bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Strength on Dissimilar Metal Joints for ITER First Wall Components
Authors: Nishi H. , Enoeda M. , Hirose T. , Tsuru D. , Tanigawa H.
Published: January 2011

The first wall (FW) of ITER blanket includes beryllium (Be) armor tiles joined to CuCrZr heat sink with stainless steel cooling tube and backing plate in order to improve plasma performance and reduce thermal stress. Therefore dissimilar materials joints are indispensable for fabricating the high heat flux components. Since these joints must withstand thermal and mechanical loads caused by the plasma and electromagnetic force, it is important to evaluate the strength and thermal fatigue life of dissimilar materials joints. When the dissimilar materials joints are subjected by external force and thermal loading, the stress of the joint may indicate singularity at the interface edge. Since the stress singularity may lower the strength of joints, the singularity is evaluated numerically for the various materials combinations and joint configuration to be used in high heat flux components of fusion reactors in this investigation. Moreover, tensile test and elasto-plastic FEM analysis are performed to investigate the fracture behavior of Be/Cu alloy and stainless steel/ Cu alloy obtained the FW mock-up. The results reveal two singular solutions of type rpj−1 for a half-plane bonded to a quarter-plane joint and the singularity is larger than that of a bonded quarter-planes joint. From the viewpoint of stress singularity, the configuration of bonded quarter-planes joint is better than the half-plane bonded to a quarter-plane joint. The singularity for W/Cu alloy combination is large compared to other combination of materials. Especially the singularity of stainless steel/ Cu alloy is very small. Tensile specimen of Be/CuCrZr joint fractured at the bonding interface due to the stress singularity. For the stainless steel/ Cu alloy, however, the specimens fractured at the Cu alloy region apart from the interface.
Applications of Energy Dissipation Technologies in Reconstruction After 2008 Wenchuan Earthquake
Authors: Lu Xilin , Zhou Ying
Published: January 2011

On May 12, 2008 a magnitude of MW 8.0 earthquake hit Wenchuan in China. The earthquake engineering specialists’ reaction to the earthquake can be divided into two stages. At the first stage, immediately following the event, they spent day to day in the field surveying the damage to buildings and evaluating the performance of structures. Based on those results, the second stage for the post-quake reconstruction started. Earthquake engineering experts devoted themselves to designing the new buildings and strengthening the damaged buildings. In the design of new buildings, new national codes were published with higher protection levels of earthquake ground motions in the quake-hit area and sustainable development concept was applied by using recycled materials of building waste to avoid further damages to environment in the area of strong earthquakes. In the retrofitting of the damaged buildings, energy dissipation devices are more acceptable than before by decision-makers for its high performance. This paper introduces engineering cases of energy dissipation technologies applied in the new and retrofit project. It is shown that, through the applications of these advanced technologies, the structural performance is effectively enhanced.
Experimental Quantification of Gasket Conformability
Authors: Wimmer Christian
Published: January 2011

A measuring method is suggested for quantifying the conformability of gasket materials to macro-irregularities. A series of measurements was performed using this method. In it, the leakage rate achieved on a sealing surface with a considerable, defined irregularity was measured. Results for different gasket materials make it possible to make comparisons and draw conclusions. Finally, the relationship between the surface hardness of the gasket and conformability is discussed.
The Impact of Key Simulation Variables on Predicted Residual Stresses in Pressuriser Nozzle Dissimilar Metal Weld Mock-Ups: Part 2—Comparison of Simulation and Measurements
Authors: Smith Michael C. , Muransky Ondrej , Goodfellow Andrew , Kingston Ed , Freyer Paula , Marlette Steve , Wilkowski Gery M. , Brust Bud , Shim Do-Jun
Published: January 2011

British Energy (BE) has funded a large work programme to assess the possible impact of primary water stress corrosion cracking on dissimilar metal welds in the primary circuit of the Sizewell ‘B’ pressurised water reactor. This effort has included the design and manufacture of representative pressuriser safety/relief valve (SRV) nozzle welds both with and without a full structural weld overlay, multiple residual stress measurements on both mock-ups using the deep hole and incremental deep hole methods, and a number of finite element weld residual stress simulations of both the mock-ups and equivalent plant welds. Three organisations have performed simulations of the safety/relief valve nozzle configuration: Westinghouse, Engineering Mechanics Corporation of Columbus (EMC2) and the Australian Nuclear Science and Technology Organisation (ANSTO). The simulations employ different welding heat input idealisations, make different assumptions about manufacturing history, and use a variety of different material constitutive models, ranging from simple bilinear kinematic hardening to a full mixed isotropic-kinematic formulation. The availability of both high quality measurements from well characterised mock-ups, and a large matrix of simulations, offers the opportunity for a “mini-round-robin” examining both the accuracy and key solution variables of dissimilar metal weld finite element simulations. This paper is one of a series at this conference that examine various aspects of the BE work programme. It draws together residual stress measurement results and the results of all three simulation campaigns (described in detail in other papers at this conference) to examine the impact of manufacturing history, thermal modelling assumptions, material constitutive models and other key solution variables on the accuracy of residual stress predictions in this dissimilar metal weld geometry.
Fault Analysis of Above Ground Oil Storage Tank Leakage Accident
Authors: Nishi Haruki , Suzuka Tatsuya , Suzuki Kota
Published: January 2011

On June 5, 2009, there was an oil leakage failure accident from an above ground oil storage tank in a large oil depot. The pump of the tank was broken, therefore, the oil contained in the pipeline leaked. The leaked oil amounted to 35,000L. The authors have investigated the tank, the pump and the pipeline to find the cause of the accident and to suggest a preventive measure against same kind of accidents. Some important issues of the investigation are fractography examination of a part on which failure occurred, strength of the pump and a type of load and its magnitude which produced during the operation. As a result, the authors have found that the accident was caused because of an excessive internal pressure rise in the pipeline because the pressure relief valve had been removed from the tank due to an improper piping work. Also the authors have estimated that the internal pressure could reach up to 5.48MPa, and then the pressure caused the brittle fracture of the pump casing.
Effect of Loading Signal Shape and of Surface Finish on the Low Cycle Fatigue Behavior of 304L Stainless Steel in PWR Environment
Authors: Le Duff Jean Alain , Lefranc¸ois Andre´ , Vernot Jean Philippe , Bossu Delphine
Published: January 2011

NUREG report CR-6909 [1] proposed in 2007 new rules for evaluating environmental effects in fatigue analyses of new reactors components. These new rules, based on simple correlations, consider that Fen penalty factors (ratio of fatigue life in air at room temperature to that in water at service temperature) are mainly function of strain rate, temperature, sulfur content and dissolved oxygen concentrations. In order to evaluate the conservatisms included in the NUREG report CR-6909, discriminating Low Cycle Fatigue (LCF) tests were performed on a 304L austenitic stainless steel in PWR environment using various modified loading signals deduced from a representative loading strain history as close as possible to actual transients. Using the strain rate integral method recommended in the NUREG/CR-6909, the expected Fen penalty factors evaluated for each modified representative loading signal was close to 6, while the experimental Fen penalty factors measured were strongly dependent of the shape of the loading signals. Experimental Fen penalty factors obtained for the various modified loading signals vary from ∼ 1.5 to ∼ 4. These discriminating LCF tests performed on polished specimens demonstrate that the detailed strain integral method cannot correctly predict the actual environmental effects for the various shapes of loading signals deduced from a representative loading strain history. Other LCF tests were also performed for various constant strain amplitudes using fully reverse triangle signals for comparison purpose with tests performed by other laboratories. It appears that, contrary to published results, environmental effects decrease when the strain amplitude decreases from 0.6% until 0.2%. In the case of the strain amplitude of 0.6%, the Fen penalty factor formulation proposed in the NUREG report CR-6909 is accurate while, for lower strain amplitude of 0.2%, the Fen penalty factor formulation is very severe. It appears that the application of the NUREG/CR-6909 including the Fen model proposed by ANL (Argonne National Laboratory) for austenitic stainless steel provides excessive margins compared to penalty factors as observed experimentally. From this experimental program, conservatisms included in the NUREG/CR-6909 methodology appear to be excessive and can lead to fatigue design issues.
Study on PWSCC Behaviors at Nickel-Based Alloy Welds Based on Weld Residual Stress Analysis and Probabilistic Fracture Mechanics
Authors: Udagawa Makoto , Katsuyama Jinya , Onizawa Kunio
Published: January 2011

A number of cracks due to primary water stress corrosion cracking (PWSCC) in PWR and Ni-based alloys stress corrosion cracking (NiSCC) in BWR have been observed near Ni-based alloy welds. One of the causes of initiation and growth due to SCC is high tensile residual stress as well as operating stress. In this study, an analysis code, PASCAL-NP, for the PWSCC/NiSCC growth at the dissimilar metal welds based on probabilistic fracture mechanics (PFM) was developed. This PFM analysis code has a function of SCC growth calculation for some patterns of crack locations and orientations in a probabilistic manner. This code can also evaluate the failure probability of Ni-based alloy welds due to PWSCC/NiSCC. Using this code and results from welding simulations, case studies on PWSCC growth have been performed focusing on the location and orientation of PWSCC. Effects of the weld residual stress and scatter of PWSCC growth rate on the crack penetration such as leakage are shown in comparison with deterministic analyses.
Life Assessment of Full-Scale EDS Vessel Under Impulsive Loadings
Authors: Yip Mien , Haroldsen Brent
Published: January 2011

The Explosive Destruction System (EDS) was developed by Sandia National Laboratories for the US Army Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) to destroy recovered, explosively configured, chemical munitions. PMNSCM currently has five EDS units that have processed over 1,400 items. The system uses linear and conical shaped charges to open munitions and attack the burster followed by chemical treatment of the agent. The main component of the EDS is a stainless steel, cylindrical vessel, which contains the explosion and the subsequent chemical treatment. Extensive modeling and testing have been used to design and qualify the vessel for different applications and conditions. The high explosive (HE) pressure histories and subsequent vessel response (strain histories) are modeled using the analysis codes CTH and LS-DYNA, respectively. Using the model results, a load rating for the EDS is determined based on design guidance provided in the ASME Code, Sect. VIII, Div. 3, Code Case No. 2564. One of the goals is to assess and understand the vessel’s capacity in containing a wide variety of detonation sequences at various load levels. Of particular interest are to know the total number of detonation events at the rated load that can be processed inside each vessel, and a maximum load (such as that arising from an upset condition) that can be contained without causing catastrophic failure of the vessel. This paper will discuss application of Code Case 2564 to the stainless steel EDS vessels, including a fatigue analysis using a J-R curve, vessel response to extreme upset loads, and the effects of strain hardening from successive events.
Computational Study of Flow Resonances and Forces on a Cylinder Vibrating In-Line to a Steady Flow
Authors: Kaiktsis Lambros , Triantafyllou George S.
Published: January 2011

We present computational results of the flow dynamics and forces on a circular cylinder oscillating in-line with respect to a steady uniform stream. A wide range of oscillation frequencies is considered, from 0.5fs to 3fs, where fs is the natural Strouhal frequency of the Karman street. The oscillation amplitude is varied up to half the cylinder diameter. The Reynolds number value is 180, corresponding to two-dimensional flow. Simulations utilize a spectral element method. The computed flow states are characterized based on processed lift signals, and flow visualization. We find that the response of the flow is very sensitive to variations of the cylinder oscillation frequency. At low oscillation frequency, the lift signal and vortex patterns remain regular for low oscillation amplitudes, i.e. correspond to a 2S type of vortex street, and become complex at high oscillation amplitudes. Cylinder oscillation at the Strouhal frequency gives a window of chaotic flow at intermediate amplitudes, while at higher amplitudes 2S wakes are generated, with the sub-harmonic fs/2 and the higher harmonic 3fs/2 dominating the lift spectrum. Oscillation at twice the Strouhal frequency results in symmetric shedding, for oscillation amplitudes close to 30% of the cylinder diameter, and higher. Finally, at an oscillation frequency equal to three times the Strouhal frequency, the flow dynamics is very rich, characterized by “islands” of symmetric and asymmetric shedding at increasing oscillation amplitude. Chaotic flow is obtained only when the excitation frequency is equal to fs or to 3fs.
New German Guideline on Reduction of Emissions and Its Impact on the Industry
Authors: Schaaf Manfred , Schoeckle Friedrich
Published: January 2011

The demands on industry to reduce fugitive emissions are steadily increasing. For the European Union the Integrated Pollution Prevention and Control (IPPC) directive determines emission levels, and this directive must be transferred into national regulations. In Germany this is done by the TA-Luft (Technical Instructions on Air Quality Control). In addition, several VDI Guidelines give details for the implementation of the TA-Luft in the industry. In the guideline VDI 2440 (“Emission Control — Mineral Oil Refineries”) there are definitions for a high-grad sealing element which must be used in bolted flange connections (BFC) in TA-Luft applications. More details are defined in the VDI guideline 2200 (“Tight Flange Connections — Selection, Calculation, Design and Assembly of Bolted Flange Connections”), the topic of which is similar to the ASME PCC-1 document. For industry the most important guideline in respect of calculation and assembly of bolted flange connections is the VDI guideline 2290 (“Reduction of Emissions — Characteristics of Tight Bolted Flange Connections”) which will be issued over the course of the year. In this guideline the tightness classes required for a particular design analysis are defined. Because of requirements on the quality management system of the operating company in respect of the assembly of the bolted flange connections, the impact of this guideline will be extensive. In the paper the most important requirements on the industry resulting of the TA-Luft and the VDI guidelines are first summarized. Then the impacts of these requirements are illustrated, and some possible implementations of these demands which are under discussion at present are shown.
Development and Evaluation of Nanostructured Coatings for Long-Term Corrosion and Oxidation Performance
Authors: Govindaraju Madhavrao , Cheruvu N. Sastry , Natesan Ken
Published: January 2011

Nanocrystalline coatings were developed on austenitic alloys to meet the high temperature oxidation and corrosion requirements of the waterwalls and superheater/reheater sections of ultra-supercritical (USC) boilers. Nanocoatings were deposited on 304 stainless steels alloys using Plasma Enhanced Magnetron Sputtering (PEMS) process. Coatings of Fe-18Cr-8Ni-xAl (where x = 0, 4, 10%) were deposited on all 304L steel substrates. The as-deposited Fe-based nano-crystalline coatings exhibited ultra-fine grain structure. The long-term oxidation behavior of nanocrystalline coatings was evaluated through cyclic oxidation tests. The results showed that the fine grain structure improved oxidation resistance, promoted selective oxidation of Cr or Al. High temperature corrosion tests were performed in simulated combustion and gasification environment with and without the presence of deposits such as coal ash, alkali sulfates, and sodium chloride. The weight loss or gain for the exposed samples was measured followed by microstructural characterization. Exposed samples were sectioned and characterized by energy dispersive x-ray analysis to identify the corrosion-product phases in the specimen scales. The results highlighted the importance of bonding between the coating and base alloys to resist the coal ash corrosion. Increasing amount of Al content is required to resist sulfur corrosion. Evaluation of samples tested in flue gas environment with SO2 showed an increase in corrosion resistance with increase in aluminum content in the coating.
A Comparison of Two Thermal Insulation and Structural Materials for Use in Type B Packagings
Authors: Blanton Paul S. , Eberl Kurt R. , Mann Paul T.
Published: January 2011

This paper presents the summary of design features and test results of two Type B Shipping Package prototype configurations comprising different insulating materials developed by the Savannah River National Laboratory (SRNL) for the Department of Energy. The materials evaluated, a closed-cell polyurethane foam and a vacu-formed ceramic fiber material, were selected to provide adequate structural protection to the package containment vessel during Normal Conditions of Transport (NCT) and Hypothetical Accident Condition (HAC) events and to provide thermal protection during the HAC fire. Polyurethane foam has been used in shipping package designs for many years because of the stiffness it provides to the structure and because of the thermal protection it provides during fire scenarios. This comparison describes how ceramic fiber material offers an alternative to the polyurethane foam in a specific overpack design. Because of the high operating temperature (∼2,300°F) of the ceramic material, it allows for contents with higher heat loads to be shipped than is possible with polyurethane foam. Methods of manufacturing and design considerations using the two materials will be addressed.
Conformity Assessment of the ITER Vacuum Vessel With the Requirements of the French Order for Nuclear Pressure Equipment
Authors: Weyn Andre´ , Vast Guy , Ru¨tze Erick , Wijns Willy
Published: January 2011

The ITER Vacuum Vessel (VV) is a nuclear pressure equipment according to the French Order of December 12th 2005. Therefore the VV manufacturer (the ITER Organization) must demonstrate that the applicable essential safety requirements and radioprotection requirements are satisfied. The paper describes several aspects requiring particular attention from the start in order to assure that the VV will finally comply with the legal requirements. - definition of responsibilities; - fixation of the design; - hazard analysis and uncertainties; - in-service inspection requirements; - classification of all VV parts; - material specifications; - structural strength evaluation; - fabrication tolerances; - assessment of the RCC-MR Code; - alternatives to meet the ESR and RPR. It’s important that all participants to the project have a good understanding of the applicable legislation and are aware of the impact of their decisions on the final conformity of the VV with the essential safety requirements and radioprotection requirements.
Qualification of Gasket Performance for Vacuum Applications
Authors: Lee Walter , Bouzid Abdel-Hakim , Huang James
Published: January 2011

Gasket performance for vacuum applications has not been well studied. Although a wealth of sealability data has been generated for pressurized systems, little is done with vacuum conditions. A new test method has been developed to study the sealing performance of gaskets for vacuum services. The tests were conducted on a standard ROTT test rig, where a vacuum chamber surrounding the gasket was created by an air pump and monitored by a pressure gauge capable of measuring pressures down to 0.1 Torr. Two levels of vacuum were used: 50 Torr and 3 Torr. Each tested gasket was compressed to various assembly stresses corresponding to the levels defined in the ROTT procedure. After the gasket was compressed to a desired stress and a target vacuum level was reached, the pumping stopped, and the leak rate was measured, using the pressure rise method. The similar leakage results with two very different vacuum levels confirm that sealing a vacuum system is simply to seal ∼1 bar of air. The air leakage was further compared with the helium leak rates obtained from the standard ROTT test with a pressure of 21 bar to determine the correlation between the two data sets. To better understand the effects of pressure and molecular size of a gas, two additional tests at 2 bar, with helium and with nitrogen, were performed. The comparison among all test data suggests that the gases at relatively low pressures follow a molecular flow behavior up to about 55 MPa of gasket stress on the tested material. As a result, a tightness curve that can be used to estimate the vacuum leakage has been established. For applications involving elevated temperatures, thermal behaviors of gaskets determined by other PVRC tests, such as the HOBT and ARLA, can be used to understand the impact of temperature on vacuum performance. A stress-tightness-temperature framework is proposed that can be used to estimate the tightness and leakage of the gasket at high temperatures. Knowing the air leak rates under different operating conditions, a gasket user will be able to determine the suitability of the gasket for a specific vacuum requirement as well as the optimal assembly stress to maintain the desired vacuum level.
Prediction of Closure Bolt Loads in Small Pressure Vessels: NUREG/CR-6007 vs. Detailed Finite Element Analysis
Authors: McKeel Charles A.
Published: January 2011

Closure bolt loads in a flanged cylindrical containment vessel under internal pressure are determined by detailed Finite Element Analysis (FEA) and compared to values determined using NUREG/CR-6007 equations. The containment vessel is of small diameter with an inwardly dished bolted head that geometrically contrasts with the large, flat lidded casks which the NUREG addressed. The comparison showed a significant difference in the magnitude of pressure driven prying load between the FEA model and the NUREG approximate equations. This difference affected the predicted pressure that overcomes preload, and the rate of load increase after preload was exceeded. The difference was likely due to the contrasts between this vessel’s closure shape compared to the more typical flat cask lid shape used in the NUREG development.
Iatan Desuperheater Pipe Failure Caused by FAC: September 28, 2007
Authors: Chiu Chong , Gockel Lance B.
Published: January 2011

At approximately 11:40 AM on May 9, 2007, Iatan Unit 1 experienced a catastrophic rupture of a 4 inch superheater (SH) attemperator spray line after nearly 27 years of commercial operations. At the time of the rupture, several plant personnel were in the immediate vicinity performing maintenance on a plugged coal feeder. Plant operators immediately initiated a plant shutdown. This incident resulted in two fatalities and one serious injury. Subsequent examination of the ruptured line indicated significant pipe wall thinning had occurred, leading to the sudden failure of the pipe pressure boundary and the pipe rupture event. The preliminary evaluation of the failed pipe determined that flow accelerated corrosion (FAC) was the likely failure mechanism. To prevent this and similar events, the PII team recommends the following actions be taken to identify other potential areas which may have similar characteristics to the failed pipe: 1. Employ the EPRI method CHECKWORKS (as has been implemented) to identify the susceptible areas. 2. Supplement the EPRI model with connected flow modeling techniques to identify additional inspection areas. 3. If the measured wall thickness is less than 30% of the minimum allowable wall thickness, replace or repair the pipe immediately. 4. If the measured wall thickness is less than the minimum allowable wall thickness (as specified by the B31.1 code), but no less than 30% of the minimum allowable, perform a safety risk assessment. If the risk is determined acceptable, replace or repair the pipe at the next planned plant outage with temporary compensatory actions (such as caution tags, leak flow blockage facilities, etc.). 5. Identify and replace all throttled gate valves and replace them as soon as practical. Until these valves are replaced, utilize NDE techniques to monitor the pipe wall thinning downstream of the valves and replace pipe based on the above criteria in 3 and 4.
Effects of Package Content Position on Slap-Down Angle
Authors: McKeel Charles A.
Published: January 2011

As part of regulatory requirements, shipping packages must be able to withstand specified height drop accidents under a worst case orientation and configuration. The burden of justifying worst case orientation and configuration is placed on the package applicant. One of the drop cases to consider is slap-down, where the package is dropped at a shallow angle (eg, nearly horizontal). Due to the shallow angle, the initial impact at one end of the package accelerates the opposite end into the target surface at greater than the net drop velocity. The dynamics of the slap-down condition are modeled using simplified rigid-body dynamics to provide test engineers with a basis for establishing a suitable package content placement that could maximize the slap-down condition.
Effects of SSI on EPR™ In-Structure Response for a Rock Site: Coherent and Incoherent High Frequency Ground Motion
Authors: Johnson James J. , Schneider Oliver , Schuetz Werner , Monette Philippe , Asfura Alejandro P.
Published: January 2011

Recently, probabilistic seismic hazard assessments (PSHAs) performed for hard sites world-wide have yielded uniform hazard response spectra (UHRS) with significant high frequency content, i.e., frequency content greater than 10 Hz. This high frequency content is frequently due to near-field relatively low magnitude events. It is well known that these high frequency ground motions are not damaging to ductile structures, systems, and components (SSCs). One method of addressing the effect of these high frequency ground motions on structure response is to take into account the incoherency of ground motion. Over the past 25 years, free-field ground motion has been recorded providing an adequate basis for the development of ground motion coherency functions necessary to assess the effect of incoherence on nuclear power plant structures. The subject of this study was the AREVA NP EPR™ (European Power Reactor) nuclear island (NI) standard design. The effect of incoherency of ground motion on in-structure response spectra (ISRS) was assessed for the NI founded on a stiff rock site and subjected to high frequency enhanced input for hard rock sites. The ISRS at numerous locations and directions in the structures were calculated and compared. SSI is shown to be an important phenomenon for structures founded on stiff sites and subjected to high frequency ground motions.
Strain Rate Evaluation of Some Typical Nuclear Power Plant Components During Plant Operation
Authors: Dozaki Koji , Chitose Hiromasa , Ogawa Hiroshi , Machida Hideo
Published: January 2011

The dynamic aspects of loading conditions for reactor internals, piping and the like, are thought to play important roles in the initiation of failures due, for example, to stress corrosion cracking (SCC) and fatigue. Some reports show that a strain rate on the order of 10−7 s−1 most affects susceptibility to SCC in the BWR reactor water environment. Environmental fatigue, which exhibits a shorter fatigue life in reactor water than that in air, is considered to have a remarkable correlation with strain rate and its affect on fatigue life. Despite its significant affect on SCC and fatigue, the actual strain rate of components is not known and practical evaluation methods have not been developed; consequently, such failure modes as SCC and fatigue are not evaluated in design. For this paper, strain rates induced by dynamic loading during such operations as plant start-up were calculated at typical points, such as reactor internals, piping and so on. The finite element method was applied to calculate the strain history of each point, and the strain rate was evaluated. The strain rate evaluation results clearly demonstrated that thermal transients provide greater peak strain rate values than pressure transients. Strain rates on the order of 10−7 s−1 were obtained for most points of major components during such thermal transients as plant start-ups. The major factors determining the strain rate magnitude were discussed, based on the calculation results. It was shown that the rate of temperature rise was the most important parameter, because it exhibited much larger sensitivity than the other parameters on the strain rate and could be controlled by plant operation procedures. In addition, a simple strain rate evaluation method based on Green’s function was developed for a specific point with a given design condition.
2010 Edition of B31.3 Process Piping Code: A First Equation for Stress Due to Sustained Loads
Authors: Edwards Don R.
Published: January 2011

For the first time in the history of the ASA [1], ANSI/ASME, ASME/ANSI, to the 2008 edition of ASME B31.3 Process Piping Code (hereafter referred to as “the Code”) [2], an equation for the Stress Due To Sustained Loads, SL, has been introduced into the Code. From its inception to the current edition, the Code has remained ambiguous in several areas. Even though the displacement stress range, SE, has been explicitly defined by both text and equation, the stress due to sustained loads, SL, is mentioned not with an explicit equation but with a statement that SL shall be limited by the allowable stress at the corresponding operating temperature, Sh. This paper describes the equation in detail and the background, the events, and the effort involved that led to the insertion of this equation into the Code.
Industry Experience With Waterhammer: Topics of Recent Interest in Waterhammer
Authors: Moody F. J.
Published: January 2011

The analysis of transient flow in a piping system containing one or more trapped gas volumes is considerably simplified when the liquid can be treated by bulk flow theory without propagation effects, complicated by moving boundaries. Many cases that have occurred in the power industry, which involve pump operation, valve opening and closure, and even some pipe ruptures, have time intervals and/or piping segments that can be shown to be dominated by bulk flow with negligible propagation effects. Often, propagation effects become important only for short time intervals at the beginning or toward the end of a given transient. This observation can greatly simplify the solution of such problems for maximum pressures and pipe loadings to a relatively simple procedure. Most models which have received attention or undergone development are based on the mass conservation and momentum principles, with gas state equations, and this is the correct approach for tracking liquid motion and gas volume compression. The energy conservation principle is not required to solve for the pressure and velocity of the liquid in the pipe, and to obtain the resulting forces. However, energy considerations are extremely useful in gaining physical insight to the overall problem. The major insight offered by the energy principle is based on the fact that when liquid flow is initiated in a pipe system containing gas pockets, the total mechanical energy added to fluid in the pipe must be distributed between the liquid and the gas in mechanical forms, namely kinetic, gravitational potential, and compressive or “spring” type energy. If one examines the gas and liquid when it has come to rest and neglects the kinetic and gravitational potential energies, the only stored energy forms are compressive. If the liquid is incompressible, or “rigid,” all the energy is stored in the gas and the resulting pressure is PR. If the liquid is elastic, or compressible, the energy will be shared so that both the gas and liquid will be at the same pressure, P. By comparing pressure P with PR, it is possible to determine if the compressible liquid is capable of storing enough energy to reduce the pressure significantly from that which would result if the liquid were incompressible and all the energy were stored in the gas. A procedure and several examples are given for starting with a given system, predicting the pressure with a rigid or incompressible liquid model, and then determining if a modified analysis is justified, incorporating liquid compressibility and propagation effects.
Preshipment Leak Testing of 9977 Containment Vessels With the TM Electronics Solution Model S1A-L2-V Leak Tester
Authors: Trapp Donald J.
Published: January 2011

Pacific Northwest National Laboratory (PNNL) is replacing its 6M nuclear shipping fleet with 9977 shipping packages, which were designed by Savannah River National Laboratory (SRNL). The new packages require PNNL to perform a preshipment leak test on the lid seals of the containment vessel before the package is shipped on public roads. Savannah River National Laboratory (SRNL) developed a preshipment leak test using a TM Electronics Solution leak tester for PNNL. The Solution is an automatic vacuum leak tester that uses the Gas Pressure Rise leak test method to check the O-ring lid seals and the test port plug seal. The two tests take three minutes each to perform. Because the Solution is fully automatic, the leak test can be done by operators after a few hours of training. This paper describes the test equipment and the testing sequence.
Comparison of Notched Bar Creep Behavior of Various Alloys
Authors: Takahashi Yukio
Published: January 2011

Possibility of creep rupture needs to be evaluated in design of various components operating at high temperatures. Multiaxial stress states need to be treated in many components and its proper consideration is of critical importance, in addition to the creep rupture behavior under uniaxial tension. In order to examine creep rupture behavior under high stress triaxiality, creep tests were conducted on notched bar specimens of various alloys used in power generation facilities. It was found that all materials showed notch-strengthening behavior but some materials showed considerable reduction of deformation at rupture, in comparison with the plain specimens. Its amount was not similar but strongly dependent on material, being larger in high chromium steels, and smaller in an austenitic stainless steel. It was found that the dependency of true rupture strain on temperature and inelastic strain rate in each material can be successfully modeled by a strain rate-temperature parameter.
Cavitation Damage Study via a Novel Repetitive Pressure Pulse Approach
Authors: Wang John Jy-An , Ren Fei , Wang Hong
Published: January 2011

Cavitation damage can significantly affect system performance. Thus, there is great interest in characterizing cavitation damage and improving materials’ resistance to cavitation damage. In this paper, we present a novel methodology to simulate cavitation environment. A pulsed laser is utilized to induce optical breakdown in the cavitation media, with the emission of shock wave and the generation of bubbles. The pressure waves induced by the optical breakdown fluctuate/propagate within the media, which enables the cavitation to occur and to further develop cavitation damage at the solid boundary. Using the repetitive pulsed-pressure apparatus developed in the current study, cavitation damage in water media was verified on stainless steel and aluminum samples. Characteristic cavitation damages such as pitting and indentation are observed on sample surfaces using scanning electron microscopy. The synergistic effect of combining cavitation and the laser heating/water cooling induced thermal cycling fatigue to the target surface damage was also demonstrated in the report.
Fracture Evaluation Using Limit Analysis for Complex Structure (Pressure Load)
Authors: Hojo Kiminobu , Ochi Mayumi , Ogawa Kazuo , Ogawa Naoki
Published: January 2011

The sensitivity study of limit analyses was performed for a cracked weld joint between a pipe and a nozzle. As limit analysis methods, the twice elastic slope method in Sec. III basis, the lower bound asymptotic method and net section criterion for straight pipes were chosen. Evaluation method, FE model’s range and material properties were the parameters for the analyses and those effects or sensitivities on failure load were investigated. Based on the results, the key issues for limit analyses for complex structures, especially a pipe with a nozzle were summarized.
Current Fusion Standards and Other Related Activities in Japan
Authors: Nakasone Yuji , Sato Kazuyoshi , Takahashi Yukio
Published: January 2011

The Japan Society of Mechanical Engineers (JSME) published the construction standard for superconducting magnet structures for nuclear fusion facilities in December, 2008. The main target of the standard is tokamak-type fusion energy facilities, especially ITER, or the International Thermonuclear Experimental Reactor. The standard consists of seven articles and twelve mandatory and non-mandatory appendices to the articles; i.e., (1) Scope, roles and responsibilities, (2) Materials, (3) Structural design, (4) Fabrication and installation, (5) Non-destructive examination, (6) Pressure and leak testing, and (7) Terms used in general requirement. Following the publication of the standard, the procurement of toroidal coil coils has started since March, 2009 and it is revealed that the revision of the standard is necessary in many respects: e.g., (1) English translation of the standard is necessary for international procurement activities, (2) more wires other than prescribed in the standard are needed, etc. The present paper describes current fusion standards activities in JSME and other related fusion activities in Japan.
Ductile Fracture Strength of Ni-Based Alloy With an Inch Thickness
Authors: Miyazaki Katsumasa , Saito Koichi
Published: January 2011

To develop the failure assessment procedure of Ni-based alloy, the fracture tests of flat plate specimens with a rectangular flaw were conducted at 302°C in temperature. The flat plate specimens were base metal plates, NCF600 and butt weld joints, whose weld metal was Alloy 182 with an inch (25 mm) in thickness. The maximum load at 302°C could be estimated by the limit load analysis (LLA) and twice elastic slope (TES) method with finite element analysis. In addition, the difference between maximum load obtained by the fracture tests and estimations by LLA and TES method became smaller with increasing the flaw area. The net stress at the maximum load depends on the flaw depth and this tendency in Ni-based alloy at 302°C is almost the same as the Hasegawa’s experimental proposal obtained by the fracture tests of austenitic stainless steel.
Influencing Factors for Improving Accuracy in Prediction of Stress Corrosion Crack Growth Rate in Boiling Water Reactor Operational Condition: Part 2—The Effect of Single Overload on SCC Growth Behavior
Authors: Ito Yuzuru , Saito Masahiro , Peng Qunjia , Kuniya Jiro , Shoji Tetsuo
Published: January 2011

The effect of a single overload on SCC growth behavior was addressed in this study by SCC testing using a CDCB specimen and an ACPD technique under simulated BWR water. The ratio of the stress intensity factors KOL/KSCC test, i.e. that of the single overload, KOL, divided by that of the SCC testing, KSCC_test, is defined as a single overload level in this study. With this in mind, changes in ACPDs, i.e. those regarded as the SCC growth behaviors, were measured after single overload levels of 1.05, 1.10, 1.20 and 1.50 respectively were applied. Retardations of SCC growth behavior were observed at the single overload levels of 1.10, 1.20, and 1.50, since the ACPDRs were reduced following the application of single overload levels without significant variations in water quality factors, such as electric conductivity and the DO concentration in the simulated BWR water. Therefore, it emerged that applying single overload levels of 1.10, 1.20, and 1.50 reduced the SCC growth rate, since the ACPDR proportional to the SCC growth rate was reduced following the single overload application. The ACPDR after the single overloads were reduced by about 14, 59 and 66% at single overload levels of 1.10, 1.20 and 1.50, respectively.
Thermal Analysis of a Proposed Transport Cask for Three Advanced Burner Reactor Used Fuel Assemblies
Authors: Bullard Tim , Greiner Miles , Dennis Matt , Bays Samuel , Weiner Ruth
Published: January 2011

Preliminary studies of used fuel generated in the US Department of Energy’s Advanced Fuel Cycle Initiative have indicated that current used fuel transport casks may be insufficient for the transportation of said fuel. This work considers transport of three 5-year-cooled oxide Advanced Burner Reactor used fuel assemblies with a burn-up of 160 MWD/kg. A transport cask designed to carry these assemblies is proposed. This design employs a 7-cm-thick lead gamma shield and a 20-cm-thick NS-4-FR composite neutron shield. The temperature profile within the cask, from its center to its exterior surface, is determined by two dimensional computational fluid dynamics simulations of conduction, convection, and radiation within the cask. Simulations are performed for a cask with a smooth external surface and various neutron shield thicknesses. Separate simulations are performed for a cask with a corrugated external surface and a neutron shield thickness that satisfies shielding constraints. Resulting temperature profiles indicate that a three-assembly cask with a smooth external surface will meet fuel cladding temperature requirements but will cause outer surface temperatures to exceed the regulatory limit. A cask with a corrugated external surface will not exceed the limits for both the fuel cladding and outer surface temperatures.
A New Approach to Creating Composite Materials Elastic Property Database With Uncertainty Estimation Using a Combination of Mechanical and Thermal Expansion Tests
Authors: Melo Jose Daniel D. , Fong Jeffrey T.
Published: January 2011

In composite structural design, a fundamental requirement is to furnish the designer with a set of elastic constants. For example, to design for a given temperature a laminate consisting of transversely isotropic fiber-reinforced laminae, we need five independent elastic constants of each lamina of interest, namely, E1, E2, ν12, G12, and ν23. At present, there exist seven tests, two of mechanical-lamina, two of thermal-expansion-lamina, and three of thermal-expansion-laminate types, to accomplish this task. It is known in the literature that the mechanical tests are capable of measuring E1, E2, and ν12, whereas the two thermal-expansion-lamina tests will measure α1 and α2, and the three thermal-expansion-laminate tests yield an over-determined system of three simultaneous equations of the remaining two unknown elastic constants, G12 and ν23. In this paper, we propose a new approach to determining those five elastic constants with uncertainty bounds using the extra information obtainable from an over-determined system. The approach takes advantage of the classical theory of error propagation for which variance formulas were derived to estimate standard deviations of some of our five elastic constants. To illustrate this approach, we apply it to a set of experimental data on PEEK/IM7 unidirectional lamina. The experiment consists of the following tests: Two tensile tests with four samples of unidirectional specimens to measure E1, E2 and ν12; two thermal-expansion-lamina tests for coefficients (α1 and α2) each using four [(0)32]T unidirectional specimens; and three thermal-expansion-laminate tests on four samples of [(+30/−30)8]s laminates. The results of our new approach are compared with those of a similar but more ad hoc approach that has appeared in the literature. The potential of applying this new methodology to the creation of a composite material elastic property database with uncertainty estimation and to the reliability analysis of composite structure is discussed.
Bubble Formation and Behaviour Under Hypergravity Conditions
Authors: Eiden Anna , Giannopapa Christina , Toth Balazs , Dowson Alan
Published: January 2011

Bubble formation and behaviour have been studied over decades, but the complex two-phase flow phenomena involved are still not fully understood. In view of the importance of two-phase flow processes in a broad range of industrial applications, such as the chemical process industry, food industry and aerospace applications, it is crucial to obtain a detailed understanding of single and multiple bubble dynamics. Gravity plays an important role in bubble formation and behaviour. Several studies have been conducted on single bubble formation under microgravity conditions, but the effects of gravitational accelerations much larger than on Earth have not been previously documented. In order to gain a full understanding of the effect of gravity on the bubble dynamics and in view of industrial applications, particularly aerospace applications, it is essential to examine bubble formation and behaviour under hypergravity conditions. Bubble formation and behaviour at the surface of a porous material and at a nozzle were investigated at hypergravity levels of 1–20g using the Large Diameter Centrifuge (LDC) at ESA/ESTEC. The formation of air bubbles through a porous filter into a water column was recorded under hypergravity conditions and the obtained data were analysed qualitatively. A decrease in bubble size and an increase in bubble formation frequency with increasing hypergravity levels could be clearly observed. Data for the experiments on air and oil bubble formation at a nozzle into a water column were recorded under hypergravity conditions using a high speed camera (for different nozzle sizes and air/oil flow rates). For the recorded data from the experiments on air and oil bubble formation at a nozzle, a decrease in bubble size and an increase in bubble formation frequency with increasing gravitational acceleration could be observed qualitatively. Quantitative analysis of the data obtained for the experiments on air bubble formation at a nozzle clearly showed a decrease in average bubble diameter with increasing hypergravity levels. The effect of the nozzle diameter on the bubble size was shown to be small and the bubble diameter was larger for higher flow rates.