bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of square and hexagonal fuel lattices for high conversion PWRs
Authors: Kotlyar D. , Shwageraus E. 
Published: December 2013

Abstract
This paper reports on an investigation into fuel design choices of a pressurized water reactor operating in a self-sustainable Th-233U fuel cycle. In order to evaluate feasibility of this concept, two types of fuel assembly lattices were considered: square and hexagonal. The hexagonal lattice may offer some advantages over the square one. For example, the fertile blanket fuel can be packed more tightly reducing the blanket volume fraction in the core and potentially allowing to achieve higher core average power density. The calculations were carried out with Monte-Carlo based BGCore code system and the results were compared to those obtained with Serpent Monte-Carlo code and deterministic transport code BOXER. One of the major design challenges associated with the SB concept is high power peaking due to the high concentration of fissile material in the seed region. The second objective of this work is to estimate the maximum achievable core power density by evaluation of limiting thermal hydraulic parameters. The analysis showed that both fuel assembly designs have a potential of achieving net breeding. Although hexagonal lattice was found to be somewhat more favorable because it allows achieving higher power density, while having breeding performance comparable to the square lattice case.
Determination of the nuclide vector for decommissioning projects at PSI (Paul Scherrer Institute, Switzerland)
Authors: Jäggi M. , Ehrlicher U. , Eikenberg J. 
Published: December 2013

Abstract
In the context of two reactor decommissioning projects, radioactive slurry from concrete cutting was collected in the retention pond (RHB) at the Paul Scherrer Institute, along with radioactive drain outlets. Additionally, there are active residues from former operations. The task was to determine the nuclide vector of the radioactive slurry before final disposal. Due to the slurry from neutron-activated concrete, activation products, like 55Fe, 60Co, 63Ni, 133Ba, 152Eu, 154Eu and 155Eu can be expected. Accumulated drain outlets from laboratories, where work with radioactive substances is being done, were expected to contain 22Na, 60Co, 134Cs, 137Cs, 133Ba, 152Eu, 154Eu, 155Eu, 241Am, 239/240Pu, 241Pu, 244Cm, 234U, 235U, 238U, 230Th, 232Th and 90Sr. For further clarification, 3H and 14C in the water and in the organic phase had to be measured as well. This work gives an overview about the slurry dissolution techniques, the radiochemical separation methods and activity concentrations of the nuclide vector. Further processing of the slurry is also discussed.
Effect of using FLiBe and FLiNaBe molten salts bearing plutonium fluorides on the neutronic performance of PACER
Authors: Acir A. 
Published: December 2013

Abstract
In this paper, the effects of using FLiBe and FLiNaBe Molten Salts Bearing Plutonium Fluorides on the neutronic performance of the PACER are investigated. The optimum radial thickness for tritium self-sufficiency of the blankets addition of plutonium fluorides to FLiNaBe (LiF-/NaF BeF2) and FLiBe (LiF-/BeF2) of a dual purpose modified PACER concept are determined. The calculations are carried out with the one dimensional transport code XSDRNPM/SCALE5. The tritium breeding capacities of FLiNaBe and FLiBe with addition of plutonium fluorides in molten salt zone are investigated and compared. The optimum molten salt zone thickness is computed as 155 cm for tritium self-sufficiency of the blankets using FLiBe +1% PuF4 whereas, the optimum thickness with FLiNaBe +1% PuF4 is calculated as 170 cm. In addition, neutron transport calculations have been performed to evaluate the energy multiplication factor, total fission rate, displacement per atom and helium gas generation for optimal radial thickness in the blanket. Also, the tritium production and the radiation damage limits should be evaluated together in a fusion blanket for determining the optimum thickness of molten salt layer.
Irradiation tests on PHWR type fuel elements in TRIGA research reactor of INR Pitesti
Authors: Horhoianu G. , Sorescu I. , Parvan M. 
Published: December 2013

Abstract
Nine PHWR type fuel elements with reduced length were irradiated in loop A of the TRIGA Research Reactor of INR Pitesti. The primary objective of the test was to determine the performance of nuclear fuel fabricated at INR Pitesti at high linear powers in pressurized water conditions. Six fuel elements were irradiated with a ramp power history, achieving a maximum power of 45 kW/m during pre-ramp and of 64 kW/m in the ramp. The maximum discharge burnup was of 216 MWh/kgU. Another three fuel elements with reduced length were irradiated with declining power history. At the beginning of irradiation the fuel elements achieved a maximum linear power of 66 kW/m. The maximum fuel power was about 1.3 times the maximum expected in PHWR. The maximum discharge burnup was 205 MWh/kgU. The elements were destructively examined in the hot cells of INR Pitesti. Temperature-sensitive parameters such as UO2 grain growth, fission-gas release and sheath deformations were examined. The tests proved the feasibility of irradiating PHWR type fuel elements at linear powers up to 66 kW/m under pressurized water conditions and demonstrated the possibility of more flexible operation of this fuel in power reactors. This paper presents the results of the investigation.
U
1 and P
1 approximations to neutron transport equation for diffusion length calculation
Authors: Bülbül A. , Öztürk H. 
Published: December 2013

Abstract

U
1 and P
1 approximations are used for the calculation of asymptotic relaxation length in one-dimensional neutron transport equation. The approximation methods are applied to anisotropic neutron transport equation with backward and forward scattering. The methods are based on the series expansion of the neutron angular flux in terms of the Chebyshev polynomials of second kind and Legendre polynomials. By applying the first order approximation to the transport equation, asymptotic relaxation lengths are calculated. Numerical results obtained from both methods are compared with each other.
A numerical method for resonance integral calculations
Authors: Tanbay T. , Ozgener B. 
Published: December 2013

Abstract
A numerical method has been proposed for resonance integral calculations and a cubic fit based on least squares approximation to compute the optimum Bell factor is given. The numerical method is based on the discretization of the neutron slowing down equation. The scattering integral is approximated by taking into account the location of the upper limit in energy domain. The accuracy of the method has been tested by performing computations of resonance integrals for uranium dioxide isolated rods and comparing the results with empirical values.
Condensation induced water hammer (CIWH) – relevance in the nuclear industry and state of science and technology
Authors: Swidersky H. 
Published: December 2013

Abstract
Condensation-induced water hammers (CIWH) are consequences of rapid condensation of steam in partially filled pipes. They present a particular hazard potential, as they seem to occur spontaneously and out of stagnation. The entire process still eludes a secured analytical or numerical predictability and determination of the fluid dynamic loads. The simulation of these processes is one of the most difficult tasks of thermal hydraulic transient analyses. Condensation induced water hammers in plants – mostly power plants – can lead to significant costs if they result in long downtimes, detailed analyses and upgrades. In this contribution, the phenomenon CIWH is explained and the relevance for nuclear engineering will be discussed. An outlook on the actual requirements of regulatory guidelines and the state of science and technology will be given.
1D Models for Condensation Induced Water Hammer in Pipelines
Authors: Blömeling F. , Neuhaus T. , Schaffrath A. 
Published: December 2013

Abstract
Condensation induced water hammer (CIWH) are caused by contact of steam and subcooled water. Thus, modeling the direct contact condensation is a crucial step towards the simulation of condensation induced water hammer with 1D pressure surge codes. Therefore, also the TÜV NORD SysTec GmbH & Co. KG inhouse pressure surge code DYVRO has been equipped with a new contact condensation model. The validation of DYVRO against an experiment dealing with CIWH is presented in this contribution.
Large Eddy Simulation of the shear flow instability in a rod-bundle assembly
Authors: Séverac E. , Fröhlich J. 
Published: December 2013

Abstract
The paper presents a Large Eddy Simulation at high Reynolds number of a section of a sub-channel in a fuel rod-bundle assembly of square pattern inside a pressurized water reactor. The focus is on the instability generated by the geometry of the sub-channel.
Numerical simulation of turbulent flow mixing inside a square chimney structure of a research reactor
Authors: Sengupta S. , Vijayan P. K. , Singh R. K. , Bhatnagar A. , Raina V. K. 
Published: December 2013

Abstract
Numerical simulation was performed to study the turbulent mixing behavior of two opposing flows inside a square chimney structure of a research reactor. The chimney design facilitates drawing pool water in the downward direction and thereby suppresses the upward flow of radioactive water jet to limit the radiation field at the reactor pool top. Analyses were carried out considering a mass flow rate of 750 kg/s for the upward flowing hot water from the core, which corresponds to Reynolds number of 3 × 106. Mass flow ratios of the downward flow and the upward flow were 0.0, 0.05, 0.1 and 0.15. The effects of mass flow ratio, chimney height on the velocity and temperature distribution inside three-dimensional chimney structure was evaluated using CFD code PHOENICS. The effect of temperature difference between the opposing flows on velocity was also analysed. It is observed that increase in downward flow causes the jet height to decrease due to the opposing momentum of downward flow against the upward jet. The effects of chimney height and temperature difference on the jet height are found to be marginal because of dominating inertial force over buoyancy force for the study.
Probabilistic safety analysis of external floods – method and application
Authors: Klügel J.-U. 
Published: December 2013

AbstractThe events of Fukushima amplified the scientific interest in the improvement of methods for probabilistic safety assessment (PSA) of extreme external events. The assessment of consequences of external floods belongs to this group of events. The paper presents the key steps of methodology for probabilistic safety assessment of external floods and a recent application for a nuclear power plant in Switzerland. The presented methodology is an extension of earlier activities and provides more focus on the PSA methodology part that may be applicable also for other studies.
Use of erbium as burnable poison for VVER reactors
Authors: Pavlovichev A. , Kosourov E. , Shcherenko A. , Saprykin V. , Lazarenko A. , Aleshin S. , Shcherenko A. 
Published: December 2013

Abstract
Problems related to use of Erbium as burnable poison for VVER are discussed. Comparison is made between neutronics characteristics of Uranium-Gadolinium and Uranium-Erbium fuel cycles. The study shows that use of Erbium as burnable poison allows decreasing the peaking factor in the core. Meanwhile residual Erbium at the end of the fuel cycle makes it necessary to increase fuel enrichment. There is made the conclusion of prospects of using Erbium as burnable poison for VVER.
The reactor dynamics code DYN3D and its trigonal-geometry nodal diffusion model
Authors: Duerigen S. , Rohde U. , Bilodid Y. , Mittag S. 
Published: December 2013

Abstract
The reactor dynamics code DYN3D is a three-dimensional best-estimate tool for simulating steady states and transients of light-water reactors and innovative reactor designs. An overview of the DYN3D features is provided. This paper further focuses on the recently developed trigonal-geometry diffusion model DYN3D-TRIDIF including a description of the underlying nodal approach and the characteristics of trigonal geometries. Via a mesh refinement study by means of a VVER-1000-type core benchmark using a fine-mesh diffusion reference solution, DYN3D-TRIDIF shows spatial convergence. Furthermore, the performance of DYN3D-TRIDIF is verified by means of a single-assembly problem on pin-cell level. Good agreement between DYN3D-TRIDIF and the detailed-geometry transport reference is achieved with an average deviation in power of less than 1%.
Robert W. Cahn: 1924–2007
Authors: Hardouin Duparc Olivier 
Published: December 2013

Abstract
R.W. Cahn died on the 9th of April. Wonderfully gifted from birth, his personality has been shaped by 20th Century history which forced him to flee from Germany to England through Spain. Chance and opportunities led him to study metallurgy at Cambridge and to later become one of the founders of Materials Science, and one of its best advocates. Some elements of his life and achievements are recalled here, as an homage to both the scientist and the man.
Solidification curves for commercial Mg alloys obtained from heat-transfer modeled DTA experiments
Authors: Mirković Djordje , Schmid-Fetzer Rainer 
Published: December 2013

Abstract
An improved method is presented for determination of solidification curves, i.e., solid fraction versus temperature, for commercial Mg alloys using heat-transfer modeled differential thermal analysis (DTA) curves. A better simulation of the measured DTA signal is attained through an independent measurement of the time constant as function of temperature for the applied equipment. This enables a better desmearing of the DTA signal. Challenging Mg alloys could be appropriately handled by redesigning the tantalum encapsulation. Due to high oxygen affinity and vapor pressure of the investigated magnesium alloys, this special adaptation of the DTA setup using sealed Ta capsules was indispensable for generation of reproducible and reliable data.
Analysis of phase formation in Ni-rich alloys of the Ni–Ta–W system by calorimetry, DTA, SEM, and TEM
Authors: Witusiewicz Victor T. , Hecht Ulrike , Warnken Nils , Fries Suzana G. , Hu Weiping 
Published: December 2013

Abstract
The partial enthalpies of dissolution of pure Ni, W and Ta in liquid ternary Ni–Ta–W alloys have been determined at (17735)K using a high temperature isoperibolic calorimeter. Measurements were performed in Ni-rich alloys (from 80 to 100 at.% Ni) along sections with constant Ta:W atomic ratios 1:0, 2:1, 1:2, and 0:1. The partial enthalpies and thereby the integral enthalpy of mixing of these ternary alloys are calculated from the partial enthalpies of dissolution using SGTE Gibbs energies for pure elements as reference.
The obtained thermochemical data confirm that in the investigated Ni-rich alloys the binary interactions between Ta and W as well as the ternary Ni–Ta–W interactions are negligibly small. Due to this the variation of the integral enthalpy of mixing of the ternary alloys is well described as linear combination of the constituent Ni–Ta and Ni–W binaries. Such behaviour of the ternary liquid alloys is related to a very low probability of new ternary stable phases to occur in solid state. This prediction is confirmed by differential thermal analysis, scanning electron microscopy, and transmission electron microscopy of the as-solidified and annealed samples obtained as last alloy compositions in the series of calorimetric dissolution.
Low temperature deposition with inductively coupled plasma
Authors: Lee Seung-Hoon , Jung Dong-Ha , Jung Seung-Jae , Hong Seung-Chan , Lee Jung-Joong 
Published: December 2013

Abstract
The processing temperature of chemical and physical vapor deposition could be successfully lowered by applying inductively coupled plasma without deteriorating the film quality. Despite the low process temperature, the deposition rate was higher than that observed in conventional deposition processes, and the impurity content could be kept low. Some examples of inductively coupled plasma applications e.g. TiB2, TiN, TiO2, and SnO2 films are shown.
Thermodynamic evaluation of the Al–Cr–C system
Authors: Hallstedt Bengt , Music Denis , Sun Zhimei 
Published: December 2013

Abstract
The system Al–Cr–C contains one ternary phase, Cr2AlC. By combining a Calphad assessment with ab initio calculations and differential thermal analysis, the Gibbs energy of Cr2AlC could be determined and the complete phase diagram calculated. Cr2AlC melts incongruently at about 1773K to form Cr7C3 (or Cr3C2) and Al4C3 in addition to liquid. According to the ab initio calculations the equilibrium composition of Cr2AlC is very nearly stoichiometric, but can dissolve some Al metastably by replacing Cr. The agreement between the thermodynamic calculation and the various sources of information is excellent.
Thermodynamic assessment of the Mn–Cr–O system for solid oxide fuel cell (SOFC) materials
Authors: Povoden Erwin , Grundy A. Nicholas , Gauckler Ludwig J. 
Published: December 2013

Abstract
By application of the CALPHAD method, a consistent set of thermodynamic model parameters is optimized for the Cr–Mn–O system based on experimental data. Chromium manganese spinel MnyCr3−yO4 and its tetragonally distorted polymorph are described using the compound energy model, and the liquid is described using the two-sublattice model for ionic liquids. Also solid solutions of the phases (Cr1–yMny)2+xO3, Mn2–yCryO3, and (Mn1–yCry)1–xO are considered. Relevance for solid oxide fuel cells is discussed.
The influence of porosity on the electrical properties of liquid-phase sintered silicon carbide
Authors: Ihle J. , Martin H.-P. , Herrmann M. , Obenaus P. , Adler J. , Hermel W. , Michaelis A. 
Published: December 2013

Abstract
The structure and the electrical properties of porous and dense liquid-phase sintered silicon carbide ceramics (LPS-SiC), containing yttria and alumina additives, have been studied.
The electrical resistance of LPS-SiC-materials varies in a wide range. This paper is focused on the influence of porosity on the electrical resistance of the sintered SiC. The porosity was controlled by the SiC grain size. Porous LPS-SiC materials were found to have substantially lower electrical resistance in comparison to dense materials of the same type.
The structure of the materials was investigated by XRD and FESEM. The porous materials consist of large grains due to the coarser starting powders in comparison to the dense materials. This results in a reduction of the dissolved and re-precipitated fraction of the SiC during sintering. Using the in-lens SEM mode, the high conductivity of the formed rims of the SiC grains could be shown. These observations reveal that the rim volume of dense LPS-SiC is much more extended than the rims of porous materials showing the higher conductivity.
Design of metal ceramic composites
Authors: Lenke Ilka T. , Rogowski Dirk 
Published: December 2013

Abstract
The reinforcement of light metal alloys with ceramic preforms offers a wide range of possibilities to improve mechanical and thermal properties and makes them usable for technical application. Starting with the Lokasil® composite material, different metal ceramic materials were created under serial-like conditions with the aim of improving the tensile strength, the bending strength, the thermal expansion, the damage tolerance, and the tribological properties.
High-temperature plasticity of SiC sintered with Lu2O3-AlN additives
Authors: Rixecker Georg , Biswas Koushik 
Published: December 2013

AbstractSiC ceramics containing Lu2O3–AlN sintering additives were gas-pressure sintered, and creep testing in four-point bending geometry was performed at temperatures between 1200°C and 1500°C in air. Compared with the more conventional additive system Y2O3–AlN, the creep resistance of the Lu2O3-containing ceramics is higher. In particular, strain rates down to 610−10s−1were measured after 60h at both 1300°C/300MPa and 1400°C/100MPa; in no case was steady-state creep reached. Annealing the ceramics at 1950°C for extended periods of time led to significant changes in the amount and distribution of intergranular phases. However, in contrast to earlier work using Y2O3–AlN additives, the influence of annealing on the creep resistance was negligible. Compliance testing as a function of temperature was conducted in order to monitor the softening behavior of materials with different additive compositions. In favorable cases, the drop in stiffness was only 12% up to a test temperature of 1450°C.
Kinetics of precipitate formation in (TixWyCrz)B2 solid solutions: influence of Cr concentration and Co impurities
Authors: Schmidt Harald , Fotsing Roland E. , Borchardt Günter , Schmalzried Clemens , Telle Rainer 
Published: December 2013

Abstract
Supersaturated (Ti0.5−xW0.5Crx)B2 (x = 0, 0.1, 0,2) solid solutions were produced by reaction sintering of transition metal diboride powders at a pressure of 60MPa at 1800°C. The formation kinetics of W2B5 precipitates were investigated at lower temperatures by X-ray diffractometry (XRD) and secondary electron microscopy (SEM). The precipitation rate constants as a function of reciprocal temperature show non-monotonic behaviour in the range between 1450 and 1700°C with a maximum at about 1650°C. At low temperatures, Arrhenius behaviour is approximately valid, where the precipitation kinetics are dominated by the diffusion of the transition metals. In contrast, at temperatures higher than 1650°C, the precipitation rates decrease rapidly, since supersaturation, and consequently nucleation, is strongly reduced. The rate constants of precipitation are identical within error limits for Cr concentrations of x=0.1 and x = 0.2, however, they are significantly lower for x=0. This means that the addition of small amounts of Cr accelerates the precipitate formation, while further addition has no further influence. Samples resulting from powders which were high-energy milled with WC/Co hard balls before reaction sintering show an increased density of precipitated crystallites but no increased rate constants of precipitation. This result can be explained under the assumption that for these samples a significant amount of additional pre-existing nuclei was present before precipitation starts, which were formed by heterogeneous nucleation at Co impurities, introduced by the milling process.
Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite
Authors: Sengupta A. K. , Bhagat R. K. , Laik A. , Kale G. B. , Jarvis T. , Majumdar S. , Kamath H. S. 
Published: December 2013

Abstract
Lead Bismuth eutectic alloy (Pb: 55.5wt.%, Bi: 44.5wt.%) is a potential candidate coolant material for high-temperature reactors because of its low melting point (124°C), high thermal conductivity, heat capacity, and better neutronic properties. Out-of-pile chemical compatibility studies of this coolant with graphite (coolant channel) have been carried out by isothermal annealing of the liquid alloy in a graphite crucible at 800, 900, 1000, and 1100°C for times ranging from 100h to 1000h. Formation of a reaction layer is observed. The growth rate of the reaction layer follows a parabolic law. Reaction layer thicknesses of 61.3 μm and 121 μm are estimated from the growth rate vs. time relation after 1year and 5years respectively. The growth of the reaction layer is diffusion-controlled and the activation energy of the reaction is estimated to be 100 KJ/mol.