialization of the model, fluid sloshing, and system transient response due to earthquake motions, are described.
ASME BPVC Treatment of Disparate Flaws in Graphite
Authors: Saitta Michael
Published: November 2024

Graphite is a quasi-brittle material that has recently become of great interest to designs of advanced nuclear reactors due to its excellent thermal and neutronic properties. When designing graphite core components for reactors, engineers must analyze the components for structural adequacy. Graphite is a quasi-brittle material with complex failure behavior. Of particular interest to this paper is the disparate flaw failure mode that results in low strength failures in some portion of graphite specimens. The nature of disparate flaws and their impact on the failure probability distribution of graphite is explored. To this end, historic data and literature is reviewed.

The American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME BPVC) contains a set of rules to aid in the design and qualification of graphite core components. The current manner in which the ASME BPVC attempts to account for disparate flaws within the full assessment and its derivation is discussed. This method is shown to have a number of problems. Alternative methods for the handling of disparate flaws are provided and the benefits of each potential method is assessed. Based on the review of disparate flaw behavior and the methods by which they may be accounted for, the authors propose a path forward which allows reactor designs to have accuracy in estimated material reliability curves without the need for excessive testing or unrealistic conservatism.
Analyses, Mitigations and Reflections From Hydrogen Stress Cracking Failure of a Duplex Stainless Steel Reactor Effluent Air Cooler (REAC) in Hydrocracker Service
Authors: Hosack Allie , Idowu Oluwaseun , Barrass Jordan , Penso Jorge , Pudwill Wesley , Dalal Mitul
Published: November 2024

During start up following an outage for a major turnaround, a Duplex Stainless Steel Reactor Effluent Air Cooler (DSS REAC) leaked. The REAC was in a hot high pressure separation circuit of a refinery hydrocracker unit. Following the leak, detailed failure investigation was completed that revealed that the leak had occurred because of hydrogen stress cracking of the REAC tube-tubesheet welds. While the susceptibility of DSS REAC welds to hydrogen stress cracking in the form of sulphide stress corrosion cracking has been previously attributed to specific features from manufacturing, for example, ferrite-austenite phase imbalance and high hardness, over the past few years there is a growing body of evidence of the REAC DSS material experiencing cracking due to hydrogen embrittlement damage. This is despite having recommended controls in place during the original manufacturing stages. This paper will discuss the case history of the leak on the DSS REAC, including the details of failure analyses and engineering evaluation conducted on the cooler. This paper will also discuss some of the mitigations that were put in place, as well as provide reflections on the mode and mechanism of the damage.
Use of Plant Systems Design Standard (PSD-1) for Complying With Generic Design Assessment
Authors: Donavin Paul , Feldman Arnold , Pellereau Benjamin
Published: November 2024

This paper highlights the similarity between the United Kingdom’s General Design Assessment (GDA) with Plant Systems Design Standard (PSD-1). The three-phase approach in the GDA aligns with the PSD-1 design approach. The GDA has initiation, fundamental assessment, and detailed assessment. Each step builds in detail towards support of regulators’ decision process. The PSD-1 has initial design, preliminary design, and detailed design. These design actions have validation processes and risk evaluation as an integral part of the standard.

The advantage of the standard is to provide a uniform methodology with a consistent level of quality and a standard approach to risk evaluation. For the applicants, the PSD-1 provides a framework to prepare the required document to comply with the GDA. For the regulators, both nuclear and environmental, it provides an auditable approach to the preparation and validation of the submittal documents.

The beginning of the GDA is a project plan. Project Management has three key aspects for a project plan. The Scope is essential for developing the project plan. PSD-1 provides a disciplined approach to determine the scope of the submittal.

Risk assessment is a critical part of the GDA. PSD-1 has a detailed requirements for determining the risk of the plant beginning with a hazard assessment. The risk evaluation and determinations are carried through the design process as critical attributes.

Regulators rely on the quality of submissions to perform their reviews. The integrity of the PSD-1 process with required and planned validations helps ensure the submissions have reasonable assurance of accuracy and quality.