bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Characterization for a Large Test Design of a Dissimilar Metals Welding With a Narrow Gap Nickel Alloy Weld: Experimental and Numerical Analysis on Specimens
Authors: Bourgeois Myriam , Ancelet Olivier , Marie Stéphane , Chapuliot Stephane 
Published: August 2013

Dissimilar metal welds are a common feature of light water reactors in connections between ferritic components and austenitic stainless steel piping systems. Inspection difficulties, variability of material properties and residual stresses all combine to create problems for structural integrity assessment.
Within the framework of European project STYLE, a fracture test on a pipe containing a through wall crack in a narrow gap Nickel alloy Dissimilar Metals (DMWinc) is under preparation. The work is focusing on the nickel alloy - ferrite steel interface which is the weakest area of such welded pipes in front of ductile tearing. The study temperature is 300°C, which covers typical temperatures in components like hot pipes in the primary coolant system of pressurized water reactors.
This paper gives an overview of the program and the first results of works which is been carried out by the French Atomic Energy Commission and Alternative Energies (CEA) in order to study the mechanical properties and integrity of component of the DMWinc pipes provided and designed by AREVA France.
Prediction of Leak Rates Through Porous Gaskets at High Temperature
Authors: Grine Lotfi , Bouzid Abdel-Hakim 
Published: August 2013

The ability of a gasket to maintain tightness under different operating conditions has been studied extensively in recent years. However most of the research studies conducted on leakage predictions was performed at room temperature. The aim of this work is to predict leakage through gaskets take into account the effect of the temperature on the fluid properties changes and gasket internal structural characteristics. The analytical model of slip flow regime to evaluate the mass leak rates through a porous gasket developed in [1] was used in this study. The results from the model were validated and compared with experimental data obtained from tests conducted on the Universal Gasket Rig with two different gases (Helium, Nitrogen). The leak rates measured are in the range of 1 to 10−4 mg/s, which is measurable using a pressure rise technique.
As a second objective the influence of the gasket displacements caused by stress and temperature on the flow leakage was studied. A relationship between displacement or void thickness and leakage is clearly demonstrated. The slip flow regime model is capable of predicting leakage at temperature with reasonable accuracy.
An Overview of Risk Management Planning for Hot-Isostatic Pressure Treatment of High-Level Waste Calcine for the Idaho Cleanup Project
Authors: Preussner Brian D. , Nenni Joseph A. , Balls Vondell J. 
Published: August 2013

The Calcine Disposition Project (CDP) of the Idaho Cleanup Project (ICP) has the responsibility to retrieve, treat, and dispose of the calcine stored at the Idaho Nuclear Technology and Engineering Center (INTEC) located at the Idaho National Laboratory. Calcine is the granular product of thermally treating, or calcining liquid high-level waste (HLW) that was produced at INTEC during the reprocessing of spent nuclear fuel (SNF) to recover uranium. The CDP is currently designing the Hot Isostatic Pressure (HIP) treatment for the calcine to provide monolithic, glass-ceramic waste form suitable for transport and disposition outside of Idaho by 2035 in compliance with the Idaho Settlement Agreement.
The HIP process has been used by industry since its invention, by Battelle Institute, in 1955. Hot isostatic pressing can be used for upgrading castings, densifying pre-sintered components, and consolidate powders. It involves the simultaneous application of a high pressure and temperature in a specially constructed vessel. The pressure is applied on all sides with a gas (usually inert) and, so, is isostatic. The CDP will use this treatment process (10,000 psi at 1,150 C) to combine physically and chemically a mixture of calcine and granular additives into a non leachable waste-form.
The HIP process for calcine involves filling a metal can with calcine and additives, heating and evacuating the can to remove volatiles, sealing the can under vacuum, and placing the can within the HIP machine for treatment. Although the HIP process has been in use for over 50 years it has not been applied in large scale radioactive service. Challenges with retrofitting such a system for Calcine treatment include 1) filling and sealing the HIP can cleanly and remotely, 2) remotely loading and unloading the HIP machine, and 3) performing maintenance and repair on a 300 ton, hydraulically actuated machine in a highly radioactive hot cell environment.
In this article, a systems engineering approach, including use of industry-proven design-for-quality tools and quantitative assessment techniques is summarized. Discussions on how these techniques were used to improve high-consequence risk management and more effectively apply failure mode, RAMI, and time and motion analyses at the earliest possible stages of design are provided.
Prediction of Creep Crack Growth for Modified 9Cr-1Mo at 600°C
Authors: Kim Nak Hyun , Kim Yun Jae , Kim Woo Gon , Lee Hyeong Yeon 
Published: August 2013

This paper introduce theoretical creep crack growth prediction model and provides experimental validation of the approach for simulating creep crack growth using finite element analysis method, recently proposed by the authors. The FE creep damage model is based on the creep ductility exhaustion concept, and incremental damage is defined by the ratio of incremental creep strain and multi-axial creep ductility. A simple linear damage summation rule is applied. When accumulated damage becomes unity, element stresses are reduced to zero to simulate progressive crack growth.
For validation, simulated results are compared with experimental data for a compact tension specimen of modified 9Cr-1Mo at 600°C under various loading levels. The simulated results agree well with experimental C*-da/dt data. The test data are also compared with theoretical CCG prediction model.
Metallic Ring Type Joints (RTJ): Overview and Recent Developments
Authors: Currie Russ 
Published: August 2013

The paper discusses the variety of metallic gaskets used in ASME B16.5 Ring Type Joint (RTJ) flanges.
Highlights the differences between ASME and API topside and subsea engineering standards with regard to geometry and types.
Discusses various testing carried out and its relevance to the development of alternative sealing products to be used in RTJ assemblies.
Gives a brief overview and findings of the application of finite elemental analysis to two commonly used gasket profiles namely; Oval and Octagonal.
Presents and discusses bolt relaxation test data on assembled RTJ connections using a flange demonstration unit (FADU). Comparing standard gaskets with serrated and faced products.
Introduces the next step in soft facing materials.
Effect of Weld Residual Stress Fitting on Stress Intensity Factor for Circumferential Surface Cracks in Pipe
Authors: Shim Do-Jun , Kerr Matthew , Xu Steven 
Published: August 2013

Recent studies have shown that the crack growth of PWSCC is mainly driven by the weld residual stress (WRS) within the dissimilar metal weld. The existing stress intensity factor (K) solutions for surface cracks in pipe typically require a 4th order polynomial stress distribution through the pipe wall thickness. However, it is not always possible to accurately represent the through thickness WRS with a 4th order polynomial fit and it is necessary to investigate the effect of the WRS fitting on the calculated stress intensity factors.
In this paper, two different methods were used to calculate the stress intensity factor for a semi-elliptical circumferential surface crack in a pipe under a given set of simulated WRS. The first method is the Universal Weight Function Method (UWFM) where the through thickness WRS distribution can be represented as a piece-wise cubic fit. In the second method, the through thickness WRS profiles are represented as a 4th order polynomial curve fit (both using the entire wall thickness data and only using data up to the crack-tip). In addition, three-dimensional finite element (FE) analyses (using the simulated weld residual stress) were conducted to serve as a reference solution.
The results of this study demonstrate the potential sensitivity of stress intensity factors to 4th order polynomial fitting artifacts. The piece-wise WRS representations used in the UWFM was not sensitive to these fitting artifacts and the UWFM solutions were in good agreement with the FE results.
Initial Development of the Extremely Low Probability of Rupture (xLPR) Version 2.0 Code
Authors: Rudland D. , Harrington C. 
Published: August 2013

NRC Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to assess compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB approvals.
Along with a series of existing qualitative steps to assure safety in LBB-approved lines experiencing PWSCC, NRC staff, working cooperatively with the Electric Power Research Institute through a memorandum of understanding, is developing a new, modular based, comprehensive piping system assessment methodology to directly assess compliance with the regulations. This project, called eXtremely Low Probability of Rupture (xLPR), will model the effects and uncertainties of relevant active degradation mechanisms and the associated mitigation activities. The resulting analytical tool will be comprehensive with respect to known and significant materials challenges (PWSCC, etc.), vetted with respect to the technical bases of models and inputs, flexible enough to permit analysis of a variety of in-service situations and adaptable such as to accommodate evolving and improving knowledge.
A multi-year project has begun that has been focused on the development of a viable method and approach to address the effects of PWSCC as well as define the requirements necessary for such a modular-based assessment tool. As reported in a previous paper, the first version of this code was developed as part of a pilot study, which leveraged existing fracture mechanics based models and software coupled to both a commercial and open source code framework to determine the framework and architecture requirements appropriate for building a modular-based code with this complexity. The pilot study focused on PWSCC in pressurizer surge nozzles, and was meant to demonstrate the feasibility of this code and approach and not to determine the absolute values of the probability of rupture.
This paper examines the plans for the xLPR Version 2.0 model which will broaden the scope of xLPR to all LBB-approved primary piping in pressurized water reactors (PWR), using an incremental approach that incorporates the design requirements and lessons learned from previous iterations. After a review of the Version 1.0 final results, this paper will document the plans for Version 2.0 including the revised management structure, the technical scope, and the progress in the code development effort to date.
A Novel Fracture Specimen for Assessment of Circumferential Complex-Cracks in Pipes
Authors: Shim Do-Jun , Wilkowski Gery , Kalyanam Sureshkumar , Brust Frederick 
Published: August 2013

The existence of a complex-crack in the US nuclear plant fleet was first discovered at the Duane Arnold BWR plant where large circumferential IGSCC cracks were found in several safe ends. In order to characterize the fracture behavior of these complex-cracks, several research projects were conducted which included full-scale pipe tests. Since then, little work has been conducted on this topic until recently. The occurrence of PWSCC in PWR plants raised the concern that a complex-crack could develop in dissimilar metal welds under certain conditions. This was demonstrated by using a detailed 3D finite element analyses that allowed a natural PWSCC crack growth. Thus, there is a need to further investigate the fracture behavior of a complex-crack in a pipe.
In this paper, lessons learned from the past complex-cracked pipe tests are summarized first. Then, based on the findings from the past work, a novel complex-cracked fracture specimen was proposed to characterize a complex-crack in a pipe. The typical C(T) and SEN(T) specimens were modified by inserting an additional notch only on one side of the specimen. These specimens were used to analyze the past complex-cracked pipe tests. The experimental results obtained from the modified SEN(T) specimen, namely complex-cracked tension [CC(T)-2] specimen, were able to reproduce the complex-crack fracture behavior observed in past pipe tests.
Improvement of Fatigue Limit by Shot Peening for High-Strength Steel Containing a Crack-Like Surface Defect: Influence of Stress Ratio
Authors: Yasuda Jun , Takahashi Koji 
Published: August 2013

It is well known that shot peening (SP) prevents the initiation and propagation of fatigue cracks and improves the fatigue limit of metals. It was recently reported that a surface crack can be rendered harmless by SP. Actual pressure vessels are generally operated under a positive stress ratio (R > 0). However, the effects of SP on the improvement of fatigue limits under R > 0 remain unclear. If these effects were clarified, the structural integrity of pressure vessels could be advanced. Thus, in this study, we investigated the influence of SP on fatigue limits and on the crack size that could be rendered harmless by SP under R > 0.
High-strength steel specimens containing a semi-circular slit were subjected to SP. Bending fatigue tests were carried out under R = 0.4. The fatigue limits of the SP specimens increased 50∼100% compared with Non-SP specimens. Slits under 0.2 mm in depth were successfully rendered harmless by SP. The increasing ratios of the fatigue limit under R = 0.4 were lower than those under R = 0. However, the size of semi-circular slit that can be rendered harmless by SP remained the same. The size of the slit that can be rendered harmless can be predicted by calculating stress intensity factors.
Assessment of Ductile Cast Iron Fracture Mechanics Analysis Within Licensing of German Transport Packages
Authors: Komann Steffen , Kiyak Yusuf , Wille Frank , Zerbst Uwe , Weber Mike , Klingbeil Dietmar 
Published: August 2013

In recent years BAM was involved in several licensing procedures of new package designs for the transport of radioactive material, where the cask body was made of Ductile Cast Iron (DCI). According to IAEA regulations type B(U) packages must withstand the defined accident conditions of transport. For the cask material DCI, it is necessary to determine the brittle fracture behaviour. Due to the complex structure of the cask body and the dynamic loading a fracture mechanical assessment in an analytical way is not always possible. Numerical calculations are necessary to determine the fracture mechanical load in the component. At the first step a numerical analysis has to be done to identify the loading state at the cask body. Secondly an analysis of a detail of the cask body is made considering the boundary conditions of the global model. An artificial flaw is considered in this detailed model to calculate the fracture mechanical loading state. The size of the artificial flaw is characterized by the ultrasonic inspection used for the quality assurance of the package. The applicant developed additional analysis tools for calculation of stress intensity factor and/or J-Integral.
The paper describes the authority assessment approach for the DCI fracture mechanics analysis.
Derivation of Input Distributions for Probabilistic Evaluation Using In-Reactor Measurements
Authors: Nadeau Eric 
Published: August 2013

Candu Energy Inc. (former commercial operation of AECL) has developed probabilistic tools to support nuclear plant operators with a risk-based fuel channel management strategy. One such tool is used to evaluate the probability of pressure tube rupture resulting from pressure tube to calandria tube contact and hydride blisters. This tool assumes that PT rupture occurs when delayed hydride cracking (DHC) initiates in a blister. The objectives of the probabilistic assessments are to:
• Determine the overall risk of PT rupture in the reactor core for comparison with the acceptance criteria.
• Determine the risk of PT rupture for specific fuel channels to assist in the development of an inspection/maintenance strategy.
• Evaluate the risk reduction that would result from different fuel channels inspection/maintenance scenarios.
• Optimize inspection/maintenance programs.
The distributions of the most critical input distributions can be derived by benchmarking against in-reactor measurements. Two benchmark methods were developed to take advantage of the recent advancements in the accuracy of the inspection tool that measures the gap profile between the PT and the CT.
Pressure Build-Up Inside Packages Containing Wet Intermediate Level Radioactive Waste due to Thermal Loads
Authors: Nehrig Marko , Bletzer Claus , Wille Frank 
Published: August 2013

Over the last years several transport approval procedures were finished for ductile cast iron containers containing wet intermediate level waste. BAM was involved in the assessment of mechanical and thermal aspects, activity release and material and component behavior regarding fulfillment of the regulatory requirements.
The radioactive contents of these package designs which were not dried, only drained, consist of saturated ion exchange resin and a small amount of free water. Regarding wet contents, the most interesting point, however, is the pressure build-up inside the package due to vaporization. This could be caused by radiolysis of the liquid and must be taken into account for the storage period.
The paper deals primarily with the pressure build-up inside the package caused by the regulatory thermal test (30 min at 800°C) as part of the cumulative test scenario under accident conditions of transport. The pressure build-up is estimated by calculation in a very conservative way regarding conduction and heat radiation. To get trustworthy results without an exact specification of the content, physical fire tests should be conducted. This paper will result in the strong advice, that contents should be dried to ensure a positive outcome of the safety assessment.
Investigation on Detection of COV Based on Infrared Camera
Authors: Thomas Benjamin , Sauger Emmanuel , Fily Sébastien , Lejeune Hubert 
Published: August 2013

In order to reduce emission of pollutants, regulations such as Clean Air Act in the United States of America or the Integrated Pollution Prevention and Control (IPPC) and the Industrial Emission Directive (IED) in Europe have been voted. On sites like refineries, the end users have implemented systematic control of Volatile Organic Compounds (COV) in the atmosphere, on their equipments (valves, flanges, pump, compressor…).
These controls involve methods of detection such as sniffing with a Flame Ionization Detector (FID) managed by an operator according to EPA21 method. This method is time-consuming and exposes operators to hazardous situations when statistical counting shows that the global emission are often connected with few equipments in refineries. Thus, the use of specific IR imaging with a camera as a remote control method sensible to selected organic gases seems a very attractive alternative, even if this method does not able to quantify very accurate leakage rates.
This study presented here investigates the influence of several parameters on the detection of COV with IR camera, under controlled laboratory conditions. External parameters such as distance of view, type of gas, wind, and camera configuration parameters are investigated.
The measurement enables definition of the limits of the IR imaging method. If the study shows that the camera must be operated by skilled and trained personal to camera tuning and image analyzing, it remains a very interesting alternative method to sniffing in many cases. The next step of the study will involve the use of the camera on various kind of sites using organic gases.
STYLE: Comparison of Leak-Before-Break Methodologies Applied in Europe
Authors: Sharples John 
Published: August 2013

The paper presents results of a sub-task of the STYLE project currently running within the 7th Framework EU programme by way of an overview of leak-before-break (LBB) methodologies used in the nuclear industry of several European countries (Germany, France, UK, Netherlands, Czech Republic, Spain and Hungary).
In relation to the various participating countries, the overview specifically focuses on: practices and procedures; regulatory position; evolution; application; past, present and planned future LBB research activities; and, future plans.
A qualitative comparison of the different methods employed in the various countries is included with the commonalities and differences among the approaches being highlighted.
Tüv Nord Group Strategy Concept Coop: An Answer for the New Requirements of the Power Plant Flexibilisation
Authors: Trieglaff Ralf , Rieck Detlef , Schulze Astrid , Schulz Axel 
Published: August 2013

The ambitious German energy program predicts a rapid expansion of regenerative power generation. Caused by the fluctuating nature of regenerative forms of energy, the need for backup capacities in the form of similar-sized thermal power plants is clear. Consequently, components of gas and coal-fired power plants are exposed to sharp transients and a high number of cycles.
If German design regulations are observed, these operating requirements will lead to high levels of depletion of the integrated components. As a result, inspection and maintenance efforts will also increase. A reduction in the components’ life cycle can lead to a significant increase in costs.
To effectively deal with significantly higher requirements, the TÜV NORD Group has designed a strategy, COOP (Cycle Optimized Operation), that allows, on the one hand, a reduction of conservative assessments and, on the other hand, the development of new safety standards in the evaluation of the service life.
Small Bore Piping System Fatigue — Determination of Favored Crack Location and Related Admissible Vibration Criterion
Authors: Berger Julien , Guillou Jacques , Poirier Emilie 
Published: August 2013

Each year, a few cracking of small bore piping systems occurs in French Nuclear Power Plant (NPP) due to vibratory fatigue. The particular design of such small bore piping system (basically composed of a socket, a small pipe and a valve with or without tubing) allows the crack initiation at two different locations of the socket weld toes: on the main pipe or on the small bore piping. The favored location depends on specific features, from geometrical and material characteristics to the weld quality.
The knowledge of the favored location with its related vibratory limit is an important issue in terms of inspection plans, plant availability and integrity of safeguard systems.
The main purpose of the present work is to provide analytical expressions for estimating the location of a potential failure by cracking fatigue and its initiation. This threshold is given by a vibratory limit expressed in terms of root mean square velocity. Inherent uncertainties (e.g. preload, weld quality…) impose to consider the proposed expressions as guidelines for the prediction of the crack location and initiation.