bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitigating LWR IronClad Fuel Cladding Dissolution Using Zinc Water Chemistry
Authors: Rebak Raul B. , Yin Liang , Larsen Michael , Umretiya Rajnikant V. , Hoffman Andrew K.
Published: November 2022

Iron-chromium-aluminum (FeCrAl) alloys are being characterized to be used in light water reactors for the cladding of the fuel. The use of accident tolerant fuel (ATF) such as FeCrAl alloys would allow for reactors operating safer, more economically, and for an extending life beyond 60 years. It was shown before that the lower or 12%Cr alloy such as C26M may have higher corrosion rate than the higher 21%Cr APMT. This article shows that the addition of a small amount of zinc (Zn) into the water reduces by more than 60% the dissolution rate of the FeCrAl. Zn incorporates into the external layer of the oxide film making the alloy more resistant to dissolution.
Determination of the Airborne Release Fraction of a 3013 Container Subjected to a Fire
Authors: Hensel Steve J. , Norkus John K.
Published: November 2022

Plutonium oxide bearing materials stabilized and packaged per DOE-STD-3013 are currently stored at the US Department of Energy Savannah River Site (SRS) in a shipping package such as a 9975. All 3013 outer containers are designed identically, however, there are two fabrication techniques: machined and flow-formed. The 3013 container is removed from the shipping package and introduced into a glove box for subsequent direct can cutting of the outer and inner 3013 containers where the oxide is down blended with an inert adulterant for permanent disposition. The hypothetical accident of interest is a fire which occurs after the 3013 is removed from the shipping package and prior to it being cut open. This calculation determines the airborne release fraction (ARF) from a 3013 container during a fire by utilizing the calculation methodology from NUREG/CR-6410 and 3013 fire test data from Sandia National Laboratories.
Mechanical Performance Evaluation of the Printed Circuit Heat Exchanger Core Experiments Under Tension and Pressure Loading
Authors: Mahajan Heramb P. , Maciel Lucas , Ngaile Gracious , Hassan Tasnim
Published: November 2022

The printed circuit heat exchanger (PCHE) has small channels with high surface area, making them an efficient solution for next-generation nuclear plants (NGNPs). These PCHEs are fabricated through a diffusion bonding process. This fabrication step changes the microstructure of wrought metal plates. The current ASME design code does not support the PCHE design for NGNPs due to a lack of test data. Hence, there has been initiative towards elevated temperature mechanical property characterization of the diffusion bonded material. One of the most common channel shapes is a semicircular channel with sharp corners. These corners act as a stress riser at the diffusion bonding interface. Evaluating elevated temperature mechanical performance of diffusion bonded material in the presence of stress risers is an essential step towards the ASME code development of PCHE design. This study selected two specimen geometries: the first is a PCHE bar specimen for tensile loading with three rows and three columns of channels, and the second is a lab-scaled PCHE with six rows and eight columns of channels. A set of elevated temperature monotonic and cyclic tests were conducted on the PCHE bar specimen to evaluate the mechanical performance under axial tensile loadings to study the failure mechanism. The lab-scaled PCHE specimens were tested under overpressure loads at room temperature, and pressure creep and pressure creep-fatigue loadings to mimic the realistic loading conditions observed in typical NGNPs. The X-ray scans of channeled specimens show interesting observations. The test results and observations are presented in the paper.
Simplified Elastic-Plastic Analysis Method for Piping Systems Based on Linear Time History Analysis
Authors: Ono Yohei , Sakai Michiya , Shimazu Ryuya , Inada Fumio , Morita Ryo , Uchiyama Yuta
Published: November 2022

A design seismic motion for design of nuclear power plant have been increased in Japan since Tohoku earthquake in 2011. Consequently, piping systems under the design seismic motion are possibly deformed plastically. Elastic-plastic FEA (Finite Element Analysis) can evaluate elastic-plastic behavior accurately. However, it takes time and cost. In this research the simplified elastic-plastic analysis method has developed. This simplified elastic-plastic analysis method can calculate an equivalent stress and stress components with considering elastic-plastic deformation based on the energy rate density equilibrium which are calculated from linear time history analysis results. Ramberg-Osgood law is defined as true stress-true strain relationship, and the hardening law is isotropic hardening. In order to validate the applicability of the simplified elastic-plastic analysis method to piping systems under seismic motion, linear and non-linear time history analyses were performed for two type of piping systems by using FEA software Abaqus2021, and simplified elastic-plastic analysis method was applied to linear time history analysis results. One of the piping systems consisted of one elbow pipe, two straight pipes and one weight. Nine sinusoidal accelerations with different frequencies were applied to this simple model in in-plane direction. The equivalent stresses at the integration point where the maximum equivalent plastic strain occur in non-linear time history analysis were compared between the simplified elastic-plastic analysis and non-linear time history analysis. At any frequency simplified elastic-plastic analysis method could predict the equivalent stresses calculated by non-linear time history FEA accurately. Another piping system simulated actual piping systems in a nuclear power plant, which include the Tee pipe and several piping supports other than elbow pipes, straight pipes and weights. The random frequency acceleration waves were applied to this model in three direction at the same time. This piping systems took into account the self-eight and the internal pressure. The equivalent stresses and stress components were compared between the simplified elastic-plastic analysis and non-linear time history analysis. As the results, the stresses calculated by the simplified elastic-plastic analysis had good agreement with the results calculated by non-linear time history analysis. Therefore, the applicability of simplified elastic-plastic analysis method to the piping systems was validated.
A Study of the Strength of ASME Section X FRP Flanges
Authors: Bouzid Sofiane , Bouzid Abdel-Hakim , Ngô Anh Dung
Published: November 2022

The development of Fiber Reinforced Plastic (FRP) composite pressure vessels and pipping has greatly advanced in the past decades in the residential and industrial sectors to combat corrosion and chemical attacks. FRP composite flanges are known for their anisotropic behavior. In the ASME code section X, FRP composite flanges are treated using an analytical approach derived from that of metallic flanges in addition to the fact that the geometries are made to fit them as much as possible and not designed independently. This is known to have caused structural flaws for certain FRP flange classes and sizes.

Using a recently developed anisotropic FRP flange approach, it is proposed to identify the most critical flanges by analyzing the flange parameters such as flange ring rotation and stresses in their different parts; flange ring, hub and shell subjected to pressure loading. The study on the strength of flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. To conduct such a study, the selected flange material is an E glass/Vinyl Ester laminate composite. The study shows that FRP flanges of class 25 and 50 are most vulnerable and should be less loaded.
The Preliminary Design and Dynamic Simulation of a Large Confinement Vessel for Explosive Charge Detonation Events
Authors: Valdiviez Robert
Published: November 2022

This engineering effort covers the preliminary design and structural dynamic simulation of a large confinement vessel that can be used for confining large explosive blasts that support shock physics experimentation. The vessel is to be able to withstand an explosive charge detonation of up to 100 pounds (45.4 kg) of TNT, or the equivalent, and maintain the dynamic response of the materials of construction to within an acceptable stress-strain range. The design goal is to maintain the material dynamic response to within the design code limits defined by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, per the former Code Case 2564. The Code Case 2564 has been incorporated into Section VIII, Division 3 per the 2019 version.

Compliance with the impulsive loading response limits defined in Section VIII, Division 3 will provide a high level of confidence that the high-hazard operation of intentionally detonating large quantities of explosives can be conducted safely within this equipment. If necessary, in order to allow for a reasonably practical vessel structure to be fielded for conducting experiments, exceptions to the requirements of Section VIII, Division 3 will be taken. Exceptions to the design requirements of Section VIII, Division 3 are possible to consider because the vessel structure does not provide personnel protection, but fills an equipment protection role. Personnel will be protected by separate bunker type structures, or an appropriate separation distance. The vessel structure protects the sensitive and expensive diagnostic equipment that is fielded near the vessel for interrogating the explosive event.
Design Modifications to the Explosive Destruction System Closure System
Authors: Ludwigsen John S. , Stofleth Jerome H. , Tribble Megan K. , Crocker Robert W.
Published: November 2022

The Explosive Destruction System (EDS), which was developed at Sandia National Laboratories, is a portable system used by the US Army to destroy recovered chemical munitions on site. The latest containment vessel is larger, much heavier and is expected to contain an explosive load over twice that of previous versions. The explosive rating for the vessel, based on the BPVC, is 24 pounds TNT for up to 1,131 detonations.

The EDS vessel consists of a stainless steel, thick wall cylindrical body with large flat doors on each end which contains the explosive detonation and the subsequent chemical treatment of the chemical agent. The vessel is sealed with a metal seal gasket located between each door and the cylinder. A three-part clamping system is used to secure each door to the cylinder at each end.

One of the design challenges for the EDS vessel is to ensure that the doors do not leak when the shock loads from the potentially very significant explosive loads impact the door. Previous versions of EDS vessels have experienced measurable transient displacement between the door and the vessel flanges that challenged the metal seal gasket to maintain a seal. To address the opening of the gap between the flanges during blast loadings, the door clamping system has been modified for this latest design referred to as P3. Only minor changes to the design were required and none to the operating procedure. Computer modeling of the new design predicts a significant reduction in the separation of the flanges when compared to a previous EDS vessels of similar design.
CFD Based Relief Valve Design: Accuracy Requirements and CFD Capability
Authors: Taggart Steven , Doyle Christopher , Dempster William
Published: November 2022

Relief valves act as a controlled weak point in a pressurised system to protect against the dangers of an overpressure event. As such, their sound and reliable operation is crucial to the longevity of any pressurised system. The correct operation of a safety valve is established by adhering to the overpressure and blowdown requirements, i.e. the pressures above and below the set pressure which the valve will open and close and for many ASME BPVC regulated valves these pressures are of the order of 3–10% of set pressure. Since the disc forces are directly proportional to pressure, the accuracy requirements of Computational Fluid Dynamics (CFD) prediction techniques need to be much lower to allow CFD prediction to be a reliable tool for valve design and to guide the development of the device. In this paper, the capability of CFD modelling as a design tool for relief valves used in gas service is investigated by assessing the CFD prediction of disc lift-force curves. A full force-lift curve was produced with a maximum uncertainty of 2% in the low-lift region controlling the overpressure and 1.5% in the high-lift region which controls the blowdown and is of the same order as the experimental measurement. When using ASME BPVC Section VIII as an example, where the requirements for overpressure and blowdown are 10% and 7% respectively, the current CFD modelling capabilities can predict disc forces to an acceptable fraction of the Section VIII certification requirements. However, when comparing the CFD error to ASME BPVC Section I requirements which are much stricter at 3% and 4% for overpressure and blowdown, the use of CFD is more challenging with the CFD uncertainty of the same order as the design requirements.
Inner Inspection of Butt Welds in Layered High-Pressure Hydrogen Vessels Using the Phased Array Ultrasonic Total Focusing Method
Authors: Teng Guoyang , Miao Cunjian , Guo Weican , Tao Yangji , Tang Ping , Ling Zhangwei , Jin Ying
Published: November 2022

Layered high-pressure hydrogen vessels have been widely used in hydrogenation stations in China. The structure of the butt weld at the head of the vessel is complicate, and it is difficult to effectively detect internal defects of the butt weld from the outside surface of the vessel due to the air-filled gap in the double-layer hemispherical head. Inner inspection conducted with the phased array ultrasonic testing method has been proved to be effective in detecting defects of the butt weld, however the inspection area is not large enough to cover the entire butt weld without moving the probe, and the signal-to-noise (SNR) of the inspection image is low. Total focusing method (TFM) performs better inspection results than conventional phased array methods. In order to verify the feasibility of TFM imaging in inspection of the butt weld, a special test block consistent with the material and structure of the head of the vessel has been customized, and the TFM inspection simulation and experiment have been carried out. The results show that the feature of defects located at the butt weld can be recognized conveniently in TFM images, and the TFM inner inspection method can be expected to be an effective means of periodic inspection of layered high-pressure hydrogen vessels.
Stress Analyses of Large Unanchored Open-Topped Oil Storage Tanks With Tapered Shells
Authors: Shi Lei , Zhao Yatong , Huang Zijian
Published: November 2022

The aim of the present paper is a deep experimental and numerical investigation of stress for large-scale oil tanks with a floating roof. Field stress testing of open-topped oil storage tanks with a capacity of 100,000 m3 was performed during the hydrostatic testing by resistance strain gauge technology to investigate the stress levels and distribution of tank bottom and shell. Large amounts of data in this testing that are valid and reliable by adopting various measures have been collected and the stress levels and distributions of tank shell and bottom which provide valuable material for the safety assessment of oil tank operation have been surveyed. Meanwhile, a new 3-D finite element model is developed to simulate stresses in the tank. By comparing the calculated results with the experimental data, the validity of the developed finite element model is verified. Both experimental and numerical results show that the tank bottom shows mainly the radial bending stress at the maximum liquid level. The tank shell at the base shows mainly the radial bending stress however tank shell occurs swelling deformation with the increasing of the height of gauge point, the circumferential membrane stress is the main component. The results suggest that the stress of the fillet joint is relatively high in the tank which will be helpful in improving the design of large-scale oil tanks and assessing the structural integrity.
Analytical Method for Evaluating a 4-Piece Retaining Ring
Authors: Reich Alton , DiSalvo Roberto
Published: November 2022

Valves used for nuclear power applications are designed according to the rules in the ASME Section III Code [1]. A review of the applicable rules governing valve design (i.e. NC-3500) reveals that the Code favors valve body designs with very conventional shapes and elements. The nuclear supplier base has contracted over the past few decades and there are significantly fewer vendors that maintain nuclear QA programs than in the past. As a result, there has been an increasing trend toward using commercial grade dedication (CGD) methods to enable the use of valves successfully deployed in other applications for use as replacement parts, or as part of plant modifications, in nuclear power plants. This paper discusses the qualification of a check valve for a Section III application that had previously been used in other industries. The valve was designed with a split ring that retained the bonnet instead of a more traditional flanged cover. The split ring design is logical from a commercial perspective — it is faster to assemble and maintain the valve, and therefore less expensive to manufacture. However, the ASME Section III Code does not contemplate a split retaining ring in the standard design elements explicitly covered by the Code. This paper provides information about the split ring design and the analytical methods we developed to conservatively evaluate the as part of the valve pressure boundary.
Overview of Piping Stress Analysis Using Shell Elements
Authors: Weyer Robert , Mohammad Karim Milad Haji
Published: November 2022

Despite the fact that shell elements more accurately model a piping system, beam elements are mainly used to model piping systems. A beam model makes use of SIFs and flexibility factors to account for local geometries in a piping system.

Recent advances in software and computer processing power now make shell modelling a realistic option. This paper will examine some of the practical considerations for how modelling of piping can be improved. This includes improvements to beam modelling as well as shell modelling. Some examples of applications will be presented and discussed. Recommendations and suggestions for using shell elements to model piping are put forward.
Pipe Clamps and Welding to the Pipe
Authors: Wiseman Phillip , Gawande Kshitij
Published: November 2022

Pipe supports and restraints are an essential part of a properly supported piping system and may be connected by clamps with threaded members, welds, etc. Depending on the application, the type of connection may favor a clamp with threaded member connection, a clamp directly welded to the pipe, or another welded pipe attachment. For example, economics, planning involved, system efficiencies, and inevitable field changes are evaluated to determine the feasibility and impact of each type of connection. Multiple types of welded pipe attachments (i.e. shear lugs, trunnions, and stanchions) are considered with their corresponding advantages and disadvantages as well as methodologies of analyses. The hybrid of threaded member and welded connections have shown advantageous in certain applications. Historically and previously, stanchions have been provided for anchors but state-of-the-art designs (i.e. base clamp with trunnion) that have been around for the last couple decades are investigated for prevention of translation and rotation of the pipe in the application of supports, guides, and anchors. Also, this study is open to straight pipe as well as short and long radius elbows. Lastly, multiple accepted approaches for analyzing welded pipe attachments are explored. Making the right connection to the pipe is essential to prevent issues after plant operation and protecting the pressure boundary.
State-of-the-Art of WPS in RPV PTS Analysis
Authors: Zarazovskii Maksym , Pištora Vladislav , Lauerova Dana , Obermeier Florian , Mora Mendez Diego Fernando , Dubyk Yaroslav , Bolinder Tobias , Cueto-Felgueroso Garcia Carlos , Szávai Szabolcs , Dudra Judit , Costa Garrido Oriol , Blain Christophe , Puustinen Markku , Katsuyama Jinya , Bass B. Richard , Williams Paul T. , Shugailo Oleksii
Published: November 2022

The APAL (Advanced Pressurized Thermal Shock (PTS) Analysis for Long-Term Operation (LTO)) project was launched in October 2020 for four years with funding from the European Union’s HORIZON 2020 program.

Within APAL, an extensive literature review was performed and experience with defining the state-of-the-art of the Warm Pre-Stress (WPS) effect, which has an impact on the reactor pressure vessel (RPV) brittle fracture margin in both deterministic and probabilistic terms, was collected. To gather the worldwide experience of the WPS approaches and models, a comprehensive questionnaire was developed followed by each APAL partner response. It mainly focused on the following aspects: collection of existing WPS approaches and models implemented in standards and rules for RPV brittle fracture assessment; identification of the WPS issues; collection and analysis of the existing experimental data.

The work presents a short description of the existing WPS national approaches and models along with standards or rules for RPV brittle fracture assessment under PTS events. Attention is focused on the applicability of WPS and its restrictions for constraint effect and crack arrest.

The second part of this work is devoted to the identification of the open issues connected to the practical WPS application in RPV integrity assessment together with the APAL partners’ views on this topic. The following problems are discussed:

- Overall view regarding including WPS in the RPV PTS assessment (applicability, benefit in practical applications);

- thermal-hydraulic aspects of a WPS approach (WPS benefits depending on the transient history);

- WPS and probabilistic RPV brittle fracture assessment (applicability);

- WPS and ductile fracture (applicability);

- WPS and residual stress (RS), (treatment of RS in regard to WPS effect).

The last part is dedicated to the analysis of experimental data for defining the WPS benefit. For this purpose, the Czech and Ukrainian experimental data (WWER materials), and the SMILE’s project data (heat-treated 17MoV8-4mod steel and 18MND5 steel) were analysed. The WPS effect on fracture toughness (FT) was evaluated using the ratio of enhanced FT KFrac (at re-load, after WPS) to FT of virgin material KIC (without pre-load), as obtained from the experimental data. It was shown, that relatively to the KIC,50% and KIC,95%, the WPS effect led to an increase of FT in 97.6% and 80.9% of cases respectively, which quantifies and confirms the benefit of WPS.

This work describes worldwide experience and best practice of the WPS and its application for the RPV integrity assessment. The paper’s conclusions are also focused on the recommendations for dealing with WPS issues.
Thermal Modeling of Hanford Lead Canister’s Heater Bench Tests
Authors: Suffield Sarah R. , Grant Christopher L. , Klymyshyn Nicholas A.
Published: November 2022

A computational fluid dynamics (CFD) model was built to simulate planned testing of heater assemblies for the Hanford Lead Canister (HLC) project. The HLC is a canister storage system that will contain heaters to simulate the decay heat of nuclear material and provide the canister storage system with environmental conditions equivalent to the operating conditions on a dry storage pad. The HLC will be equipped with long-term data collection and monitoring systems to provide an early warning of corrosion, pitting, cracking, or other signs of canister degradation that might threaten the integrity of the containment boundary over the potentially long term of dry storage. An important part of the HLC development is to confirm the function and ability of the electric heater assemblies that were specially designed to provide heating similar to the decay heat of nuclear material contained within the canister storage system. Heater bench testing is planned for early 2022 in a test configuration that does not include the canister. The goal of the bench testing is to verify that the heaters can replicate the decay heat of a canister with nuclear material and to validate the thermal models, which are critical to understanding the HLC’s thermal environment, including the local air flow within the canister storage system. Testing of the heater assemblies inside the canister system are planned in the future to validate canister level thermal models, and rigorous pre-deployment testing of the complete HLC cask and canister system is intended to be completed before the HLC is deployed in the 2025–2026 timeframe.

This study presents the pre-test temperature predictions of the bench testing. A description of the heater assemblies and planned bench testing is presented. The model was developed with the commercial CFD code STAR-CCM+. An uncertainty analysis was run with the CFD model to determine the uncertainty in the temperature predictions and provide a range over which the predicted temperatures are expected to vary. The uncertainty analysis was performed by coupling STAR-CCM+ with the software Dakota, which provides advanced parametric analyses, including quantification of margins and uncertainty with computational models. This work is expected to provide insight into SNF canister behavior1.
Determination of Johnson-Cook Fracture Strain Model for Austenitic Stainless Steel 304
Authors: Seo Jun-Min , Kim Hune-Tae , Kim Yun-Jae , Yamada Hiroyuki , Kumagai Tomohisa , Tokunaga Hayato , Miura Naoki
Published: November 2022

In this study, Johnson-Cook fracture strain model considering the effect of stress triaxiality and strain rate is determined for austenitic stainless steel 304. Tensile test data of four different stress triaxiality and six different strain rate conditions are used to determine the parameters in the J-C fracture strain model. To see the effect of local variation of stress triaxiality and strain rate in the specimen, the J-C fracture models are determined in two different ways. The first case uses the initial stress triaxiality and nominal strain rate, and the second case uses the average value of local stress triaxiality and strain rate obtained from finite element analysis. The use of initial stress triaxiality gives conservative estimate of fracture strain at low stress triaxiality, and non-conservative estimate at high stress triaxiality. The use of nominal strain rate gives overall conservative estimate of fracture strain.
Round Robin Analysis of Small Punch Testing on 15Kh2NMFA Reference Material
Authors: Welschen Romy , Gillemot Ferenc , Simonovski Igor , Martin Oliver , Adamech Marek , Petzova Jana , Hernandez Rebeca , Kopriva Radim , Naziris Frederiki , Molenaar Boy , Kolluri Murthy
Published: November 2022

Miniature / sub-sized specimen test methods for the mechanical characterization of metallic alloys like the small punch test (SPT) have the benefit that only small quantities of material are needed to perform a reasonable number of tests. This makes such tests in particular interesting if only limited quantities of material are available for mechanical characterization, like irradiated specimens from reactor pressure vessel (RPV) surveillance programs of light water reactors (LWRs). The SPT only requires small discs of 8mm diameter and 0.5mm thickness and such specimens can be manufactured from broken Charpy impact test specimens that were previously tested within RPV surveillance programs. With the publication of EN 10371 earlier in 2021 the SPT is now a standardized test that can be used in principle to determine tensile, creep, fracture toughness properties and ductile-to-brittle transition temperatures (DBTTs). However, fabrication and testing of irradiated SPT specimens remotely in hot cell environments has several practical challenges. Any deviation in specification as laid down in the standard can lead to variations in test outcome. To address this issue an SPT Round Robin exercise on VVER RPV steel 15Kh2NMFA reference material has been performed in the context of the Horizon 2020 Euratom project STRUMAT-LTO. Several research organizations, namely NRG, EK/CER, JRC, VUJE, CIEMAT and UJV, have participated in this round robin exercise to validate sample manufacturing, test procedures and test equipment and to determine tensile properties and DBTTs of the above RPV steel. In this paper results and conclusions of the STRUMAT-LTO SPT round robin exercise are presented.
Technical Background for the Update and Extension of the Time-Dependent Allowable Stresses of Type 304H and 316H Stainless Steels
Authors: Sham Ting-Leung , McMurtrey Michael
Published: November 2022

Type 304H and 316H stainless steels are codified in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code for Section III, Division 5, Class A construction for up to 1500°F (816°C) and 300,000 hours. The extension of design lifetimes to 500,000 hours has been undertaken by various research projects and by the ASME Section III, Division 5 Code Committees. Due to a long-standing issue related to non-classical creep behavior on the use of the time to the onset of tertiary creep as one of the time-dependent allowable stress criteria, little progress was made in the extension of the time-dependent allowable stresses for Type 304H and 316H stainless steels. A recent effort by Dabrow and Nestell (Impact of Tertiary Creep on Time Dependent Allowable Stresses for Type 304H and 316H Stainless Steels, Report 0300-0003-RPT-001, MPR Associates, Alexandria, VA, 2020) has provided a rational method for the treatment of the highly variable data for the time to onset of tertiary creep. This paper presents the background formulas for determining the time-dependent allowable stress values of Type 304H and 316H stainless steels, as assembled from relevant project work. These updates and extensions are being recommended to the ASME Section III Code committees for approval and are subject to change upon feedback from those committees.
Electric-Field-Assisted Diffusion Welding to Fabricate Alloy 617 Compact Heat Exchangers
Authors: Zhang Xinchang , Rupp Ryann E. , Rufner Jorgen F. , McMurtrey Michael D.
Published: November 2022

Compact heat exchangers are of interest for a number of applications including advanced reactors. Alloy 617 is one of the top candidate materials for the gas-cooled reactor intermediate heat exchanger. Previous endeavors to diffusion weld Alloy 617 utilized hot pressing (HP). It was reported that grain boundary migration across the interface was hindered by extensive precipitation. Bonds of this nature have been observed to reduce the elevated-temperature mechanical properties compared to the wrought-product form. It was hypothesized that the electric current applied during electric-field-assisted sintering (EFAS) can overcome these challenges, resulting in improved diffusion welding (DW). This study investigated DW of Alloy 617 via EFAS. Stacks composed of three sheets that were 20 mm in diameter were welded using EFAS. Specimens were welded with an applied electric current, a pressure of 30 MPa, hold time of 30 min, and temperatures of 1050°C, 1100°C, and 1150°C. DW using HP as the zero-current analog of EFAS was also performed at the most promising EFAS conditions. Results revealed that both the applied electric current and temperature played a key role in precipitation and grain boundary migration in diffusion-welded Alloy 617. Precipitates were observed at the interface of the hot-pressed samples which limited grain boundary migration. Electric current was found to prevent precipitate formation along the interface at 1150°C. The electric current coupled with a temperature of 1150°C during EFAS resulted in significant grain boundary migration across the interface.
On the Use of Artificial Neural Network Technique for Seismic Fragility Analysis of a Three-Dimensional Industrial Frame
Authors: Quinci Gianluca , Phan Nam Hoang , Paolacci Fabrizio
Published: November 2022

Fragility function that defines the probability of exceedance of a damage state given a ground motion intensity (IM) is an essential ingredient of modern approaches to seismic engineering as the performance-based earthquake engineering methodology. Epistemic as well as aleatory uncertainties associated with seismic loads and structural behavior are usually taken into account to analytically develop such curves. However, structural analyses are time-consuming, requiring generally a high computational effort. Moreover, the conditional probability of failure is usually computed by regression analysis assuming predefined probability functions, like the log-normal distribution, without prior information on the real probability distribution. To overcome these problems, the artificial neural network (ANN) technique is used for the development of structural seismic fragility curves considering record-to-record variability and structural parameter uncertainties. In this respect, the following aspects are addressed in this paper: (a) implementation of an efficient algorithm to select IMs as inputs for ANN, selecting the most relevant ones; (b) derivation of surrogate models by using the ANN technique, c) computation of fragility curves with Monte Carlo Simulations method and verification of the validity. These methods enable the implicit treatment of uncertainty in either or both of ground motion intensity and structural properties without making any prior assumption about the probability function. This methodology is then applied to estimate the probability of failure of a non-structural component (NSC), i.e., vertical tank, located on a typical three-dimensional industrial frame. First, an extensive sensitivity analysis on the ANN input parameters is performed (feature selection), identifying the type and number of seismic intensity measures (amplitude-based, frequency-based, and time-based IM). Then different surrogate models are derived investigating the number of hidden layers and parameters. A multiple stripe analysis is then performed on a nonlinear model of the structure, deriving the set of data for the ANN. Different training and test subsets are used to derive the surrogate model. Finally, a Monte Carlo simulation is performed to derive the fragility curves for the limit state considered. Finally, the risk assessment is obtained, evaluating the mean annual rate of failure of the NSC.
Research on X-Ray Digital Imaging Inspection Method of Carbon Fiber Wrapped Cylinder With Aluminum Liner for Vehicle
Authors: Gao Zhaojiang , Chai Sen , Wang Qian , Huang Liang , Li Xiang , Deng Guide
Published: November 2022

The fully-wrapped carbon fiber reinforced cylinders with an aluminum liner are currently the most common high-pressure hydrogen storage tank for vehicles. However, it is difficult to detect it by traditional detection methods effectively. X-ray digital radiographic inspection technology is currently a feasible way to detect the typical defects of the winding layer and aluminum liner of the fully-wrapped carbon fiber reinforced cylinders with an aluminum liner for vehicles. In order to verify the detection ability of digital radiographic inspection for the main defects of carbon fiber wound gas cylinders with aluminum liner and to provide quantitative data of the detection ability, this paper aims at the fiber layer fracture, scratches, and pores that may occur during the use and manufacture of gas cylinders. In order to simulate the above-mentioned natural defects, the images of artificial defects were taken through the optimized transillumination parameters. The test results show that the digital radiographic inspection method can detect the axial notches, circumferential notches, oblique notches with a depth of 0.2 mm on the fiber layer, and axial and circumferential notches with a depth of 0.2 mm on the liner. Furthermore, it can also detect artificial defects such as 0.5mm fiber layer flat-bottom hole and 0.2mm depth /Φ1mm aluminum liner flat-bottom hole. This proves that digital radiographic inspection can be used for the early stage of a significant failure of the fully-wrapped carbon fiber reinforced cylinders with an aluminum liner and provides strong support for its safe use.
Fiber-Optic Sensing for Seating Stress Quantification in Semi-Metallic Gaskets
Authors: Cloostermans Ben , Pronk Dick , Bruckenburg Björn , Geernaert Thomas
Published: November 2022

Modern sealing components are essential in today’s industry. The recent global focus on environment, sustainability and safety is encouraging gasket manufacturers to innovate and think of the gasket of tomorrow. Not only are performance expectations increasing rapidly, but advancements in gasket manufacturing and material technologies are producing gaskets that — in both theory and practice — generate tighter seals and reduce harmful emissions. The major impediment to attaining these results in the field is the lack of advancement in assembly accuracy and real-time monitoring of gasket stress. Currently the user relies on industrial calculation standards that are designed to determine the required bolt load to maintain a leak free seal over the required timeframe. Such calculations often yield a proper approximation of the situation, but they inherently rely on simplifications and assumptions. Furthermore, the correct execution of installation protocols is difficult to verify. The state-of-play does not allow in-situ measurements of the seating stress in the gasket. This study addresses state-of-the-art shortcomings in bolted flange connections and proposes a solution to mitigate them by means of sensors. We successfully integrate optical fiber sensors inside semi-metallic gaskets and experimentally demonstrate the direct measurement of seating stress. Such in-situ seating stress quantification enables installation and condition monitoring serving an optimal lifecycle prediction and failure prevention. As such, this approach contributes to increased sustainability of bolted flange connections.
Investigating the Role of Ferritic Steel Microstructure and Strength in Fracture Resistance in High-Pressure Hydrogen Gas
Authors: Ronevich Joseph A. , Kagay Brian , San Marchi Chris , Wang Yiyu (Jason) , Feng Zhili , Wang Yanli , Findley Kip
Published: November 2022

Despite their susceptibility to hydrogen-assisted fracture, ferritic steels make up a large portion of the hydrogen infrastructure. It is impractical and too costly to build large scale components such as pipelines and pressure vessels out of more hydrogen-resistant materials such as austenitic stainless steels. Therefore, it is necessary to understand the fracture behavior of ferritic steels in high-pressure hydrogen environments to manage design margins and reduce costs. Quenched and tempered (Q&T) martensite is the predominant microstructure of high-pressure hydrogen pressure vessels, and higher strength grades of this steel type are more susceptible to hydrogen degradation than lower strength grades. In this study, a single heat of 4340 alloy was heat treated to develop alternative microstructures for evaluation of fracture resistance in hydrogen gas. Fracture tests of several microstructures, such as lower bainite and upper bainite with similar strength to the baseline Q&T martensite, were tested at 21 and 105 MPa H2. Despite a higher MnS inclusion content in the tested 4340 alloy which reduced the fracture toughness in air, the fracture behavior in hydrogen gas fit a similar trend to other previously tested Q&T martensitic steels. The lower bainite microstructure performed similar to the Q&T martensite, whereas the upper bainite microstructure performed slightly worse. In this paper, we extend the range of high-strength microstructures evaluated for hydrogen-assisted fracture beyond conventional Q&T martensitic steels.
Development of Generic Unirradiated Values of T0 and RTTo for Use in ASME Code Applications
Authors: Erickson Marjorie , Kirk Mark , Long Elliot J.
Published: November 2022

A companion paper presented at this conference summarizes a recently published EPRI report that provides a Technical Basis for Code Case N-914, “Accounting for the Effect of Embrittlement on Fracture Toughness Properties Used in Evaluations of Pressure Boundary Materials in Class 1 Ferritic Steel Components, Section XI, Division 1.” CC N-914 is being developed by the Section XI Working Group on Operating Plant Criteria to provide a consistent and comprehensive methodology to account for embrittlement, including the effects of uncertainty, for both conventional Code applications that use RTNDT as an index temperature as well as newer methodologies that adopt the Master Curve based reference temperatures T0 or RTTo. At least in the United States it has become common practice to sometimes use “generic” values of unirradiated RTNDT that have been established as mean values for a class of materials (e.g., a weld made from a particular weld wire heat, a plate made to a certain ASTM specification, etc.) along with an associated uncertainty term in situations where a plant/material specific RTNDT value is not available. The objective of this paper is to describe a methodology that can be used to establish similar generic unirradiated values for RTTo and T0 using data published in the open literature. Such values provide a low-cost point of entry for use of Master Curve techniques such as those now in the Code itself and in various Code Cases (e.g., CC N-830-1, proposed CC N-914). Generic values may provide relief from excessively conservative RTNDT estimates while plant-specific Master Curve data is being developed.
Low Cycle Fatigue Behavior and Failure Probability of Elbow Pipes Based on High Acceleration Vibration Test
Authors: Shimazu Ryuya , Sakai Michiya , Ono Yohei
Published: November 2022

For the seismic fragility assessment of piping systems in a nuclear power plant, the failure probability of piping systems is calculated elastically under the assumption that ductile rupture occurs. However, some previous studies have reported that the primary failure mode of piping systems is fatigue. There exists a possibility that the result of the fragility assessment that assumed ductile rupture may have included some safety margins. In fragility assessments, it is important to accurately recognize the actual capacity and uncertainty by eliminating the safety margins considered in the design. In this study, to conduct a fragility assessment considering elastic-plastic behavior under the assumption that fatigue failure occurs, the low cycle fatigue behavior of elbow pipes was obtained via high acceleration vibration and static loading tests. The analysis model of the tests was developed for the evaluation of the fatigue failure probability of the elbow pipe. The linear cumulative damage of the specimen at the initiation of the fatigue crack was calculated. The equivalent strain amplitude was calculated, and the test results were plotted on the fatigue curve. Then, the failure probability of elbow pipes was evaluated by using the analysis model under the assumption that the vibration test results produced the median strength value. This evaluation result was compared with the case in which the value obtained from the conventional fatigue diagram was used as the median strength.
Engineering Critical Assessment (ECA) of Onshore Natural Gas Pipelines Using Partial Safety Factors (PSFs)
Authors: Kagita Gurumurthy , S. K. Pottem Penchala , Gupta Deepak , G. S. Achary Gudimella , V. R. Sripada Subramanyam
Published: November 2022

Pipeline design codes recognize the potential risks posed by gas pipelines by relating the factors which affect the probability of failure to consequences in particular locations. To maintain more or less uniform risk level, ASME B31.8 Code adopted risk based concepts indirectly through location classifications by specifying different design factors (DFs). Engineering Critical Assessment (ECA) of onshore natural gas pipelines in accordance with pipeline-specific methods such as API 1104 allow much deeper defects in higher class pipe, which is in contrary to the basic design concept. This is due to the lack of consideration for the higher consequences in the higher classes even though they were considered at the design stage. To ensure the failure probability within a target value, generic fitness for service standards such as API 579-1/ASME FFS-1 and BS 7910 recommend partial safety factors (PSFs) to key variables. However, there is no correlation between the design factors used during the pipeline design stage and the PSFs used for the ECA. To achieve the basic intent of design code i.e., to maintain risk level as per location classifications, this paper proposes to use PSFs based on class location. Few case studies are presented to demonstrate the proposed methodology.
Fugitive Emission for Different Seals and Flange Designs – Test Results and Design Prediction
Authors: Wellings Stuart , Lutkiewicz Przemyslaw , Robertson David
Published: November 2022

In today’s environment, the functionality of a sealing solution is highly valued. The ability to provide a solution with high sealing integrity and low fugitive emissions follows the industry trend for developing a more environmentally friendly solution. There are some existing standards and methodologies that provide a basis for practical testing activities. Other methodologies, such as FEA and hand calculations, are available to evaluate the seal tightness on a theoretical basis during the design stage and predict fugitive emissions values. Test measurement for fugitive emissions is subject to the design of the flange and seal components, the quality of those components, and the test set-up methods employed. This paper will focus on the comparison of different flange designs currently available in the market, as well as a comparison of various metal to metal seal types. The scope of this paper covers flanges designed to ASME B16.5, API 6A, non-standard flanges (e.g. compact flanges) as well as clamp connectors. For metal seals, this paper will cover HX, BX and Techlok seal rings. Test methodologies and set up will be detailed and the test results listed, with the theoretical predicted fugitive emissions values also provided for comparison. Results for previous compact flange analysis are also included for reference.