bluuebunny/crossref_metadata_2025 huggingface dataset:
Fire PSA of the French PWR 900 MWe series
Authors: Barrachin G. , Corenwinder F. , Vial E.
Published: December 2013

The Institute for Radioprotection and Nuclear Safety (IRSN) has developed a Fire Probabilistic Safety Assessment of the operating French 900 MWe PWR in order to organize into a hierarchy the items of equipments and the compartments, impacting the core melt frequency following a fire, and to reinforce deterministic safety analysis with functional analysis and realistic fire scenarios. The IRSN Fire PSA is composed of two stages: the first one concerns the selection of critical zones and the second one concerns the detailed study of the critical compartments, corresponding to the development of the fire scenarios and of the fire-induced core damage sequences. The first version of the IRSN Fire PSA has been updated by integrating the specificities of the Fire Action Plan, implemented by the utility on the French 900 MWe PWR. This study shows that four compartments are preponderant. The integration of the Fire Action Plan allowed decreasing the number of preponderant compartments. The integration of the symptom-oriented procedures and the removal of conservatisms should lead to a lower core damage frequency for these preponderant compartments. The results show that fire is not a negligible risk but the implementation of the Fire Action Plan has a significant positive impact on safety.
Modelling of Carbon-14, Iodine-129 and Cesium-137 releases from near surface radioactive waste disposal and their impact on environment and humans
Authors: Adliene D. , Skridaila N. , Motiejunas S. , Meurville C.
Published: December 2013

Near surface disposal of low and intermediate level radioactive waste is probably the best solution for a long term radioactive waste management today. For safety assurance all near surface disposal aspects and evolution scenarios should be reviewed and analyzed including repository design and site selection, because releases of radionuclides from the repository into the environment cause radiation exposure to the public. Mechanisms of 14C, 129I and 137Cs transportation from the repository into the environment, modelled for the hypothetical radioactive waste disposal facility in Lithuania, are investigated and the results of effective dose calculations for the main exposure pathways are discussed in this paper. The RESRAD-OFFSITE code has been used in this study for modelling purposes. It is shown that the radionuclide transport time into the environment, its radioactive contamination and the radiation exposure to the public mostly depends on the mobility and sorption properties of radionuclides and on the appropriate transport pathways from the repository into the environment.
Radiological consequences of potential sabotage attack to storage casks on the ISFSI site
Authors: Wang W. H. , Lin U. T.
Published: December 2013

Interim storage is one major program of fuel cycle. Because there are some individuals staying or living very close to the ISFSI site that is being constructed, this paper examines the potential radiological consequences of hypothesized events for storage casks. This study uses ORIGEN, HOTSPOT and RESRAD software to calculate the source terms, acute dose and long-term dose, separately. The results show that explosive-induced buoyancy would disperse the source much farther than the site boundary in a sabotage accident. Nevertheless, the amount of radioactivity released to offsite would be very low, and the maximum dose received by any individual staying or living in the vicinity of ISFSI, even under the most conservative scenario, would be very much less than the local public relocation dose limit.
AVR prototype pebble bed reactor: a safety re-evaluation of its operation and consequences for future reactors
Authors: Moormann R.
Published: December 2013

The AVR pebble bed reactor (46 MWth) was operated 1967 – 1988 at coolant outlet temperatures up to 990°C, which are suitable for process heat applications. Also because of a lack of other experience the AVR operation is a basis for future HTRs. This paper deals with insufficiently published but unresolved safety problems of AVR and draws conclusions for future pebble bed HTRs: Although the AVR was operated only for about 4 years at coolant temperatures > 900 °C its primary circuit is heavily contaminated with dust bound metallic fission products (90Sr, 137Cs), which create major problems in current dismantling. The end of life contamination reached several percent of a single core inventory. The AVR contamination was mainly caused by inadmissible high core temperatures, and not – as presumed in the past – by inadequate fuel quality only. The high core temperatures, which cannot be easily measured in pebble beds, are probably caused by the insufficiently examined pebble bed mechanics. Safety of future reactors requires a gas tight containment and in addition elaborate R&D or reduction of requirements concerning temperatures and burn-up.
Consideration of ageing within probabilistic safety assessment models and results
Authors: Čepin M. , Volkanovski A.
Published: December 2013

Ageing is a process, where the properties of systems and processes may degrade through the time and age. The objective of the paper is to analyze the possibilities of introduction of ageing directly into the probabilistic safety assessment. Theoretical models of ageing and examples of their application are investigated, which show, how the current models can be upgraded in sense to directly include the effects of ageing into the models of probabilistic safety assessment. This paper shows that consideration of ageing is theoretically a straightforward issue, which can be dealt with in several ways, which are demonstrated in the paper. The most important problem is the lack of data about the effects of ageing, which would suit to the detailed models of ageing. The results, which are obtained, do not show significantly different results compared to the initial models without direct consideration of ageing. The majority of risk measures change slightly or notably, but no major break through has been found. Contribution of ageing may be smaller then contribution of changes due to other parameters.
Atmospheric dispersion modelling applying advanced model approaches
Authors: Martens R. , Thielen H.
Published: December 2013

Incidents and accidents occurring in nuclear facilities, transport accidents or malevolent actions associated with radioactive material may involve a release of airborne radionuclides. For these situations, a realistic assessment of the radiological consequences for the public is of great importance with respect to adequate emergency measures. Within this context, the determination of the spatial distribution of the resulting airborne concentration as well as of the deposition of radionuclides on the ground, vegetation and building surfaces are necessary prerequisites. For such calculations, advanced atmospheric dispersion models are increasingly used. Their characteristics and fields of application are presented.
Legendre polynomial series of the infinite medium Green's Function in neutral particle transport theory: the half-space albedo problem
Authors: Güleçyüz M.Ç. , Kaşkaş A.
Published: December 2013

Series expansion of the infinite medium Green's function in terms of Legendre polynomials is used to solve the half-space albedo problem. The importance of this procedure is that it can be used for the solution of many different physical problems in plane geometry and can be extended to find the solution of the problems in other geometries.
Heat transfer to the building structures of the Ignalina NPP accident localisation system
Authors: Babilas E. , Rimkevičius S. , Urbonavičius E.
Published: December 2013

The performed thermal-hydraulic analysis of the Accident Localisation System (ALS) has shown, that in the case of a Maximum Design Basis Accident (MDBA), in the long term, a significant amount of energy (∼40%) is transferred to the building structures. Therefore, special attention should be paid to the correct simulation of the building structures and heat transfer processes. Free convection, forced convection, condensation and conductivity are the phenomena, which are connected with the heat transfer to the building structures and should be investigated. In this paper, the heat transfer models available in the COCOSYS code, which is applied for the analysis, are discussed. The influence of the heat transfer models on the behaviour of thermal-hydraulic parameters in ALS compartments during MDBA is investigated.
Production cross sections of medical 110,111In radionuclides
Authors: Büyükuslu H. , Kaplan A. , Yıldırım G. , Aydin A. , Tel E. , Bölükdemir M. H.
Published: December 2013

In this study, production routes of medical 110,111In radionuclides produced by 110Cd(p, n)110In, 111Cd(p, 2n)110In, 112Cd(p, 3n)110In, 107Ag(α, n)110In, 109Ag(α, 3n)110In, 111Cd(p, n)111In, 112Cd(p, 2n)111In, 113Cd(p, 3n)111In, 114Cd(p, 4n)111In, 109Ag(α, 2n)111In, 107Ag(α, γ)111In and 113In(n, 3n)111In reactions have been investigated up to 70 MeV incident particle energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the geometry dependent hybrid model and the cascade exciton model. The full exciton model has also been used to investigate the pre-equilibrium direct effects. Equilibrium effects are calculated according to the Weisskopf–Ewing model. The calculated results are compared with the experimental data taken from the literature.
Asymptotic solution of critical thickness with direct second kind Chebyshev polynomial approximation in forward and backward scattering
Authors: Yaşa F.
Published: December 2013

To develop a model with scattering medium, a consistent backward forward scattering kernel is described and applied to the transport equation in plane geometry. Asymptotic solutions of critical half thicknesses are computed by using the direct second kind Chebyshev polynomial method (UN).
Assessment of different mechanisms of C-14 production in irradiated graphite of RBMK-1500 reactors
Authors: Narkunas E. , Smaizys A. , Poskas P. , Kilda R.
Published: December 2013

Two RBMK-1500 water-cooled graphite-moderated channel-type power reactors at the Ignalina Nuclear Power Plant (INPP) are under decommissioning now. The total mass of irradiated graphite in the cores of both units is more than 3600 tons. The main source of uncertainty in the numerical assessment of graphite activity is the uncertainty of the initial impurities content in graphite. Nitrogen is one of the most important impurities, having a large neutron capture cross-section. This impurity may become the dominant source of C-14 production. RBMK reactors graphite stacks operate in the cooling mixture of helium-nitrogen gases and this may additionally increase the quantity of the nitrogen impurity. In this paper the results of the numerical modelling of graphite activation for the INPP Unit 1 reactor are presented. In order to evaluate the C-14 activity dependence on the nitrogen impurity content, several cases with different nitrogen content were modelled taking into account initial nitrogen impurity quantities in the graphite matrix and possible nitrogen quantities entrapped in the graphite pores from cooling gases.
3D thermal hydraulic simulation of the hot channel of a typical material testing reactor under normal operation conditions
Authors: El-Morshedy S. El-Din , Salama A.
Published: December 2013

The hot channel in a typical Material Testing Reactor (MTR) is subjected to 3D simulation. Because of the existence of similarity planes, only a quarter of the hot channel including meat thickness, clad, and coolant channel is considered for CFD analysis using the FLUENT code. For the simulation, steady state normal operation regime at the reactor nominal power is assumed. In order to build confidence in our modeling approach, the results obtained in this work are compared with those obtained from the one-dimensional simulation code, MTRTHA. That is, modified variables were generated in order to match those obtained by MTRTHA and to allow comparisons. Quite good agreement is generally observed, however, the maximum clad surface temperature predicted by the 3D calculations, located at the clad mid-width, is higher than the 1D prediction by about 8°C but still below the onset of subcooled boiling by adequate safety margin. The results show quite interesting 3D patterns in both the flow field and the heat transfer. Temperature profiles, velocity profiles and contours are all presented to highlight the essential 3D features of this system.
Effect of thermal gap conductance for MoO3 ampoules irradiated in a high neutron flux
Authors: Abdelhady A.
Published: December 2013

During the irradiation process of MoO3 powder with in a high neutron flux, energy deposited in the powder must be released to avoid energy accumulation. The temperature increasing in the powder due to energy accumulation may cause powder phase change and under certain conditions the temperature may reach the melting point. An analytical model was developed to study the effect of gap conductance on the temperature distribution in the powder during the irradiation process. The gap conductance model was studied for helium and nitrogen gases at different pressures to obtain the optimum conditions verifying the safety in heat transfer point of view. It was found that the gap conductance is a function of gas pressure. The model provided the optimum conductivity for the gap filled with helium gas at 1 atm pressure.
U1 approximation to the neutron transport equation and calculation of the asymptotic relaxation length
Authors: Öztürk H. , Bülbül A. , Kara A.
Published: December 2013

The U1 approximation is used to determine the asymptotic relaxation length (diffusion length) for one-speed neutrons in a homogeneous slab. The method is based on the series expansion of the neutron angular flux in terms of the Chebyshev polynomials of second kind and then calculating the diffusion length by applying the first order approximation to transport equation. Analytic and numerical results are obtained for the diffusion length and compared with the ones obtained from the method of separation of variables and simple diffusion theory (P1 approximation).
Determination of effects of burn up and reflector material on the kinetic parameters for open pool reactor using MCNP code
Authors: Shawer M. , Aly N. , Nagy M. , Amin E.
Published: December 2013

The analysis of research reactor transients depends on the kinetic parameters (i.e. effective neutron generation time Λ∗ and the effective delayed neutron fraction βeff).

In this work we will calculate these parameters using the MCNP code. Effects of burn up and of Be reflector and cobalt irradiation device on kinetic parameters were also studied using the MCNP code. The results were compared with reported values. The calculations were performed for the start-up core configuration (reference core configuration) at different burn up steps with equilibrium concentration and with zero concentration of Xe, and repeated for the sixth core configuration (core configuration during the study).
CFD analyses of fibre transport and fibre deposition at plunging jet conditions
Authors: Krepper E. , Cartland-Glover G. , Grahn A. , Weiß F.-P. , Alt S. , Kratzsch A. , Renger S. , Kästner W.
Published: December 2013

The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during all types of loss of coolant accidents. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Görlitz (HSZG) and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description (see [10–12]). While the experiments are performed at the University at Zittau/Görlitz, the theoretical modelling efforts are concentrated in Rossendorf. In the current paper, the basic concepts for CFD modelling are described and feasibility studies are presented. The model capabilities are demonstrated via complex flow situations, where a plunging jet agitates insulation debris.
Determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy
Authors: Hao Le Cong , Van Tao Chau , Van Dong Nguyen , Van Thong Luong , Linh Duong Mong
Published: December 2013

In this study, a simple procedure for the determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy is described. This procedure allows a sequential extraction polonium, uranium, thorium and radium radionuclides from the same sample in two to three days. It was tested and validated with the analysis of certified reference materials from the IAEA.
Lessons learnt from PSA for new and advanced reactors in Russia
Authors: Tokmachev G. , Morozov V.
Published: December 2013

Customer requirements to probabilistic safety targets are usually stronger than existing Regulatory or IAEA ones. It appears that industry takes the lead over regulation in this case and forces the designer to find and implement appropriate means to enhance safety, which sometimes have no reference to practical experience. On the other hand, regulatory documents and the existing PSA methodology are mainly oriented to operating plants. This creates problems when developing a PSA as well as performing regulatory reviews. The scope of the PSA may be different depending on a design stage such as the development conceptual, basic or detailed design. In addition, the base case PSA is usually performed for NPP in design. However, a customer may require additional PSA applications to consider, for instance, risk monitoring. In this case the scope of the PSA should be extended to implement special attributes of the application needed that often requires specific information not available at the design stage. Lack of design information affecting PSA development may be associated with incompleteness of the design that is typical for interim design stages and communication problems caused by the involvement of many different companies in the deign activity. To deal with this issue bounding technologies and the iterative PSA development are used. However this sometimes contradicts to the “best estimate” approach recommended by regulatory guides. PSA development for advanced NPPs has raised some issues originated from unknown new components, processes and technologies incorporated into the design of an advanced plant. The paper addresses some issues resolved while carrying out PSAs for advanced NPPs. Some PSA results for new advanced VVER plants under construction and the first lessons learnt from the Fukushima accident are also discussed.
Cosmic ray angular distribution employing plastic scintillation detectors and flash-ADC/FPGA-based readout systems
Authors: Hai V. H. , Dao N. Q. , Nomachi M.
Published: December 2013

It is known that secondary cosmic rays are high energetic particles which are products of shower particles, when primary cosmic rays from outer space hit the atmosphere molecules. Many studies of cosmic rays show that cosmic flux depends on the depth of atmosphere. At ground level, most secondary cosmic rays are muons, a type of charged particle, and have angular dependence. The purpose of this article was to develop the telescope with two plastic scintillation detectors to investigate the angular distribution of cosmic rays at ground level. Directions of investigation were carried out vertical, 45-degree oblique and horizontal directions with respect to earth surface, approximately from North to South. Electronic readout system was developed from Flash Analog Digital Converter (Flash-ADC) of 8 bits-250Ms/sec, and Embedded Field Programmable Gate Array (FPGA)-based trigger. LabVIEWTM interface was written for controlling trigger system and taking data. For each direction measurement, the deposited energy spectra in the scintillators were obtained. The interest of cosmic-ray events was analyzed for counting. Angular distribution was obtained quantitatively. The experiment has been done at University of Science-HCMC.
Studies on boiling water reactor design with reduced moderation and analysis of reactivity accidents using the code DYN3D-MG
Authors: Rohde U. , Pivovarov V. , Matveev Y.
Published: December 2013

The multi-group version of the DYN3D reactor dynamics code was used for calculations for a new concept of a boiling water reactor with tight lattice of fuel rods and reduced neutron moderation. For that purpose, a 5-group cross section library was prepared and connected to the DYN3D code. Comparison calculations with the steady-state finite-difference code ACADEM showed a very good agreement. The capability of the DYN3D multi-group code in modeling transients in boiling water reactors with tight fuel element lattices was demonstrated by the analysis of two reactivity accidents initiated by the ejection of one control rod and unauthorized withdrawal of a control rod bank from the reactor core. The corresponding analyses were performed for begin of cycle conditions, when the considered control rods are at their maximum insertion depth.
Dose contributions due to radiation scattered by air (skyshine) in the case of x-ray machines
Authors: Sahre P. , Kaden M. , Schönmuth T. , Pawelke J. , Naumann B. , Reichelt U.
Published: December 2013

Radiation transport simulations had to be done in preparation of operation of the X-ray tube ISOVOLT 320 kV/13mA in a special laboratory. At first simulation was done without shielding the roof of the laboratory, showing a dose rate maximum of more than 100 mSv/h. This dose rate results in a skyshine dose rate of at most 2 μSv/h in the surrounding of the building without shielding the roof. For similar geometries the skyshine is negligible for dose rates at the unshielded roof of less than 3 mSv/h (exclusion area).
Evaluations of the CCFL and critical flow models in TRACE for PWR LBLOCA analysis
Authors: Yang J.-H. , Lin H.-T. , Wang J.-R. , Shih C.
Published: December 2013

This study aims to develop the Maanshan Pressurized Water Reactor (PWR) analysis model by using the TRACE (TRAC/RELAP Advanced Computational Engine) code. By analyzing the Large Break Loss of Coolant Accident (LBLOCA) sequence, the results are compared with the Maanshan Final Safety Analysis Report (FSAR) data. The critical flow and Counter Current Flow Limitation (CCFL) play an important role in the overall performance of TRACE LBLOCA prediction. Therefore, the sensitivity study on the discharge coefficients of critical flow model and CCFL modeling among different regions are also discussed. The current conclusions show that modeling CCFL in downcomer has more significant impact on the peak cladding temperature than modeling CCFL in hot-legs does. No CCFL phenomena occurred in the pressurizer surge line. The best value for the multipliers of critical flow model would be 0.5 and the TRACE could consistently predict the break flow rate in the LBLOCA analysis as shown in FSAR.
High-resolution two-phase flow measurement techniques for the generation of experimental data for CFD code qualification
Authors: Hampel U. , Krepper E. , Lucas D. , Beyer M. , Szalinski L. , Banowski M. , Barthel F. , Hoppe D. , Bieberle A. , Barth T.
Published: December 2013

Computational fluid dynamics simulations for two-phase flows are important in different fields of engineering and science. Since two-phase flows are inherently complex, also CFD modeling development requires special attention. The validation of model implementation and the derivation of physics based models for momentum, heat, and mass transfer in two-phase flow require experiments with generation of high-resolution measurement data. This, however, is a great challenge, since most standard flow measurement tools used in single phase flow situations, are not suited for multiphase flows. In this article we report on advanced imaging and measuring methods for two-phase flow experiments, which have been extensively used in the recent past to conduct experiments for two-phase flows at the Helmholtz-Zentrum Dresden-Rossendorf. In particular the application of wire-mesh sensors, ultrafast X-ray tomography, gamma ray tomography and positron emission tomography will be introduced and discussed.
Case studies for evaluating conditional probabilities of external explosions
Authors: Hauschild J. , Andernacht M. , Berg H. P.
Published: December 2013

In recent years international experience has shown that external hazards can be safety significant contributors to the risk for nuclear power plants because such hazards have the potential to reduce simultaneously the level of redundancy by damaging redundant systems. Therefore, effective protections against external hazards have to be accurately assessed applying deterministic, probabilistic or combined methodologies. With respect to the external hazard “explosion” – two different types of risky situations for the plant under consideration have to be investigated: the explosive material is available as a stationary source in the neighbourhood of the plant or the explosive material is mobile (i. e. by ships, rails or trucks). In the latter case, the situation changes with the varying distances. Moreover, the transport way could be a straight line or a bent which also has to be addressed in the calculations. Methods which can be applied to evaluate the probability of occurrence of an external explosion event are, e. g., fault tree analyses, event tree analyses and Monte Carlo simulations. Two case studies applying Monte Carlo simulations for assessing the probability of occurrence of external explosion events, given an accident with creation of an explosive gas cloud, are presented.
Modeling of DECL accident in the reactor containment by the CONTAIN 2.0 code
Authors: Abbasi M. , Rahgoshay M.
Published: December 2013

In this paper, a specific type of the Loss of Coolant Accident (LOCA), the DECL (Double Ended Cold Leg) break, that means totally guillotine type of break in the cold leg pipe, has been modeled. The accident is simulated with the CONTAIN 2.0 code. In the event of a LOCA accident, coolant mass and energy are released to the containment through the break. This causes an increase of pressure and temperature in the containment. The modeling is performed in the VVER-1000 reactor containment. The analysis includes average pressure in the containment and temperature distribution in sample cells in the long-time. The results are compared with the existing reports on studies that used the ANGAR code. Results show that the CONTAIN 2.0 code is an adaptable tool for the analysis of nuclear events such as DECL accident.
Seasonally gross alpha and beta activity concentration in surface water and sediments in Sır Dam Pond
Authors: Çam H. , Doğru M. , Küçükönder A. , Karatepe S.
Published: December 2013

Seasonally gross alpha–beta activities were measured in surface water and sediments in Sır Dam Pond (Kahramanmaras, Turkey). Six sampling sites were pre-defined in different locations of the Sır Dam Pond. Preliminary studies of gross-α and gross-β activities in the surface water and deep sediments were determined. The results obtained from the determination of the activity indicate that gross-α and gross-β activities were ranging from 0,007 ± 0,005 to 0,077 ± 0,006 Bq/l and from 0,028 ± 0,006 to 0,189 ± 0,009 Bq/l for the surface water and from 0,001 ± 0.001 to 0,229 ± 0,032 Bq/g and from 0,144 ± 0,026 to 0,419 ± 0,033 Bq/g for deep sediment, respectively.
Evolution of the mixed-mode character of solid-state phase transformations in metals involving solute partitioning
Authors: Sietsma Jilt , Mecozzi M. Giuseppina , van Bohemen Stefan M. C. , van der Zwaag Sybrand
Published: December 2013

Partitioning phase transformations in the solid state are principally subjected to two processes that take place: the redistribution, through long-range diffusion, of the partitioning element, and the lattice transformation taking place at the interface. Consequently, the usual approximation to consider one of these two processes as controlling the rate of the phase transformation is of limited accuracy. For a more accurate description, the so-called mixed-mode character of partitioning phase transformations is to be taken into account. In the present study, it is shown that the mixed-mode character can be quantified and that it has a significant effect on the kinetics. By means of examples involving either substitutional (Mo in Ti) or interstitial (C in Fe) partitioning elements, it is shown that a gradual change of the character of the transformation occurs during the phase transformation, shifting from initially interface-controlled (which implies the largest interface velocity) towards more diffusion-controlled.
An indirect approach to measure glass transition temperature in metallic glasses
Authors: Jin H. J. , Lu K.
Published: December 2013

Glass transition behavior of metallic glasses under some extraordinary conditions (such as under high pressures) remains unexplored. Conventional measurements of glass transition temperature, Tg, are very difficult to perform under these extraordinary circumstances. In the present paper, we introduce an indirect approach to characterize glass transition, using enthalpy recovery experiments. With annealing deeply relaxed glassy samples and subsequent DSC measurements, a variation of enthalpy change upon heating with annealing temperature can be obtained. The variation of enthalpy change, a signature of glass transition, was found to correlate well with the directly measured DSC curves for the glass transition. This unique method was successfully applied in determining Tg of several metallic glasses under hydrostatic high pressures and compression stresses.
Experimental investigation and thermodynamic modelling of the Mg–Al-rich region of the Mg–Al–Sr System
Authors: Cao Hongbo , Zhu Jun , Zhang Chuan , Wu Kaisheng , Saddock Nicholas D. , Jones J. Wayne , Pollock Tresa M. , Schmid-Fetzer Rainer , Chang Y. Austin
Published: December 2013

A thermodynamic description of the Mg–Al–Sr ternary in the Mg–Al-rich region was developed based on the microstructures, the crystal structures and compositions of the phases in three samples in the as-cast and 673K annealed states. The gross compositions of the three alloys were identified for investigation based on a calculated isotherm using the description obtained from those of the constituent binaries via extrapolation. The calculated liquidus projection using the developed description was found to be consistent with the primary phases of solidification obtained from two additional alloys in the as-cast state. In addition, the model-calculated isotherm and liquidus projection are able to rationalize results reported in a recent publication for this ternary. This paper demonstrates the power of using a preliminary calculated phase diagram for selecting key alloys for experimentation, on basis of which a reliable thermodynamic description can be developed.
Knudsen effusion mass spectrometric studies of the Al–Ni system: Thermodynamic properties over {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni}
Authors: Narasimhan Tiruppatur Subramaniam Lakshmi , Kath Dieter , Wessel Egbert , Markus Torsten , Hilpert Klaus
Published: December 2013

Vaporisation studies on Al–Ni alloys with x(Ni)=0.43, 0.42, 0.35, and 0.32 were carried out by Knudsen effusion mass spectrometry. Partial pressure-temperature relations of Al(g) over the two phase regions {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni} were determined in the temperature ranges 1104–1278K and 1021–1122K, respectively. The corresponding equations are log(p(Al)/Pa) = −(20039±84)/T(K) + (13.4640.070) for {AlNi + Al3Ni2} and log(p(Al)/Pa) = −(16836 ± 235)/T(K) + (11.3450±.219) for {Al3Ni2 + Al3Ni}. The vaporisation reactions, Al3Ni2.025(s) = 2.6436AlNi0.766(s) + 0.3564Al(g) and Al3Ni(s) = 0.572Al3Ni1.747(s) + 1.284Al(g) were evaluated and subsequently the enthalpy and Gibbs energy of formation of Al3Ni1.747(s) were derived.
Comparing the thermodynamic behaviour of Al(l) + ZrO2(4%Y2O3) and Al(l) + Al2O3
Authors: Copland Evan
Published: December 2013

In an effort to better determine the thermodynamic properties of Al(g) and Al2O(g) the vapour in equilibrium with Al(l) + 4at.% yttria-stabilized zirconia (YSZ) was compared to the vapour in equilibrium with Al(l) + Al2O3(s) over the temperature range 1197–1509K. This comparison was made directly by Knudsen effusion-cell mass spectrometry with an instrument configured for a multiple effusion-cell vapour source (multi-cell KEMS). Second-law enthalpies of vaporization of Al(g) and Al2O(g) together with activity measurements show that Al(l) + YSZ is thermodynamically equivalent to Al(l) + Al2O3(s), indicating that Al(l) remained pure and Al2O3(s) was present in the YSZ-cell. Subsequent observation of the Al(l)/YSZ and vapour/YSZ interfaces revealed a thin Al2O3-layer had formed, separating the YSZ-cell from Al(l) and Al(g) + Al2O(g), effectively transforming it into an Al2O3effusion-cell. This behaviour agreed with observations made for -NiAl(Pt) alloys measured in YSZ effusion-cell.
The deformation behaviour of electrodeposited nanocrystalline Ni in an atomic force microscope with a newly developed in situ bending machine
Authors: Yang B. , Vehoff H. , Hempelmann R.
Published: December 2013

Four-point-bending and strain-controlled fatigue experiments were performed on electrodeposited nanocrystalline nickel specimens at room temperature. For the first time, the deformation behaviour of bulk nanonickel specimens was studied in an atomic force microscope with a newly developed in situ bending machine. Results show that grain boundary sliding plays an important role during deformation, and the fatigue crack propagates along grain boundaries.
Experimental and thermodynamic evaluation of the Co–Cr–C system
Authors: Markström Andreas , Norgren Susanne , Frisk Karin , Jansson Bo , Sterneland Thérèse
Published: December 2013

New experimental results on the liquid+graphite+M7C3equilibrium are presented. The solubility of Co in the M7C3carbide has been measured at 1523 and 1723K. These measurements together with recently published measurements on the fcc+graphite+M7C3equilibrium show that the solubility of Co in the M7C3is much higher than predicted from thermodynamic calculations. A new thermodynamic description of the Co–Cr–C system is presented which accurately describes the solubility of Co in the M7C3carbide in the temperature range 1373–1723K.
The influence of orientation and aluminium content on the deformation mechanisms of Hadfield steel single crystals
Authors: Astafurova Elena G. , Kireeva Irina V. , Chumlyakov Yuriy I. , Maier Hans J. , Sehitoglu Huseyin
Published: December 2013

The low stacking fault energy and high carbon content in Hadfield steel make twinning the basic deformation mechanism from the onset of plastic deformation in [1¯11] and [011] oriented single crystals in tension at T = 77 – 300 K. Alloying with aluminium (2.7 Al in wt.%) results in an increase of stacking fault energy from 0.03 J · m2 to 0.05 J · m−2 and moves twinning to higher degrees of deformation (∊pl > 15 %). In aluminium-free [1¯23] crystals twinning starts after 20 % strain. For [1¯23], [001] orientations, aluminium additions change the dislocation arrangement from a uniform distribution to a planar dislocation arrangment and also suppress twinning. Intersections of dislocation pile-ups were found to be the governing factor for hardening in the aluminium-alloyed [001] crystals.
Fracture behavior of overmatched ductile iron weldment
Authors: Cetinel Hakan
Published: December 2013

The fracture behavior of welded ductile iron is discussed by means of experimental and theoretical studies. Ferritic nodular cast irons were joined by cold arc welding in order to obtain over-matched weldment in which the yield strength of the weld metal is higher than that of the base metal. As a result of the welding process, various regions with different mechanical properties formed in the welded specimens.

In the experimental part of the study, the mechanical properties of the different regions in the welded specimens were identified and J-Integral toughness values were determined by fracture toughness tests for different crack locations including the base metal, the heat affected zone and the weld metal.

In the numerical part of the study, finite element analyses were conducted by fixing 3-D models precracked at different locations for different crack lengths. In these models, after stress – strain analysis, stress triaxiality and plastic deformation characteristics around the crack tip were determined for each crack location and different crack sizes. It was found that stress triaxiality values increase with growing crack length. Different regions with different strength levels in the weldment affect the extension of plastic deformation in the models. Hindrance to the extension of plastic deformation at the heat affected zone and diffusion line causes an extra increase in stress triaxiality at the crack tip.
Model of a superlattice indentation
Authors: Kravchuk A. , Rymuza Z.
Published: December 2013

This paper deals with the problem of penetration of a conical indenter into a multilayer rigid – perfectly-plastic body. The penetration of the indenter is studied on the basis of the Haar and von Karman hypothesis. The analytical distribution of the contact stress is obtained. A relationship between Meyer hardness and yield stresses of the layers is established.
Effect of Ho additions on the microstructure and mechanical properties of Nb-22Ti-16Si-7Cr-3Al-3Ta-2Hf alloys
Authors: Tian Y. X. , Guo J. T. , Liang Y. C. , Wu C. L. , Zhou L. Z. , Ye H. Q.
Published: December 2013

The effect of Ho additions on the microstructure and compressive properties of the alloy Nb-22Ti-16Si-7Cr-3Al-3Ta-2Hf (at.%) was investigated by using scanning electron microscopy, X-ray diffraction, transmission electron microscopy and by performing compression tests. The results show that Ho additions cause remarkable microstructural refinement. The addition of 0.1 at.% Ho to the alloy increases its strength and ductility. When the amount of Ho is increased to 0.2 at.%, the strength and ductility decreases. Ho addition inhibits the formation of the (Ti, Nb)5Si3 phase and the amount of the (Ti, Nb)5Si3 phase decreases, even disappears, with increasing Ho content. In addition, the fracture surfaces of Ho-free alloys deformed at room temperature in compression tests exhibit cleavage for both the (Nb, Ti) solid solution and the (Nb, Ti)5Si3 intermetallic compound, while limited local plastic strain of the (Nb, Ti) solid solution is observed in Ho-doped alloys. The effect and mechanism of strengthening and plastic deformation of Ho additions to the alloy was discussed in view of the microstructure.
Study of interfacial reactions between Sn–Ag–Cu alloys and Au substrate
Authors: Jao Chien-Chung , Yen Yee-Wen , Zhang Shu-Hao , Lin Chung-Yung , Lee Chiapyng
Published: December 2013

Interfacial reactions between Sn – Ag – Cu lead-free solders and Au were investigated by the use of SAC/Au solid/solid reaction couples which were annealed at 150, 180 and 200 °C for various reaction times. Five intermetallic compounds, AuSn, AuSn2, AuSn4, (Au, Cu)Sn, and (Cu, Au)5Sn6, were formed at a higher temperature and lower Cu content. As the reaction temperature was dropped and Cu content was increased, only three intermetallic layers, AuSn, (Au, Cu)Sn, and (Cu, Au)5Sn6, could be observed. Meanwhile, when the Cu content in SAC alloys increased, the thickness of total reaction layers decreased, but that of (Au, Cu)Sn/(Cu, Au)6Sn5 layers increased. It likely resulted from (Au, Cu)Sn/(Cu, Au)6Sn5 layers acting as a diffusion barrier to resist Sn diffusing to Au – Sn intermetallic compounds and decrease the growth rate of Au – Sn intermetallic compounds. The growth and formation of intermetallic compounds are sensitive to the reaction temperature and Cu content in the SAC/Au couple systems.
Bismuth activity measurements and thermodynamic re-optimization of the Ni–Bi System
Authors: Vassilev Gueorgui P. , Romanowska Jolanta , Wnuk Grzegorz
Published: December 2013

Bismuth thermodynamic activities in Ni – Bi liquid solutions have been measured by the modified isothermal isopiestic method at 1723, 1753 and 1773 K. These results are coupled with thermochemical and topological data from literature, in order to achieve reliable re-optimization of the Ni – Bi system by the CALPHAD method. The model of disordered substitutional solutions has been applied to the liquid phase and to the face-centered cubic solid solutions (Ni). The compound NiBi3 is stoichiometric and is modeled by a two-sublattice model corresponding to its formula. The nickel solubility in the solid bismuth is negligible, which is why the phase (Bi) is considered as consisting of bismuth only. The description Bi: Ni, Va has been used for the thermodynamic modeling of the nonstoichiometric NiBi phase.
Adaptierung einer Hochtemperatur-Belastungseinrichtung für die Raster-Elektronenmikroskopie mit Unterstützung von Finite-Elemente-Modellierung
Authors: Dimmler G. , Weidinger Th. , Cerjak H.
Published: December 2013

Kurzfassung

Die Möglichkeit einer direkten Verfolgung zeitlich ablaufender werkstoffkundlicher Prozesse ohne Unterbrechung des Belastungskollektivs (“in-situ”-Untersuchungen) mit Hilfe einer Hochtemperatur-Belastungseinrichtung im REM stellt neue Perspektiven für das tiefere Verständnis von Werkstoffphänomenen dar. Im Rahmen dieser Arbeit wurde eine geeignete Probengeometrie hinsichtlich Temperatur- und Spannungsverteilung mit Unterstützung von Finite- Elemente- Modellierung erarbeitet. Das gewonnene Verständnis der unterschiedlichen Wechselwirkungen zwischen der Belastungseinrichtung und dem Rasterelektronenmikroskop ist dabei eine wichtige Basis für eine weitere Optimierung der Versuchsdurchführung. Derzeit können kinetische Prozesse an speziellen Proben bei Temperaturen bis 650°C und einer Zug-/Druckbelastung von theoretisch bis zu 10 000 N untersucht werden. Zusätzlich ist die Simulation eines beliebigen Spannungs- und Temperaturprofils durch die volldigitalisierte Mikroprozessorsteuerung gegeben. Mit der Belastungseinrichtung können Kurzzeit-Kriechversuche mit kontinuierlicher Dehnungsmessung und Strukturuntersuchung der Oberfläche bei konstanter und frei wählbarer Temperatur durchgeführt werden. Ein durchgeführter Kurzzeitkriechversuch soll dabei als Vorbereitung für zukünftige in-situ Schädigungsuntersuchungen an 9–12% Cr-Stähle dienen.
Elektronenmikroskopische Untersuchungen an mit FIB-Präparation hergestellten Grenzflächen von biologischen Materialien und Werkstoffen: erste Ergebnisse
Authors: Burkhardt C. , Nisch W.
Published: December 2013

Kurzfassung

Für die Untersuchung der Ultrastruktur von biologischen Zellen und Geweben ist die Elektronenmikroskopie ein wichtiges Hilfsmittel. Damit mit dieser Methode auch die Grenzfläche von biologischen Systemen und Werkstoffoberflächen gezielt untersucht werden kann, wurden in der vorliegenden Arbeit klassische Methoden der biologischen Präparation, die kritische Punkt- Trocknung und das Einbetten von kontrastierten Zellen in einem Polymer mit der Focused-Ion-Beam-Technik (FIB) kombiniert. Die Arbeiten wurden in einem Zwei-Strahl-Gerät durchgeführt, so dass die FIB-Präparation eines Querschnitts bei hoher Auflösung im Rasterelektronenmikroskop beobachtet werden kann. Es wird gezeigt, dass es möglich ist, Zellen und die Kontaktstellen der Zellen zu einem Substrat auf einer Sub-Mikrometer-Skala zu präparieren und abzubilden.
Schadensfall Schäden an Kupferrohren einer Fußbodenheizung
Authors: Panzenböck M.
Published: December 2013

Kurzfassung

Kupfer wird sehr gerne im Bauwesen aus Gründen der sehr guten Korrosionsbeständigkeit und Verarbeitbarkeit eingesetzt. Trotz der hervorragenden Eigenschaften kommt es immer wieder zum Versagen von Rohrleitungen mit erheblichen Folgeschäden. Im diesem Fall kam es zum Auftreten von Leckagen an einer Fußbodenheizung. Die Schädigung ist nicht auf eine Wechselwirkung des Wärmetransportmediums mit dem Rohrwerkstoff zurückzuführen. Die Untersuchungen lassen erkennen, dass die Einflüsse von außen kommen und der Werkstoffzustand dabei eine entscheidende Rolle spielt.
Effect of Sr Addition on the Microstructure of a Rapidly Solidified Al-12 wt.% Si Alloy
Authors: Wang Yan , Zhang Zhonghua , Zheng Shaohua , Wang Weimin , Bian Xiufang
Published: December 2013

The effect of Sr addition on the microstructure of a melt-spun Al-12% Si alloy has been investigated using X-ray diffraction and transmission electron microscopy. The Sr addition has no effect on the phase constitution but has a marked effect on the microstructure of the melt-spun alloy. The distribution, morphology and orientation of Si in the melt-spun alloy with the Sr addition are different from those in the alloy without Sr. Under rapid solidification conditions, cooling rates play a dominant role in the microstructure formation of the Al-12% Si alloy.
Surface Upheavals, Pseudo Martensite, and Martensite Ghosts
Authors: Hornbogen E.
Published: December 2013

A survey is made on the application of some metallographic methods for the analysis of martensitic reactions. In this context the following aspects are discussed:

Reverse reactions can be martensitic, to restore faultlessly the austenite, not fully reversible (defects accumulate), or diffusion controlled. In the last case austenite b must form by new nucleation and growth (crystallographic irreversibility). Then no surface upheavals form.
TEM-Untersuchungen an Erosionskratern, die durch elektrische Entladungen erzeugt werden
Authors: Soldera Flavio , Ilic Nenad , Mücklich Frank
Published: December 2013

Kurzfassung

Durch elektrische Plasmaentladungen wurden Krater an der Materialoberfläche einer Pt-Probe erzeugt. Mittels FIB wurden TEM-Lamellen der Kraterquerschnitte präpariert, um die Gefügeänderung nach dem Entladungseinschlag zu beobachten. Das Material, das im flüssigen Zustand zum Kraterrand verschoben wurde, konnte identifiziert werden. Unter diesem Kraterrand bilden sich Mikroporen. Die Körner unter dem Krater erstrecken sich bis an die Krateroberfläche durch epitaxiales Wachstum.
FIB-Präparation und TEM-Analytik an AlSi1-Bondkontakten
Authors: Geißler Ute , Engelmann Hans-Jürgen , Urban Ingrid , Rooch Heidemarie
Published: December 2013

Kurzfassung

Bei der Untersuchung der Verbindungsbildung von Bondkontakten sehr geringer Ausdehnung (25 μm-AlSi1-Draht auf Cu/Ni/Au-Metallisierung einer Leiterplatte) steht mit der Methode des Fokusierten Ionenstrahles (FIB) für die TEM-Zielpräparation ein sehr effektives Verfahren zur Verfügung, das die genaue Entnahme einer Lamelle aus dem interessierenden Probenbereich ermöglicht. Dabei gelingt es mit dem in-situ-lift-out-Verfahren im Vergleich zum ex-situ-lift-out-Verfahren dünnere Folien zu präparieren (ca. 40 nm), an denen im Bereich der Grenzfläche zwischen Bonddraht und dem Metallisierungschichtsystem EFTEM-Mappings und HRTEM-Untersuchungen möglich werden. Diese Untersuchungen liefern zusammen mit der Anwendung des FIB als Rasterionenmikroskop neue Erkenntnisse zum Gefüge der Bondkontakte und zum Aufbau der Grenzfläche und erweitern das Verständnis der Verbindungsbildung beim Drahtbonden.
Gemeinschaftsversuch an ausgewählten Magnesium-Legierungen
Authors: Carle Veronika , Täffner Ulrike , Kopp Wolf-Ulrich
Published: December 2013

Kurzfassung

Über einen Gemeinschaftsversuch des Arbeitskreises “Probenpräparation” im Fachausschuss Materialographie der DGM wird berichtet. Von 10 Teilnehmern wurden eine Magnesium-Gusslegierung AZ 61, sowie 2 Magnesium-Knetlegierungen ZM 21 und AM 50 präpariert und qualitativ ausgewertet. Die von den Teilnehmern durchgeführten Präparationsschritte werden beschrieben, Bilder einzelner Gefüge gezeigt und Details erläutert. Ein Vorschlag zur Präparation wird gegeben.