bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination and evaluation of the radiological situation using mobile measurements during the ground phase
Authors: Obrecht R. , Pohl H. , Schneider S. , Grimm Ch. , Neff U. , Coutinho P. , Müller U. , Mandel C. , Wilbois T. , Ren Y. , Chaves F.
Published: December 2013

The nuclear reactor remote monitoring system of the state of Baden-Württemberg (Kernreaktor-Fernüberwachung Baden-Württemberg – KFÜ BW) is implemented according to the recently renewed “recommendations for remote monitoring of nuclear power plants”. In Baden-Württemberg, the application area of the system covers both, the surveillance of internal procedures on one hand, and the handling of incidents or accidents on the other. The following paper shows the role of the KFÜ regarding the determination and evaluation of the radiological situation in the range of off-site emergency response. Progress is reported on the measurement conception and the technical possibilities for the investigation of the radiological situation after the end of the deposition of radio nuclides (ground phase).
The boundary problem in the 1D-CANDLE burn-up reactor
Authors: Seifritz W.
Published: December 2013

We have analytically solved the boundary problem for a solitary CANDLE-Burn Up wave in a slab reactor configuration using the affine approach which can be considered as the analogon to the Buckling-Concept for spatially/stationary critical zones in linear reactor physics. It sheds some light on the problems, we are confronted with, when we have to deal with nonlinear mathematics in this new field of reactor physics.
Nuclear level density parameters of some largely deformed nuclei of medical radionuclides in low-lying collective excitation modes
Authors: Okuducu Ş. , Aktı N. N.
Published: December 2013

In this study, the nuclear energy level density based on nuclear collective excitation mechanism has been identified in terms of low-lying collective level bands near the neutron binding energy. Nuclear level density parameters of some large deformed nuclei of radionuclides widely used in medical applications have been calculated by using different collective excitation modes of observed nuclear spectra. The calculated parameters have been used successfully in estimation of the neutron-capture cross section basic data for the production of new medical radionuclides. The investigated radionuclides have been considered in the region of mass number 150 < A < 200. The method used in the present work assumes equidistance spacing of the collective coupled state bands of the interest radionuclides. The calculated results have been compared with the compiled values from the literatures for s-wave neutron resonance data.
Targetry of Y2O3 on a copper substrate for the non-carrier-added 89Zr production via 89Y(p, n)89Zr reaction
Authors: Sadeghi M. , Kakavand T. , Taghilo M.
Published: December 2013

A thick layer of Yttrium oxide was deposited on cupper substrate via two special sedimentation methods for the production of 89Zr. For deposition of Y2O3 on cupper substrate, 435 mg of Y2O3, 152.25 mg of ethyl cellulose and 4 ml of acetone were used to prepare a Y2O3 layer of 11.69 cm2. Also, 435 mg of Y2O3, 174 mg of methyl cellulose and 7.25 ml of water were used. The targets were checked by SEM and thermal shock test. The deposited target was irradiated for 20 min at a current of 20 μA and a proton beam of 15 MeV.
Reflection on the ductility of irradiated zircaloy-4 fuel rod cladding
Authors: Sauer G.
Published: December 2013

An approach is presented that allows the computational determination of the ductility of irradiated zircaloy-4 cladding by transferring experimental results yielded under conditions atypical for normal power operation to typical loadings encountered in an usual pressurized water reactor. The transfer bases on a damage function that describes the gradual development of material separations during the cladding creep in the reactor. The numerical values of the needed equation parameters are derived from experimental results. Creep and damage evolutions are coupled leading to a simultaneous computation of both processes. The calculations indicate that the minimum strains that irradiated cladding material can accommodate are greater than 5% under pure pressure loading up to hoop stresses of 100 MPa and greater 7% when fuel swelling corresponding to a linear rod power of maximum 400 W/cm dictates the creep.
Cyclotron production of 101Pd/101mRh radionuclide generator for radioimmunotherapy
Authors: Enferadi M. , Sadeghi M. , Ensaf M.
Published: December 2013

101mRh is one of such radionuclides that has been considered as a potential candidate for targeted radiotherapeutic use, due to its nuclear decay and chemical properties. Electrodeposition of rhodium metal on a copper backing was performed in acidic sulphate. The target was bombarded with a current intensity of 120 μA (Ep = 29 → 25 MeV) for 30 min (60 μAh). Radiochemical methods were investigated to optimize the production of no-carrier-added 101Pd/101mRh. The use of a cyclotron target with radiochemical processes (i.e. electrodeposition, electrodissolution and ion-exchange column chromatography) were carried out to produce this radionuclide in high-specific activity and radiochemical form suitable for radiopharmaceutical syntheses.
Analyses of loads on reactor pressure vessel internals in a pressurized water reactor due to a loss-of-coolant accident considering fluid-structure interaction
Authors: Akimov P. , Obereisenbuchner L.
Published: December 2013

During a postulated loss-of-coolant accident, significant structural loadings on the reactor pressure vessel and its internals can be exerted due to the non-uniform and time-dependent pressure differences. The integrity of the internals must be secured, so as to ensure reactor shutdown and post-accident heat removal. Two developed computer codes to be discussed in this paper are used for the analysis of loads on the reactor pressure vessel internals. In the analyses the fluid-structure interaction effects are taken into account in the annular space between the pressure vessel and the core support barrel as well as in the upper plenum. This is a more realistic approach with respect to peak loadings and structural response frequencies.
Simulation of natural circulation in a rectangular loop using CFD code PHOENICS
Authors: Kumar M. , Borghain A. , Maheshwari N. K. , Vijayan P. K.
Published: December 2013

Single phase natural circulation in a rectangular loop is simulated using the PHOENICS code, a general purpose Computational Fluid Dynamics (CFD) code. The rectangular loop, having different operating power levels, has been modeled with the help of the Multiple Block Fine Grid Embedment (MBFGE) technique. The Co-located Co-variant Method (CCM) is used to simulate this loop in PHOENICS. Extensive experimental and CFD studies have been conducted on single phase natural circulation in a rectangular loop. The paper presents the results of three-dimensional CFD analysis for the prediction of steady state behavior in a rectangular loop and its comparison with experimental data. The results of code prediction and readily available experimental data show good agreement.
Analyses of loss-of-coolant accidents involving release of insulation material under consideration of the measures taken for PWR from expert's point of view
Authors: Huber J. , Becker M. , Unterrainer J. , Thiele T. , Reichel C. , Schiefer S.
Published: December 2013

The incident, which happened in the Swedish nuclear power plant Barsebäck 2 on 28th of July, 1992 brought about a re-evaluation of the design requirements for the control of loss-of-coolant accidents (LOCA) involving the release of insulation material that were valid in Germany up to that time. The current paper provides an overview on the aspects that need to be taken into consideration for analyses as well as a description of the important boundary conditions. In giving details of the analyses, the actual state is also described. It is also illustrated that sufficient examinations and tests have been performed for the German PWR plants and corresponding measures have been taken providing a sufficient basis for a final positive evaluation of the issue “LOCA involving release of insulation material”.
Analyses and estimation of insulation material release in E.ON-PWR under loss of coolant conditions
Authors: Koring R.
Published: December 2013

In 1992, strainers on the suction side of the ECCS pumps in Barsebäck NPP Unit 2 became partially and temporary clogged with mineral wool after steam jet induced releases of parts of the mineral wool insulation. Although Barsebäck NPP Unit 2 is a Boiling Water Reactor (BWR) this event induced large investigations to under-stand und maintain strainer clogging effects after a loss-of-coolant accident for all reactor types.

Especially for the German Pressurized Water Reactors (PWR) a program was launched by the German Utilities together with the plant manufacturer. The final estimations of all theoretical and experimental results caused different steps of modifications of the insulation material, the strainer area and mesh sizes in most of the German PWR including the E.ON PWR. Moreover, interactions and procedures were carried out such as back flushing actions to remove the mineral wool from the strainers supported by an additional differential pressure measurement at the strainers. All measures were implemented to assure the performance of emergency core cooling during the containment sump recirculation mode and to improve the NPP safety.
Influence of nuclear data uncertainties on reactor core calculations
Authors: Klein M. , Gallner L. , Krzykacz-Hausmann B. , Pautz A. , Zwermann W.
Published: December 2013

To investigate the influence of nuclear data uncertainties on reactor core calculations systematically, the sampling based uncertainty and sensitivity software package SUSA developed at GRS was extended for the use with nuclear covariance data. Varied nuclear data are generated randomly corresponding to the uncertainty information from the covariance matrices. After performing a large number of calculations with these data, the results are statistically evaluated; this can be done not only for integral, but also for local output quantities like the assembly power distribution. The method is applied to multi-group Monte Carlo calculations stationary states of the PWR MOX/UO2 core transient benchmark, and to corresponding nodal diffusion calculations. Unexpectedly large uncertainties result for the radial power distribution. The uncertainties in the nodal results agree very well with those in the Monte Carlo reference results; thus, it is possible to apply the random sampling method to determine the influence of nuclear data uncertainties on transient core calculations.
BWR transient analysis with the coupled code system S3K/RELAP5
Authors: Jönsson C. , Moberg L. , Grandi G. , Judd J.
Published: December 2013

This paper describes the coupled code system S3K-RELAP5 and the application of the code system to BWR transients without scram. In addition short descriptions are given for application of the coupled system to fast transients and rod drop accidents. The models and methods of the code system are presented. Validation results are shown for a recorded transient event in the Forsmark 3 reactor. It is concluded that S3K-RELAP5 adequately captures the complicated interaction between physical processes in the reactor as well as the essential reactor protection and control systems, which qualifies it for applications to fast and slow transients, with or without scram, and Reactivity Initiated Accidents (RIA).
The development and assessment of TRACE model for Lungmen ABWR
Authors: Lin H.-T. , Wang J.-R. , Shih C.
Published: December 2013

For the nuclear power plant Lungmen (two blocks of Advanced Boiling Water Reactor (ABWR)) in Taiwan a plant model for the thermal hydraulic program TRACE (TRAC/RELAP Advanced Computational Engine) was developed. This model is and will be used for the simulation of normal and anomalous plant behaviour as well as for the simulation of incident scenarios. The presentation of this model is done in three steps: The first step is the development of a TRACE model of Lungmen nuclear power plant (NPP) which includes the vessel, the main steam lines and important control systems (such as the feedwater control system, recirculation flow control system, etc.). Key parameters were identified to refine the model further in the frame of a steady state analysis. The second step is the performance of TRACE transient analyses, such as MSIV closure direct scram (MSIVCD, MSIV = Main Steamline Isolation Valve) and loss of feedwater flow (LOFW). The above transient data of Final Safety Analysis Report (FSAR) are used to verify the Lungmen NPP TRACE model. The trends of their analysis results are roughly similar. It indicates that TRACE model is satisfying for the purpose of Lungmen NPP safety analyses. The third step is the prediction analysis of Lungmen NPP startup tests by using the TRACE model. The prediction analysis results of TRACE comply with the startup tests procedure criteria.
Best estimate analysis of PHEBUS FPT1 experiment bundle phase using ASTEC code ICARE module
Authors: Vileiniskis V. , Kaliatka A.
Published: December 2013

The main objective of the PHEBUS FPT1 experiment was to study the release of fission products and their subsequent transport and deposition in the primary circuit and the containment under the conditions representative of a severe accident of a Pressurised Water Reactor. The FPT1 test was divided into the bundle degradation, aerosol, washing and chemistry phases. The objective of this paper is related to the best estimate analysis of the bundle degradation phase using ASTEC code ICARE module. GRS (Germany) best estimate method was used for the simulation of FPT1 test by employing SUSA 3.5 package. The performed best estimate analysis showed that ICARE module is capable to model the main severe accidents phenomena in the fuel bundle, heating and melting, taking into account the used physical and code parameters uncertainties.
An analytical benchmark of MYRRHA ADS in cylindrical geometry
Authors: Atak H. , Yilmazer A.
Published: December 2013

In this study, the steady and transient neutronic behaviour of MYRRHA ADS is investigated. For this purpose, a recently proposed analytical benchmark of the diffusion kinetics as 1D slab model of the MYRRHA ADS concept developed in Belgium has been extended to the cylindrical geometry which represents the system more realistically. Analytical calculations are performed using the Customized Solution Method and numerical Laplace inversion techniques such as Fixed-Talbot and Gaver-Wynn-Rho algorithms. Results are compared with the finite element program FLEXPDE® and they are found to be in complete agreement. The necessity of modeling the MYRHHA reactor in cylindrical geometry rather than slab geometry to obtain more realistic benchmark results is demonstrated.
Emergency exercises conducted by the BMU
Authors: Bühling A. , Kuhlen J.
Published: December 2013

According to the Precautionary Radiation Protection Act, responsibility for crisis management in the case of events which do not pose an imminent danger lies with the Federal Ministry for the Environment (BMU). To fulfil this obligation, technical as well as organisational arrangements are required, and the BMU staff has to be made familiar with the relevant tasks. To accomplish this, suitable exercises are essential. In recent years exercise series have been initiated by international organisations and by the EU, which deal with practical experience in managing urgent radiological information exchange and crisis management according to international agreements. They cover both the early phase of nuclear accidents and the specific requirements of the late phase.
Maintaining competence in nuclear safety and waste management research by BMBF
Authors: Ehrlich A.
Published: December 2013

Germany is to undertake a structured phasing-out of power generation from nuclear energy. Until the last nuclear power plant is shut down, safety must be guaranteed in line with the very latest developments in science and technology. The R&D work performed is in accord with the resolution for the structured phasing-out of the use of nuclear power.

The Federal Ministry of Education and Research (BMBF) with its “Basic Energy Research 2020+” funding concept supplements institutionally funded work of Helmholtz Institutes in a few core areas to further extend co-operation with universities. Close coordination between institutional and project funding will be ensured via the Alliance for Competence in Nuclear Technology in Germany (“Kompetenzverbund Kerntechnik”).

In the area of nuclear safety and disposal research, R&D is carried out on the scientific and technological aspects of safety in existing nuclear reactors, the safety of nuclear disposal, the minimisation of highly radioactive substances ultimately requiring disposal and radiation research. Special attention is to be paid within this concept to the funding of young scientists. In addition to doctorate posts in research projects, special funding instruments are to be offered to promote the next generation of scientists.
Condensation induced water hammer and steam assisted gravity drainage in the Athabasca oil sands
Authors: Carlson M. R.
Published: December 2013

Most people will have been exposed to some aspect of the debate about the Athabasca Oil Sands in North-Eastern Alberta and the significant role that the oil sands are expected to play in supplying conventional fossil fuels. Part of the bitumen is recovered from mines and part is recovered from in situ projects utilizing the Steam Assisted Gravity Drainage Process (SAGD). SAGD utilizes a considerable amount of steam, that is injected into geological formations. Hot water, bitumen and some vapour are recovered from the production wells. With significant steam generation, transmission and injection, there is the very real possibility of condensation induced water hammers. There have been a number of catastrophic failures to date. The intent of the paper is to provide interesting background information on the in situ oil sands industry. More importantly, to show some interesting and broader applications of thermalhydraulics developed in the nuclear industry. The expertise developed may have potential markets, with some adaptation, to the oil sands industry. Finally, there has been some discussion about using nuclear power for steam generation in the oil sands.
An analytical solution for the consideration of the effect of adjacent fuel assemblies; extension to VVER-440 type fuel assemblies
Authors: Merk B. , Rohde U.
Published: December 2013

A new analytical method is described to deal with the Leakage Environmental Effect for the cross section production. The method is based on the one dimensional analytical solution of the two-group diffusion equation for two adjacent, homogenized fuel assemblies. The high quality of the results for this highly efficient method is demonstrated for square fuel assemblies. In additional tests the limiting case for the transferability of the concept to the small hexagonal VVER-440 type fuel assemblies is shown.
Effect of spacer grid mixing vanes on coolant outlet temperature distribution
Authors: Rämä T. , Lahtinen T. , Brandt T. , Toppila T.
Published: December 2013

In Loviisa VVER-440-type NPP the coolant outlet temperature of the hot subchannel is constantly monitored during the operation. According to the authority requirement the maximum subchannel outlet temperature must not exceed the saturation temperature. Coolant temperature distribution inside the fuel assembly is affected by the efficiency of the coolant mixing. In order to enhance the coolant mixing the fuel manufacturer is introducing the additional mixing vanes on the fuel bundle spacer grids. In the paper the effect of the different mixing vane modifications is studied with computational fluid dynamics (CFD) simulation. Goal of the modelling is to find vane modifications with which sufficient mixing is reached with acceptable increase in the spacer grid pressure loss. The results of the studies are discussed in the paper.
Analytical investigation of the properties of the neutron noise induced by vibrating absorber and fuel rods
Authors: Jonsson A. , Tran H. N. , Dykin V. , Pázsit I.
Published: December 2013

Analytical solution methods for the neutron noise in a one-dimensional multi-region system in two-group theory, which have so far been based on the adjoint function technique, are extended here to using the forward Green's function technique. The forward Green's functions were calculated analytically for a noise source in a core surrounded by reflector regions at both sides. It is shown that with symbolic computation methods, the forward Green's function can be used for the calculation of the space- and frequency-dependent noise in the first order approximation for arbitrary noise sources which have an analytical representation. The properties of the induced neutron noise were investigated for vibrations of both absorbers and fuel assemblies, with two representations of the noise sources: a point-like source which corresponds to the vibrations of a fuel rod, and a finite width source which corresponds to vibrations of a fuel assembly. The contributions of the components induced by the fluctuations of the various types of macroscopic cross sections in the total noise are also discussed and the information content of the noise in the fast group is explored for the identification of fuel assembly vibrations.
Dynamic assessment for life extension of nuclear power plants (NPPs) using system dynamics (SD) method
Authors: Woo T. H.
Published: December 2013

It has been proposed to extend the life of nuclear power plants (NPPs) for the economic purpose. Especially, the primary systems in reactor are considered in the thermohydraulic and neutronic aspect, which is related to the safety system. The electric power and the lifespan of components are expressed as economic situation. In addition, political considerations are given by the presidential change and the nuclear non-proliferation characteristics. The dynamical investigation using system dynamics (SD) shows the effective time for the life extension of the NPPs by Monte-Carlo simulations. This non-linear algorithm is incorporated with the feedback loop of the event sequences. The expected event is related to the past event, which affects to the dynamical simulations of lifetime in the NPPs. In the conclusions, the safety guarantee as well as the economic profit in the re-use of long term operated power plants is presented, which is mentioned as the transient time between 2019 and 2021 in this paper.
Effects on criticality of selected scattering phase functions in neutron transport equation using the Chebyshev approximation
Authors: Kara A. , Anlı F.
Published: December 2013

Criticality and diffusion problems have been widely studied in neutron transport theory using polynomial expansion techniques in different geometries. In this study, instead of conventional scattering functions, two different phase function will be used in slab geometry transport equation by using the TN approximation and Marshak boundary conditions. Critical half thicknesses of the slab will be calculated. The numerical results obtained will be presented in tables.
Effect of Cu2+/Al3+ mole ratio on structure of Cu – Al bimetallic nanoparticles prepared by radiation induced method
Authors: Abedini A. , Larki F. , Saion E. , Noroozi M.
Published: December 2013

Cu–Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aqueous solutions containing metal chlorides as precursors, polyvinyl alcohol (PVA) as a capping agent, isopropanol as a radical scavenger, and distilled water as a solvent. The Cu–Al bimetallic nanoparticles were characterized by transmission electron microscopy (TEM), UV-visible absorption spectrometry, powder X-ray diffractometer (XRD), and Energy-dispersive X-ray spectroscopy (EDX). The TEM, XRD, EDX, and absorption analyses confirmed the formation of core-shell structure of Cu–Al bimetallic nanoparticles at lower Cu2+/Al3+ mole ratio, and the formation of Cu–Al alloy nanoparticles at higher Cu2+/Al3+ mole ratio. The TEM analysis for particle size and size distribution revealed that the average particle size of Cu–Al bimetallic nanoparticles decreased with the increase of absorbed dose. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic nanoparticles under irradiation.
Experiments of condensation-induced water hammers at the UniBw Munich
Authors: Dirndorfer S. , Kulisch H. , Malcherek A.
Published: December 2013

Condensation-induced water hammers belong to the most serious and complex pressure surges. Experimental data from literature are scanty, incomplete, not public or simply missing. A new test facility at the UniBw (University of the German Armed Forces) was constructed to perform own experiments within a research alliance. This new test facility uses a complete new approach. In contrast to other test stations, the UniBw water hammer test facility is a closed system. This leads on the one hand to a more complex handling with respect of conducting experiments but on the other hand also to a more realistic characterization of thermo-hydraulic phenomena which can occur in a power plant. The first results of a measured condensation-induced water hammer are presented.
On-site power system reliability of a nuclear power plant after the earthquake
Authors: Volkanovski A.
Published: December 2013

Continuous and reliable sources of electrical energy are required during all modes of operation of a nuclear power plant in order to assure the safety of the plant. The electrical energy to the safety systems of the nuclear power plant is provided from the on-site power system. The objective of this paper is to analyze the nuclear power plant on-site power system reliability during normal operation and after the earthquakes with given intensity. The obtained results show the importance of the on-site power system reliability in general and battery supported section of the Class 1E power system in particular for the safety of the nuclear power plant. High level of reliability is obtained for the Class 1E and Non-1E power system during normal operation and safe shutdown earthquake. Obtained results show high level of reliability of a Class 1E power system after the earthquake with peak ground acceleration equal to the one measured at the Fukushima Daiichi nuclear power plant. Recommendation for revision of the current guideline for assessment of the acceptable station blackout duration capability is recommended considering the results of the analysis and identified deficiencies in the current guideline.
How to construct a seismic risk model?
Authors: Sperbeck S. T. , Türschmann M.
Published: December 2013

The German PSA Guideline and its technical documents on PSA methods and data require probabilistic safety analyses (PSA) to be carried out in the frame of safety reviews for nuclear power plants. Since 2005 this also includes a seismic PSA (SPSA) for sites with design earthquake intensities exceeding the value VII (MSK-64/EMS-98). It is shown how the plant model of PSA Level 1 for internal events can be extended on the level of fault tree basic events to get a quantifiable seismic plant model. A two-step screening procedure can be applied to derive the seismic equipment list (SEL) and a list of all possibly seismic-induced dependent equipment failures. The screening procedure is supported by a database. The database keeps at hand all the data and information to extend the plant model of PSA Level 1 in a proper manner.
Albedo and constant source problems for extremely anisotropic scattering
Authors: Koçmen M. A. , Teğmen A. , Türeci D. , Güleçyüz M. Ç. , Türeci R. G.
Published: December 2013

The half-space albedo problem and the constant source problem have been solved for a combination of the linearly anisotropic scattering and İnönü’s scattering functions. The linear transport equation for extremely anisotropic scattering kernel can be converted into an equivalent equation with a linearly anisotropic scattering kernel and the modified FN method can be used for albedo calculations.
Burnup calculations using serpent code in accelerator driven thorium reactors
Authors: Korkmaz M. E. , Yiğit M. , Ağar O.
Published: December 2013

In this study, burnup calculations have been performed for a sodium cooled Accelerator Driven Thorium Reactor (ADTR) using the Serpent 1.1.16 Monte Carlo code. The ADTR has been designed for burning minor actinides, mixed 232Th and mixed 233U fuels. A solid Pb-Bi spallation target in the center of the core is used and sodium as coolant. The system is designed for a heating power of 2000 MW and for an operation time of 600 days. For burnup calculations the Advanced Matrix Exponential Method CRAM (Chebyshev Rational Approximation Method) and different nuclear data libraries (ENDF7, JEF2.2, JEFF3.1.1) were used. The effective multiplication factor change from 0.93 to 0.97 for different nuclear data libraries during the reactor operation period.
The estimation of the control rods absorber burn-up during the VVER-1000 operation
Authors: Bolshagin S. , Gorodkov S. , Sukhino-Khomenko E.
Published: December 2013

The isotopic composition of the control rods absorber changes under the neutron flux influence, so the control rods efficiency can decrease. In the VVER-1000 control rods boron carbide and dysprosium titanate are used as absorbing materials. In boric part the efficiency decreases due to the 10B isotope burn-up. Dysprosium isotopes turn into other absorbing isotopes, so the absorbing properties of dysprosium part decrease to a lesser degree. Also the control rod's shells may be deformed as a consequence of boron carbide radiation swelling. This fact should be considered in substantiation of control rods durability. For the estimation of the control rods absorber burn-up two models are developed: VVER-1000 3-D fuel assembly with control rods partially immersed (imitation of the control rods operation in the working group) and VVER-1000 3-D fuel assembly with control rods, located at the upper limit switch (imitation of the control rods operation in groups of the emergency shutdown system).
The main characteristic of the evolution project SuperVVER with spectrum shift regulation
Authors: Alekseev P. N. , Chibinyaev A. V. , Gorohov V. F. , Teplov P. S.
Published: December 2013

The researches on the increase of achievable fuel burn-up in light water reactors (LWR) with so-called “spectrum shift” have been carried out in the world for a long time. The main idea of the “spectrum shift” is based on neutron spectrum shifting from the resonance energy region at the beginning of the cycle to the thermal region at the end of the cycle. There are many different ways of such regulation in the core – starting from coolant density variation during reactor cycle, to changing water-uranium ratio with some mechanical equipment. Spectrum shift regulation with depleted uranium or zirconium displacers is presented in this paper for uranium and mixed uranium and plutonium oxide (MOX) fuel loadings. New fuel assemblies with special guide tubes for displacers were developed for these purposes.
Application of statistical uncertainty and sensitivity evaluations to a PWR LBLOCA analysis calculated with the code ATHLET. Part 1: uncertainty analysis
Authors: Kozmenkov Y. , Rohde U.
Published: December 2013

Usually, reactor safety analyses are based on the traditional conservative deterministic approach. An alternative approach to reactor safety analyses uses best estimate computer codes in combination with quantification of uncertainties in model and plant parameters. The German Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) has applied the methodology of uncertainty analysis based on the Wilks’ approach. According to this approach, the number of calculations required to perform a probabilistic estimation of an output parameter with a given coverage/confidence level (e.g., 95%/95%) does not depend on the number of input uncertainty parameters. In this paper, the results of an uncertainty analysis for a Large Break LOCA scenario for a generic German PWR of the Konvoi design are reported. All calculations were performed using the system code ATHLET Mod 2.2 Cycle A. The EXCEL-integrated software SUSA developed by GRS was used for generation of the uncertainty parameter vectors, their incorporation into ATHLET input files and for statistical evaluation of the results.
Tracer transport modeling with the Alliances platform in the presence of evapotranspiration
Authors: Constantin A. , Genty A. , Diaconu D. , Bucur C.
Published: December 2013

The knowledge and understanding of water flow and solute transport in the unsaturated zone is becoming increasingly important especially in mitigation of groundwater pollution. Fate of radionuclide in the geological environment is a topic to address in performance and safety assessment studies for nuclear waste disposal and may be modeled considering flow and transport in porous media. However, often, due to the heterogeneity and anisotropy of the real systems, the computer simulations may be difficult to render the real behavior. This paper addresses the simulation of a tracer transport in the unsaturated zone of the Saligny site, the potential location for the Romanian low and intermediate level waste (LILW) disposal. Computation was based on experimental data and was performed with the Alliances platform, a numerical tool developed by French organizations CEA, ANDRA and EDF. In order to obtain information regarding the solute migration in depth and the solute lateral dispersion, the dispersivity coefficients of iodine were investigated in order to match the experimental concentration determined on samples from different locations of the site. A close fit of the simulation over experimental data for the water saturation profile at a depth of 0.5 m in transient state was targeted by taking into account evapotranspiration in order to obtain a realistic estimation of the water infiltration in the porous media. Dispersivity coefficients obtained from the simulation of the tracer transport are in good order of magnitude for the unsaturated area and allow to have a good preview of the tracer plume. However, further investigations are recommended on new samples in order to validate the migration of the tracer plume as expected.
Thermodynamic assessment of the Mg–Nd system
Authors: Guo Cuiping , Du Zhenmin
Published: December 2013

The Mg–Nd system was critically assessed by means of the CALPHAD technique. The solution phases (liquid, body-centered cubic, double hexagonal close-packed and hexagonal close-packed) were modeled with the Redlich–Kister equation. The intermetallic compounds Mg41Nd5, Mg3Nd and MgNd, which have a homogeneity range, were treated as the formulae (Mg, Nd)41(Mg, Nd)5, Mg3(Mg, Nd) and Mg(Mg, Nd) by a two-sublattice model with Mg and Nd or Mg on the first sublattice, and Mg and Nd on the second one, respectively. The compound Mg2Nd was treated as a stoichiometric compound. A set of self-consistent thermodynamic parameters of the Mg–Nd system was obtained.
Phase diagram of the Co–Cu–Ti system at 850°C
Authors: Xu Honghui , Du Yong , Huang Baiyun , Jin Zhanpeng , Li Shitong , Zhang Xiang
Published: December 2013

The phase equilibria of the Co–Cu–Ti system at 850°C are investigated using a high-efficiency diffusion couple and six key ternary alloys. The samples are examined by means of optical microscopy, scanning electron microscopy, and electron probe microanalysis. At 850°C, no ternary compound is found. The Ti3Cu phase is a metastable phase. The solubilities of Cu in Ti2Co, TiCo, TiCo2(c) and TiCo3 were determined to be 8.7, 35.8, 2.1, and 5.4 at.%, respectively. And the solubilities of Co in Ti2Cu, TiCu, Ti3Cu4, and TiCu2 were measured to be 6.6, 0.7, 2.4, and 10.2 at.%, respectively. The following 9 three-phase equilibria are observed: (Ti) + Ti2Co + Ti2Cu, Ti2Co + Ti2Cu + TiCo, Ti2Cu + TiCu + TiCo, TiCu + Ti3Cu4 + TiCo, Ti3Cu4 + TiCu2 + TiCo, TiCu2 + TiCo + (Cu), TiCo + TiCo2(c) + (Cu), TiCo2(h) + TiCo3 + (Cu), and TiCo3 + (Co) + (Cu).
Fabrication and electrical sliding wear of graphitic Cu–Cr–Zr matrix composites
Authors: Zhan Yongzhong , Zeng Jianmin
Published: December 2013

The present work was undertaken to prepare graphitic Cu–Cr–Zr matrix composites in order to develop new materials for application under sliding contact in an electrical field. The electrical sliding wear behavior of the graphite (Gr)/CuCrZr composite was investigated from a microstructural viewpoint, compared with the matrix alloy. The results indicate that by using the water atomized Cu–Cr–Zr powder and copper-coated graphite particles as starting materials, compact and homogeneous microstructure can be obtained in the composites. Fine and coherent particulate precipitations are formed in the Cu–Cr–Zr matrix during the aging treatment process, which help to improve the mechanical properties. Under the electrical sliding wear condition, incorporation of graphite in the Cu–Cr–Zr matrix not only decrease the wear loss of the sliding pair but also maintain steady-state friction coefficient. The main reason is that the graphite film that smears on the contacting surfaces can alleviate materials loss induced by electric arc discharge and adhesion wear. Proper aging treatment helps to make full use of the solid lubricant effect of the graphite particles.
Influence of Sb additions on surface tension and density of Sn–Sb, Sn–Ag–Sb andSn–Ag–Cu–Sb alloys: Experiment vs. modeling
Authors: Moser Z. , Gąsior W. , Pstruś J. , Ohnuma I. , Ishida K.
Published: December 2013

Surface tension and density measurements by maximum bubble pressure and dilatometric techniques were carried out in an extensive range of temperature on liquid alloys close to the ternary eutectic Sn3.3Ag0.76Cu with different Sb content. It has been found that the addition of Sb to Sn, Sn–Sb, to binary eutectic Sn–Ag and to Sn3.3Ag0.76Cu decreases the surface tension and density. The values of the surface tension calculated by the Butler model and by the method based on the binary alloys surface tension data with the ternary and quaternary correction factors were compared with the experimental results. The best agreement between the measured and the calculated values was observed for the model comprising the binary data with the correction factors.
Development of long-period ordered structures during crystallisation of amorphous Mg80Cu10Y10 and Mg83Ni9Y8
Authors: Garcés G. , Pérez P. , González S. , Adeva P.
Published: December 2013

The different transformations occurring during the crystallisation of amorphous Mg80Cu10Y10 and Mg83Ni9Y8 alloys have been elucidated. The formation of several unknown metastable phases was observed. The present work confirms that such phases exhibit long-period structures originated by the periodic alignment of (Y,TM)-layers (TM: transition metal). The long-period stacking-ordered phase, identified in the crystallised Ni-containing alloy, is stable at higher temperatures than that in the Cu-containing alloy.
Thermodynamic properties and phase relations of Zn-rich alloys in the system Pt–Zn
Authors: Huang Yongzhang , Richter Klaus W. , Yuan Wenxia , Qiao Zhiyu , Ipser Herbert
Published: December 2013

Zinc vapor pressures over binary Pt–Zn alloys were determined in the composition range from 63 to 84 at.% Zn for temperatures between 840–1150K using an isopiestic method. The phase boundaries of four different phase fields in this composition range could be fixed based on the experimental data. Thermodynamic activities and partial molar enthalpies of zinc within these phase fields were derived from the vapor pressure data and the composition dependence of the zinc activity was calculated for 1023 K. The integral Gibbs energy at 1273 K was derived as a function of composition by Gibbs–Duhem integration, combining the activity data of the present investigation with earlier results from the literature.
Metastable phases and nanocrystalline-forming ability (NFA) of melt-quenched Ni-rich (Zr,Hf)–Ni alloys
Authors: Bakonyi Imre
Published: December 2013

In this paper, the basic principles of and some recent advances in rapid solidification are briefly considered, with main emphasis on the formation of single-phase metastable states during meltquenching in Ni-rich Zr–Ni and Hf–Ni alloys. Factors controlling nanocrystalline-forming ability are discussed in detail, with particular view on the preparation of single-phase nanocrystalline alloys by the meltquenching process.
Three-dimensional printing of TiAl3/Al2O3 composites
Authors: Yin Xiaowei , Travitzky Nahum , Melcher Reinhold , Greil Peter
Published: December 2013

Intermetallic/ceramic composites were fabricated by reactive infiltration of an Al melt into a porous TiO2 preform which was prepared by indirect three-dimensional printing. At 1450°C the highly negative Gibbs energy of reaction (Gr=–279.950kJ/mol) is the driving force for the redox reaction 13/2 Al+3/2 TiO23/2 TiAl3+Al2O3 to take place. Wetting of molten Al on the preform surface was improved by adding a carbon-bearing binder ((C6H10O5)n, dextrin) to the powder blend, which decomposed to amorphous carbon (carbon yield 25wt.% of initial dextrin weight) after being heat-treated up to 800°C in an inert atmosphere. During annealing to 1400°C, carbon partially reduced TiO2 at least on the surface of the grains to form Ti3O5 and Ti2O3, which exhibit a significantly lower wetting angle compared to TiO2. In a low-oxygen-containing inert atmosphere and at 1200°C, Al melt spontaneously penetrated into the printed preform via inter-agglomerate pores (mean size 8lm) and intra-agglomerate pores (mean size 1lm). A fine-grained TiAl3/Al2O3 composite microstructure was produced with a residual porosity of 9%.
Re-optimization of the Mg–Sb system under topological constraints
Authors: Malakhov Dmitri V. , Balakumar Thevika
Published: December 2013

Non-existing inverted miscibility gaps in the liquid phase at high temperatures, reappearance of the liquid phase at low temperatures or reappearance of a solid phase at elevated temperatures, and other “approximation phantoms” sometimes result from thermodynamic assessments. A method for struggling against such artifacts is proposed. The method is based on introducing a sufficiently dense mesh of knots (not related to experimental points utilized in the optimization) and ensuring that specific inequality conditions (topological constraints) governing the appearance of the phase diagram are satisfied in these knots. It is shown that the syntax of the language describing conditions and experiments in the PARROT module of Thermo-Calc is suitable for performing such optimization. The workability of the approach proposed is exemplified by carrying out a re-optimization of the Mg–Sb system.
Thermodynamic description of the Ni–Si–Ti ternary system
Authors: Du Yong , He Cuiyun , Schuster J. C. , Liu Shuhong , Xu Honghui
Published: December 2013

A thermodynamic modeling of the Ni–Si–Ti system is conducted. All of the experimental phase diagram data available from the literature are critically reviewed and assessed using thermodynamic models for the Gibbs energies of individual phases. The thermodynamic parameters for five ternary compounds (τ1: Ti1Ni1Si1, τ2: Ti4Ni4Si7, τ3: Ti13Ni40Si31, τ4: Ti6Ni16Si7, and τ5: Ti2Ni3Si1), the ternary solution phases (liquid, bcc_A2, bcc_B2, fcc_A1, and L12) as well as the binary phases (Ti5Si3, Ni3Si, Ni5Si2, and TiNi3) showing noticeable solubilities for the third element are adjusted in the optimization. The order/disorder transitions between disordered bcc_A2 and ordered bcc_B2 phases as well as between disordered fcc_A1 and ordered L12 phases are treated using a two-sublattice model. The calculations indicate that the disordered and ordered phases can be described with a single equation. Comprehensive comparisons between the calculated and measured phase diagrams show that in the measured isothermal sections at 750°C, 900°C, 1000°C and 1100°C, most of the observed primary phase regions, as well as 16 out of the 26 experimentally observed invariant reaction temperatures are satisfactorily accounted for by the thermodynamic description. The liquidus projection and reaction scheme for the entire system are also presented. Further experimental work to solve a few discrepancies between calculation and experiment is emphasized.
Gas-phase surface alloying under “kinetic control”: A novel approach to improving the surface properties of titanium alloys
Authors: Ernst F. , Michal G. M. , Oba F. , Liu L. , Blush J. , Heuer A. H.
Published: December 2013

A novel process, “nitridation under kinetic control of the nitrogen activity”, has been developed for diffusing substantial amounts (≍10at.%) of interstitially dissolved nitrogen into the surface of Ti alloys (Ti–6Al–4V). By operating with a gas phase providing a very small, controlled nitrogen activity, this process generates a homogeneous Ti–N solid solution, free of detrimental titanium nitride precipitates, in which the nitrogen concentration smoothly decreases from the surface towards the interior. The process is conformal (applicable to workpieces of arbitrary shape) and provides a substantial (about twofold) increase in surface hardness. The hardened surface layer appears to possess adequate ductility for many structural applications. The concept of “surface alloying under kinetic control” is very general and may also serve to generate well-controlled surface concentration profiles of carbon or oxygen in Ti-base and other structural alloys.
The sintering mechanism and microstructure evolution in SiC–AlN ceramics studiedby EFTEM
Authors: Huang Rong , Gu Hui , Chen Zhongming , Tan Shouhong , Jiang Dongliang
Published: December 2013

The microstructures of three hot-pressed SiC ceramic materials with 5vol.%, 10vol.%, and 15vol.% AlN were investigated by analytical electron microscopy, especially electron energy-loss spectroscopic mapping (EELS mapping). AlN additives dissolve into SiC to form a core/rim structure and to refine the SiC grains. The crystallographic configurations for cores revealed by EELS mapping elucidate the sintering mechanism as liquid-phase sintering in the SiC–AlN composites. The additional 0.5wt.% Y2O3 additives that distribute in the intergranular regions facilitate the formation of liquids to improve the sintering property. With the increase of AlN, the microstructure evolution experienced three stages characterized as solid solution with core/rim structure for a few elongated grains, core/rim for the general equiaxed grains, and the emergence of individual AlN grains with SiC-rich precipitations, respectively. The refined grains and a variety of microstructures contribute to an excellent combination of mechanical properties, with the flexural strength as high as 1000MPa while the fracture toughness remains moderately high.
Electroless deposition of brushite (CaHPO4 · 2H2O) crystals on Ti–6Al–4V at room temperature
Authors: Tas A. Cuneyt
Published: December 2013

An electroless, room temperature solution growth method of depositing 50 to 150 μm thick, well-crystallized brushite (CaHPO4 · 2H2O, DCPD, dicalcium phosphate dihydrate) layers on the surface of an implantable medical device, such as a titanium alloy (Ti–6Al–4V) substrate, was developed. High ionic strength (189 to 609 mM) solutions with a Ca/P molar ratio of 2.50 and a pH value between 4.70 and 6.10 were prepared by dissolving appropriate quantities of CaCl2 · 2H2O, NaH2PO4, NaHCO3, and NaCl in deionized water. Surface-etched Ti–6Al–4V substrates were simply soaked in the solutions from 24 to 72 hours at room temperature. Elongated CaHPO4 · 2H2O crystals were in-situ- grown on the entire surfaces of the etched Ti–6Al–4V substrates.