Whole Core Transport Calculation Methodology for a Hexagonal Core
Energy Technology Data Exchange (ETDEWEB)
Cho, J. Y.; Kim, K. S.; Lee, C. C.; Zee, S. Q.; Joo, H. G
2007-07-15
This report discusses the hexagonal module implemented to the DeCART code and the performance of them. The implemented hexagonal module includes the hexagonal ray tracing and the CMFD acceleration modules. The performance of the implemented hexagonal module is examined for 4 tests of: (1) CMFD acceleration test, (2) the accuracy test of the hexagonal module, (3) the performance test for 2-D NGNP problem and (4) the applicability test for 3-D NGNP problem. The features of the implemented hexagonal modules are: (1) The Modular ray tracing scheme based on a hexagonal assembly and a path linking scheme between the modular rays. (2) Segment generation based on the structure unit. (3) Cell ray approximation: This feature is developed to reduce the memory required to store the segment information. (4) Modified cycle ray scheme that begins the ray tracing at a given surface and finishes if the reflected ray meets the starting surface. This feature is developed to reduce the memory required for the angular flux at the core boundary. (5) Fixed assembly geometry. The pin geometry of the single pin per assembly problem is different from that of the multi-pin problem. The core geometry of a single assembly problem is also different from that of the multi-assembly problem. (6) CMFD module based on unstructured cell. This feature is to deal with the irregular gap cells that are positioned at the assembly boundaries. The examination results of the 4 tests can be summarized as: (1) The CMFD acceleration test shows that the CMFD module speedups about greater than 200 for the core problem. (2) The accuracy test shows that the hexagonal MOC module produces an accurate solution of less than 60 pcm of eigenvalue and less than 2 % of local pin power errors. (3) The performance test for 2-D NGNP problem shows that the implemented hexagonal module works soundly and produces a reasonable solution by cooperating with the existing DeCART library and the other modules. (4) The applicability
Three dimensions transport calculations for PWR core; Calcul de coeur R.E.P. en transport 3D
Energy Technology Data Exchange (ETDEWEB)
Richebois, E
2000-07-01
The objective of this work is to define improved 3-D core calculation methods based on the transport theory. These methods can be particularly useful and lead to more precise computations in areas of the core where anisotropy and steep flux gradients occur, especially near interface and boundary conditions and in regions of high heterogeneity (bundle with absorbent rods). In order to apply the transport theory a new method for calculating reflector constants has been developed, since traditional methods were only suited for 2-group diffusion core calculations and could not be extrapolated to transport calculations. In this thesis work, the new method for obtaining reflector constants is derived regardless of the number of energy groups and of the operator used. The core calculations results using the reflector constants thereof obtained have been validated on the EDF's power reactor Saint Laurent B1 with MOX loading. The advantages of a 3-D core transport calculation scheme have been highlighted as opposed to diffusion methods; there are a considerable number of significant effects and potential advantages to be gained in rod worth calculations for instance. These preliminary results obtained with on particular cycle will have to be confirmed by more systematic analysis. Accidents like MSLB (main steam line break) and LOCA (loss of coolant accident) should also be investigated and constitute challenging situations where anisotropy is high and/or flux gradients are steep. This method is now being validated for others EDF's PWRs' reactors, as well as for experimental reactors and other types of commercial reactors. (author)
VVER-440 Ex-Core Neutron Transport Calculations by MCNP-5 Code and Comparison with Experiment
Energy Technology Data Exchange (ETDEWEB)
Borodkin, Pavel; Khrennikov, Nikolay [Scientific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS) Malaya Krasnoselskaya ul., 2/8, bld. 5, 107140 Moscow (Russian Federation)
2008-07-01
Ex-core neutron transport calculations are needed to evaluate radiation loading parameters (neutron fluence, fluence rate and spectra) on the in-vessel equipment, reactor pressure vessel (RPV) and support constructions of VVER type reactors. Due to these parameters are used for reactor equipment life-time assessment, neutron transport calculations should be carried out by precise and reliable calculation methods. In case of RPVs, especially, of first generation VVER-440s, the neutron fluence plays a key role in the prediction of RPV lifetime. Main part of VVER ex-core neutron transport calculations are performed by deterministic and Monte-Carlo methods. This paper deals with precise calculations of the Russian first generation VVER-440 by MCNP-5 code. The purpose of this work was an application of this code for expert calculations, verification of results by comparison with deterministic calculations and validation by neutron activation measured data. Deterministic discrete ordinates DORT code, widely used for RPV neutron dosimetry and many times tested by experiments, was used for comparison analyses. Ex-vessel neutron activation measurements at the VVER-440 NPP have provided space (in azimuth and height directions) and neutron energy (different activation reactions) distributions data for experimental (E) validation of calculated results. Calculational intercomparison (DORT vs. MCNP-5) and comparison with measured values (MCNP-5 and DORT vs. E) have shown agreement within 10-15% for different space points and reaction rates. The paper submits a discussion of results and makes conclusions about practice use of MCNP-5 code for ex-core neutron transport calculations in expert analysis. (authors)
Energy Technology Data Exchange (ETDEWEB)
Girardi, E.; Ruggieri, J.M. [CEA Cadarache, CEA/DEN/CAD/DER/SPRC/LEPH, 13 - Saint-Paul Lez Durance (France)
2003-07-01
The aim of this paper is to present the last developments made on a domain decomposition method applied to reactor core calculations. In this method, two kind of balance equation with two different numerical methods dealing with two different unknowns are coupled. In the first part the two balance transport equations (first order and second order one) are presented with the corresponding following numerical methods: Variational Nodal Method and Discrete Ordinate Nodal Method. In the second part, the Multi-Method/Multi-Domain algorithm is introduced by applying the Schwarz domain decomposition to the multigroup eigenvalue problem of the transport equation. The resulting algorithm is then provided. The projection operators used to coupled the two methods are detailed in the last part of the paper. Finally some preliminary numerical applications on benchmarks are given showing encouraging results. (authors)
Energy Technology Data Exchange (ETDEWEB)
Palau, J.M. [CEA Cadarache, Service de Physique des Reacteurs et du Cycle, Lab. de Projets Nucleaires, 13 - Saint-Paul-lez-Durance (France)
2005-07-01
This paper presents how Monte-Carlo calculations (French TRIPOLI4 poly-kinetic code with an appropriate pre-processing and post-processing software called OVNI) are used in the case of 3-dimensional heterogeneous benchmarks (slab reactor cores) to reduce model biases and enable a thorough and detailed analysis of the performances of deterministic methods and their associated data libraries with respect to key neutron parameters (reactivity, local power). Outstanding examples of application of these tools are presented regarding the new numerical methods implemented in the French lattice code APOLLO2 (advanced self-shielding models, new IDT characteristics method implemented within the discrete-ordinates flux solver model) and the JEFF3.1 nuclear data library (checked against JEF2.2 previous file). In particular we have pointed out, by performing multigroup/point-wise TRIPOLI4 (assembly and core) calculations, the efficiency (in terms of accuracy and computation time) of the new IDT method developed in APOLLO2. In addition, by performing 3-dimensional TRIPOLI4 calculations of the whole slab core (few millions of elementary volumes), the high quality of the new JEFF3.1 nuclear data files and revised evaluations (U{sup 235}, U{sup 238}, Hf) for reactivity prediction of slab cores critical experiments has been stressed. As a feedback of the whole validation process, improvements in terms of nuclear data (mainly Hf capture cross-sections) and numerical methods (advanced quadrature formulas accounting validation results, validation of new self-shielding models, parallelization) are suggested to improve even more the APOLLO2-CRONOS2 standard calculation route. (author)
Energy Technology Data Exchange (ETDEWEB)
Nagao, Yoshiharu [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment
1998-03-01
In material testing reactors like the JMTR (Japan Material Testing Reactor) of 50 MW in Japan Atomic Energy Research Institute, the neutron flux and neutron energy spectra of irradiated samples show complex distributions. It is necessary to assess the neutron flux and neutron energy spectra of an irradiation field by carrying out the nuclear calculation of the core for every operation cycle. In order to advance core calculation, in the JMTR, the application of MCNP to the assessment of core reactivity and neutron flux and spectra has been investigated. In this study, in order to reduce the time for calculation and variance, the comparison of the results of the calculations by the use of K code and fixed source and the use of Weight Window were investigated. As to the calculation method, the modeling of the total JMTR core, the conditions for calculation and the adopted variance reduction technique are explained. The results of calculation are shown. Significant difference was not observed in the results of neutron flux calculations according to the difference of the modeling of fuel region in the calculations by K code and fixed source. The method of assessing the results of neutron flux calculation is described. (K.I.)
Energy Technology Data Exchange (ETDEWEB)
Zwermann, W.; Aures, A.; Bernnat, W.; and others
2013-06-15
This report documents the status of the research and development goals reached within the reactor safety research project RS1503 ''Development and Application of Neutron Transport Methods and Uncertainty Analyses for Reactor Core Calculations'' as of the 1{sup st} quarter of 2013. The superordinate goal of the project is the development, validation, and application of neutron transport methods and uncertainty analyses for reactor core calculations. These calculation methods will mainly be applied to problems related to the core behaviour of light water reactors and innovative reactor concepts. The contributions of this project towards achieving this goal are the further development, validation, and application of deterministic and stochastic calculation programmes and of methods for uncertainty and sensitivity analyses, as well as the assessment of artificial neutral networks, for providing a complete nuclear calculation chain. This comprises processing nuclear basis data, creating multi-group data for diffusion and transport codes, obtaining reference solutions for stationary states with Monte Carlo codes, performing coupled 3D full core analyses in diffusion approximation and with other deterministic and also Monte Carlo transport codes, and implementing uncertainty and sensitivity analyses with the aim of propagating uncertainties through the whole calculation chain from fuel assembly, spectral and depletion calculations to coupled transient analyses. This calculation chain shall be applicable to light water reactors and also to innovative reactor concepts, and therefore has to be extensively validated with the help of benchmarks and critical experiments.
Multilevel transport solution of LWR reactor cores
Energy Technology Data Exchange (ETDEWEB)
Jose Ignacio Marquez Damian; Cassiano R.E. de Oliveira; HyeonKae Park
2008-09-01
This work presents a multilevel approach for the solution of the transport equation in typical LWR assemblies and core configurations. It is based on the second-order, even-parity formulation of the transport equation, which is solved within the framework provided by the finite element-spherical harmonics code EVENT. The performance of the new solver has been compared with that of the standard conjugate gradient solver for diffusion and transport problems on structured and unstruc-tured grids. Numerical results demonstrate the potential of the multilevel scheme for realistic reactor calculations.
Energy Technology Data Exchange (ETDEWEB)
Xhonneux, Andre, E-mail: a.xhonneux@fz-juelich.de [Forschungszentrum Jülich, 52425 Jülich (Germany); Institute for Reactor Safety and Reactor Technology RWTH-Aachen, 52064 Aachen (Germany); Allelein, Hans-Josef [Forschungszentrum Jülich, 52425 Jülich (Germany); Institute for Reactor Safety and Reactor Technology RWTH-Aachen, 52064 Aachen (Germany)
2014-05-01
The computer codes FRESCO-I, FRESCO-II, PANAMA and SPATRA developed at Forschungszentrum Jülich in Germany in the early 1980s are essential tools to predict the fission product release from spherical fuel elements and the TRISO fuel performance, respectively, under given normal or accidental conditions. These codes are able to calculate a conservative estimation of the source term, i.e. quantity and duration of radionuclide release. Recently, these codes have been reversed engineered, modernized (FORTRAN 95/2003) and combined to form a consistent code named STACY (Source Term Analysis Code System). STACY will later become a module of the V/HTR Code Package (HCP). In addition, further improvements have been implemented to enable more detailed calculations. For example the distinct temperature profile along the pebble radius is now taken into account and coated particle failure rates can be calculated under normal operating conditions. In addition, the absolute fission product release of an V/HTR pebble bed core can be calculated by using the newly developed burnup code Topological Nuclide Transformation (TNT) replacing the former rudimentary approach. As a new functionality, spatially resolved fission product release calculations for normal operating conditions as well as accident conditions can be performed. In case of a full-core calculation, a large number of individual pebbles which follow a random path through the reactor core can be simulated. The history of the individual pebble is recorded, too. Main input data such as spatially resolved neutron fluxes and fluid dynamics data are provided by the VSOP code. Capabilities of the FRESCO-I and SPATRA code which allow for the simulation of the redistribution of fission products within the primary circuit and the deposition of fission products on graphitic and metallic surfaces are also available in STACY. In this paper, details of the STACY model and first results for its application to the 200 MW(th) HTR
Energy Technology Data Exchange (ETDEWEB)
Maeng, Young Jae; Kim, Byoung Chul; Lim, Mi Joung; Kim, Kyung Sik; Jeon, Young Kyou [Korea Reactor Integrity Surveillance Technology, Daejeon (Korea, Republic of); Yoo, Chun Sung [Korea Atomic Energy Research Institutes, Daejeon (Korea, Republic of)
2013-10-15
The DORT code for 2D/1D synthesis has been actively applied to calculate the fast neutron (E>1.0MeV) fluence exposure of RPV. RAPTOR-M3G code is also applied for the comparison of 2D/1D synthesis, and it was found that 2D/1D synthesis method generally provided more conservative results than RAPTOR-M3G at both RPV and surveillance capsule locations. As a result, definitely RAPTOR-M3G for 3D calculation must apply for accurate evaluation of the integrity and ageing of RPV and internal structures. Therefore, the purpose of this paper is to compare the differences in terms of geometric aspect of KSNP model between 2D/1D synthesis and RAPTOR-M3G at core barrel area. 2D/1D synthesis method shows still higher results at the shortest distance of bypass water region. The reason is that 2D/1D synthesis method has excessive conservatism because of having just one model of R-θ and R-Z separately. Angles (5, 25, 45, 65 and 90 degrees) that RAPTOR-M3G results are higher than 2D/1D synthesis results seem to have almost regular interval. The reason can be that neutron flux to reach to barrel is affected by the nearest core definitely and all of near core areas including bypass water. RAPTOR-M3G performing 3D calculation can be applied to various reactor structures, because the code can simulate the model realistically and reasonably in geometric view points. Understanding the phenomenon that 45 degree shows downward peak, in spite of baffle corner location, remains.
Language in calculation: a core mechanism?
Benn, Yael; Zheng, Ying; Wilkinson, Iain D; Siegal, Michael; Varley, Rosemary
2012-01-01
Although there is evidence that exact calculation recruits left hemisphere perisylvian language systems, recent work has shown that exact calculation can be retained despite severe damage to these networks. In this study, we sought to identify a "core" network for calculation and hence to determine the extent to which left hemisphere language areas are part of this network. We examined performance on addition and subtraction problems in two modalities: one using conventional two-digit problems that can be easily encoded into language; the other using novel shape representations. With regard to numerical problems, our results revealed increased left fronto-temporal activity in addition, and increased parietal activity in subtraction, potentially reflecting retrieval of linguistically encoded information during addition. The shape problems elicited activations of occipital, parietal and dorsal temporal regions, reflecting visual reasoning processes. A core activation common to both calculation types involved the superior parietal lobule bilaterally, right temporal sub-gyral area, and left lateralized activations in inferior parietal (BA 40), frontal (BA 6/8/32) and occipital (BA 18) regions. The large bilateral parietal activation could be attributed to visuo-spatial processing in calculation. The inferior parietal region, and particularly the left angular gyrus, was part of the core calculation network. However, given its activation in both shape and number tasks, its role is unlikely to reflect linguistic processing per se. A possibility is that it serves to integrate right hemisphere visuo-spatial and left hemisphere linguistic and executive processing in calculation. Copyright © 2011 Elsevier Ltd. All rights reserved.
Radiation transport calculations and simulations.
Fassò, A; Ferrari, A; Sala, P R
2009-11-01
This article is an introduction to the Monte Carlo method as used in particle transport. After a description at an elementary level of the mathematical basis of the method, the Boltzmann equation and its physical meaning are presented, followed by Monte Carlo integration and random sampling, and by a general description of the main aspects and components of a typical Monte Carlo particle transport code. In particular, the most common biasing techniques are described, as well as the concepts of estimator and detector. After a discussion of the different types of errors, the issue of quality assurance is briefly considered.
Radiation Transport Calculations and Simulations
Energy Technology Data Exchange (ETDEWEB)
Fasso, Alberto; /SLAC; Ferrari, A.; /CERN
2011-06-30
This article is an introduction to the Monte Carlo method as used in particle transport. After a description at an elementary level of the mathematical basis of the method, the Boltzmann equation and its physical meaning are presented, followed by Monte Carlo integration and random sampling, and by a general description of the main aspects and components of a typical Monte Carlo particle transport code. In particular, the most common biasing techniques are described, as well as the concepts of estimator and detector. After a discussion of the different types of errors, the issue of Quality Assurance is briefly considered.
Energy Technology Data Exchange (ETDEWEB)
Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog
2005-03-15
Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too.
KARATE - a code for VVER-440 core calculation
Energy Technology Data Exchange (ETDEWEB)
Gado, J.; Hegedus, Cs.J.; Hegyi, Gy.; Kereszturi, A.; Makai, M.; Maraczi, Cs.; Telbisz, M.
1994-12-31
A modular calculation system has been elaborated at the KFKI Atomic Energy Research Institute for VVER-440 cores. The purpose of KARATE is the calculation of neutron physical and thermal-hydraulic processes in the core at normal, startup, and slow transient conditions. KARATE is under validation and verification (V&V) against mathematical, experimental, and operational data.
Core transport studies in fusion devices
Strand, Pär; Nordman, Hans
2010-01-01
The turbulence in magnetically confined fusion plasmas has important and non-trivial effects on the quality of the energy confinement. These effects are hard to make a quantitative assessment of analytically. The problem investigated in this article is the transport of energy and particles, in particular impurities, in a Tokamak plasma. Impurities from the walls of the plasma vessel cause energy losses if they reach the plasma core. It is therefore important to understand the transport mechanisms to prevent impurity accumulation and minimize losses. This is an area of research where turbulence plays a major role and is intimately associated with the performance of future fusion reactors, such as ITER.
Dose Rate Calculations for Rotary Mode Core Sampling Exhauster
Foust, D J
2000-01-01
This document provides the calculated estimated dose rates for three external locations on the Rotary Mode Core Sampling (RMCS) exhauster HEPA filter housing, per the request of Characterization Field Engineering.
Environment-based pin-power reconstruction method for homogeneous core calculations
Energy Technology Data Exchange (ETDEWEB)
Leroyer, H.; Brosselard, C.; Girardi, E. [EDF R and D/SINETICS, 1 av du General de Gaulle, F92141 Claman Cedex (France)
2012-07-01
Core calculation schemes are usually based on a classical two-step approach associated with assembly and core calculations. During the first step, infinite lattice assemblies calculations relying on a fundamental mode approach are used to generate cross-sections libraries for PWRs core calculations. This fundamental mode hypothesis may be questioned when dealing with loading patterns involving several types of assemblies (UOX, MOX), burnable poisons, control rods and burn-up gradients. This paper proposes a calculation method able to take into account the heterogeneous environment of the assemblies when using homogeneous core calculations and an appropriate pin-power reconstruction. This methodology is applied to MOX assemblies, computed within an environment of UOX assemblies. The new environment-based pin-power reconstruction is then used on various clusters of 3x3 assemblies showing burn-up gradients and UOX/MOX interfaces, and compared to reference calculations performed with APOLLO-2. The results show that UOX/MOX interfaces are much better calculated with the environment-based calculation scheme when compared to the usual pin-power reconstruction method. The power peak is always better located and calculated with the environment-based pin-power reconstruction method on every cluster configuration studied. This study shows that taking into account the environment in transport calculations can significantly improve the pin-power reconstruction so far as it is consistent with the core loading pattern. (authors)
Xenon instability study of large core Monte Carlo calculations
Energy Technology Data Exchange (ETDEWEB)
Bogdanova, E.V. [National Research Nuclear University ' MEPHi' , Moscow (Russian Federation); Gorodkov, S.S.
2016-09-15
One of the goals of neutronic calculations of large cores may be self-consistent distribution of equilibrium xenon through the reactor core. In deterministic calculations such self consistency is relatively simply achieved with the help of additional outer iterations by xenon, which can increase several times solution run time. But in stochastic calculation of large cores such increase is utterly undesirable, since even without these outer iterations it demands modeling of billion of histories, which in case of complicated large core may take about a day of 100 processors work. In addition the unavoidable statistical uncertainty here plays role of transient process, which excites xenon oscillations. In this work the rise of such oscillations and the way of their overcoming with the help of hybrid stochastic/deterministic calculation is studied. It is proposed to make at first single static Monte Carlo calculation of given core and to receive multi-group mesh cell characteristics for future use in operative code. This one will evaluate xenon distribution through the core, which will be equilibrium for deterministic solution and substantially close to equilibrium Monte Carlo solution, paid with enormous computing cost.
Transport calculations of antiproton-nucleus interactions
Larionov, A B; Pshenichnov, I A; Satarov, L M; Greiner, W
2010-01-01
The Giessen Boltzmann-Uehling-Uhlenbeck transport model is extended and applied to the antiproton-nucleus interactions in a wide beam momentum range. The model calculations are compared with the experimental data on $\\bar p$-absorption cross sections on nuclei with an emphasis on extraction of the real part of an antiproton optical potential. The possibility of the cold compression of a nucleus by an antiproton in-flight is also considered.
Core Physics and Kinetics Calculations for the Fissioning Plasma Core Reactor
Butler, C.; Albright, D.
2007-01-01
Highly efficient, compact nuclear reactors would provide high specific impulse spacecraft propulsion. This analysis and numerical simulation effort has focused on the technical feasibility issues related to the nuclear design characteristics of a novel reactor design. The Fissioning Plasma Core Reactor (FPCR) is a shockwave-driven gaseous-core nuclear reactor, which uses Magneto Hydrodynamic effects to generate electric power to be used for propulsion. The nuclear design of the system depends on two major calculations: core physics calculations and kinetics calculations. Presently, core physics calculations have concentrated on the use of the MCNP4C code. However, initial results from other codes such as COMBINE/VENTURE and SCALE4a. are also shown. Several significant modifications were made to the ISR-developed QCALC1 kinetics analysis code. These modifications include testing the state of the core materials, an improvement to the calculation of the material properties of the core, the addition of an adiabatic core temperature model and improvement of the first order reactivity correction model. The accuracy of these modifications has been verified, and the accuracy of the point-core kinetics model used by the QCALC1 code has also been validated. Previously calculated kinetics results for the FPCR were described in the ISR report, "QCALC1: A code for FPCR Kinetics Model Feasibility Analysis" dated June 1, 2002.
Molecular transport calculations with Wannier Functions
DEFF Research Database (Denmark)
Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel
2005-01-01
We present a scheme for calculating coherent electron transport in atomic-scale contacts. The method combines a formally exact Green's function formalism with a mean-field description of the electronic structure based on the Kohn-Sham scheme of density functional theory. We use an accurate plane...... is applied to a hydrogen molecule in an infinite Pt wire and a benzene-dithiol (BDT) molecule between Au(111) surfaces. We show that the transmission function of BDT in a wide energy window around the Fermi level can be completely accounted for by only two molecular orbitals. (c) 2005 Elsevier B.V. All...
Energy Technology Data Exchange (ETDEWEB)
Jammes, Ch
1997-11-28
The aim of this work is to create, validate theoretically and experimentally a calculation route for a thermal irradiation reactor. This is the research reactor of the University of Strasbourg, which presents all of characteristics of this reactor-type: compact and heterogeneous core, slab-type fuel with a high 235-uranium enrichment. This calculation route is based on the first use of the following two modern transport methods: the TDT method and the Monte Carlo method. The former, programmed within the APOLLO2 code, is a two dimensional collision probabilities method. The later, used by the TRIPOLI4 code, is a stochastic method. Both can be applied to complex geometries. After a few theoretical reminders about transport codes, a set of integral experiments is described which have been realized within the research reactor of the University of Strasbourg. One of them has been performed for this study. At the beginning of the theoretical part, significant errors are apparent due to the use of calculation route based on homogenization, condensation and the diffusion approximation. An extensive comparison between the discrete ordinates method and the TDT method carries out that the use of the TDT method is relevant for the studied reactor. The treatment of axial leakage with this method is the only disadvantage. Therefore, the use of the code TRIPOLI4 is recommended for a more accurate study of leakage within a reflector. By means of the experimental data, the ability of our calculation route is confirmed for essential neutronics questions such as the critical mass determination, the power distribution and the fuel management. (author)
Transport and influence of angular momentum in collapsing dense cores
Hennebelle, P.
2013-09-01
Angular momentum is playing a key role during the collapse of prestellar cores since it is leading to disk formation and to some extent to binary formation. On the other hand, it has long been recognized that the stars possess a tiny fraction of the initial momentum that their parent clouds retain, an issue known as the "angular momentum problem". In these lectures, we attempt to present the most recent calculations performed to investigate the angular momentum transport and the influence angular momentum has, during the collapse of prestellar cores. After a brief introduction of the star formation context and a broad description of the important features within collapsing cores, we discuss the so-called catastrophic braking. Indeed when magnetic field and rotation axis are aligned, the magnetic braking is so efficient that the formation of early disks is completely prevented. We then present the various studies which have attempted to explore the robustness of this efficient transport including influence of non-ideal MHD, misalignment between magnetic field and rotation axis and turbulence. While the role of the first, is not entirely clear; the two other effects diminish the efficacity of the magnetic braking making the issue less severe than in the pure ideal MHD aligned configuration. Finally, we discuss the fragmentation of low and high mass cores with particular emphasis on the impact of the magnetic field. In particular, we discuss the drastic stabilization that magnetic field has on low mass cores and the possible solution to this apparent conundrum. In the context of high mass stars, its influence is much more limited reducing the number of fragments by a factor of the order of two. However when both radiative feedback and magentic field are included, the fragmentation is very significantly reduced.
Framework Application for Core Edge Transport Simulation (FACETS)
Energy Technology Data Exchange (ETDEWEB)
Krasheninnikov, Sergei; Pigarov, Alexander
2011-10-15
The FACETS (Framework Application for Core-Edge Transport Simulations) project of Scientific Discovery through Advanced Computing (SciDAC) Program was aimed at providing a high-fidelity whole-tokamak modeling for the U.S. magnetic fusion energy program and ITER through coupling separate components for each of the core region, edge region, and wall, with realistic plasma particles and power sources and turbulent transport simulation. The project also aimed at developing advanced numerical algorithms, efficient implicit coupling methods, and software tools utilizing the leadership class computing facilities under Advanced Scientific Computing Research (ASCR). The FACETS project was conducted by a multi-discipline, multi-institutional teams, the Lead PI was J.R. Cary (Tech-X Corp.). In the FACETS project, the Applied Plasma Theory Group at the MAE Department of UCSD developed the Wall and Plasma-Surface Interaction (WALLPSI) module, performed its validation against experimental data, and integrated it into the developed framework. WALLPSI is a one-dimensional, coarse grained, reaction/advection/diffusion code applied to each material boundary cell in the common modeling domain for a tokamak. It incorporates an advanced model for plasma particle transport and retention in the solid matter of plasma facing components, simulation of plasma heat power load handling, calculation of erosion/deposition, and simulation of synergistic effects in strong plasma-wall coupling.
Efficient implementation of core-excitation Bethe Salpeter equation calculations
Gilmore, K; Shirley, E L; Prendergast, D; Pemmaraju, C D; Kas, J J; Vila, F D; Rehr, J J
2016-01-01
We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including x-ray absorption (XAS), x-ray emission (XES), and both resonant and non-resonant inelastic x-ray scattering spectra (N/RIXS). Calculations are based on density functional theory (DFT) electronic structures generated either by abinit or Quantumespresso, both plane-wave basis, pseudopotential codes. This electronic structure is improved through the inclusion of a GW self energy. The projector augmented wave technique is used to evaluate transition matrix elements between core-level and band states. Final two-particle scattering states are obtained with the NIST core-level BSE solver (NBSE). We have previously reported this implementation, which we refer to as ocean (Obtaining Core Excitations from Ab initio electronic structure and NBSE) [Phys. Rev. B 83, 115106 (2011)]. Here, we present additional efficiencies that enable us to evaluate spectra for systems ten times larger than previous...
Neutron and photon transport calculations in fusion system. 2
Energy Technology Data Exchange (ETDEWEB)
Sato, Satoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment
1998-03-01
On the application of MCNP to the neutron and {gamma}-ray transport calculations for fusion reactor system, the wide range design calculation has been carried out in the engineering design activities for the international thermonuclear fusion experimental reactor (ITER) being developed jointly by Japan, USA, EU and Russia. As the objects of shielding calculation for fusion reactors, there are the assessment of dose equivalent rate for living body shielding and the assessment of the nuclear response for the soundness of in-core structures. In the case that the detailed analysis of complicated three-dimensional shapes is required, the assessment using MCNP has been carried out. Also when the nuclear response of peripheral equipment due to the gap streaming between blanket modules is evaluated with good accuracy, the calculation with MCNP has been carried out. The analyses of the shieldings for blanket modules and NBI port are explained, and the examples of the results of analyses are shown. In the blanket modules, there are penetrating holes and continuous gap. In the case of the NBI port, shielding plug cannot be installed. These facts necessitate the MCNP analysis with high accuracy. (K.I.)
Calculation of transport coefficients in an axisymmetric plasma
Energy Technology Data Exchange (ETDEWEB)
Shumaker, D.E.
1977-01-01
A method of calculating the transport coefficient in an axisymmetric toroidal plasma is presented. This method is useful in calculating the transport coefficients in a Tokamak plasma confinement device. The particle density and temperature are shown to be a constant on a magnetic flux surface. Transport equations are given for the total particle flux and total energy flux crossing a closed toroidal surface. Also transport equations are given for the toroidal magnetic flux. A computer code was written to calculate the transport coefficients for a three species plasma, electrons and two species of ions. This is useful for calculating the transport coefficients of a plasma which contains impurities. It was found that the particle and energy transport coefficients are increased by a large amount, and the transport coefficients for the toroidal magnetic field are reduced by a small amount.
Energy Technology Data Exchange (ETDEWEB)
Magat, Ph
1997-04-01
The aim of this study is to compare two calculation methods implemented in the neutronic code CRONOS 2: the diffusion approximation and the SP{sub n} method. The APOLLO 2 code is used to build the multiparameter cross section libraries.The comparison is based on the first core of N4 type Chooz reactor. The rod worth and the power map have been calculated. Some recommendations about the SP{sub n} development order of flux are made and the results show that the diffusion calculations over-estimate the black rod efficiency up to 10%. (A.C.) 12 refs.
DFT calculation of core-electron binding energies
Energy Technology Data Exchange (ETDEWEB)
Takahata, Yuji; Chong, Delano P. E-mail: chong@chem.ubc.ca
2003-11-01
A total of 59 core-electron binding energies (CEBEs) were studied with the Amsterdam Density Functional Program (ADF) program and compared with the observed values. The results indicate that a polarized triple-zeta basis set of Slater-type orbitals is adequate for routine assessment of the performance of each method of computation. With such a basis set, seven density functionals were tested. In addition, the performance of 21 energy density functionals were computed from the density calculated with the statistical average of orbital potentials (SAOP). Among all the choices tested, the best density functional for core-electron binding energies of C to F turns out to be the combination of Perdew-Wang (1986) functional for exchange and the Perdew-Wang (1991) functional for correlation, confirming earlier studies based on contracted Gaussian-type orbitals. For this best functional, five Slater-type orbital basis sets were examined, ranging from polarized double-zeta quality to the largest set available in the ADF package. For the best functional with the best basis set, the average absolute deviation (AAD) of the calculated value from experiment is only 0.16 eV.
Recent Developments in No-Core Shell-Model Calculations
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Quaglioni, S; Stetcu, I; Barrett, B R
2009-03-20
We present an overview of recent results and developments of the no-core shell model (NCSM), an ab initio approach to the nuclear many-body problem for light nuclei. In this aproach, we start from realistic two-nucleon or two- plus three-nucleon interactions. Many-body calculations are performed using a finite harmonic-oscillator (HO) basis. To facilitate convergence for realistic inter-nucleon interactions that generate strong short-range correlations, we derive effective interactions by unitary transformations that are tailored to the HO basis truncation. For soft realistic interactions this might not be necessary. If that is the case, the NCSM calculations are variational. In either case, the ab initio NCSM preserves translational invariance of the nuclear many-body problem. In this review, we, in particular, highlight results obtained with the chiral two- plus three-nucleon interactions. We discuss efforts to extend the applicability of the NCSM to heavier nuclei and larger model spaces using importance-truncation schemes and/or use of effective interactions with a core. We outline an extension of the ab initio NCSM to the description of nuclear reactions by the resonating group method technique. A future direction of the approach, the ab initio NCSM with continuum, which will provide a complete description of nuclei as open systems with coupling of bound and continuum states is given in the concluding part of the review.
Uncertainty calculation in transport models and forecasts
DEFF Research Database (Denmark)
Manzo, Stefano; Prato, Carlo Giacomo
in a four-stage transport model related to different variable distributions (to be used in a Monte Carlo simulation procedure), assignment procedures and levels of congestion, at both the link and the network level. The analysis used as case study the Næstved model, referring to the Danish town of Næstved2...... the uncertainty propagation pattern over time specific for key model outputs becomes strategically important. 1 Manzo, S., Nielsen, O. A. & Prato, C. G. (2014). The Effects of uncertainty in speed-flow curve parameters on a large-scale model. Transportation Research Record, 1, 30-37. 2 Manzo, S., Nielsen, O. A...
LDRD Final Review: Radiation Transport Calculations
Energy Technology Data Exchange (ETDEWEB)
Goorley, John Timothy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Morgan, George Lake [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lestone, John Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-06-22
Both high-fidelity & toy simulations are being used to understand measured signals and improve the Area 11 NDSE diagnostic. We continue to gain more and more confidence in the ability for MCNP to simulate neutron and photon transport from source to radiation detector.
Guideline of Monte Carlo calculation. Neutron/gamma ray transport simulation by Monte Carlo method
2002-01-01
This report condenses basic theories and advanced applications of neutron/gamma ray transport calculations in many fields of nuclear energy research. Chapters 1 through 5 treat historical progress of Monte Carlo methods, general issues of variance reduction technique, cross section libraries used in continuous energy Monte Carlo codes. In chapter 6, the following issues are discussed: fusion benchmark experiments, design of ITER, experiment analyses of fast critical assembly, core analyses of JMTR, simulation of pulsed neutron experiment, core analyses of HTTR, duct streaming calculations, bulk shielding calculations, neutron/gamma ray transport calculations of the Hiroshima atomic bomb. Chapters 8 and 9 treat function enhancements of MCNP and MVP codes, and a parallel processing of Monte Carlo calculation, respectively. An important references are attached at the end of this report.
Nonlinear acceleration of SN transport calculations
Energy Technology Data Exchange (ETDEWEB)
Fichtl, Erin D [Los Alamos National Laboratory; Warsa, James S [Los Alamos National Laboratory; Calef, Matthew T [Los Alamos National Laboratory
2010-12-20
The use of nonlinear iterative methods, Jacobian-Free Newton-Krylov (JFNK) in particular, for solving eigenvalue problems in transport applications has recently become an active subject of research. While JFNK has been shown to be effective for k-eigenvalue problems, there are a number of input parameters that impact computational efficiency, making it difficult to implement efficiently in a production code using a single set of default parameters. We show that different selections for the forcing parameter in particular can lead to large variations in the amount of computational work for a given problem. In contrast, we present a nonlinear subspace method that sits outside and effectively accelerates nonlinear iterations of a given form and requires only a single input parameter, the subspace size. It is shown to consistently and significantly reduce the amount of computational work when applied to fixed-point iteration, and this combination of methods is shown to be more efficient than JFNK for our application.
Boltzmann transport calculation of collinear spin transport on short timescales
Nenno, Dennis M.; Kaltenborn, Steffen; Schneider, Hans Christian
2016-09-01
A spin-dependent Boltzmann transport equation is used to describe charge and spin dynamics resulting from the excitation of hot electrons in a ferromagnet/normal metal heterostructure. As the microscopic Boltzmann equation works with k -dependent distribution functions, it can describe far-from-equilibrium excitations, which are outside the scope of drift-diffusion theories. We study different scenarios for spin-dependent carrier injection into a nonmagnetic metal using an effectively two-dimensional phase space. While the charge signal is robust for various excitation schemes, the shape of the resulting spin current/density depends critically on the interplay between transport and scattering, and on the energetic distribution of the injected carriers. Our results imply that the energy dependence of the injected hot electrons has a decisive effect on the spin dynamics.
Hybrid parallel code acceleration methods in full-core reactor physics calculations
Energy Technology Data Exchange (ETDEWEB)
Courau, T.; Plagne, L.; Ponicot, A. [EDF R and D, 1, Avenue du General de Gaulle, 92141 Clamart Cedex (France); Sjoden, G. [Nuclear and Radiological Engineering, Georgia Inst. of Technology, Atlanta, GA 30332 (United States)
2012-07-01
When dealing with nuclear reactor calculation schemes, the need for three dimensional (3D) transport-based reference solutions is essential for both validation and optimization purposes. Considering a benchmark problem, this work investigates the potential of discrete ordinates (Sn) transport methods applied to 3D pressurized water reactor (PWR) full-core calculations. First, the benchmark problem is described. It involves a pin-by-pin description of a 3D PWR first core, and uses a 8-group cross-section library prepared with the DRAGON cell code. Then, a convergence analysis is performed using the PENTRAN parallel Sn Cartesian code. It discusses the spatial refinement and the associated angular quadrature required to properly describe the problem physics. It also shows that initializing the Sn solution with the EDF SPN solver COCAGNE reduces the number of iterations required to converge by nearly a factor of 6. Using a best estimate model, PENTRAN results are then compared to multigroup Monte Carlo results obtained with the MCNP5 code. Good consistency is observed between the two methods (Sn and Monte Carlo), with discrepancies that are less than 25 pcm for the k{sub eff}, and less than 2.1% and 1.6% for the flux at the pin-cell level and for the pin-power distribution, respectively. (authors)
Road Transport Congestion Costs Calculations-Adaptation to Engineering Approach
Directory of Open Access Journals (Sweden)
Marjan Lep
2008-01-01
Full Text Available The article represents so called engineering approach for computing the total road transport congestion costs. According to economic welfare theory, the total costs of transport congestion are defined as dead weight loss (DWL of infrastructure use. With a set of equations DWL could be formulated in a mathematical way. Because such form of equation is not directly applicable for concrete road network calculations it should be transformed into engineering form, which comprises transport engineering related data as classified road links, traffic volumes, passenger unit costs, etc. The equation is well applicable on the interurban road network; adaptations are needed for the urban road network cost calculations, where time losses are not so much related to the link travel time. The final equation was derived for the purposes of national road congestion cost calculation.
Improvement of neutronic calculations on a Masurca core using adaptive mesh refinement capabilities
Energy Technology Data Exchange (ETDEWEB)
Fournier, D.; Archier, P.; Le Tellier, R.; Suteau, C., E-mail: damien.fournier@cea.fr, E-mail: pascal.archier@cea.fr, E-mail: romain.le-tellier@cea.fr, E-mail: christophe.suteau@cea.fr [CEA, DEN, DER/SPRC/LEPh, Cadarache, Saint Paul-lez-Durance (France)
2011-07-01
The simulation of 3D cores with homogenized assemblies in transport theory remains time and memory consuming for production calculations. With a multigroup discretization for the energy variable and a discrete ordinate method for the angle, a system of about 10{sup 4} coupled hyperbolic transport equations has to be solved. For these equations, we intend to optimize the spatial discretization. In the framework of the SNATCH solver used in this study, the spatial problem is dealt with by using a structured hexahedral mesh and applying a Discontinuous Galerkin Finite Element Method (DGFEM). This paper shows the improvements due to the development of Adaptive Mesh Refinement (AMR) methods. As the SNATCH solver uses a hierarchical polynomial basis, p−refinement is possible but also h−refinement thanks to non conforming capabilities. Besides, as the flux spatial behavior is highly dependent on the energy, we propose to adapt differently the spatial discretization according to the energy group. To avoid dealing with too many meshes, some energy groups are joined and share the same mesh. The different energy-dependent AMR strategies are compared to each other but also with the classical approach of a conforming and highly refined spatial mesh. This comparison is carried out on different quantities such as the multiplication factor, the flux or the current. The gain in time and memory is shown for 2D and 3D benchmarks coming from the ZONA2B experimental core configuration of the MASURCA mock-up at CEA Cadarache. (author)
Graphical User Interface for Simplified Neutron Transport Calculations
Energy Technology Data Exchange (ETDEWEB)
Schwarz, Randolph; Carter, Leland L
2011-07-18
A number of codes perform simple photon physics calculations. The nuclear industry is lacking in similar tools to perform simplified neutron physics shielding calculations. With the increased importance of performing neutron calculations for homeland security applications and defense nuclear nonproliferation tasks, having an efficient method for performing simple neutron transport calculations becomes increasingly important. Codes such as Monte Carlo N-particle (MCNP) can perform the transport calculations; however, the technical details in setting up, running, and interpreting the required simulations are quite complex and typically go beyond the abilities of most users who need a simple answer to a neutron transport calculation. The work documented in this report resulted in the development of the NucWiz program, which can create an MCNP input file for a set of simple geometries, source, and detector configurations. The user selects source, shield, and tally configurations from a set of pre-defined lists, and the software creates a complete MCNP input file that can be optionally run and the results viewed inside NucWiz.
Efficient wave-function matching approach for quantum transport calculations
DEFF Research Database (Denmark)
Sørensen, Hans Henrik Brandenborg; Hansen, Per Christian; Petersen, Dan Erik;
2009-01-01
The wave-function matching (WFM) technique has recently been developed for the calculation of electronic transport in quantum two-probe systems. In terms of efficiency it is comparable to the widely used Green's function approach. The WFM formalism presented so far requires the evaluation of all ...
Energy Technology Data Exchange (ETDEWEB)
Sugino, Kazuteru [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center
1998-07-01
As a tool to perform a fast reactor core calculations with high accuracy, NSHEX the nodal transport calculation code for three-dimensional hexagonal-Z geometry is under development. To improve the practical applicability of NSHEX, for instance, in its application to safety analysis and commercial reactor core design studies, we investigated the basic theory used in it, improved the program performance, and evaluated its applicability to the analysis of commercial reactor cores. The current studies show the following: (1) An improvement in the treatment of radial leakage in the radial nodal coupling equation bettered calculational convergence for safety analysis calculation, so the applicability of NSHEX to safety analysis was improved. (2) As a result of comparison of results from NSHEX and the standard core calculation code, it was confirmed that there was consistency between them. (3) According to the evaluation of the effect due to the difference of calculational condition, it was found that the calculation under appropriate nodal expansion orders and Sn orders correspond to the one under most detailed condition. However further investigation is required to reduce the uncertainty in calculational results due to the treatment of high order flux moments. (4) A whole core version of NSHEX enabling calculation for any FBR core geometry has been developed, this improved general applicability of NSHEX. (5) An investigation of the applicability of the rebalance method to acceleration clarified that this improved calculational convergence and it was effective. (J.P.N.)
Efficient calculation of dissipative quantum transport properties in semiconductor nanostructures
Energy Technology Data Exchange (ETDEWEB)
Greck, Peter
2012-11-26
We present a novel quantum transport method that follows the non-equilibrium Green's function (NEGF) framework but side steps any self-consistent calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. We termed this method the multi-scattering Buettiker-Probe (MSB) method. It generalizes the so-called Buettiker-Probe model but takes into account all relevant individual scattering mechanisms. It is orders of magnitude more efficient than a fully selfconsistent non-equilibrium Green's function calculation for realistic devices, yet accurately reproduces the results of the latter method as well as experimental data. This method is fairly easy to implement and opens the path towards realistic three-dimensional quantum transport calculations. In this work, we review the fundamentals of the non-equilibrium Green's function formalism for quantum transport calculations. Then, we introduce our novel MSB method after briefly reviewing the original Buettiker-Probe model. Finally, we compare the results of the MSB method to NEGF calculations as well as to experimental data. In particular, we calculate quantum transport properties of quantum cascade lasers in the terahertz (THz) and the mid-infrared (MIR) spectral domain. With a device optimization algorithm based upon the MSB method, we propose a novel THz quantum cascade laser design. It uses a two-well period with alternating barrier heights and complete carrier thermalization for the majority of the carriers within each period. We predict THz laser operation for temperatures up to 250 K implying a new temperature record.
Energy Technology Data Exchange (ETDEWEB)
Chen, Y. [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Zhuang, G.; Ross, P.N. [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Van Hove, M.A.; Fadley, C.S. [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)]|[Department of Physics, University of California at Davis, Davis, California 95616 (United States)
1998-10-01
The equivalent-core approximation is implemented in a novel way so as to calculate core-level relaxation energies in photoelectron spectroscopy. The method is based on self-consistent field (SCF) Hartree{endash}Fock molecular-orbital calculations via linear combinations of atomic orbitals, and involves evaluating the difference of sums of two-electron Coulomb and exchange integrals, for all electrons in an atom and in its equivalent-core ion. By thus avoiding SCF calculations with a core hole present (the true final state of photoemission), this procedure is shown to significantly save computing time in comparison with an exact SCF direct-hole calculation. Application of the method in single atoms and selected molecules shows about a 10{percent} difference with respect to direct-hole calculation results. The approximation introduces about 1{endash}6 eV errors compared to the experimental results of gas phase molecules. This method thus should be a generally useful procedure for estimating relaxation energies in core spectra. {copyright} {ital 1998 American Institute of Physics.}
Energy Technology Data Exchange (ETDEWEB)
Liang, Jingang; Wang, Kan; Qiu, Yishu [Dept. of Engineering Physics, LiuQing Building, Tsinghua University, Beijing (China); Chai, Xiao Ming; Qiang, Sheng Long [Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu (China)
2016-06-15
Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC) codes in accomplishing pin-wise three-dimensional (3D) full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC) code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.
Exposure calculation code module for reactor core analysis: BURNER
Energy Technology Data Exchange (ETDEWEB)
Vondy, D.R.; Cunningham, G.W.
1979-02-01
The code module BURNER for nuclear reactor exposure calculations is presented. The computer requirements are shown, as are the reference data and interface data file requirements, and the programmed equations and procedure of calculation are described. The operating history of a reactor is followed over the period between solutions of the space, energy neutronics problem. The end-of-period nuclide concentrations are determined given the necessary information. A steady state, continuous fueling model is treated in addition to the usual fixed fuel model. The control options provide flexibility to select among an unusually wide variety of programmed procedures. The code also provides user option to make a number of auxiliary calculations and print such information as the local gamma source, cumulative exposure, and a fine scale power density distribution in a selected zone. The code is used locally in a system for computation which contains the VENTURE diffusion theory neutronics code and other modules.
Exposure calculation code module for reactor core analysis: BURNER
Energy Technology Data Exchange (ETDEWEB)
Vondy, D.R.; Cunningham, G.W.
1979-02-01
The code module BURNER for nuclear reactor exposure calculations is presented. The computer requirements are shown, as are the reference data and interface data file requirements, and the programmed equations and procedure of calculation are described. The operating history of a reactor is followed over the period between solutions of the space, energy neutronics problem. The end-of-period nuclide concentrations are determined given the necessary information. A steady state, continuous fueling model is treated in addition to the usual fixed fuel model. The control options provide flexibility to select among an unusually wide variety of programmed procedures. The code also provides user option to make a number of auxiliary calculations and print such information as the local gamma source, cumulative exposure, and a fine scale power density distribution in a selected zone. The code is used locally in a system for computation which contains the VENTURE diffusion theory neutronics code and other modules.
Development of Library Processing System for Neutron Transport Calculation
Energy Technology Data Exchange (ETDEWEB)
Song, J. S.; Park, S. Y.; Kim, H. Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] (and others)
2008-12-15
A system for library generation was developed for the lattice neutron transport program for pressurized water reactor core analysis. The system extracts multi energy group nuclear data for requested nuclides from ENDF/B whose data are based on continuous energy, generates hydrogen equivalent factor and resonance integral table as functions of temperature and background cross section for resonance nuclides, generates subgroup data for the lattice program to treat resonance exactly as possible, and generates multi-group neutron library file including nuclide depletion data for use of the lattice program.
Heavy ion transport in the core of ASDEX upgrade
Energy Technology Data Exchange (ETDEWEB)
Odstrcil, Tomas [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); Physik-Department E28, Technische Universitaet Muenchen, 85747 Garching (Germany); Puetterich, Thomas; Angioni, Clemente; Bilato, Roberto; Gude, Anja; Vezinet, Didier [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); Mazon, Didier [CEA, IRFM F-13108 Saint Paul-lez-Durance (France); Collaboration: ASDEX Upgrade Team
2016-07-01
High impurity concentration in the core of the future fusion reactors can lead to the serious degradation of the achievable fusion gain. Therefore, a better understanding of the underlying impurity transport processes is necessary for higher performance, more efficient power exhaust and avoidance of impurity accumulation. Radial impurity transport is mainly driven by neoclassical and turbulent particle fluxes. Both these components show substantial variation depending on the poloidal angle. Consequently, an asymmetry in the poloidal distribution of impurities leads to significant changes in the radial impurity flow and the total content of the plasma core. The aim of this contribution is to experimentally verify a model describing the poloidal asymmetry of heavy impurities using measurements from ASDEX Upgrade. The observed asymmetries are caused mainly by the centrifugal force and poloidal electric force created by the fast particles produced by intensive ion-cyclotron heating. Finally, a change in the radial transport of the tungsten ions will be presented in the case of large inboard and outboard impurity accumulation.
Direct method for calculating temperature-dependent transport properties
Liu, Yi; Yuan, Zhe; Wesselink, R. J. H.; Starikov, Anton A.; van Schilfgaarde, Mark; Kelly, Paul J.
2015-06-01
We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. By introducing a simple Debye-like model of spin disorder parameterized to reproduce the experimental magnetization, the temperature dependence of the average resistivity, the anisotropic magnetoresistance, and the spin polarization of a Ni80Fe20 alloy are calculated and found to be in good agreement with existing data. Extension of the method to complex, inhomogeneous materials as well as to the calculation of other finite-temperature physical properties within the adiabatic approximation is straightforward.
Accounting for chemical kinetics in field scale transport calculations
Energy Technology Data Exchange (ETDEWEB)
Bryan, N.D. [Manchester Univ. (United Kingdom). Dept. of Chemistry
2005-04-01
The modelling of column experiments has shown that the humic acid mediated transport of metal ions is dominated by the non-exchangeable fraction. Metal ions enter this fraction via the exchangeable fraction, and may transfer back again. However, in both directions these chemical reactions are slow. Whether or not a kinetic description of these processes is required during transport calculations, or an assumption of local equilibrium will suffice, will depend upon the ratio of the reaction half-time to the residence time of species within the groundwater column. If the flow rate is sufficiently slow or the reaction sufficiently fast then the assumption of local equilibrium is acceptable. Alternatively, if the reaction is sufficiently slow (or the flow rate fast), then the reaction may be 'decoupled', i.e. removed from the calculation. These distinctions are important, because calculations involving chemical kinetics are computationally very expensive, and should be avoided wherever possible. In addition, column experiments have shown that the sorption of humic substances and metal-humate complexes may be significant, and that these reactions may also be slow. In this work, a set of rules is presented that dictate when the local equilibrium and decoupled assumptions may be used. In addition, it is shown that in all cases to a first approximation, the behaviour of a kinetically controlled species, and in particular its final distribution against distance at the end of a calculation, depends only upon the ratio of the reaction first order rate to the residence time, and hence, even in the region where the simplifications may not be used, the behaviour is predictable. In this way, it is possible to obtain an estimate of the migration of these species, without the need for a complex transport calculation. (orig.)
Experiment and calculation on seismic behavior of RC composite core walls with concealed steel truss
Institute of Scientific and Technical Information of China (English)
Wanlin CAO; Weihua CHANG; Changjun ZHAO; Jianwei ZHANG
2009-01-01
To improve the seismic performance of reinforced concrete core walls, reinforced concrete com-posite core walls with concealed steel truss were proposed and systemically investigated. Two 1/6 scale core wall specimens, including a normal reinforced concrete core wall and a reinforced concrete composite core wall with concealed steel truss, were designed. The experimental study on seismic performance under cyclic loading was carried out. The load-carrying capacity, stiffness, ductility,hysteretic behavior and energy dissipation of the core walls were discussed. The test results showed that the seismic performance of core walls is improved greatly by the concealed steel truss. The calculated results were found to agree well with the actual measured ones.
Calculations of Bed-Material Transport, Chetco River, Oregon
Anderson, S.; Wallick, R.; Cannon, C.; O'Connor, J. E.
2009-12-01
The Chetco River drains 914 square kilometers of the Klamath Mountains in far southwestern Oregon. The lower 18 kilometers of the river are flanked by large and abundant gravel bars, which have been commercially mined for aggregate during most of the last century. Increasing concern regarding the impact of this mining on aquatic habitats motivated an assessment of historical channel change and sediment transport rates along this lower reach. A key component of this research was estimating bed-material transport through the application of sediment transport equations at multiple locations along the study reach. Flow hydraulics were estimated with a 1-D hydraulic model constructed in HEC-RAS, using a combination of LiDAR and bathymetric surveys to characterize the valley morphology. Once calibrated to USGS rating curves, low flow water surfaces, and several high flow photos, this model allowed us to calculate energy slopes for a given cross section at a variety of flows. These flow-energy slope pairs, along with cross sections and sediment data collected from surface pebble counts, were then applied to a number of different modern bedload transport equations. This process was facilitated by the Bedload Assessment in Gravel-bedded Streams Excel macro, or BAGS, which allows users to quickly apply multiple transport equations using a single set of inputs (Pitlick et al., 2009). A review of the literature, along with tests of internal consistency and comparisons to direct bedload measurements taken in the winter of 2008-09, led us to choose the Parker (1991) and Wilcock-Crowe (2003) equations as the two most applicable to the Chetco River. Sediment transport-flow curves for both equations were calculated for seven cross sections spanning the study area. For each of these cross sections, we estimated annual transport fluxes using derived transport rating curves in conjunction with unit flow data from a USGS gage at the upstream end of study reach, with data extending back
An accurate {delta}f method for neoclassical transport calculation
Energy Technology Data Exchange (ETDEWEB)
Wang, W.X.; Nakajima, N.; Murakami, S.; Okamoto, M. [National Inst. for Fusion Science, Toki, Gifu (Japan)
1999-03-01
A {delta}f method, solving drift kinetic equation, for neoclassical transport calculation is presented in detail. It is demonstrated that valid results essentially rely on the correct evaluation of marker density g in weight calculation. A general and accurate weighting scheme is developed without using some assumed g in weight equation for advancing particle weights, unlike the previous schemes. This scheme employs an additional weight function to directly solve g from its kinetic equation using the idea of {delta}f method. Therefore the severe constraint that the real marker distribution must be consistent with the initially assumed g during a simulation is relaxed. An improved like-particle collision scheme is presented. By performing compensation for momentum, energy and particle losses arising from numerical errors, the conservations of all the three quantities are greatly improved during collisions. Ion neoclassical transport due to self-collisions is examined under finite banana case as well as zero banana limit. A solution with zero particle and zero energy flux (in case of no temperature gradient) over whole poloidal section is obtained. With the improvement in both like-particle collision scheme and weighting scheme, the {delta}f simulation shows a significantly upgraded performance for neoclassical transport study. (author)
Quinet, Pascal
2014-09-01
A detailed investigation of the atomic structure and radiative parameters involving the lowest states within the 6p4, 6p36d, 6p37s, 6p37p and 6p37d configurations of neutral polonium is reported in the present paper. Using different physical models based on the pseudo-relativistic Hartree-Fock approach, the influence of intravalence, core-valence and core-core electron correlation on the atomic parameters is discussed in detail. This work allowed us to fix the spectroscopic designation of some experimental level energy values and to provide for the first time a set of reliable oscillator strengths corresponding to 31 Po I spectral lines in the wavelength region from 175 to 987 nm.
Hydraulic calculation of gravity transportation pipeline system for backfill slurry
Institute of Scientific and Technical Information of China (English)
ZHANG Qin-li; HU Guan-yu; WANG Xin-min
2008-01-01
Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline transportation of backfill slurry were investigated. The results show that the backfill capability of the backfill system should be higher than 74.4m3/h according to the mining production and backfill times in the mine; the minimum velocity (critical velocity) and practical working velocity of the backfill slurry are 1.44 and 3.82m/s, respectively. Various formulae give the maximum ratio of total length to vertical height of pipeline (L/H ratio) of the backfill system of 5.4, and then the reliability and capability of the system can be evaluated.
Quantum confinement effect in Si/Ge core-shell nanowires: First-principles calculations
Yang, Li; Musin, Ryza N.; Wang, Xiao-Qian; Chou, M. Y.
2008-05-01
The electronic structure of Si/Ge core-shell nanowires along the [110] and [111] directions are studied with first-principles calculations. We identify the near-gap electronic states that are spatially separated within the core or the shell region, making it possible for a dopant to generate carriers in a different region. The confinement energies of these core and shell states provide an operational definition of the “band offset,” which is not only size dependent but also component dependent. The optimal doping strategy in Si/Ge core-shell nanowires is proposed based on these energy results.
ON THE ACCELERATION OF SHORTEST PATH CALCULATIONS IN TRANSPORTATION NETWORKS
Energy Technology Data Exchange (ETDEWEB)
BAKER, ZACHARY K. [Los Alamos National Laboratory; GOKHALE, MAYA B. [Los Alamos National Laboratory
2007-01-08
Shortest path algorithms are a key element of many graph problems. They are used in such applications as online direction finding and navigation, as well as modeling of traffic for large scale simulations of major metropolitan areas. As the shortest path algorithms are an execution bottleneck, it is beneficial to move their execution to parallel hardware such as Field-Programmable Gate Arrays (FPGAs). Hardware implementation is accomplished through the use of a small A core replicated on the order of 20 times on an FPGA device. The objective is to maximize the use of on-board random-access memory bandwidth through the use of multi-threaded latency tolerance. Each shortest path core is responsible for one shortest path calculation, and when it is finished it outputs its result and requests the next source from a queue. One of the innovations of this approach is the use of a small bubble sort core to produce the extract-min function. While bubble sort is not usually considered an appropriate algorithm for any non-trivial usage, it is appropriate in this case as it can produce a single minimum out of the list in O(n) cycles, whwere n is the number of elements in the vertext list. The cost of this min operation does not impact the running time of the architecture, because the queue depth for fetching the next set of edges from memory is roughly equivalent to the number of cores in the system. Additionally, this work provides a collection of simulation results that model the behavior of the node queue in hardware. The results show that a hardware queue, implementing a small bubble-type minimum function, need only be on the order of 16 elements to provide both correct and optimal paths. Because the graph database size is measured in the hundreds of megabytes, the Cray SRAM memory is insufficient. In addition to the A* cores, they have developed a memory management system allowing round-robin servicing of the nodes as well as virtual memory managed over the Hypertransport
Criticality coefficient calculation for a small PWR using Monte Carlo Transport Code
Energy Technology Data Exchange (ETDEWEB)
Trombetta, Debora M.; Su, Jian, E-mail: dtrombetta@nuclear.ufrj.br, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Chirayath, Sunil S., E-mail: sunilsc@tamu.edu [Department of Nuclear Engineering and Nuclear Security Science and Policy Institute, Texas A and M University, TX (United States)
2015-07-01
Computational models of reactors are increasingly used to predict nuclear reactor physics parameters responsible for reactivity changes which could lead to accidents and losses. In this work, preliminary results for criticality coefficient calculation using the Monte Carlo transport code MCNPX were presented for a small PWR. The computational modeling developed consists of the core with fuel elements, radial reflectors, and control rods inside a pressure vessel. Three different geometries were simulated, a single fuel pin, a fuel assembly and the core, with the aim to compare the criticality coefficients among themselves.The criticality coefficients calculated were: Doppler Temperature Coefficient, Coolant Temperature Coefficient, Coolant Void Coefficient, Power Coefficient, and Control Rod Worth. The coefficient values calculated by the MCNP code were compared with literature results, showing good agreement with reference data, which validate the computational model developed and allow it to be used to perform more complex studies. Criticality Coefficient values for the three simulations done had little discrepancy for almost all coefficients investigated, the only exception was the Power Coefficient. Preliminary results presented show that simple modelling as a fuel assembly can describe changes at almost all the criticality coefficients, avoiding the need of a complex core simulation. (author)
Neutron and gamma ray transport calculations in shielding system
Energy Technology Data Exchange (ETDEWEB)
Masukawa, Fumihiro; Sakamoto, Hiroki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-03-01
In the shields for radiation in nuclear facilities, the penetrating holes of various kinds and irregular shapes are made for the reasons of operation, control and others. These penetrating holes and gaps are filled with air or the substances with relatively small shielding performance, and radiation flows out through them, which is called streaming. As the calculation techniques for the shielding design or analysis related to the streaming problem, there are the calculations by simplified evaluation, transport calculation and Monte Carlo method. In this report, the example of calculation by Monte Carlo method which is represented by MCNP code is discussed. A number of variance reduction techniques which seem effective for the analysis of streaming problem were tried. As to the investigation of the applicability of MCNP code to streaming analysis, the object of analysis which are the concrete walls without hole and with horizontal hole, oblique hole and bent oblique hole, the analysis procedure, the composition of concrete, and the conversion coefficient of dose equivalent, and the results of analysis are reported. As for variance reduction technique, cell importance was adopted. (K.I.)
Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures.
Cao, Qi-Long; Wang, Pan-Pan; Huang, Duo-Hui; Yang, Jun-Sheng; Wan, Ming-Jie; Wang, Fan-Hou
2014-03-21
Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T(-1) scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores.
Parallelization of a three-dimensional whole core transport code DeCART
Energy Technology Data Exchange (ETDEWEB)
Jin Young, Cho; Han Gyu, Joo; Ha Yong, Kim; Moon-Hee, Chang [Korea Atomic Energy Research Institute, Yuseong-gu, Daejon (Korea, Republic of)
2003-07-01
Parallelization of the DeCART (deterministic core analysis based on ray tracing) code is presented that reduces the computational burden of the tremendous computing time and memory required in three-dimensional whole core transport calculations. The parallelization employs the concept of MPI grouping and the MPI/OpenMP mixed scheme as well. Since most of the computing time and memory are used in MOC (method of characteristics) and the multi-group CMFD (coarse mesh finite difference) calculation in DeCART, variables and subroutines related to these two modules are the primary targets for parallelization. Specifically, the ray tracing module was parallelized using a planar domain decomposition scheme and an angular domain decomposition scheme. The parallel performance of the DeCART code is evaluated by solving a rodded variation of the C5G7MOX three dimensional benchmark problem and a simplified three-dimensional SMART PWR core problem. In C5G7MOX problem with 24 CPUs, a speedup of maximum 21 is obtained on an IBM Regatta machine and 22 on a LINUX Cluster in the MOC kernel, which indicates good parallel performance of the DeCART code. In the simplified SMART problem, the memory requirement of about 11 GBytes in the single processor cases reduces to 940 Mbytes with 24 processors, which means that the DeCART code can now solve large core problems with affordable LINUX clusters. (authors)
Energy Technology Data Exchange (ETDEWEB)
Miyoshi, Yoshinori; Yamamoto, Toshihiro; Nakamura, Takemi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2001-08-01
In order to validate the availability of criticality calculation codes and related nuclear data library, a series of fundamental benchmark experiments on low enriched uranyl nitrate solution have been performed with a Static Experiment Criticality Facility, STACY in JAERI. The basic core composed of a single tank with water reflector was used for accumulating the systematic data with well-known experimental uncertainties. This paper presents the outline of the core configurations of STACY, the standard calculation model, and calculation results with a Monte Carlo code and JENDL 3.2 nuclear data library. (author)
Hand calculations for transport of radioactive aerosols through sampling systems.
Hogue, Mark; Thompson, Martha; Farfan, Eduardo; Hadlock, Dennis
2014-05-01
Workplace air monitoring programs for sampling radioactive aerosols in nuclear facilities sometimes must rely on sampling systems to move the air to a sample filter in a safe and convenient location. These systems may consist of probes, straight tubing, bends, contractions and other components. Evaluation of these systems for potential loss of radioactive aerosols is important because significant losses can occur. However, it can be very difficult to find fully described equations to model a system manually for a single particle size and even more difficult to evaluate total system efficiency for a polydispersed particle distribution. Some software methods are available, but they may not be directly applicable to the components being evaluated and they may not be completely documented or validated per current software quality assurance requirements. This paper offers a method to model radioactive aerosol transport in sampling systems that is transparent and easily updated with the most applicable models. Calculations are shown with the R Programming Language, but the method is adaptable to other scripting languages. The method has the advantage of transparency and easy verifiability. This paper shows how a set of equations from published aerosol science models may be applied to aspiration and transport efficiency of aerosols in common air sampling system components. An example application using R calculation scripts is demonstrated. The R scripts are provided as electronic attachments.
Using the Chebychev expansion in quantum transport calculations
Energy Technology Data Exchange (ETDEWEB)
Popescu, Bogdan; Rahman, Hasan; Kleinekathöfer, Ulrich, E-mail: u.kleinekathoefer@jacobs-university.de [Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany)
2015-04-21
Irradiation by laser pulses and a fluctuating surrounding liquid environment can, for example, lead to time-dependent effects in the transport through molecular junctions. From the theoretical point of view, time-dependent theories of quantum transport are still challenging. In one of these existing transport theories, the energy-dependent coupling between molecule and leads is decomposed into Lorentzian functions. This trick has successfully been combined with quantum master approaches, hierarchical formalisms, and non-equilibrium Green’s functions. The drawback of this approach is, however, its serious limitation to certain forms of the molecule-lead coupling and to higher temperatures. Tian and Chen [J. Chem. Phys. 137, 204114 (2012)] recently employed a Chebychev expansion to circumvent some of these latter problems. Here, we report on a similar approach also based on the Chebychev expansion but leading to a different set of coupled differential equations using the fact that a derivative of a zeroth-order Bessel function can again be given in terms of Bessel functions. Test calculations show the excellent numerical accuracy and stability of the presented formalism. The time span for which this Chebychev expansion scheme is valid without any restrictions on the form of the spectral density or temperature can be determined a priori.
Using the Chebychev expansion in quantum transport calculations.
Popescu, Bogdan; Rahman, Hasan; Kleinekathöfer, Ulrich
2015-04-21
Irradiation by laser pulses and a fluctuating surrounding liquid environment can, for example, lead to time-dependent effects in the transport through molecular junctions. From the theoretical point of view, time-dependent theories of quantum transport are still challenging. In one of these existing transport theories, the energy-dependent coupling between molecule and leads is decomposed into Lorentzian functions. This trick has successfully been combined with quantum master approaches, hierarchical formalisms, and non-equilibrium Green's functions. The drawback of this approach is, however, its serious limitation to certain forms of the molecule-lead coupling and to higher temperatures. Tian and Chen [J. Chem. Phys. 137, 204114 (2012)] recently employed a Chebychev expansion to circumvent some of these latter problems. Here, we report on a similar approach also based on the Chebychev expansion but leading to a different set of coupled differential equations using the fact that a derivative of a zeroth-order Bessel function can again be given in terms of Bessel functions. Test calculations show the excellent numerical accuracy and stability of the presented formalism. The time span for which this Chebychev expansion scheme is valid without any restrictions on the form of the spectral density or temperature can be determined a priori.
Investigating the Use of 3-D Deterministic Transport for Core Safety Analysis
Energy Technology Data Exchange (ETDEWEB)
H. D. Gougar; D. Scott
2004-04-01
An LDRD (Laboratory Directed Research and Development) project is underway at the Idaho National Laboratory (INL) to demonstrate the feasibility of using a three-dimensional multi-group deterministic neutron transport code (Attila®) to perform global (core-wide) criticality, flux and depletion calculations for safety analysis of the Advanced Test Reactor (ATR). This paper discusses the ATR, model development, capabilities of Attila, generation of the cross-section libraries, comparisons to experimental results for Advanced Fuel Cycle (AFC) concepts, and future work planned with Attila.
Depletion methodology in the 3-D whole core transport code DeCART
Energy Technology Data Exchange (ETDEWEB)
Kim, Kang Seog; Cho, Jin Young; Zee, Sung Quun
2005-02-01
Three dimensional whole-core transport code DeCART has been developed to include a characteristics of the numerical reactor to replace partly the experiment. This code adopts the deterministic method in simulating the neutron behavior with the least assumption and approximation. This neutronic code is also coupled with the thermal hydraulic code CFD and the thermo mechanical code to simulate the combined effects. Depletion module has been implemented in DeCART code to predict the depleted composition in the fuel. The exponential matrix method of ORIGEN-2 has been used for the depletion calculation. The library of including decay constants, yield matrix and others has been used and greatly simplified for the calculation efficiency. This report summarizes the theoretical backgrounds and includes the verification of the depletion module in DeCART by performing the benchmark calculations.
First Cost Calculation Methods for Road Freight Transport Activity
Directory of Open Access Journals (Sweden)
Kovács György
2017-06-01
Full Text Available The transport activity is one of the most expensive processes in the supply chain. Forwarding and transport companies focuses on the optimization of transportation and the reduction of transport costs.
Reference neutron transport calculation note for Korea nuclear power plants with 3-loop PWR reactors
Energy Technology Data Exchange (ETDEWEB)
Kim, Byung Cheol; Chang, Ki Oak
1997-05-01
Reactor pressure vessel (RPV) steels are subjected to neutron irradiation at a temperature of about 290 deg C. This radiation exposure alters the mechanical properties, leading to a shift of the brittle-to-ductile transition temperature toward higher temperatures and to a diminution of the rupture energy as determined by Charpy V-notch tests. This radiation embrittlement is one of the important aging factors of nuclear power plants. U.S. NRC recommended the basic requirements for the determination of the pressure vessel fluence by regulatory guide DG-1025 in order to reduce the uncertainty in the determination of neutron fluence calculation and measurements. The determination of the pressure vessel fluence is based on both calculations and measurements. The fluence prediction is made with a calculation and the measurements are used to qualify the calculational methodology. Because of the importance and the difficulty of these calculations, the method`s qualification by comparison to measurement must be made to ensure a reliable and accurate vessel fluence determination. This reference calculation note is to provide a series of forward and adjoint neutron transport calculations for use in the evaluation of neutron dosimetry from surveillance capsule irradiations at 3-loop PWR reactor as well as for use in the determination of the neutron exposure of the reactor vessel wall in accordance with U.S Regulatory Guide DG-1025 requirements. The calculations of the pressure vessel fluence consist of the following steps; (1) Determination of the geometrical and material input data, (2) Determination of the core neutron source, and (3) Propagation of the neutron fluence from the core to the vessel and into the cavity. (author). 12 tabs., 3 figs., 7 refs.
Calculated characteristics of subcritical assembly with anisotropic transport of neutrons
Energy Technology Data Exchange (ETDEWEB)
Gorin, N.V.; Lipilina, E.N.; Lyutov, V.D.; Saukov, A.I. [Zababakhin Russian Federal Nuclear Center - All-Russian Scientific Researching Institute of Technical Physics (Russian Federation)
2003-07-01
There was considered possibility of creating enough sub-critical system that multiply neutron fluence from a primary source by many orders. For assemblies with high neutron tie between parts, it is impossible. That is why there was developed a construction consisting of many units (cascades) having weak feedback with preceding cascades. The feedback attenuation was obtained placing layers of slow neutron absorber and moderators between the cascades of fission material. Anisotropy of fast neutron transport through the layers was used. The system consisted of many identical cascades aligning one by another. Each cascade consists of layers of moderator, fissile material and absorber of slow neutrons. The calculations were carried out using the code MCNP.4a with nuclear data library ENDF/B5. In this construction neutrons spread predominantly in one direction multiplying in each next fissile layer, and they attenuate considerably in the opposite direction. In a calculated construction, multiplication factor of one cascade is about 1.5 and multiplication factor of whole construction composed of n cascades is 1.5{sup n}. Calculated keff value is 0.9 for one cascade and does not exceed 0.98 for a system containing any number of cascades. Therefore the assembly is always sub-critical and therefore it is safe in respect of criticality. There was considered using such a sub-critical assembly to create a powerful neutron fluence for neutron boron-capturing therapy. The system merits and demerits were discussed. (authors)
First-principles calculations of mass transport in magnesium borohydride
Yu, Chao; Ozolins, Vidvuds
2013-03-01
Mg(BH4)2 is a hydrogen storage material which can decompose to release hydrogen in the following reaction: Mg(BH4)2(solid) -->1/6 MgB12H12(solid) + 5/6MgH2(solid) +13/6 H2(gas) --> MgH2(solid) + 2B(solid) + 4H2(gas). However, experiments show that hydrogen release only occurs at temperatures above 300 °C, which severely limits applications in mobile storage. Using density-functional theory calculations, we systematically study bulk diffusion of defects in the reactant Mg(BH4)2 and products MgB12H12 and MgH2 during the first step of the solid-state dehydrogenation reaction. The defect concentrations and concentration gradients are calculated for a variety of defects, including charged vacancies and interstitials. We find that neutral [BH3] vacancies have the highest bulk concentration and concentration gradient in Mg(BH4)2. The diffusion mechanism of [BH3] vacancy in Mg(BH4)2 is studied using the nudged elastic band method. Our results shows that the calculated diffusion barrier for [BH3] vacancies is ~ . 2 eV, suggesting that slow mass transport limits the kinetics of hydrogen desorption.
OECD/NEA benchmark for time-dependent neutron transport calculations without spatial homogenization
Energy Technology Data Exchange (ETDEWEB)
Hou, Jason, E-mail: jason.hou@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Ivanov, Kostadin N. [Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Boyarinov, Victor F.; Fomichenko, Peter A. [National Research Centre “Kurchatov Institute”, Kurchatov Sq. 1, Moscow (Russian Federation)
2017-06-15
Highlights: • A time-dependent homogenization-free neutron transport benchmark was created. • The first phase, known as the kinetics phase, was described in this work. • Preliminary results for selected 2-D transient exercises were presented. - Abstract: A Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development (OECD) benchmark for the time-dependent neutron transport calculations without spatial homogenization has been established in order to facilitate the development and assessment of numerical methods for solving the space-time neutron kinetics equations. The benchmark has been named the OECD/NEA C5G7-TD benchmark, and later extended with three consecutive phases each corresponding to one modelling stage of the multi-physics transient analysis of the nuclear reactor core. This paper provides a detailed introduction of the benchmark specification of Phase I, known as the “kinetics phase”, including the geometry description, supporting neutron transport data, transient scenarios in both two-dimensional (2-D) and three-dimensional (3-D) configurations, as well as the expected output parameters from the participants. Also presented are the preliminary results for the initial state 2-D core and selected transient exercises that have been obtained using the Monte Carlo method and the Surface Harmonic Method (SHM), respectively.
Energy Technology Data Exchange (ETDEWEB)
Vidal, J. F.; Archier, P.; Calloo, A.; Jacquet, P.; Tommasi, J. [CEA, DEN, DER, Cadarache, F-13108 Saint-Paul-lez-Durance (France); Le Tellier, R. [CEA, DEN, DTN, Cadarache, F-13108 Saint-Paul-lez-Durance (France)
2012-07-01
In the framework of the ASTRID project, sodium cooled fast reactor studies are conducted at CEA in compliance with GEN IV reactors criteria, particularly for safety requirements. An improved safety requires better calculation tools to obtain accurate reactivity effects (especially sodium void effect) and power map distributions. The current calculation route lies on the JEFF3.1.1 library and the classical two-step approach performed with the ECCO module of the ERANOS code system at the assembly level and the Sn SNATCH solver - implemented within the PARIS platform - at the core level. 33-group cross sections used by SNATCH are collapsed from 1968-group self-shielded cross-section with a specific flux-current weighting. Recent studies have shown that this collapsing is non-conservative when dealing with core-reflector interface and can lead to reactivity discrepancies larger than 500 pcm in the case of a steel reflector. Such a discrepancy is due to the flux anisotropy at the interface, which is not taken into account when cross sections are obtained from separate fuel and reflector assembly calculations. A new approach is proposed in this paper. It consists in separating the self-shielding and the flux calculations. The first one is still performed with ECCO on separate patterns. The second one is done with SNATCH on a 1D traverse, representative of the core-reflector interface. An improved collapsing method using angular flux moments is then carried out to collapse the cross sections onto the 33-group structure. In the case of a simplified ZONA2B 2D homogeneous benchmark, results in terms of k{sub eff} and power map are strongly improved for a small increase of the computing time. (authors)
Effects of electron correlations on transport properties of iron at Earth's core conditions.
Zhang, Peng; Cohen, R E; Haule, K
2015-01-29
Earth's magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection, resulting in the investigation of chemically driven convection. These calculations for resistivity were based on electron-phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT) to iron and find that at high temperatures electron-electron scattering is comparable to the electron-phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core. The conventional thermal dynamo picture is safe. We find that electron-electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important.
Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I
Filippin, Livio; Ekman, Jörgen; Jönsson, Per
2016-01-01
The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the $^{26}$Mg$-^{24}$Mg pair of isotopes. Different models for electron correlation are adopted. It is shown that although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.
VENUS-2 MOX Core Benchmark: Results of ORNL Calculations Using HELIOS-1.4 - Revised Report
Energy Technology Data Exchange (ETDEWEB)
Ellis, RJ
2001-06-01
The Task Force on Reactor-Based Plutonium Disposition (TFRPD) was formed by the Organization for Economic Cooperation and Development/Nuclear Energy Agency (OECD/NEA) to study reactor physics, fuel performance, and fuel cycle issues related to the disposition of weapons-grade (WG) plutonium as mixed-oxide (MOX) reactor fuel. To advance the goals of the TFRPD, 10 countries and 12 institutions participated in a major TFRPD activity: a blind benchmark study to compare code calculations to experimental data for the VENUS-2 MOX core at SCK-CEN in Mol, Belgium. At Oak Ridge National Laboratory, the HELIOS-1.4 code system was used to perform the comprehensive study of pin-cell and MOX core calculations for the VENUS-2 MOX core benchmark study.
KALIMER-600-clad Core Fuel Assembly Calculation using MATRA-LMR (V2.0) Code
Energy Technology Data Exchange (ETDEWEB)
Kim, Young Gyun; Kim, Young Il
2006-12-15
Since the sodium boiling point is very high, maximum cladding and pin temperatures are used for design limit condition in sodium cooled liquid metal reactor. It is necessary to predict accurately the temperature distribution in the core and in the subassemblies to increase the sodium coolant efficiency. Based on the MATRA code, which is developed for PWR analysis, MATRA-LMR has been developed for SFR. The major modifications are: the sodium properties table is implemented as subprogram in the code, Heat transfer coefficients are changed for SFR, te pressure drop correlations are changed for more accurate calculations, which are Novendstern, Chiu-Rohsenow-Todreas, and Cheng-Todreas correlations. This This report describes briefly code structure and equations of MATRA-LMR (Version 2.0), explains input data preparation and shows some calculation results for the KALIMER-600-clad core fuel assembly for which has been performed the conceptual design of the core in the year 2006.
Electronic Structure Calculations and Adaptation Scheme in Multi-core Computing Environments
Energy Technology Data Exchange (ETDEWEB)
Seshagiri, Lakshminarasimhan; Sosonkina, Masha; Zhang, Zhao
2009-05-20
Multi-core processing environments have become the norm in the generic computing environment and are being considered for adding an extra dimension to the execution of any application. The T2 Niagara processor is a very unique environment where it consists of eight cores having a capability of running eight threads simultaneously in each of the cores. Applications like General Atomic and Molecular Electronic Structure (GAMESS), used for ab-initio molecular quantum chemistry calculations, can be good indicators of the performance of such machines and would be a guideline for both hardware designers and application programmers. In this paper we try to benchmark the GAMESS performance on a T2 Niagara processor for a couple of molecules. We also show the suitability of using a middleware based adaptation algorithm on GAMESS on such a multi-core environment.
Benchmark calculation of no-core Monte Carlo shell model in light nuclei
Abe, T; Otsuka, T; Shimizu, N; Utsuno, Y; Vary, J P; 10.1063/1.3584062
2011-01-01
The Monte Carlo shell model is firstly applied to the calculation of the no-core shell model in light nuclei. The results are compared with those of the full configuration interaction. The agreements between them are within a few % at most.
Tritium transport calculations for the IFMIF Tritium Release Test Module
Energy Technology Data Exchange (ETDEWEB)
Freund, Jana, E-mail: jana.freund@kit.edu; Arbeiter, Frederik; Abou-Sena, Ali; Franza, Fabrizio; Kondo, Keitaro
2014-10-15
Highlights: • Delivery of material data for the tritium balance in the IFMIF Tritium Release Test Module. • Description of the topological models in TMAP and the adapted fusion-devoted Tritium Permeation Code (FUS-TPC). • Computation of release of tritium from the breeder solid material into the purge gas. • Computation of the loss of tritium over the capsule wall, rig hull, container wall and purge gas return line. - Abstract: The IFMIF Tritium Release Test Module (TRTM) is projected to measure online the tritium release from breeder ceramics and beryllium pebble beds under high energy neutron irradiation. Tritium produced in the pebble bed of TRTM is swept out continuously by a purge gas flow, but can also permeate into the module's metal structures, and can be lost by permeation to the environment. According analyses on the tritium inventory are performed to support IFMIF plant safety studies, and to support the experiment planning. This paper describes the necessary elements for calculation of the tritium transport in the Tritium Release Test Module as follows: (i) applied equations for the tritium balance, (ii) material data from literature and (iii) the topological models and the computation of the five different cases; namely release of tritium from the breeder solid material into the purge gas, loss of tritium over the capsule wall, rig hull, container wall and purge gas return line in detail. The problem of tritium transport in the TRTM has been studied and analyzed by the Tritium Migration Analysis Program (TMAP) and the adapted fusion-devoted Tritium Permeation Code (FUS-TPC). TMAP has been developed at INEEL and now exists in Version 7. FUS-TPC Code was written in MATLAB with the original purpose to study the tritium transport in Helium Cooled Lead Lithium (HCLL) blanket and in a later version the Helium Cooled Pebble Bed (HCPB) blanket by [6] (Franza, 2012). This code has been further modified to be applicable to the TRTM. Results from the
Considerations of beta and electron transport in internal dose calculations
Energy Technology Data Exchange (ETDEWEB)
Bolch, W.E.; Poston, J.W. Sr.
1990-12-01
Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial transport of electron and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each case, preliminary results are very encouraging and plans for further research are detailed within this document.
Framework Application for Core Edge Transport Simulation (FACETS)
Energy Technology Data Exchange (ETDEWEB)
Malony, Allen D; Shende, Sameer S; Huck, Kevin A; Mr. Alan Morris, and Mr. Wyatt Spear
2012-03-14
The goal of the FACETS project (Framework Application for Core-Edge Transport Simulations) was to provide a multiphysics, parallel framework application (FACETS) that will enable whole-device modeling for the U.S. fusion program, to provide the modeling infrastructure needed for ITER, the next step fusion confinement device. Through use of modern computational methods, including component technology and object oriented design, FACETS is able to switch from one model to another for a given aspect of the physics in a flexible manner. This enables use of simplified models for rapid turnaround or high-fidelity models that can take advantage of the largest supercomputer hardware. FACETS does so in a heterogeneous parallel context, where different parts of the application execute in parallel by utilizing task farming, domain decomposition, and/or pipelining as needed and applicable. ParaTools, Inc. was tasked with supporting the performance analysis and tuning of the FACETS components and framework in order to achieve the parallel scaling goals of the project. The TAU Performance System® was used for instrumentation, measurement, archiving, and profile / tracing analysis. ParaTools, Inc. also assisted in FACETS performance engineering efforts. Through the use of the TAU Performance System, ParaTools provided instrumentation, measurement, analysis and archival support for the FACETS project. Performance optimization of key components has yielded significant performance speedups. TAU was integrated into the FACETS build for both the full coupled application and the UEDGE component. The performance database provided archival storage of the performance regression testing data generated by the project, and helped to track improvements in the software development.
Density-Based and Transport-Based Core-Periphery Structures in Networks
Lee, Sang Hoon; Porter, Mason A
2013-01-01
Networks often possess mesoscale structures, and studying them can yield insights into both structure and function. It is most common to study community structure, but numerous other types of mesoscale structures also exist. In this paper, we examine core-periphery structures based on both density and transportation. In such structures, core network components are well-connected both among themselves and to peripheral components, which are not well-connected to anything. We examine core-periphery structures in a wide range of examples of transportation, social, and financial networks---including road networks in large urban areas, a rabbit warren, a dolphin social network, a European interbank network, and a migration network between counties in the United States. We illustrate that a recently developed transport-based notion of node coreness is very useful for characterizing transportation networks. We also generalize this notion to examine core versus peripheral edges, and we show that this new diagnostic i...
Introducing FACETS, the Framework Application for Core-Edge Transport Simulations
Energy Technology Data Exchange (ETDEWEB)
Cary, John R. [Tech-X Corporation; Candy, Jeff [General Atomics; Cohen, Ronald H. [Lawrence Livermore National Laboratory (LLNL); Krasheninnikov, Sergei I [ORNL; McCune, Douglas C [ORNL; Estep, Donald J [Colorado State University, Fort Collins; Larson, Jay W [ORNL; Malony, Allen [University of Oregon; Worley, Patrick H [ORNL; Carlsson, Johann Anders [ORNL; Hakim, A H [Tech-X Corporation; Hamill, P [Tech-X Corporation; Kruger, Scott E [ORNL; Muzsala, S [Tech-X Corporation; Pletzer, Alexander [ORNL; Shasharina, Svetlana [Tech-X Corporation; Wade-Stein, D [Tech-X Corporation; Wang, N [Tech-X Corporation; McInnes, Lois C [ORNL; Wildey, T [Tech-X Corporation; Casper, T. A. [Lawrence Livermore National Laboratory (LLNL); Diachin, Lori A [ORNL; Epperly, Thomas [Lawrence Livermore National Laboratory (LLNL); Rognlien, T. D. [Lawrence Livermore National Laboratory (LLNL); Fahey, Mark R [ORNL; Kuehn, Jeffery A [ORNL; Morris, A [University of Oregon; Shende, Sameer [University of Oregon; Feibush, E [Tech-X Corporation; Hammett, Gregory W [ORNL; Indireshkumar, K [Tech-X Corporation; Ludescher, C [Tech-X Corporation; Randerson, L [Tech-X Corporation; Stotler, D. [Princeton Plasma Physics Laboratory (PPPL); Pigarov, A [University of California, San Diego; Bonoli, P. [Massachusetts Institute of Technology (MIT); Chang, C S [New York University; D' Ippolito, D. A. [Lodestar Research Corporation; Colella, Philip [Lawrence Berkeley National Laboratory (LBNL); Keyes, David E [Columbia University; Bramley, R [Indiana University; Myra, J. R. [Lodestar Research Corporation
2007-06-01
The FACETS (Framework Application for Core-Edge Transport Simulations) project began in January 2007 with the goal of providing core to wall transport modeling of a tokamak fusion reactor. This involves coupling previously separate computations for the core, edge, and wall regions. Such a coupling is primarily through connection regions of lower dimensionality. The project has started developing a component-based coupling framework to bring together models for each of these regions. In the first year, the core model will be a 1 dimensional model (1D transport across flux surfaces coupled to a 2D equilibrium) with fixed equilibrium. The initial edge model will be the fluid model, UEDGE, but inclusion of kinetic models is planned for the out years. The project also has an embedded Scientific Application Partnership that is examining embedding a full-scale turbulence model for obtaining the crosssurface fluxes into a core transport code.
Introducing FACETS, the Framework Application for Core-Edge Transport Simulations
Cary, J. R.; Candy, J.; Cohen, R. H.; Krasheninnikov, S.; McCune, D. C.; Estep, D. J.; Larson, J.; Malony, A. D.; Worley, P. H.; Carlsson, J. A.; Hakim, A. H.; Hamill, P.; Kruger, S.; Muzsala, S.; Pletzer, A.; Shasharina, S.; Wade-Stein, D.; Wang, N.; McInnes, L.; Wildey, T.; Casper, T.; Diachin, L.; Epperly, T.; Rognlien, T. D.; Fahey, M. R.; Kuehn, J. A.; Morris, A.; Shende, S.; Feibush, E.; Hammett, G. W.; Indireshkumar, K.; Ludescher, C.; Randerson, L.; Stotler, D.; Pigarov, A. Yu; Bonoli, P.; Chang, C. S.; D'Ippolito, D. A.; Colella, P.; Keyes, D. E.; Bramley, R.; Myra, J. R.
2007-07-01
The FACETS (Framework Application for Core-Edge Transport Simulations) project began in January 2007 with the goal of providing core to wall transport modeling of a tokamak fusion reactor. This involves coupling previously separate computations for the core, edge, and wall regions. Such a coupling is primarily through connection regions of lower dimensionality. The project has started developing a component-based coupling framework to bring together models for each of these regions. In the first year, the core model will be a 1 ½ dimensional model (1D transport across flux surfaces coupled to a 2D equilibrium) with fixed equilibrium. The initial edge model will be the fluid model, UEDGE, but inclusion of kinetic models is planned for the out years. The project also has an embedded Scientific Application Partnership that is examining embedding a full-scale turbulence model for obtaining the crosssurface fluxes into a core transport code.
VENUS-2 MOX Core Benchmark: Results of ORNL Calculations Using HELIOS-1.4
Energy Technology Data Exchange (ETDEWEB)
Ellis, RJ
2001-02-02
The Task Force on Reactor-Based Plutonium Disposition, now an Expert Group, was set up through the Organization for Economic Cooperation and Development/Nuclear Energy Agency to facilitate technical assessments of burning weapons-grade plutonium mixed-oxide (MOX) fuel in U.S. pressurized-water reactors and Russian VVER nuclear reactors. More than ten countries participated to advance the work of the Task Force in a major initiative, which was a blind benchmark study to compare code benchmark calculations against experimental data for the VENUS-2 MOX core at SCK-CEN in Mol, Belgium. At the Oak Ridge National Laboratory, the HELIOS-1.4 code was used to perform a comprehensive study of pin-cell and core calculations for the VENUS-2 benchmark.
Historical summary of the Three Mile Island Unit 2 core debris transportation campaign
Energy Technology Data Exchange (ETDEWEB)
Schmitt, R.C.; Tyacke, M.J. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Quinn, G.J. [Wastren, Inc., Germantown, MD (United States)
1993-03-01
Transport of the damaged core materials from the Unit 2 reactor of the Three Mile Island Nuclear Power Station (TMI-2) to the Idaho National Engineering Laboratory (INEL) for examination and storage presented many technical and institutional challenges, including assessing the ability to transport the damaged core; removing and packaging core debris in ways suitable for transport; developing a transport package that could both meet Federal regulations and interface with the facilities at TMI-2 and the INEL; and developing a transport plan, support logistics, and public communications channels suited to the task. This report is a historical summary of how the US Department of Energy addressed those challenges and transported, received, and stored the TMI-2 core debris at the INEL. Subjects discussed include preparations for transport, loading at TMI-2, institutional issues, transport operations, receipt and storage at the INEL, governmental inquiries/investigations, and lessons learned. Because of public attention focused on the TMI-2 Core Debris Transport Program, the exchange of information between the program and public was extensive. This exchange is a focus for parts of this report to explain why various operations were conducted as they were and why certain technical approaches were employed. And, because of that exchange, the program may have contributed to a better public understanding of such actions and may contribute to planning and execution of similar future actions.
Energy Technology Data Exchange (ETDEWEB)
Vitruk, S.G.; Korsun, A.S. [Moscow Engineering Physics Institute (Russian Federation); Ushakov, P.A. [Institute of Physics and Power Engineering, Obninsk (R)] [and others
1995-09-01
The multilevel mathematical model of neutron thermal hydrodynamic processes in a passive safety core without assemblies duct walls and appropriate computer code SKETCH, consisted of thermal hydrodynamic module THEHYCO-3DT and neutron one, are described. A new effective discretization technique for energy, momentum and mass conservation equations is applied in hexagonal - z geometry. The model adequacy and applicability are presented. The results of the calculations show that the model and the computer code could be used in conceptual design of advanced reactors.
Efficient implementation of core-excitation Bethe-Salpeter equation calculations
Gilmore, K.; Vinson, John; Shirley, E. L.; Prendergast, D.; Pemmaraju, C. D.; Kas, J. J.; Vila, F. D.; Rehr, J. J.
2015-12-01
We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including X-ray absorption (XAS), X-ray emission (XES), and both resonant and non-resonant inelastic X-ray scattering spectra (N/RIXS). Calculations are based on density functional theory (DFT) electronic structures generated either by ABINIT or QuantumESPRESSO, both plane-wave basis, pseudopotential codes. This electronic structure is improved through the inclusion of a GW self energy. The projector augmented wave technique is used to evaluate transition matrix elements between core-level and band states. Final two-particle scattering states are obtained with the NIST core-level BSE solver (NBSE). We have previously reported this implementation, which we refer to as OCEAN (Obtaining Core Excitations from Ab initio electronic structure and NBSE) (Vinson et al., 2011). Here, we present additional efficiencies that enable us to evaluate spectra for systems ten times larger than previously possible; containing up to a few thousand electrons. These improvements include the implementation of optimal basis functions that reduce the cost of the initial DFT calculations, more complete parallelization of the screening calculation and of the action of the BSE Hamiltonian, and various memory reductions. Scaling is demonstrated on supercells of SrTiO3 and example spectra for the organic light emitting molecule Tris-(8-hydroxyquinoline)aluminum (Alq3) are presented. The ability to perform large-scale spectral calculations is particularly advantageous for investigating dilute or non-periodic systems such as doped materials, amorphous systems, or complex nano-structures.
Nuclear structure calculations in $^{20}$Ne with No-Core Configuration-Interaction model
Konieczka, Maciej
2016-01-01
Negative parity states in $^{20}$Ne and Gamow-Teller strength distribution for the ground-state beta-decay of $^{20}$Na are calculated for the very first time using recently developed No-Core Configuration-Interaction model. The approach is based on multi-reference density functional theory involving isospin and angular-momentum projections. Advantages and shortcomings of the method are briefly discussed.
Axial power distribution calculation using a neural network in the nuclear reactor core
Energy Technology Data Exchange (ETDEWEB)
Kim, Y. H.; Cha, K. H.; Lee, S. H. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1997-12-31
This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore detector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place. 7 refs., 4 figs. (Author)
First-principles calculation of core-level binding energy shift in surface chemical processes
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Combined with third generation synchrotron radiation light sources, X-ray photoelectron spectroscopy (XPS) with higher energy resolution, brilliance, enhanced surface sensitivity and photoemission cross section in real time found extensive applications in solid-gas interface chemistry. This paper reports the calculation of the core-level binding energy shifts (CLS) using the first-principles density functional theory. The interplay between the CLS calculations and XPS measurements to uncover the structures, adsorption sites and chemical reactions in complex surface chemical processes are highlight. Its application on clean low index (111) and vicinal transition metal surfaces, molecular adsorption in terms of sites and configuration, and reaction kinetics are domonstrated.
Computer program for calculating thermodynamic and transport properties of fluids
Hendricks, R. C.; Braon, A. K.; Peller, I. C.
1975-01-01
Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.
Core Radial Electric Field and Transport in Wendelstein 7-X Plasmas
Pablant, Novimir
2016-10-01
Results from the investigation of core transport and the role of the radial electric field profile (Er) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the Er profile are expected to have a strong effect on both the particle and heat fluxes. Neoclassical particle fluxes are not intrinsically ambipolar, which leads to the formation of a radial electric field that enforces ambipolarity. The radial electric field is closely related to the perpendicular plasma flow (u⊥) through the force balance equation. This allows the radial electric field to be inferred from measurements of the perpendicular flow velocity from the x-ray imaging crystal spectrometer (XICS) and correlation reflectometry diagnostics. Large changes in the perpendicular rotation, on the order of Δu⊥ 5km /s (ΔEr 12kV / m), have been observed within a set of experiments where the heating power was stepped down from 2 MW to 0.6 MW . These experiments are examined in detail to explore the relationship between, heating power, response of the temperature and density profiles and the response of the radial electric field. Estimations of the core transport are based on power balance and utilize electron temperature (Te) profiles from the ECE and Thomson scattering, electron density profiles (ne) from interferometry and Thomson scattering, ion temperature (Ti) profiles from XICS, along with measurements of the total stored energy and radiated power. Also described are a set core impurity confinement experiments and results. Impurity confinement has been investigated through the injection of trace amount of argon impurity gas at the plasma edge in conjunction with measurements of the density of various ionization states of argon from the XICS and High Efficiency eXtreme-UV Overview Spectrometer (HEXOS) diagnostics. Finally the inferred Er and heat flux profiles are compared to initial neoclassical calculations using measured
Porter, Troy A
2013-01-01
Cosmic dust particles effectively attenuate starlight. Their absorption of starlight produces emission spectra from the near- to far-infrared, which depends on the sizes and properties of the dust grains, and spectrum of the heating radiation field. The near- to mid-infrared is dominated by the emissions by very small grains. Modeling the absorption of starlight by these particles is, however, computationally expensive and a significant bottleneck for self-consistent radiation transport codes treating the heating of dust by stars. In this paper, we summarize the formalism for computing the stochastic emissivity of cosmic dust, which was developed in earlier works, and present a new library HEATCODE implementing this formalism for the calculation for arbitrary grain properties and heating radiation fields. Our library is highly optimized for general-purpose processors with multiple cores and vector instructions, with hierarchical memory cache structure. The HEATCODE library also efficiently runs on co-processo...
Polyester-Based, Biodegradable Core-Multishell Nanocarriers for the Transport of Hydrophobic Drugs
Directory of Open Access Journals (Sweden)
Karolina A. Walker
2016-05-01
Full Text Available A water-soluble, core-multishell (CMS nanocarrier based on a new hyperbranched polyester core building block was synthesized and characterized towards drug transport and degradation of the nanocarrier. The hydrophobic drug dexamethasone was encapsulated and the enzyme-mediated biodegradability was investigated by NMR spectroscopy. The new CMS nanocarrier can transport one molecule of dexamethasone and degrades within five days at a skin temperature of 32 °C to biocompatible fragments.
Energy Technology Data Exchange (ETDEWEB)
Kosaka, Shinya; Saji, Etsuro [In-Core Fuel Management System Department, Toden Software, Inc., Tokyo (Japan)
2000-12-01
A characteristics transport theory code, CHAPLET, has been developed for the purpose of making it practical to perform a whole LWR core calculation with the same level of calculational model and accuracy as that of an ordinary single assembly calculation. The characteristics routine employs the CACTUS algorithm for drawing ray tracing lines, which assists the two key features of the flux solution in the CHAPLET code. One is the direct neutron path linking (DNPL) technique which strictly connects angular fluxes at each assembly interface in the flux solution separated between assemblies. Another is to reduce the required memory storage by sharing the data related to ray tracing among assemblies with the same configuration. For faster computation, the coarse mesh rebalance (CMR) method and the Aitken method were incorporated in the code and the combined use of both methods showed the most promising acceleration performance among the trials. In addition, the parallelization of the flux solution was attempted, resulting in a significant reduction in the wall-clock time of the calculation. By all these efforts, coupled with the results of many verification studies, a whole LWR core heterogeneous transport theory calculation finally became practical. CHAPLET is thought to be a useful tool which can produce the reference solutions for analyses of an LWR (author)
Gritzay, Olena; Kalchenko, Oleksandr; Klimova, Nataliya; Razbudey, Volodymyr; Sanzhur, Andriy; Binney, Stephen
2005-05-01
The presented results show our consecutive steps in developing a neutron source with parameters required by Boron Neutron Capture Therapy (BNCT) at the Kyiv Research Reactor (KRR). The main goal of this work was to analyze the influence of installation of different types of uranium converters close to the reactor core on neutron beam characteristics and on level of reactor safety. The general Monte Carlo radiation transport code MCNP, version 4B, has been used for these calculations.
Energy Technology Data Exchange (ETDEWEB)
Juncosa Rivera, Ricardo; Xu, Tianfu; Pruess, Karsten
2001-01-01
FADES-CORE and TOUGHREACT are codes used to model the non-isothermal multiphase flow with multicomponent reactive transport in porous media. Different flow and reactive transport problems were used to compare the FADES-CORE and TOUGHREACT codes. These problems take into account the different cases of multiphase flow with and without heat transport, conservative transport, and reactive transport. Consistent results were obtained from both codes, which use different numerical methods to solve the differential equations resulting from the various physicochemical processes. Here we present the results obtained from both codes for various cases. Some results are slightly different with minor discrepancies, which have been remedied, so that both codes would be able to reproduce the same processes using the same parameters. One of the discrepancies found is related to the different calculation for thermal conductivity in heat transport, which affects the calculation of the temperatures, as well as the pH of the reaction of calcite dissolution problem modeled. Therefore it is possible to affirm that the pH is highly sensitive to temperature. Generally speaking, the comparison was concluded to be highly satisfactory, leading to the complete verification of the FADES-CORE code. However, we must keep in mind that, as there are no analytical solutions available with which to verify the codes, the TOUGHREACT code has been thoroughly corroborated, given that the only possible way to prove that the code simulation is correct, is by comparing the results obtained with both codes for the identical problems, or to validate the simulation results with actual measured data.
Calculation of Design Parameters for an Equilibrium LEU Core in the NBSR
Energy Technology Data Exchange (ETDEWEB)
Hanson, A.L.; Diamond, D.
2011-09-30
A plan is being developed for the conversion of the NIST research reactor (NBSR) from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Previously, the design of the LEU fuel had been determined in order to provide the users of the NBSR with the same cycle length as exists for the current HEU fueled reactor. The fuel composition at different points within an equilibrium fuel cycle had also been determined. In the present study, neutronics parameters have been calculated for these times in the fuel cycle for both the existing HEU and the proposed LEU equilibrium cores. The results showed differences between the HEU and LEU cores that would not lead to any significant changes in the safety analysis for the converted core. In general the changes were reasonable except that the figure-of-merit for neutrons that can be used by experimentalists shows there will be a 10% reduction in performance. The calculations included kinetics parameters, reactivity coefficients, reactivity worths of control elements and abnormal configurations, and power distributions.
Directory of Open Access Journals (Sweden)
Jingang Liang
2016-06-01
Full Text Available Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC codes in accomplishing pin-wise three-dimensional (3D full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.
Two-Dimensional Core-Collapse Supernova Models with Multi-Dimensional Transport
Dolence, Joshua C; Zhang, Weiqun
2014-01-01
We present new two-dimensional (2D) axisymmetric neutrino radiation/hydrodynamic models of core-collapse supernova (CCSN) cores. We use the CASTRO code, which incorporates truly multi-dimensional, multi-group, flux-limited diffusion (MGFLD) neutrino transport, including all relevant $\\mathcal{O}(v/c)$ terms. Our main motivation for carrying out this study is to compare with recent 2D models produced by other groups who have obtained explosions for some progenitor stars and with recent 2D VULCAN results that did not incorporate $\\mathcal{O}(v/c)$ terms. We follow the evolution of 12, 15, 20, and 25 solar-mass progenitors to approximately 600 milliseconds after bounce and do not obtain an explosion in any of these models. Though the reason for the qualitative disagreement among the groups engaged in CCSN modeling remains unclear, we speculate that the simplifying ``ray-by-ray' approach employed by all other groups may be compromising their results. We show that ``ray-by-ray' calculations greatly exaggerate the ...
Modeling and Calculator Tools for State and Local Transportation Resources
Air quality models, calculators, guidance and strategies are offered for estimating and projecting vehicle air pollution, including ozone or smog-forming pollutants, particulate matter and other emissions that pose public health and air quality concerns.
SHTV, as a technique for core calculation using spatial homogenization and temperature variation
Energy Technology Data Exchange (ETDEWEB)
Moghaddam, Nader Maleki, E-mail: nader.moghaddam@gmail.co [Department of Nuclear Engineering and Physics, Amir Kabir University of Technology (Tehran polytechnique), Hafez Street, Tehran (Iran, Islamic Republic of); Zahedinejad, Ehsan, E-mail: ehsanzahedinejad@gmail.co [Department of Energy Engineering, Sharif University of Technology, Azadi Street, Tehran (Iran, Islamic Republic of); Kashi, Samira, E-mail: smr.kashi@gmail.co [Department of Nuclear Engineering, Shahid Beheshti University, Evin Street, Tehran (Iran, Islamic Republic of); Davilu, Hadi, E-mail: Davilu@aut.ac.i [Department of Nuclear Engineering and Physics, Amir Kabir University of Technology (Tehran polytechnique), Hafez Street, Tehran (Iran, Islamic Republic of)
2010-09-15
The accuracy of static neutronic parameters in the nuclear reactors depends upon the determination of group constants of the diffusion equation in the desired geometry. Although several methods have been proposed for calculating these parameters, there is still the need for more reliable methods. In this paper a powerful and innovative method based on Spatial Homogenization and Temperature Variation (SHTV) of physical properties of a WWER-1000 nuclear reactor core for calculating the relative power distribution of Fuel Assemblies (FA) and the hot fuel rod, is presented. The method is based on replacing the heterogeneous lattices of materials with different properties by an equivalent homogeneous mixture of these material for determining the few group constants, while the effect of temperature variation in the fuel and coolant density along the axial core direction is considered. All calculations are performed using WIMS and CITATION codes. The obtained results are compared with the results of Final Safety Analysis Report (FSAR) prepared by the designer, and good agreement between the two results is shown.
Relativistic semiempirical-core-potential calculations of Sr+ using Laguerre and Slater spinors
Jiang, Jun; Mitroy, J.; Cheng, Yongjun; Bromley, Michael W. J.
2016-12-01
A relativistic description of the structure of heavy alkali-metal atoms and alkali-like ions using S-spinors and L-spinors is developed. The core wave function is defined by a Dirac-Fock calculation using an S-spinor basis. The S-spinor basis is then supplemented with a large set of L-spinors for calculation of the valence wave function in a frozen-core model. The numerical stability of the L-spinor approach is demonstrated by computing the energies and decay rates of several low-lying hydrogen eigenstates, along with the polarizabilities of a Z =60 hydrogenic ion. The approach is then applied to calculate the dynamic polarizabilities of the 5 s , 4 d , and 5 p states of Sr+. The magic wavelengths at which the Stark shifts between different pairs of transitions are 0 are computed. Determination of the magic wavelengths for the 5 s →4 d3/2 and 5 s →4 d5/2 transitions near 417 nm (near the wavelength for the 5 s →5 pj transitions) would allow determination of the oscillator strength ratio for the 5 s →5 p1/2 and 5 s →5 p3/2 transitions.
Final Report for the "Fusion Application for Core-Edge Transport Simulations (FACETS)"
Energy Technology Data Exchange (ETDEWEB)
Cary, John R; Kruger, Scott
2014-10-02
The FACETS project over its lifetime developed the first self-consistent core-edge coupled capabilities, a new transport solver for modeling core transport in tokamak cores, developed a new code for modeling wall physics over long time scales, and significantly improved the capabilities and performance of legacy components, UEDGE, NUBEAM, GLF23, GYRO, and BOUT++. These improved capabilities leveraged the team’s expertise in applied mathematics (solvers and algorithms) and computer science (performance improvements and language interoperability). The project pioneered new methods for tackling the complexity of simulating the concomitant complexity of tokamak experiments.
Direct method for calculating temperature-dependent transport properties
Liu, Y.; Yuan, Z.; Wesselink, R.J.H.; Starikov, A.A.; Schilfgaarde, van M.; Kelly, P.J.
2015-01-01
We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calcula
Energy Technology Data Exchange (ETDEWEB)
Malouch, F. [Saclay Center CEA, DEN/DANS/DM2S/SERMA, F-91191 Gif-sur-Yvette Cedex (France)
2011-07-01
The control of the temperature in material samples irradiated in a material testing reactor requires the knowledge of the nuclear heating caused by the energy deposition by neutrons and photons interacting in the irradiation device structures. Thus, a neutron-photonic three-dimensional calculation scheme has been developed to evaluate the nuclear heating in experimental devices irradiated in the core of the OSIRIS MTR reactor (CEA/Saclay Center). The aim is to obtain a predictive tool for the nuclear heating estimation in irradiation devices. This calculation scheme is mainly based on the TRIPOLI-4 three-dimensional continuous-energy Monte Carlo transport code, developed by CEA (Saclay Center). An experimental validation has been carried out on the basis of nuclear heating measurements performed in the OSIRIS core. After an overview of the experimental devices irradiated in the OSIRIS reactor, we present the calculation scheme and the first results of the experimental validation. (authors)
Emergence of rotational bands in ab initio no-core configuration interaction calculations
Caprio, M A; Vary, J P; Smith, R
2015-01-01
Rotational bands have been observed to emerge in ab initio no-core configuration interaction (NCCI) calculations for p-shell nuclei, as evidenced by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. We investigate the ab initio emergence of nuclear rotation in the Be isotopes, focusing on 9Be for illustration, and make use of basis extrapolation methods to obtain ab initio predictions of rotational band parameters for comparison with experiment. We find robust signatures for rotational motion, which reproduce both qualitative and quantitative features of the experimentally observed bands.
Accelerating Convergence by Change of Basis for No-Core Configuration Interaction Calculations
Flores, Abraham R.; Caprio, Mark A.; Constantinou, Chrysovalantis
2016-09-01
Ab initio no-core configuration interaction (NCCI) calculations attempt to describe the structure of nuclei using realistic internucleon interactions. However, we can only describe these many-body systems within the limits of our computational power. As the number of nucleons increases, the calculations require more memory and processing power to reach convergence. Being able to accelerate convergence is crucial in extending the reach of NCCI calculations. Convergence can be obtained through a change of basis, for which we need to compute the overlaps of the radial functions for the new basis with those for the old basis. A large number of overlaps must be computed in order to accurately transform the many-body problem. Using alternative bases also requires the calculation of the one-body matrix elements for operators such as r2 and p2 in the new basis. We report a computer code that uses cubic spline interpolation to compute radial overlaps and radial integrals. This code facilitates using new bases to accelerate the convergence of NCCI calculations. Supported by the US NSF under Grant NSF-PHY05-52843 the US DOE under Grant DE-FG02-95ER-40934.
Transport properties of boron nanotubes investigated by ab initio calculation
Institute of Scientific and Technical Information of China (English)
Guo Wei; Hu Yi-Bin; Zhang Yu-Yang; Du Shi-Xuan; Gao Hong-Jun
2009-01-01
We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory(DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequi-librium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form (N, 0) tubes than (M, M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N, 0) tubes have a higher conductance than the (M, M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.
Molecular-dynamics calculation of the vacancy heat of transport
Energy Technology Data Exchange (ETDEWEB)
Schelling, Patrick K.; Ernotte, Jacques; Shokeen, Lalit; Tucker, William C. [Advanced Material Processing and Analysis Center and Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States); Woods Halley, J. [Department of Physics, University of Minnesota, 116 Church Street SE, Minneapolis, Minnesota 555455 (United States)
2014-07-14
We apply the recently developed constrained-dynamics method to elucidate the thermodiffusion of vacancies in a single-component material. The derivation and assumptions used in the method are clearly explained. Next, the method is applied to compute the reduced heat of transport Q{sub v}{sup *}−h{sub fv} for vacancies in a single-component material. Results from simulations using three different Morse potentials, with one providing an approximate description of Au, and an embedded-atom model potential for Ni are presented. It is found that the reduced heat of transport Q{sub v}{sup *}−h{sub fv} may take either positive or negative values depending on the potential parameters and exhibits some dependence on temperature. It is also found that Q{sub v}{sup *}−h{sub fv} may be correlated with the activation entropy. The results are discussed in comparison with experimental and previous simulation results.
The calculation of transport phenomena in electromagnetically levitated metal droplets
El-Kaddah, N.; Szekely, J.
1982-01-01
A mathematical representation has been developed for the electromagnetic force field, fluid flow field, and solute concentration field of levitation-melted metal specimens. The governing equations consist of the conventional transport equations combined with the appropriate expressions for the electromagnetic force field. The predictions obtained by solving the governing equations numerically on a digital computer are in good agreement with lifting force and average temperature measurements reported in the literature.
O'Connor, Evan
2015-01-01
We present results from computational simulations of core-collapse supernovae in {\\tt FLASH} using a newly-implemented multidimensional neutrino transport scheme and a newly-implemented general relativistic (GR) treatment of gravity. For the neutrino transport, we use a two moment method with an analytic closure (so-called M1 transport). This transport is multienergy, multispecies and truly multidimensional since we do not assume the commonly used ray-by-ray approximation. Our GR gravity is implemented in our Newtonian hydrodynamics simulations via an effective relativistic potential that closely reproduces the GR structure of neutron stars and has been shown to match GR simulations of core collapse quite well. In axisymmetry, we simulate core-collapse supernovae with five different progenitor models in both Newtonian and GR gravity. We find that the more compact protoneutron star structure realized in simulations with GR gravity gives higher neutrino luminosities and higher neutrino energies. These differenc...
Calculation and analysis of generator limiting regimes with respect to stator end core heating
Directory of Open Access Journals (Sweden)
Kostić Miloje
2015-01-01
Full Text Available A new simplified procedure for defining the limiting operating regimes on the generator capability curve, with respect to stator end core heating, is proposed and described in this paper. First of all, a simplified analysis of axial flux leakage that penetrates into the end plates of the stator is carried out and the corresponding power losses are calculated. Then the analysis of measured point temperature increases over the stator end core, and a qualitative and quantitative overview of the effects, are presented. A simplified procedure for defining the limiting regime with regard to the heating stator end core, which is illustrated for the case of an operating diagram for a given generator of apparent power of 727 MVA (B2 is also described. The given limiting line constructed using this method is similar to the appropriate line constructed on the basis of complex and lengthy factory and on-site tests performed by the manufacturer and the user. According to the results and the check, the proposed method has been proved and the application of the simplified procedure can be recommended for use along with other procedures, at least when it comes to similar synchronous generators in Serbia's Electric Power Industry.
Development of Monte Carlo decay gamma-ray transport calculation system
Energy Technology Data Exchange (ETDEWEB)
Sato, Satoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Kawasaki, Nobuo [Fujitsu Ltd., Tokyo (Japan); Kume, Etsuo [Japan Atomic Energy Research Inst., Center for Promotion of Computational Science and Engineering, Tokai, Ibaraki (Japan)
2001-06-01
In the DT fusion reactor, it is critical concern to evaluate the decay gamma-ray biological dose rates after the reactor shutdown exactly. In order to evaluate the decay gamma-ray biological dose rates exactly, three dimensional Monte Carlo decay gamma-ray transport calculation system have been developed by connecting the three dimensional Monte Carlo particle transport calculation code and the induced activity calculation code. The developed calculation system consists of the following four functions. (1) The operational neutron flux distribution is calculated by the three dimensional Monte Carlo particle transport calculation code. (2) The induced activities are calculated by the induced activity calculation code. (3) The decay gamma-ray source distribution is obtained from the induced activities. (4) The decay gamma-rays are generated by using the decay gamma-ray source distribution, and the decay gamma-ray transport calculation is conducted by the three dimensional Monte Carlo particle transport calculation code. In order to reduce the calculation time drastically, a biasing system for the decay gamma-ray source distribution has been developed, and the function is also included in the present system. In this paper, the outline and the detail of the system, and the execution example are reported. The evaluation for the effect of the biasing system is also reported. (author)
Results From Core-Collapse Simulations with Multi-Dimensional, Multi-Angle Neutrino Transport
Brandt, Timothy D; Ott, Christian D
2010-01-01
We present new results from the only 2D multi-group, multi-angle calculations of core-collapse supernova evolution. The first set of results from these calculations was published in Ott et al. (2008). We have followed a nonrotating and a rapidly rotating 20 solar mass model for ~400 ms after bounce. We show that the radiation fields vary much less with angle than the matter quantities in the region of net neutrino heating. This obtains because most neutrinos are emitted from inner radiative regions and because the specific intensity is an integral over sources from many angles at depth. The latter effect can only be captured by multi-angle transport. We then compute the phase relationship between dipolar oscillations in the shock radius and in matter and radiation quantities throughout the postshock region. We demonstrate a connection between variations in neutrino flux and the hydrodynamical shock oscillations, and use a variant of the Rayleigh test to estimate the detectability of these neutrino fluctuation...
An improved filtered spherical harmonic method for transport calculations
Energy Technology Data Exchange (ETDEWEB)
Ahrens, C. [Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO 80401 (United States); Merton, S. [Computational Physics Group, AWE Aldermaston, Berkshire (United Kingdom)
2013-07-01
Motivated by the work of R. G. McClarren, C. D. Hauck, and R. B. Lowrie on a filtered spherical harmonic method, we present a new filter for such numerical approximations to the multi-dimensional transport equation. In several test problems, we demonstrate that the new filter produces results with significantly less Gibbs phenomena than the filter used by McClarren, Hauck and Lowrie. This reduction in Gibbs phenomena translates into propagation speeds that more closely match the correct propagation speed and solutions that have fewer regions where the scalar flux is negative. (authors)
Numerical Toy-Model Calculation of the Nucleon Spin Autocorrelation Function in a Supernova Core
Raffelt, G G; Raffelt, Georg; Sigl, Guenter
1999-01-01
We develop a simple model for the evolution of a nucleon spin in a hot and dense nuclear medium. A given nucleon is limited to one-dimensional motion in a distribution of external, spin-dependent scattering potentials. We calculate the nucleon spin autocorrelation function numerically for a variety of potential densities and distributions which are meant to bracket realistic conditions in a supernova core. For all plausible configurations the width of the spin-density structure function is found to be less than the temperature. This is in contrast with a naive perturbative calculation based on the one-pion exchange potential which overestimates the width and thus suggests a large suppression of the neutrino opacities by nucleon spin fluctuations. Our results suggest that it may be justified to neglect the collisional broadening of the spin-density structure function for the purpose of estimating the neutrino opacities in the deep inner core of a supernova. On the other hand, we find no indication that process...
Radial basis function networks applied to DNBR calculation in digital core protection systems
Energy Technology Data Exchange (ETDEWEB)
Lee, Gyu-Cheon E-mail: gclee@kopec.co.kr; Heung Chang, Soon
2003-10-01
The nuclear power plant has to be operated with sufficient margin from the specified DNBR limit for assuring its safety. The digital core protection system calculates on-line real-time DNBR by using a complex subchannel analysis program, and triggers a reliable reactor shutdown if the calculated DNBR approaches the specified limit. However, it takes a relatively long calculation time even for a steady state condition, which may have an adverse effect on the operation flexibility. To overcome the drawback, a new method using a radial basis function network is presented in this paper. Nonparametric training approach is utilized, which shows dramatic reduction of the training time, no tedious heuristic process for optimizing parameters, and no local minima problem during the training. The test results show that the predicted DNBR is within about {+-}2% deviation from the target DNBR for the fixed axial flux shape case. For the variable axial flux case including severely skewed shapes that appeared during accidents, the deviation is within about {+-}10%. The suggested method could be the alternative that can calculate DNBR very quickly while guaranteeing the plant safety.
The Suppression of Energy Discretization Errors in Multigroup Transport Calculations
Energy Technology Data Exchange (ETDEWEB)
Larsen, Edward [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences
2013-06-17
The Objective of this project is to develop, implement, and test new deterministric methods to solve, as efficiently as possible, multigroup neutron transport problems having an extremely large number of groups. Our approach was to (i) use the standard CMFD method to "coarsen" the space-angle grid, yielding a multigroup diffusion equation, and (ii) use a new multigrid-in-space-and-energy technique to efficiently solve the multigroup diffusion problem. The overall strategy of (i) how to coarsen the spatial an energy grids, and (ii) how to navigate through the various grids, has the goal of minimizing the overall computational effort. This approach yields not only the fine-grid solution, but also coarse-group flux-weighted cross sections that can be used for other related problems.
Efficient algorithms for large-scale quantum transport calculations
Brück, Sascha; Calderara, Mauro; Bani-Hashemian, Mohammad Hossein; VandeVondele, Joost; Luisier, Mathieu
2017-08-01
Massively parallel algorithms are presented in this paper to reduce the computational burden associated with quantum transport simulations from first-principles. The power of modern hybrid computer architectures is harvested in order to determine the open boundary conditions that connect the simulation domain with its environment and to solve the resulting Schrödinger equation. While the former operation takes the form of an eigenvalue problem that is solved by a contour integration technique on the available central processing units (CPUs), the latter can be cast into a linear system of equations that is simultaneously processed by SplitSolve, a two-step algorithm, on general-purpose graphics processing units (GPUs). A significant decrease of the computational time by up to two orders of magnitude is obtained as compared to standard solution methods.
Sakamoto, Y
2002-01-01
In the prevention of nuclear disaster, there needs the information on the dose equivalent rate distribution inside and outside the site, and energy spectra. The three dimensional radiation transport calculation code is a useful tool for the site specific detailed analysis with the consideration of facility structures. It is important in the prediction of individual doses in the future countermeasure that the reliability of the evaluation methods of dose equivalent rate distribution and energy spectra by using of Monte Carlo radiation transport calculation code, and the factors which influence the dose equivalent rate distribution outside the site are confirmed. The reliability of radiation transport calculation code and the influence factors of dose equivalent rate distribution were examined through the analyses of critical accident at JCO's uranium processing plant occurred on September 30, 1999. The radiation transport calculations including the burn-up calculations were done by using of the structural info...
Assessment of uncertainty in full core reactor physics calculations using statistical methods
Energy Technology Data Exchange (ETDEWEB)
McEwan, C., E-mail: mcewac2@mcmaster.ca [McMaster Univ., Hamilton, Ontario (Canada)
2012-07-01
The best estimate method of safety analysis involves choosing a realistic set of input parameters for a proposed safety case and evaluating the uncertainty in the results. Determining the uncertainty in code outputs remains a challenge and is the subject of a benchmarking exercise proposed by the Organization for Economic Cooperation and Development. The work proposed in this paper will contribute to this benchmark by assessing the uncertainty in a depletion calculation of the final nuclide concentrations for an experiment performed in the Fukushima-2 reactor. This will be done using lattice transport code DRAGON and a tool known as DINOSAUR. (author)
The spectral code Apollo2: from lattice to 2D core calculations
Energy Technology Data Exchange (ETDEWEB)
Coste-Delclaux, M.; Santandrea, S.; Damian, F.; Blanc-Tranchant, P.; Zmijarevic, I. [CEA Saclay (DEN/DANS/SERMA), 91 - Gif-sur-Yvette (France); Santamarina, A. [CEA Cadarache (CEA/DEN/DER/SPRC), 13 - Saint Paul lez Durance (France)
2005-07-01
Apollo2 is a powerful code dedicated to neutron transport, it is a highly qualified tool for a wide range of applications from research and development studies to industrial applications. Today Apollo2 is part of several advanced 3-dimensional nuclear code packages dedicated to reactor physics, fuel cycle, criticality and safety analysis. The presentations have been organized into 7 topics: -) an introduction to Apollo2, -) cross-sections, -) flux calculation, -) advanced applications, -) Apollo2 users, specialized packages, -) qualification program, and -) the future of Apollo2. This document gathers only the slides of the presentations.
Rauhalahti, Markus; Taubert, Stefan; Sundholm, Dage; Liégeois, Vincent
2017-03-08
Magnetically induced current density susceptibilities and ring-current strengths have been calculated for neutral and doubly charged persubstituted benzenes C6X6 and C6X6(2+) with X = F, Cl, Br, I, At, SeH, SeMe, TeH, TeMe, and SbH2. The current densities have been calculated using the gauge-including magnetically induced current (GIMIC) method, which has been interfaced to the Gaussian electronic structure code rendering current density calculations using effective core potentials (ECP) feasible. Relativistic effects on the ring-current strengths have been assessed by employing ECP calculations of the current densities. Comparison of the ring-current strengths obtained in calculations on C6At6 and C6At6(2+) using relativistic and non-relativistic ECPs show that scalar relativistic effects have only a small influence on the ring-current strengths. Comparisons of the ring-current strengths and ring-current profiles show that the C6I6(2+), C6At6(2+), C6(SeH)6(2+), C6(SeMe)6(2+), C6(TeH)6(2+), C6(TeMe)6(2+), and C6(SbH2)6(2+) dications are doubly aromatic sustaining spatially separated ring currents in the carbon ring and in the exterior of the molecule. The C6I6(+) radical cation is also found to be doubly aromatic with a weaker ring current than obtained for the dication.
Indian Academy of Sciences (India)
ZIRAN CHEN; ZHANRONG HE; YOUHUI XU; WENHAO YU
2017-09-01
Charge transport rate is one of the key parameters determining the performance of organic electronic devices. In this paper, we used density functional theory (DFT) at the M06-2X/6−31+G(d) level to compute the charge transport rates of nine coronene topological structures. The results show that the energy gap of these nine coronene derivatives is in the range 2.90–3.30 eV, falling into the organic semiconductor category. The size of the conjugate ring has a large influence on the charge transport properties. Incorporation of methyl groupson the rigid core of tetrabenzocoronene and hexabenzocoronene is more conducive to the hole transport of the molecule than incorporating methoxyl groups. The derivatisation of a ‘long plate-like’ coronene with methoxylgroups facilitates both hole and electron transport. This class of molecules can thus be used in the design of ambipolar transport semiconductor materials.
Ab Initio No-Core Shell Model Calculations Using Realistic Two- and Three-Body Interactions
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Ormand, W E; Forssen, C; Caurier, E
2004-11-30
There has been significant progress in the ab initio approaches to the structure of light nuclei. One such method is the ab initio no-core shell model (NCSM). Starting from realistic two- and three-nucleon interactions this method can predict low-lying levels in p-shell nuclei. In this contribution, we present a brief overview of the NCSM with examples of recent applications. We highlight our study of the parity inversion in {sup 11}Be, for which calculations were performed in basis spaces up to 9{Dirac_h}{Omega} (dimensions reaching 7 x 10{sup 8}). We also present our latest results for the p-shell nuclei using the Tucson-Melbourne TM three-nucleon interaction with several proposed parameter sets.
Improving accuracy of the calculation of in-core power distributions for light water reactors
Energy Technology Data Exchange (ETDEWEB)
Tsuiki, M.; Beere, W.H. (Institute for energy technology, OECD Halden Reactor Project (Norway))
2009-10-15
Comparisons have been made of VNEM prototype system to the measured data obtained from Ringhals unit 3 NPP at its beginning of life, hot-stand-by state. Three cases with difference control rod bank positions and Boron concentrations have been compared: Case 1: nearly all rod banks withdrawn, Boron = 1315 ppm Case 2: bank C = nearly half-inserted, bank D = fully inserted, Boron = 1131 ppm Case 3: banks C and D = fully inserted, Boron = 1060 ppm The results can be summarized as: error: maximum detector reading (%) error: keff (%) Case 1 -2.1 -0.175 Case 2 1.5 -0.022 Case 3 -0.5 -0.044 Excellent agreement was observed in the comparison of the neutron detector readings and the core eigenvalues. The method of core modelling and parameters used in calculation of VNEM is completely the same as the 'PWR standard option' determined from similar comparisons of VNEM and other PWRs. No empirical, or any sort of adjustment was done. (author)
Applying Advanced Neutron Transport Calculations for Improving Fuel Performance Codes
Energy Technology Data Exchange (ETDEWEB)
Botazzoli, P.; Luzzi, L. [Politecnico di Milano, Department of Energy, Nuclear Engineering Division - CeSNEF, Milano (Italy); Schubert, A.; Van Uffelen, P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, Karlsruhe (Germany); Haeck, W. [Institute de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)
2009-06-15
TRANSURANUS is a computer code for the thermal and mechanical analysis of fuel rods in nuclear reactors. As part of the code, the TUBRNP model calculates the local concentration of the actinides (U, Pu, Am, Cm), the main fission products (Xe, Kr, Cs and Nd) and {sup 4}He produced during the irradiation as a function of the radial position across a fuel pellet (radial profiles). These local quantities are required for the determination of the local power density, the local burn-up, and the source term of fission products and other inert gases. In previous works the neutronic code ALEPH has been used to validate the models for the actinides and fission products concentrations in UO{sub 2} fuels. A similar approach has been adopted in the present work for verifying the Helium production. The present paper focuses on the modelling of the Helium production in PWR oxide fuels (MOX and UO{sub 2}). A reliable prediction of the Helium production and release in LWR oxide fuels is of great interest in case of increasing burn-up, linear heat generation rates and Plutonium content. The contribution of the Helium released plays a fundamental role in the gap pressure and subsequently in the mechanical behaviour of the fuel rod, in particular during the storage of the high burn-up spent fuel. Helium is produced in oxide fuels by three main paths: (i) alpha decay of the actinides (the main contribution is due to {sup 242}Cm, {sup 238}Pu and {sup 244}Cm); (ii) (n,{alpha}) reactions; and (iii) ternary fission. In the present work, the contributions due to ternary fission and the (n,{alpha}) reaction on {sup 16}O as well as some refinements in the {sup 241}Am burn-up chain have been included in TUBRNP. The VESTA neutronic code has been used for the validation of the He production model. The generic VESTA Monte Carlo depletion interface developed at IRSN allows us to couple different Monte Carlo codes with a depletion module. It currently allows for combining the ORIGEN 2.2 isotope
Svehla, R. A.; Mcbride, B. J.
1973-01-01
A FORTRAN IV computer program for the calculation of the thermodynamic and transport properties of complex mixtures is described. The program has the capability of performing calculations such as:(1) chemical equilibrium for assigned thermodynamic states, (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. Condensed species, as well as gaseous species, are considered in the thermodynamic calculation; but only the gaseous species are considered in the transport calculations.
Applicability of 3D Monte Carlo simulations for local values calculations in a PWR core
Bernard, Franck; Cochet, Bertrand; Jinaphanh, Alexis; Jacquet, Olivier
2014-06-01
As technical support of the French Nuclear Safety Authority, IRSN has been developing the MORET Monte Carlo code for many years in the framework of criticality safety assessment and is now working to extend its application to reactor physics. For that purpose, beside the validation for criticality safety (more than 2000 benchmarks from the ICSBEP Handbook have been modeled and analyzed), a complementary validation phase for reactor physics has been started, with benchmarks from IRPHEP Handbook and others. In particular, to evaluate the applicability of MORET and other Monte Carlo codes for local flux or power density calculations in large power reactors, it has been decided to contribute to the "Monte Carlo Performance Benchmark" (hosted by OECD/NEA). The aim of this benchmark is to monitor, in forthcoming decades, the performance progress of detailed Monte Carlo full core calculations. More precisely, it measures their advancement towards achieving high statistical accuracy in reasonable computation time for local power at fuel pellet level. A full PWR reactor core is modeled to compute local power densities for more than 6 million fuel regions. This paper presents results obtained at IRSN for this benchmark with MORET and comparisons with MCNP. The number of fuel elements is so large that source convergence as well as statistical convergence issues could cause large errors in local tallies, especially in peripheral zones. Various sampling or tracking methods have been implemented in MORET, and their operational effects on such a complex case have been studied. Beyond convergence issues, to compute local values in so many fuel regions could cause prohibitive slowing down of neutron tracking. To avoid this, energy grid unification and tallies preparation before tracking have been implemented, tested and proved to be successful. In this particular case, IRSN obtained promising results with MORET compared to MCNP, in terms of local power densities, standard
DEFF Research Database (Denmark)
Giannouli, Myrsini; Samaras, Zissis; Keller, Mario
2006-01-01
The scope of this paper is to summarise a methodology developed for TRENDS (TRansport and ENvironment Database System-TRENDS). The main objective of TRENDS was the calculation of environmental pressure indicators caused by transport. The environmental pressures considered are associated with air...
Zhivkov, P.; Furman, W.; Stoyanov, Ch
2014-09-01
The main characteristics of the neutron field formed within the massive (512 kg) natural uranium target assembly (TA) QUINTA irradiated by deuteron beam of JINR Nuclotron with energies 1,2,4, and 8 GeV as well as the spatial distributions and the integral numbers of (n,f), (n,γ) and (n,xn)- reactions were calculated and compared with experimental data [1] . The MCNPX 27e code with ISABEL/ABLA/FLUKA and INCL4/ABLA models of intra-nuclear cascade (INC) and experimental cross-sections of the corresponding reactions were used. Special attention was paid to the elucidation of the role of charged particles (protons and pions) in the fission of natural uranium of TA QUINTA. Extensive calculations have been done for quasi-infinite (with very small neutron leakage) depleted uranium TA BURAN having mass about 20 t which are intended to be used in experiments at Nuclotron in 2014-2016. As in the case of TA QUINTA which really models the central zone of TA BURAN the total numbers of fissions, produced 239Pu nuclei and total neutron multiplicities are predicted to be proportional to proton or deuteron energy up to 12 GeV. But obtained values of beam power gain are practically constant in studied incident energy range and are approximately four. These values are in contradiction with the experimental result [2] obtained for the depleted uranium core weighting three tons at incident proton energy 0.66 GeV.
MELTSPREAD-1 calculations of the transient spreading of core materials in the KNGR
Energy Technology Data Exchange (ETDEWEB)
Song, Yong Mann; Park, Soo Yong
1999-03-01
Major purpose of the report is to predict whether or not the melt will spread to cover the full floor area under severe accident conditions in KNGR (Korea Next Generation Reactor) cavity and to determine the local distribution of spread material depth as well as concrete attack upon the cavity floor. For this analysis, MELTSPREAD-1 computer code developed at ANL (Argonne National Laboratory) is first applied domestically. This code was originally developed to model the discharge of corium from the vessel and its spreading on the floor of a prototypical BWR Mark 1 containment, but is known to have the flexibility of LWR application via user-specified nodalization scheme. The analysis methodology in this report is assessed to be valid by independent ABB-CE review [ABB-CE 1988]. For the conservative analysis of melt spreading and erosion characteristics, a medium LOCA (loss of coolant accident) as the typical in-vessel low pressure accident, with 100% core mass release into the wet cavity is chosen as the basic sequence. For specified conditions of release from the failed reactor vessel lower head, the core materials are calculated to spread within a very short time and cover the full accessible cavity floor area. The spreading profiles are shown as a scene view according to time with detailed predictions of the extent of local melting-induced erosion of the concrete floor. The MELTSPREAD-1 results are important to the assessment of melt coolability following the transients spreading phase, and the results of the basic LOCA sequence can serve as the bounding calculation in the melt spreading and ablation for the KNGR cavity. In addition to this, sensitivity studies are made for important factors and crust formation and heat transfer models together with initial cavity condition and initial corium mass/temperature are appeared to be significant for the results. For the last, both MELTSPREAD-1 code input deck and calculation note used for the sequence analysis are
Aydin, E. D.; Katsimichas, S.; de Oliveira, C. R. E.
2005-10-01
In this paper, the finite-element-spherical harmonics (FE-PN) method is applied to the solution of transient Boltzmann transport equation. Firstly, transport and diffusion calculations are obtained for homogeneous and inhomogeneous circular regions. Results are compared in order to show the effects of different absorption coefficient values on the propagation of photons. Significant differences between two theories are shown to occur especially in cases when the absorption is increased. Secondly, to validate the FE-PN method, results from this method are compared with Monte Carlo calculations for different cases. Comparisons show good agreements between FE-transport and Monte Carlo solutions and demonstrate the correctness of the results obtained.
Energy Technology Data Exchange (ETDEWEB)
T. Downar
2009-03-31
The overall objective of the work here has been to eliminate the approximations used in current resonance treatments by developing continuous energy multi-dimensional transport calculations for problem dependent self-shielding calculations. The work here builds on the existing resonance treatment capabilities in the ORNL SCALE code system.
Protostellar disk formation and transport of angular momentum during magnetized core collapse
Joos, Marc; Ciardi, Andrea
2012-01-01
Theoretical studies of collapsing clouds found that the presence of a relatively strong magnetic field may prevent the formation of disks and their fragmentation. However most previous studies have been limited to cases where the magnetic field and the rotation axis of the cloud are aligned. We study the transport of angular momentum, and the effects on disk formation, for non-aligned initial configurations, and for a range magnetic intensities. We perform three-dimensional, adaptive mesh, numerical simulations of magnetically supercritical collapsing dense cores using the magneto-hydrodynamic code Ramses. At variance to earlier analysis, we show that the transport of angular momentum acts less efficiently in collapsing cores with non-aligned rotation and magnetic field. Analytically this result can be understood by taking into account the bending of field lines occurring during the gravitational collapse. We find that massive disks, containing at least 10% of the intial core mass, can form during the earlies...
Calculation of transport coefficient profiles in modulation experiments as an inverse problem
Escande, D F
2011-01-01
The calculation of transport profiles from experimental measurements belongs in the category of inverse problems which are known to come with issues of ill-conditioning or singularity. A reformulation of the calculation, the matricial approach, is proposed for periodically modulated experiments, within the context of the standard advection-diffusion model where these issues are related to the vanishing of the determinant of a 2x2 matrix. This sheds light on the accuracy of calculations with transport codes, and provides a path for a more precise assessment of the profiles and of the related uncertainty.
Stemke, JA; Santiago, LS
2011-01-01
The proportional light absorptance by photosynthetic tissue (α) is used with chlorophyll (Chl) fluorescence methods to calculate electron transport rate (ETR). Although a value of α of 0.84 is often used as a standard for calculating ETR, many succulent plant species and species with crassulacean acid metabolism (CAM) have photosynthetic tissues that vary greatly in color or are highly reflective, and could have values of α that differ from 0.84, thus affecting the calculation of ETR. We meas...
Performing three-dimensional neutral particle transport calculations on tera scale computers
Energy Technology Data Exchange (ETDEWEB)
Woodward, C S; Brown, P N; Chang, B; Dorr, M R; Hanebutte, U R
1999-01-12
A scalable, parallel code system to perform neutral particle transport calculations in three dimensions is presented. To utilize the hyper-cluster architecture of emerging tera scale computers, the parallel code successfully combines the MPI message passing and paradigms. The code's capabilities are demonstrated by a shielding calculation containing over 14 billion unknowns. This calculation was accomplished on the IBM SP ''ASCI-Blue-Pacific computer located at Lawrence Livermore National Laboratory (LLNL).
Energy Technology Data Exchange (ETDEWEB)
Panka, Istvan; Kereszturi, Andras [Hungarian Academy of Sciences, Budapest (Hungary). Reactor Analysis Dept.
2013-09-15
In this paper the uncertainties of the neutronic calculations at core level - originating from the uncertainties of the basic nuclear data - are presented. The investigations have been made for a VVER-1000 core (Kozloduy-6) defined in the frame of the OECD NEA UAM benchmark. In the first part of the paper, the uncertainties of the effective multiplication factor, the assembly-wise radial power distribution, the axial power distribution and the rod worth are shown. After that the preliminary evaluation of the uncertainties of the neutron kinetic calculations are presented for a rod movement transient at HZP (Hot Zero Power) state, where the uncertainties of the time dependent core and assembly powers and the dynamic reactivity were evaluated. In both cases, we will see that the most important quantities - at core level and at HZP state - have a considerable uncertainty which is originating from the uncertainties of the basic cross section library in these investigations. (orig.)
Mohammadi, A; Hassanzadeh, M; Gharib, M
2016-02-01
In this study, shielding calculation and criticality safety analysis were carried out for general material testing reactor (MTR) research reactors interim storage and relevant transportation cask. During these processes, three major terms were considered: source term, shielding, and criticality calculations. The Monte Carlo transport code MCNP5 was used for shielding calculation and criticality safety analysis and ORIGEN2.1 code for source term calculation. According to the results obtained, a cylindrical cask with body, top, and bottom thicknesses of 18, 13, and 13 cm, respectively, was accepted as the dual-purpose cask. Furthermore, it is shown that the total dose rates are below the normal transport criteria that meet the standards specified.
COMET-PE: an incident fluence response expansion transport method for radiotherapy calculations
Hayward, Robert M.; Rahnema, Farzad
2013-05-01
Accurate dose calculation is a central component of radiotherapy treatment planning. A new method of dose calculation has been developed based on transport theory and validated by comparison to Monte Carlo methods. The coarse mesh transport method has been extended to allow coupled photon-electron transport in 3D. The method combines stochastic pre-computation with a deterministic solver to achieve high accuracy and precision. To enhance the method for radiotherapy calculations, a new angular basis was derived, and an analytical source treatment was developed. Validation was performed by comparison to DOSXYZnrc using a heterogeneous interface phantom composed of water, aluminum, and lung. Calculations of both kinetic energy released per unit mass and dose were compared. Good agreement was found with a maximum error and root mean square relative error of less than 1.5% for all cases. The results show that the new method achieves an accuracy comparable to Monte Carlo.
Directory of Open Access Journals (Sweden)
KOHIO Niéssan
2014-12-01
Full Text Available In this paper we calculate the transport coefficients of plasmas formed by air and water vapor mixtures. The calculation, which assume local thermodynamic equilibrium (LTE are performed in the temperature range from 500 to 12000 K. We use the Gibbs free energy minimization method to determine the equilibrium composition of the plasmas, which is necessary to calculate the transport coefficients. We use the Chapman-Enskog method to calculate the transport coefficients. The results are presented and discussed according to the rate of water vapor. The results of the total thermal conductivity and electrical conductivity show in particular that the increasing of the rate of water vapor in air can be interesting for power cut. This could be improve the performance of plasma during current breaking in air contaminate by the water vapor.
Turbulent momentum transport in core tokamak plasmas and penetration of scrape-off layer flows
Abiteboul, J.; Ghendrih, Ph; Grandgirard, V.; Cartier-Michaud, T.; Dif-Pradalier, G.; Garbet, X.; Latu, G.; Passeron, C.; Sarazin, Y.; Strugarek, A.; Thomine, O.; Zarzoso, D.
2013-07-01
The turbulent transport of toroidal angular momentum in the core of a tokamak plasma is investigated in global, full-f gyrokinetic simulations, performed with the GYSELA code in the flux-driven regime. During the initial turbulent phase, a front of positive Reynolds stress propagates radially, generating intrinsic toroidal rotation from a vanishing initial profile. This is also accompanied by a propagating front of turbulent heat flux. In the statistical steady-state regime, turbulent transport exhibits large-scale avalanche-like events which are found to transport both heat and momentum, and similar statistical properties are obtained for both fluxes. The impact of scrape-off layer flows is also investigated by modifying the boundary conditions in the simulations. The observed impact is radially localized for L-mode like poloidal profiles of parallel velocity at the edge, while a constant velocity at the edge can modify the core toroidal rotation profile in a large fraction of the radial domain.
Logistic Core Operations with SAP Inventory Management, Warehousing, Transportation, and Compliance
Kappauf, Jens; Koch, Matthias
2012-01-01
“Logistic Core Operations with SAP” not only provides an overview of core logistics processes and functionality—it also shows how SAP’s Business Suite covers logistic core operations, what features are supported, and which systems can be used to implement end-to-end processes in the following logistic core disciplines: Procurement, Distribution, Transportation, Warehouse Logistics and Inventory Management, and Compliance and Reporting. In this context the authors not only explain their integration, the organizational set-up, and master data, but also which solution fits best for a particular business need. This book serves as a solid foundation for understanding SAP software. No matter whether you are a student or a manager involved in an SAP implementation, the authors go far beyond traditional function and feature descriptions, helping you ask the right questions, providing answers, and making recommendations. The book assists you in understanding SAP terminology, concepts and technological compo...
DEFF Research Database (Denmark)
Olsen, Nils; Whaler, K. A.; Finlay, Chris
2014-01-01
Monthly means of the magnetic field measurements taken by ground observatories are a useful data source for studying temporal changes of the core magnetic field and the underlying core flow. However, the usual way of calculating monthly means as the arithmetic mean of all days (geomagnetic quiet...... as well as disturbed) and all local times (day and night) may result in contributions from external (magnetospheric and ionospheric) origin in the (ordinary, omm) monthly means. Such contamination makes monthly means less favourable for core studies. We calculated revised monthly means (rmm...... a secular variation spherical harmonic model. The main field is specified by the CHAOS-4 model. Data from up to 128 observatories between 1997 and 2013 were used to calculate 185 flow models from the omm and rmm, for each possible set of three consecutive months. The full 3x3 (non-diagonal) data covariance...
Energy Technology Data Exchange (ETDEWEB)
Malouch, Fadhel [Alternative Energies and Atomic Energy Commission - CEA, Saclay Center, DEN/DANS/DM2S/SERMA, F-91191 Gif-sur-Yvette Cedex (France)
2015-07-01
Technological irradiations carried out in material testing reactors (MTRs) are used to study the behavior of materials under irradiation conditions required by different types of nuclear power plants (NPPs). For MTRs, specific instrumentation is required for the experiment monitoring and for the characterization of irradiation conditions, in particular the flux of neutrons and photons. To measure neutron and photon flux in experimental locations, different sensors can be used, such as SPNDs (self-powered neutron detectors), SPGDs (self-powered gamma detectors) and ionization chambers. These sensors involve interactions producing ultimately a measurable electric current. Various sensors have been recently tested in the core periphery of the OSIRIS reactor (located at the CEA-Saclay center) in order to qualify their responses to the neutron and the photon flux. One of the key input data for this qualification is to have a relevant evaluation of neutron and gamma fluxes at the irradiation location. The objective of this work is to evaluate the neutron and the gamma flux in the core periphery of the OSIRIS reactor. With this intention, specific neutron-photonic three-dimensional calculations have been performed and are mainly based on the TRIPOLI-4{sup R} three-dimensional continuous-energy Monte Carlo code, developed by CEA (Saclay Center) and extensively validated against reactor dosimetry benchmarks. In the case of the OSIRIS reactor, TRIPOLI-4{sup R} code has been validated against experimental results based on neutron flux and nuclear heating measurements performed in ex-core and in-core experiments. In this work, simultaneous contribution of neutrons and gamma photons in the core periphery is considered using neutron-photon coupled transport calculations. Contributions of prompt and decay photons have been taken into account for the gamma flux calculation. Specific depletion codes are used upstream to provide the decay-gamma sources required by TRIPOLI-4
Energy Technology Data Exchange (ETDEWEB)
Jeong, J.J.; Joo, H.G.; Cho, B.O.; Zee, S.Q.; Lee, W.J. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)
2001-07-01
To assess the performance of KAERI coupled multi-dimensional system thermal- hydraulics (T/H) and three-dimensional (3-D) kinetics code, MARS/MASTER, Exercise III of the OECD main steam line break benchmark problem is solved. The coupled code is capable of employing an individual flow channel for each fuel assembly as well as lumped ones. The basic analysis model of the reference plant consists of four major components: a 3-D core neutronics model, a 3-D thermal-hydraulic model for the reactor vessel employing lumped flow channels, a refined core T/H model and a 1-D T/H model for coolant system. Calculations were performed with and without the refined core T/H model. The results of the basic calculation performed without the refined core T/H model show that the core power distribution evolves to a highly localized shape due to the presence of a stuck rod, as well as asymmetric flow distribution in the reactor core. The results of the refined core T/H model indicate that the local peaking factor can be reduced by as much as 22 % through accurate representation of the local T/H feedback effects. Nonetheless, the global transient behaviors are not significantly affected. (author)
Atmospheric Transport and Mixing linked to Rossby Wave Breaking in GFDL Dynamical Core
Liu, C.; Barnes, E. A.
2015-12-01
Atmospheric transport and mixing plays an important role in the global energy balance and the distribution of health-related chemical constituents. Previous studies suggest a close linkage between large-scale transport and Rossby wave breaking (RWB). In this work, we use the GFDL spectral dynamical core to investigate this relationship and study the response of RWB-related transport in different climate scenarios. In a standard control run, we quantify the contribution of RWB to the total transport and mixing of an idealized tracer. In addition, we divide the contribution further into the two types of RWB - anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB) -- and contrast their efficiency at transport and mixing. Our results are compared to a previous study in which the transport ability of the two types of RWB is studied for individual baroclinic wave life-cycles. In a series of sensitivity runs, we study the response of RWB-related transport and mixing to various states of the jet streams. The responses of the mean strength, frequency, and the efficiency of RWB-related transport are documented and the implications for the transport and mixing in a warmer climate are discussed.
Energy Technology Data Exchange (ETDEWEB)
Casoli, P.; Authier, N.; Baud, J. [Commissariat a l' energie Atomique, Centre de Valduc, 21120 Is-sur-Tille (France)
2009-07-01
Several experimental devices are operated by the Criticality and Neutron Science Research Department of the CEA Valduc Laboratory. One of these is the metallic core reactor Caliban. The knowledge of the fundamental kinetic parameters of the reactor is very useful, indeed necessary, to the operator. The purpose of this study was to develop and perform experiments allowing to determinate some of these parameters. The prompt neutron decay constant and particularly its value at criticality can be measured with reactor noise techniques such as the interval-distribution, the Feynman variance-to-mean, and the Rossi-{alpha} methods. By introducing the Nelson number, the effective delayed neutron fraction and the average neutron lifetime can also be calculated with the Rossi-{alpha} method. Subcritical, critical, and even supercritical experiments were performed. With the Rossi-{alpha} technique, it was found that the prompt neutron decay constant at criticality was (6.02*10{sup 5} {+-} 9%). Experiments also brought out the limitations of the used experimental parameters. (authors)
Efficient method for the calculation of dissipative quantum transport in quantum cascade lasers.
Greck, Peter; Birner, Stefan; Huber, Bernhard; Vogl, Peter
2015-03-09
We present a novel and very efficient method for calculating quantum transport in quantum cascade lasers (QCLs). It follows the nonequilibrium Green's function (NEGF) framework but sidesteps the calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. This method generalizes the phenomenological Büttiker probe model by taking into account individual scattering mechanisms. It is orders of magnitude more efficient than a fully self-consistent NEGF calculation for realistic devices. We apply this method to a new THz QCL design which works up to 250 K - according to our calculations.
Energy Technology Data Exchange (ETDEWEB)
Gorodkov, S.S.; Kalugin, M.A. [Nuclear Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation)
2015-09-15
Up to now core calculations with Monte Carlo provided only average cross-sections of mesh cells for further use either in finite difference calculations or as benchmark ones for approximate spectral algorithms. Now MCU code is capable to handle functions, which may be interpreted as average diffusion coefficients. Subsequently the results of finite difference calculations with cells characteristic sets obtained in such a way can be compared with Monte Carlo results as benchmarks, giving reliable information on quality of production code under consideration. As an example of such analysis, the results of mesh calculations with 1-, 2-, 4-, 8- and 12 neutron groups of some model VVER fuel assembly are presented in comparison with the exact Monte Carlo solution. As a second example, an analysis is presented of water gap approximate enlargement between fuel assemblies, allowing VVER core region be covered by regular mesh.
Energy Technology Data Exchange (ETDEWEB)
Moeller, M. P.; Urbanik, II, T.; Desrosiers, A. E.
1982-03-01
This paper describes the methodology and application of the computer model CLEAR (Calculates Logical Evacuation And Response) which estimates the time required for a specific population density and distribution to evacuate an area using a specific transportation network. The CLEAR model simulates vehicle departure and movement on a transportation network according to the conditions and consequences of traffic flow. These include handling vehicles at intersecting road segments, calculating the velocity of travel on a road segment as a function of its vehicle density, and accounting for the delay of vehicles in traffic queues. The program also models the distribution of times required by individuals to prepare for an evacuation. In order to test its accuracy, the CLEAR model was used to estimate evacuatlon tlmes for the emergency planning zone surrounding the Beaver Valley Nuclear Power Plant. The Beaver Valley site was selected because evacuation time estimates had previously been prepared by the licensee, Duquesne Light, as well as by the Federal Emergency Management Agency and the Pennsylvania Emergency Management Agency. A lack of documentation prevented a detailed comparison of the estimates based on the CLEAR model and those obtained by Duquesne Light. However, the CLEAR model results compared favorably with the estimates prepared by the other two agencies.
Effects of non-uniform core flow on peak cladding temperature: MOXY/SCORE sensitivity calculations
Energy Technology Data Exchange (ETDEWEB)
Chang, S.C.
1979-08-15
The MOXY/SCORE computer program is used to evaluate the potential effect on peak cladding temperature of selective cooling that may result from a nonuniform mass flux at the core boundaries during the blowdown phase of the LOFT L2-4 test. The results of this study indicate that the effect of the flow nonuniformity at the core boundaries will be neutralized by a strong radial flow redistribution in the neighborhood of core boundaries. The implication is that the flow nonuniformity at the core boundaries has no significant effect on the thermal-hydraulic behavior and cladding temperature at the hot plane.
Boundary-projection acceleration: A new approach to synthetic acceleration of transport calculations
Energy Technology Data Exchange (ETDEWEB)
Adams, M.L.; Martin, W.R.
1987-01-01
We present a new class of synthetic acceleration methods which can be applied to transport calculations regardless of geometry, discretization scheme, or mesh shape. Unlike other synthetic acceleration methods which base their acceleration on P1 equations, these methods use acceleration equations obtained by projecting the transport solution onto a coarse angular mesh only on cell boundaries. We demonstrate, via Fourier analysis of a simple model problem as well as numerical calculations of various problems, that the simplest of these methods are unconditionally stable with spectral radius less than or equal toc/3 (c being the scattering ratio), for several different discretization schemes in slab geometry. 28 refs., 4 figs., 3 tabs.
Metallic impurities induced electronic transport in WSe2: First-principle calculations
Li, Hongping; Liu, Shuai; Huang, Songlei; Zhang, Quan; Li, Changsheng; Liu, Xiaojuan; Meng, Jian; Tian, Yi
2016-08-01
Using density functional theory calculations, we have systematically explored the effect of V, Nb and Ta impurities on the electronic transport properties of 2H-WSe2. The formation energies elucidate dopants are preferred to substitute W atoms, and the incorporation of Nb into WSe2 is most thermodynamically favorable. The crystal structures almost hold the pristine WSe2 structure-type in spite of with slightly bond relaxation. More importantly, a pronounced electronic transport behavior has realized in all doped systems, which is mainly triggered by metal impurities. Our calculation suggests chemical doping is an effective way to precisely modulate WSe2 performance for target technological applications.
Transport hysteresis of core plasma, isotope effect, and H-mode physics
Itoh, S.-I.; Itoh, K.; Inagaki, S.
2017-02-01
This article assesses the understanding of and impact by the hysteresis in transport relation. The rapid changes of fluxes compared to slow changes of plasma parameters are overviewed for both edge barrier and core plasmas. The theoretical approaches to understanding the direct influence of heating power on turbulent transport are addressed. Based on this new theoretical framework, the ‘isotope effect’ of plasma confinement time is discussed. A trial explanation is given for this unresolved mystery in plasma confinement. The advanced data analysis method to research the hysteresis in gradient-flux relation is explained.
Quasiballistic quantum transport through Ge/Si core/shell nanowires.
Kotekar-Patil, D; Nguyen, B-M; Yoo, J; Dayeh, S A; Frolov, S M
2017-09-20
We study signatures of ballistic quantum transport of holes through Ge/Si core/shell nanowires at low temperatures. We observe Fabry-Pérot interference patterns as well as conductance plateaus at integer multiples of 2e (2)/h at zero magnetic field. Magnetic field evolution of these plateaus reveals relatively large effective Landé g-factors. Ballistic effects are observed in nanowires with silicon shell thickness of 1-3 nm, but not in bare germanium wires. These findings inform the future development of spin and topological quantum devices which rely on ballistic sub-band-resolved transport.
Directory of Open Access Journals (Sweden)
A. A. Sulim
2014-01-01
Full Text Available At present a great attention is paid to increasing of energy efficiency at operated electrified urban transport. Perspective direction for increasing energy efficiency at that type of transport is the application of regenerative braking. For additional increasing of energy efficiency there were suggested the use of capacitive drive on tires of traction substation. One of the main task is the analysis of energy recovery application with drive and without it.These analysis demonstrated that the calculation algorithms don’t allow in the full volume to carry out calculations of amount and cost of energy recovery without drive and with it. That is why we see the current interest to this topic. The purpose of work is to create methods of algorithms calculation for definite amount and cost of consumed, redundant and recovery energy of electrified urban transport due to definite regime of motion on wayside. There is algorithm developed, which allow to calculate amount and cost of consumed, redundant and recovery energy of electrified urban transport on wayside during the installation capacitive drive at traction substation. On the basis of developed algorithm for the definite regime of wagon motion of subway there were fulfilled the example of energy recovery amount and its cost calculation, among them with limited energy intensity drive, when there are 4 trains on wayside simultaneously.
Improved method for calculating neoclassical transport coefficients in the banana regime
Energy Technology Data Exchange (ETDEWEB)
Taguchi, M., E-mail: taguchi.masayoshi@nihon-u.ac.jp [College of Industrial Technology, Nihon University, Narashino 275-8576 (Japan)
2014-05-15
The conventional neoclassical moment method in the banana regime is improved by increasing the accuracy of approximation to the linearized Fokker-Planck collision operator. This improved method is formulated for a multiple ion plasma in general tokamak equilibria. The explicit computation in a model magnetic field shows that the neoclassical transport coefficients can be accurately calculated in the full range of aspect ratio by the improved method. The some neoclassical transport coefficients for the intermediate aspect ratio are found to appreciably deviate from those obtained by the conventional moment method. The differences between the transport coefficients with these two methods are up to about 20%.
Microwave emulations and tight-binding calculations of transport in polyacetylene
Stegmann, Thomas; Franco-Villafañe, John A.; Ortiz, Yenni P.; Kuhl, Ulrich; Mortessagne, Fabrice; Seligman, Thomas H.
2017-01-01
A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene.
Calculation of shear strength of prestressed hollow core slabs by use of plastic theory
DEFF Research Database (Denmark)
Hoang, Linh Cao; Jørgensen, Henrik Brøner; Nielsen, Mogens Peter
2014-01-01
saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and Anchorage failure than ordinary two-way spanning...
Calculation of shear strength of prestressed hollow core slabs by use of plastic theory
DEFF Research Database (Denmark)
Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter
2014-01-01
saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and anchorage failure than ordinary two-way spanning...
A new multi-tracer transport scheme for the dynamical core of NCAR's Community Atmosphere Model
Erath, C.
2012-04-01
The integration of a conservative semi-Lagrangian multi-tracer transport scheme (CSLAM) in NCAR's High-Order Method Modeling Environment (HOMME) is considered here. HOMME is a highly scalable atmospheric modeling framework, and its current horizontal discretization relies on spectral element (SE) and/or discontinuous Galerkin (DG) methods on the cubed-sphere. It is one dynamical core of NCAR's Community Atmosphere Model (CAM). The main advantage of CSLAM is that the upstream cell (trajectories) information and computation of weights of integrals can be reused for each additional tracer. This makes CSLAM particularly interesting for global atmospheric modeling with growing number of tracers, e.g. more than 100 tracers for the chemistry version of CAM. An algorithm specifically designed for multiple processors and on the cubed-sphere grid for CSLAM in HOMME is a challenging task. HOMME is running on an element ansatz on the six cube faces. Inside these elements we create an Eulerian finite volume grid of equiangular gnomonic type, which represents the arrival grid in the scheme. But CSLAM relies on backward trajectories, which entails a departure grid. That means departure and arrival grid don't necessary have to be on the same element and certainly not on the same cube face. Also the reconstruction for higher order modeling needs a patch of tracer values which extend the element. Here we consider a third order reconstruction method. Therefore, we introduce a halo for the tracer values in the cell centers of a cube-element. The size of this halo depends on the Courant number (CFL condition) and the reconstruction type. Note that for a third order scheme and CFL number communication can be limited to one per time step. This data structure allows us to consider an element with its halo as one task where we have to be extra carful for elements which share a cube edge due to projection and orientation reasons. We stress that the reconstruction coefficients for elements
Buras, R; Rampp, M; Kifonidis, K
2005-01-01
1D and 2D supernova simulations for stars between 11 and 25 solar masses are presented, making use of the Prometheus/Vertex neutrino-hydrodynamics code, which employs a full spectral treatment of the neutrino transport. Multi-dimensional transport aspects are treated by the ``ray-by-ray plus'' approximation described in Paper I. Our set of models includes a 2D calculation for a 15 solar mass star whose iron core is assumed to rotate rigidly with an angular frequency of 0.5 rad/s before collapse. No important differences were found depending on whether random seed perturbations for triggering convection are included already during core collapse, or whether they are imposed on a 1D collapse model shortly after bounce. Convection below the neutrinosphere sets in about 40 ms p.b. at a density above 10**12 g/cm^3 in all 2D models, and encompasses a layer of growing mass as time goes on. It leads to a more extended proto-neutron star structure with accelerated lepton number and energy loss and significantly higher ...
Doiron, Charles; Hencken, Kai
2013-09-01
Computational fluid-dynamic simulations nowadays play a central role in the development of new gas circuit breakers. For these simulations to be reliable, a good knowledge of the pressure and temperature-dependence of the thermodynamic and transport properties of ionized gases is required. A key ingredient in the calculation of thermodynamic properties of thermal plasmas is the calculation of the chemical equilibrium composition of the gas. The general-purpose, open-source software toolkit Cantera provides most functionality required to carry out such thermodynamic calculations. In this contribution, we explain how we tailored Cantera specifically to calculate material properties of plasmas. The highly modular architecture of this framework made it possible to add support for Debye-Hückel non-ideality corrections in the calculation of the chemical equilibrium mixture, as well as to enable the calculation of the key transport parameters needed in CFD-based electric arc simulations: electrical and thermal conductivity, viscosity, and diffusion coefficients. As an example, we discuss the thermodynamic and transport properties of mixtures of carbon dioxide and copper vapor.
Applicability of the wide-band limit in DFT-based molecular transport calculations
Verzijl, C.J.O.; Seldenthuis, J.S.; Thijssen, J.M.
2013-01-01
Transport properties of molecular junctions are notoriously expensive to calculate with ab initio methods, primarily due to the semi-infinite electrodes. This has led to the introduction of different approximation schemes for the electrodes. For the most popular metals used in experiments, such as g
Svehla, R. A.; Mcbride, B. J.
1973-01-01
Program performs calculations such as chemical equilibrium for assigned thermodynamic states, theoretical rocket performance for both equilibrium and frozen compositions during expansion, incident and reflected shock properties, and Chapman-Jouget detonation properties. Features include simplicity of input and storage of all thermodynamic and transport property data on master tape.
Svizhenko, Alexel; Anantram, M. P.; Maiti, Amitesh
2003-01-01
This paper presents viewgraphs on the modeling of the electromechanical response of carbon nanotubes, utilizing molecular dynamics and transport calculations. The topics include: 1) Simulations of the experiment; 2) Effect of diameter, length and temperature; and 3) Study of sp3 coordination-"The Table experiment".
Nobuhara, Fumiyoshi; Kuroyanagi, Makoto; Masumoto, Kazuyoshi; Nakamura, Hajime; Toyoda, Akihiro; Takahashi, Katsuhiko
2017-09-01
In order to evaluate the state of activation in a cyclotron facility used for the radioisotope production of PET diagnostics, we measured the neutron flux by using gold foils and TLDs. Then, the spatial distribution of neutrons and induced activity inside the cyclotron vault were simulated with the Monte Calro calculation code for neutron transport and DCHAIN-SP for activation calculation. The calculated results are in good agreement with measured values within factor 3. Therefore, the adaption of the advanced evaluation procedure for activation level is proved to be important for the planning of decommissioning of these facilities.
Directory of Open Access Journals (Sweden)
Zahra Nasrazadani
2017-02-01
Full Text Available The heavy water zero power reactor (HWZPR, which is a critical assembly with a maximum power of 100 W, can be used in different lattice pitches. The last change of core configuration was from a lattice pitch of 18–20 cm. Based on regulations, prior to the first operation of the reactor, a new core was simulated with MCNP (Monte Carlo N-Particle-4C and WIMS (Winfrith Improved Multigroup Scheme–CITATON codes. To investigate the criticality of this core, the effective multiplication factor (Keff versus heavy water level, and the critical water level were calculated. Then, for safety considerations, the reactivity worth of D2O, the reactivity worth of safety and control rods, and temperature reactivity coefficients for the fuel and the moderator, were calculated. The results show that the relevant criteria in the safety analysis report were satisfied in the new core. Therefore, with the permission of the reactor safety committee, the first criticality operation was conducted, and important physical parameters were measured experimentally. The results were compared with the corresponding values in the original core.
Energy Technology Data Exchange (ETDEWEB)
Mueller, Bernhard
2009-05-07
In this thesis, we have presented the first multi-dimensional models of core-collapse supernovae that combine a detailed, up-to-date treatment of neutrino transport, the equation of state, and - in particular - general relativistic gravity. Building on the well-tested neutrino transport code VERTEX and the GR hydrodynamics code CoCoNuT, we developed and implemented a relativistic generalization of a ray-by-ray-plus method for energy-dependent neutrino transport. The result of these effort, the VERTEX-CoCoNuT code, also incorporates a number of improved numerical techniques that have not been used in the code components VERTEX and CoCoNuT before. In order to validate the VERTEX-CoCoNuT code, we conducted several test simulations in spherical symmetry, most notably a comparison with the one-dimensional relativistic supernova code AGILE-BOLTZTRAN and the Newtonian PROMETHEUSVERTEX code. (orig.)
Microwave emulations and tight-binding calculations of transport in polyacetylene
Energy Technology Data Exchange (ETDEWEB)
Stegmann, Thomas, E-mail: stegmann@icf.unam.mx [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Franco-Villafañe, John A., E-mail: jofravil@fis.unam.mx [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, 72570 Puebla (Mexico); Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Ortiz, Yenni P. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Kuhl, Ulrich [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Mortessagne, Fabrice, E-mail: fabrice.mortessagne@unice.fr [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Seligman, Thomas H. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Centro Internacional de Ciencias, 62210 Cuernavaca (Mexico)
2017-01-05
A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene. - Highlights: • Electronic transport in individual polyacetylene chains is studied. • Microwave emulation experiments and tight-binding calculations agree well. • In long chains a band-gap opens due the dimerization of the chain. • In short chains edge atoms cause strong resonance peaks in the center of the band-gap.
A new approach to calculate the transport matrix in RF cavities
Energy Technology Data Exchange (ETDEWEB)
Eidelman, Yu.; /Novosibirsk, IYF; Mokhov, N.; Nagaitsev, S.; Solyak, N.; /Fermilab
2011-03-01
A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm will be implemented into the MARS15 code. A realistic approach to calculate the transport matrix in RF cavities is developed. Complete agreement for tracking results with existed code ASTRA is achieved. New algorithm will be implemented into MARS15 code.
Xie, Hang; Sha, Wei E I
2015-01-01
Numerical methods are developed in the quantum transport calculations for electron in the waveguides with spin-orbital (Rashba) interaction. The methods are based on a hybrid mode-matching scheme in which the wavefunctions are expressed as the superposition of eigenmodes in the lead regions and in the device region the wavefunction is expressed on the discrete basis. Two versions are presented for the lead without and with the Rashba interaction. In the latter case the eigenmodes are obtained from a quadratic eigenproblem calculation. These methods are suitable for the systems with variable geometries or arbitrary potential profiles. The computation can be effectively accelerated by the sparse matrix technique. We also investigate the Fano-Rashba bound states in the Rashba waveguides by some nonlinear eigenstate calculation. This calculation is based on a mode-matching method and self-consistent results are obtained in our calculations.
A computational approach to calculate the heat of transport of aqueous solutions
Di Lecce, Silvia; Albrecht, Tim; Bresme, Fernando
2017-01-01
Thermal gradients induce concentration gradients in alkali halide solutions, and the salt migrates towards hot or cold regions depending on the average temperature of the solution. This effect has been interpreted using the heat of transport, which provides a route to rationalize thermophoretic phenomena. Early theories provide estimates of the heat of transport at infinite dilution. These values are used to interpret thermodiffusion (Soret) and thermoelectric (Seebeck) effects. However, accessing heats of transport of individual ions at finite concentration remains an outstanding question both theoretically and experimentally. Here we discuss a computational approach to calculate heats of transport of aqueous solutions at finite concentrations, and apply our method to study lithium chloride solutions at concentrations >0.5 M. The heats of transport are significantly different for Li+ and Cl− ions, unlike what is expected at infinite dilution. We find theoretical evidence for the existence of minima in the Soret coefficient of LiCl, where the magnitude of the heat of transport is maximized. The Seebeck coefficient obtained from the ionic heats of transport varies significantly with temperature and concentration. We identify thermodynamic conditions leading to a maximization of the thermoelectric response of aqueous solutions.
The transport history of two Saharan dust events archived in an Alpine ice core
Directory of Open Access Journals (Sweden)
H. Sodemann
2006-01-01
Full Text Available Mineral dust from the Saharan desert can be transported across the Mediterranean towards the Alpine region several times a year. When coinciding with snowfall, the dust can be deposited on Alpine glaciers and then appears as yellow or red layers in ice cores. Two such significant dust events were identified in an ice core drilled at the high-accumulation site Piz Zupó in the Swiss Alps (46°22' N, 9°55' E, 3850 m a.s.l.. From stable oxygen isotopes and major ion concentrations, the events were approximately dated as October and March 2000. In order to link the dust record in the ice core to the meteorological situation that led to the dust events, a novel methodology based on back-trajectory analysis was developed. It allowed the detailed analysis of the specific meteorologic flow evolution that was associated with Saharan dust transport into the Alps, and the identification of dust sources, atmospheric transport paths, and wet deposition periods for both dust events. Differences in the chemical signature of the two dust events were interpreted with respect to contributions from the dust sources and aerosol scavenging during the transport. For the October event, the trajectory analysis indicated that dust deposition took place during 13–15 October 2000. Mobilisation areas of dust were mainly identified in the Algerian and Libyan deserts. A combination of an upper-level potential vorticity streamer and a midlevel jet across Algeria first brought moist Atlantic air and later mixed air from the tropics and Saharan desert across the Mediterranean towards the Alps. The March event consisted of two different deposition phases which took place during 17–19 and 23–25 March 2000. The first phase was associated with an exceptional transport pathway past Iceland and towards the Alps from northerly directions. The second phase was similar to the October event. A significant peak of methanesulphonic acid associated with the March dust event was most
Usang, M. D.; Ivanyuk, F. A.; Ishizuka, C.; Chiba, S.
2016-10-01
Nuclear fission is treated by using the Langevin dynamical description with macroscopic and microscopic transport coefficients (mass and friction tensors), and it is elucidated how the microscopic (shell and pairing) effects in the transport coefficients, especially their dependence on temperature, affects various fission observables. We found that the microscopic transport coefficients, calculated by linear response theory, change drastically as a function of temperature: in general, the friction increases with growing temperature while the mass tensor decreases. This temperature dependence brings a noticeable change in the mass distribution and kinetic energies of fission fragments from nuclei around 236U at an excitation energy of 20 MeV. The prescission kinetic energy decreases from 25 MeV at low temperature to about 2.5 MeV at high temperature. In contrast, the Coulomb kinetic energy increases as the temperature increases. Interpolating the microscopic transport coefficients among the various temperatures enabled our Langevin equation to use the microscopic transport coefficients at a deformation-dependent local temperature of the dynamical evolution. This allowed us to compare directly the fission observables of both macroscopic and microscopic calculations, and we found almost identical results under the conditions considered in this work.
Energy Technology Data Exchange (ETDEWEB)
Abtew, Tesfaye A; Drabold, D A [Department of Physics and Astronomy, Ohio University, Athens, OH 45701-2979 (United States)
2004-11-10
In this paper we study electron dynamics and transport in models of amorphous silicon and amorphous silicon hydride. By integrating the time-dependent Kohn-Sham equation, we compute the time evolution of electron states near the gap, and study the spatial and spectral diffusion of these states due to lattice motion. We perform these calculations with a view to developing ab initio hopping transport methods. The techniques are implemented with the ab initio local basis code SIESTA, and may be applicable to molecular, biomolecular and other condensed matter systems.
Coarse mesh methods for the transport calculation in the CRONOS reactor code
Energy Technology Data Exchange (ETDEWEB)
Fedon-Magnaud, C.; Lautard, J.J.; Akherraz, B.; Wu, G.J. [Commissariat a l`Energie Atomique, Gif sur Yvette (France)
1995-12-31
Homogeneous transport methods have been recently implemented in the kinetic code CRONOS dedicated mainly to PWR calculations. Two different methods are presented. The first one is based on the even parity flux formalism and uses finite element spatial discretization and a discrete ordinates angular approximation; the treatment of the anisotropic scattering is described in detail. The second method uses the odd flux as the main unknown, it is closely connected to nodal methods. This method is used to solve two different problems, the simplified PN equations and the exact transport equation using an angular PN expansion. Numerical results are presented for some standard benchmarks and the methods are compared.
Coarse mesh methods for the transport calculation in the Cronos reactor code
Energy Technology Data Exchange (ETDEWEB)
Fedon-Magnaud, C.; Lautard, J.J.; Akherraz, B.; Wu, G.J.
1995-12-31
Homogeneous transports methods have been recently implemented in the kinetic code CRONOS dedicated mainly to PWR calculations. Two different methods are presented. The first one is based on the even parity flux formalism and uses finite element spatial discretization and a discrete ordinates angular approximation; the treatment of the anisotropic scattering is described in detail. The second method uses the odd flux as the main unknown, it is closely to nodal methods. This method is used to solve different problems, the simplified PN equations and the exact transport equation using an angular PN expansion. Numerical results are presented for some standard benchmarks and the method are compared. (authors). 18 refs., 3 tabs.
The effect of gamma-ray transport on afterheat calculations for accident analysis
Energy Technology Data Exchange (ETDEWEB)
Reyes, S.; Latkowski, J.F.; Sanz, J.
2000-05-01
Radioactive afterheat is an important source term for the release of radionuclides in fusion systems under accident conditions. Heat transfer calculations are used to determine time-temperature histories in regions of interest, but the true source term needs to be the effective afterheat, which considers the transport of penetrating gamma rays. Without consideration of photon transport, accident temperatures may be overestimated in others. The importance of this effect is demonstrated for a simple, one-dimensional problem. The significance of this effect depends strongly on the accident scenario being analyzed.
Mathews, Alyssa
Emissions from the combustion of fossil fuels are a growing pollution concern throughout the global community, as they have been linked to numerous health issues. The freight transportation sector is a large source of these emissions and is expected to continue growing as globalization persists. Within the US, the expanding development of the natural gas industry is helping to support many industries and leading to increased transportation. The process of High Volume Hydraulic Fracturing (HVHF) is one of the newer advanced extraction techniques that is increasing natural gas and oil reserves dramatically within the US, however the technique is very resource intensive. HVHF requires large volumes of water and sand per well, which is primarily transported by trucks in rural areas. Trucks are also used to transport waste away from HVHF well sites. This study focused on the emissions generated from the transportation of HVHF materials to remote well sites, dispersion, and subsequent health impacts. The Geospatial Intermodal Freight Transport (GIFT) model was used in this analysis within ArcGIS to identify roadways with high volume traffic and emissions. High traffic road segments were used as emissions sources to determine the atmospheric dispersion of particulate matter using AERMOD, an EPA model that calculates geographic dispersion and concentrations of pollutants. Output from AERMOD was overlaid with census data to determine which communities may be impacted by increased emissions from HVHF transport. The anticipated number of mortalities within the impacted communities was calculated, and mortality rates from these additional emissions were computed to be 1 in 10 million people for a simulated truck fleet meeting stricter 2007 emission standards, representing a best case scenario. Mortality rates due to increased truck emissions from average, in-use vehicles, which represent a mixed age truck fleet, are expected to be higher (1 death per 341,000 people annually).
Sadasivam, Sridhar; Ye, Ning; Feser, Joseph P.; Charles, James; Miao, Kai; Kubis, Tillmann; Fisher, Timothy S.
2017-02-01
Heat transfer across metal-semiconductor interfaces involves multiple fundamental transport mechanisms such as elastic and inelastic phonon scattering, and electron-phonon coupling within the metal and across the interface. The relative contributions of these different transport mechanisms to the interface conductance remains unclear in the current literature. In this work, we use a combination of first-principles calculations under the density functional theory framework and heat transport simulations using the atomistic Green's function (AGF) method to quantitatively predict the contribution of the different scattering mechanisms to the thermal interface conductance of epitaxial CoSi2-Si interfaces. An important development in the present work is the direct computation of interfacial bonding from density functional perturbation theory (DFPT) and hence the avoidance of commonly used "mixing rules" to obtain the cross-interface force constants from bulk material force constants. Another important algorithmic development is the integration of the recursive Green's function (RGF) method with Büttiker probe scattering that enables computationally efficient simulations of inelastic phonon scattering and its contribution to the thermal interface conductance. First-principles calculations of electron-phonon coupling reveal that cross-interface energy transfer between metal electrons and atomic vibrations in the semiconductor is mediated by delocalized acoustic phonon modes that extend on both sides of the interface, and phonon modes that are localized inside the semiconductor region of the interface exhibit negligible coupling with electrons in the metal. We also provide a direct comparison between simulation predictions and experimental measurements of thermal interface conductance of epitaxial CoSi2-Si interfaces using the time-domain thermoreflectance technique. Importantly, the experimental results, performed across a wide temperature range, only agree well with
Nabi, Jameel-Un
2014-01-01
Few white dwarfs, located in binary systems, may acquire sufficiently high mass accretion rates resulting in the burning of carbon and oxygen under nondegenerate conditions forming a O+Ne+Mg core. These O+Ne+Mg cores are gravitationally less bound than more massive progenitor stars and can release more energy due to the nuclear burning. They are also amongst the probable candidates for low entropy r-process sites. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rekindle the interest in 8 -- 10 M$_{\\odot}$ which develop O+Ne+Mg cores. Microscopic calculations of capture rates on $^{24}$Mg, which may contribute significantly to the collapse of O+Ne+Mg cores, using shell model and proton-neutron quasiparticle random phase approximation (pn-QRPA) theory, were performed earlier and comparisons made. Simulators, however, may require these capture rates on a fine scale. For the first time a detailed microscopic calculation of the electron and positron captur...
Parametric HECTR calculations of hydrogen transport and combustion at N Reactor
Energy Technology Data Exchange (ETDEWEB)
Payne, A.C. Jr.; Camp, A.L.
1987-06-01
This report describes a limited number of parametric calculations of hydrogen transport and combustion in the N Reactor confinement for selected accident sequences. The calculations are performed using the HECTR computer code, which is a lumped-parameter code developed specifically for evaluating hydrogen behavior in reactor containments. A number of parameters are evaluated in this study, including hydrogen source rate, spray effects, and source location. The calculations indicate that mixing within major compartments tends to occur fairly rapidly, but that mixing between compartments can be inhibited in certain situations, resulting in the formation of flammable mixtures. These results are being compared to calculations performed with other computer codes, including a code that uses finite-difference models. United Nuclear Corporation will present the results of these code comparisons in future reports.
Core-scale solute transport model selection using Monte Carlo analysis
Malama, Bwalya; James, Scott C
2013-01-01
Model applicability to core-scale solute transport is evaluated using breakthrough data from column experiments conducted with conservative tracers tritium (H-3) and sodium-22, and the retarding solute uranium-232. The three models considered are single-porosity, double-porosity with single-rate mobile-immobile mass-exchange, and the multirate model, which is a deterministic model that admits the statistics of a random mobile-immobile mass-exchange rate coefficient. The experiments were conducted on intact Culebra Dolomite core samples. Previously, data were analyzed using single- and double-porosity models although the Culebra Dolomite is known to possess multiple types and scales of porosity, and to exhibit multirate mobile-immobile-domain mass transfer characteristics at field scale. The data are reanalyzed here and null-space Monte Carlo analysis is used to facilitate objective model selection. Prediction (or residual) bias is adopted as a measure of the model structural error. The analysis clearly shows ...
Imachi, Hiroto; Yokoyama, Seiya; Kaji, Takami; Abe, Yukiya; Tada, Tomofumi; Hoshi, Takeo
2016-12-01
One-hundred-nm-scale electronic structure calculations were carried out on the K supercomputer by our original simulation code ELSES (http://www.elses.jp/) The present paper reports preliminary results of transport calculations for condensed organic polymers. Large-scale calculations are realized by novel massively parallel order-N algorithms. The transport calculations were carried out as a theoretical extension for the quantum wavepacket dynamics simulation. The method was applied to a single polymer chain and condensed polymers.
Calculation of a plasma HgDyI{sub 3} transport coefficients
Energy Technology Data Exchange (ETDEWEB)
Hajji, S.; HadjSalah, S.; Benhalima, A.; Charrada, K. [IPEIM, Unité d' Etude des Milieux Ionisés et Réactifs, 5019 route de Kairouan Monastir (Tunisia); Zissis, G. [Laboratoire Plasma et Conversion d' Énergie, 118 rte Narbonne, Bât3R2, 31062 Toulouse (France)
2015-05-15
This work is devoted to the calculation of the chemical composition and transport coefficients of HgDyI{sub 3} plasmas in thermal equilibrium. These calculations are performed for pressures equal to 2MP and for temperatures varying from 1000 to 10 000 K. The thermal and electrical conductivity as well as viscosity have been computed as a function of temperature at different atomic ratios. The computational method proposed by Devoto from the classical formalism described by Hirschfelder et al. [Molecular Theory of Gases and Liquids (John Wiley and Sons, New York, 1954)] is used.
DEFF Research Database (Denmark)
Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin
2013-01-01
different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...
DEFF Research Database (Denmark)
Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin
2013-01-01
different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...
Energy Technology Data Exchange (ETDEWEB)
Hartini, Entin, E-mail: entin@batan.go.id; Andiwijayakusuma, Dinan, E-mail: entin@batan.go.id [Center for Development of Nuclear Informatics - National Nuclear Energy Agency, PUSPIPTEK, Serpong, Tangerang, Banten (Indonesia)
2014-09-30
This research was carried out on the development of code for uncertainty analysis is based on a statistical approach for assessing the uncertainty input parameters. In the butn-up calculation of fuel, uncertainty analysis performed for input parameters fuel density, coolant density and fuel temperature. This calculation is performed during irradiation using Monte Carlo N-Particle Transport. The Uncertainty method based on the probabilities density function. Development code is made in python script to do coupling with MCNPX for criticality and burn-up calculations. Simulation is done by modeling the geometry of PWR terrace, with MCNPX on the power 54 MW with fuel type UO2 pellets. The calculation is done by using the data library continuous energy cross-sections ENDF / B-VI. MCNPX requires nuclear data in ACE format. Development of interfaces for obtaining nuclear data in the form of ACE format of ENDF through special process NJOY calculation to temperature changes in a certain range.
Hartini, Entin; Andiwijayakusuma, Dinan
2014-09-01
This research was carried out on the development of code for uncertainty analysis is based on a statistical approach for assessing the uncertainty input parameters. In the butn-up calculation of fuel, uncertainty analysis performed for input parameters fuel density, coolant density and fuel temperature. This calculation is performed during irradiation using Monte Carlo N-Particle Transport. The Uncertainty method based on the probabilities density function. Development code is made in python script to do coupling with MCNPX for criticality and burn-up calculations. Simulation is done by modeling the geometry of PWR terrace, with MCNPX on the power 54 MW with fuel type UO2 pellets. The calculation is done by using the data library continuous energy cross-sections ENDF / B-VI. MCNPX requires nuclear data in ACE format. Development of interfaces for obtaining nuclear data in the form of ACE format of ENDF through special process NJOY calculation to temperature changes in a certain range.
Parsafar, G. A.; Shokouhi, M.
A new hard-core potential model was recently used to calculate thermodynamic properties of some model fluids, including equilibrium properties, such as compressibility factor and internal energy. A Lennard-Jones (LJ) like potential has been used to modify the repulsive part of the potential. The modified potential contains five parameters, namely, α, R, ɛ, σ, and σHS. The parameter α is the tail of the attractive branch whose value changes from zero to one. In this work, we have chosen α = 1 to make the potential continuous at separation r = Rσ, where the parameter R is the well width. R lies in the range 1.2 to 2.5, and R = 1.3 was found to be the best value for all real gases studied. The parameter ɛ is the well depth of potential function, and σ is the separation at which the potential function is zero. σHS is the effective hard sphere diameter, which depends on temperature and an additional parameter. Using statistical mechanics along with the Boltzmann factor criterion (BFC) for the effective hard sphere diameter, an analytical expression has been derived for the reduced second virial coefficient in terms of the reduced temperature. Fitting experimental data to expression derived for the second virial coefficient, the potential parameters ɛ and σ are obtained. Since this potential is spherical (depending only on distance), three types of species are chosen, namely Ar and He (monoatomic), N2and O2 (diatomic), and methane (spherical molecule), to show how appropriate this potential model is for them. This model predicts an inversion temperature for the second virial coefficient (temperature at which the second virial coefficient pass through a maximum) at ILM0001, where T1 is the inversion temperature, and TB is the Boyle temperature. The predicted value is better than that of the L-J model (for which ILM0002). The maximum percentage deviation of the second virial coefficient is about 2%, except around the Boyle temperature. Then the transport
PyTransport: A Python package for the calculation of inflationary correlation functions
Mulryne, David J
2016-01-01
PyTransport constitutes a straightforward code written in C++ together with Python scripts which automatically edit, compile and run the C++ code as a Python module. It has been written for Unix-like systems (OS X and Linux). Primarily the module employs the transport approach to inflationary cosmology to calculate the tree-level power-spectrum and bispectrum of user specified models of multi-field inflation, accounting for all sub and super-horizon effects. The transport method we utilise means only coupled differential equations need to be solved, and the implementation presented here combines the speed of C++ with the functionality and convenience of Python. At present the code is restricted to canonical models. This document details the code and illustrates how to use it with a worked example.
Gao, Haiyuan; Li, Meijiao; Guo, Zhendong; Chen, Hongshen; Jin, Zhonghe; Yu, Bin
2011-01-01
Electronic transport properties of monolayer graphene with extreme physical bending up to 90o angle are studied using ab Initio first-principle calculations. The importance of key structural parameters including step height, curvature radius and bending angle are discussed how they modify the transport properties of the deformed graphene sheet comparing to the corresponding flat ones. The local density of state reveals that energy state modification caused by the physical bending is highly localized. It is observed that the transport properties of bent graphene with a wide range of geometrical configurations are insensitive to the structural deformation in the low-energy transmission spectra, even in the extreme case of bending. The results support that graphene, with its superb electromechanical robustness, could serve as a viable material platform in a spectrum of applications such as photovoltaics, flexible electronics, OLED, and 3D electronic chips.
Ab initio transport calculations of molecular wires with electron-phonon couplings
Hirose, Kenji; Kobayashi, Nobuhiko
2009-03-01
Understanding of electron transport through nanostructures becomes important with the advancement of fabrication process to construct atomic-scale devices. Due to the drastic change of transport properties by contact conditions to electrodes in local electric fields, first-principles calculation approaches are indispensable to understand and characterize the transport properties of nanometer-scale molecular devices. Here we study the transport properties of molecular wires between metallic electrodes, especially focusing on the effects of contacts to electrodes and of the electron-phonon interactions. We use an ab initio calculation method based on the scattering waves, which are obtained by the recursion-transfer-matrix (RTM) method, combined with non-equilibrium Green's function (NEGF) method including the electron-phonon scatterings. We find that conductance shows exponential behaviors as a function of the length of molecular wires due to tunneling process determined by the HOMO-LUMO energy gap. From the voltage drop behaviors inside the molecular wires, we show that the contact resistances are dominant source for the bias drop and thus are related to local heating. We will present the electron-phonon coupling effects at contact on the inelastic scattering and discuss on the local heating and local temperature, comparing them with those of metallic atomic wires.
Validity of Viscous Core Correction Models for Self-Induced Velocity Calculations
Van Hoydonck, Wim
2012-01-01
Viscous core correction models are used in free wake simulations to remove the infinite velocities at the vortex centreline. It will be shown that the assumption that these corrections converge to the Biot-Savart law in the far field is not correct for points near the tangent line of a vortex segment. Furthermore, the self-induced velocity of a vortex ring with a viscous core is shown to converge to the wrong value. The source of these errors in the model is identified and an improved model is presented that rectifies the errors. It results in correct values for the self-induced velocity of a viscous vortex ring and induced velocities that converge to the values predicted by the Biot-Savart law for all points in the far field.
Energy Technology Data Exchange (ETDEWEB)
Chi, C.-C.; Hsiao, C.-H.; Ouyang, Chuenhou, E-mail: houyang@mx.nthu.edu.tw [Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Skoropata, E.; Lierop, J. van [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)
2015-05-07
Significant efforts towards understanding bi-magnetic core-shell nanoparticles are underway currently as they provide a pathway towards properties unavailable with single-phased systems. Recently, we have demonstrated that the magnetism of γ-Fe2O3/CoO core-shell nanoparticles, in particular, at high temperatures, originates essentially from an interfacial doped iron-oxide layer that is formed by the migration of Co{sup 2+} from the CoO shell into the surface layers of the γ-Fe2O3 core [Skoropata et al., Phys. Rev. B 89, 024410 (2014)]. To examine directly the nature of the intermixed layer, we have used high-resolution transmission electron microscopy (HRTEM) and first-principles calculations to examine the impact of the core-shell intermixing at the atomic level. By analyzing the HRTEM images and energy dispersive spectra, the level and nature of intermixing was confirmed, mainly as doping of Co into the octahedral site vacancies of γ-Fe2O3. The average Co doping depths for different processing temperatures (150 °C and 235 °C) were 0.56 nm and 0.78 nm (determined to within 5% through simulation), respectively, establishing that the amount of core-shell intermixing can be altered purposefully with an appropriate change in synthesis conditions. Through first-principles calculations, we find that the intermixing phase of γ-Fe2O3 with Co doping is ferromagnetic, with even higher magnetization as compared to that of pure γ-Fe2O3. In addition, we show that Co doping into different octahedral sites can cause different magnetizations. This was reflected in a change in overall nanoparticle magnetization, where we observed a 25% reduction in magnetization for the 235 °C versus the 150 °C sample, despite a thicker intermixed layer.
Kasteel, R.; Pütz, Th.; Vereecken, H.
2003-04-01
Lysimeter studies are one step within the registration procedure of pesticides. Flow and transport in these free-draining lysimeters do not reflect the field situation mainly because of the occurence of a zone of local saturation at the lower boundary (seepage face). The objective of this study is to evaluate the impact of flow and transport behaviour of bromide detected with different measuring devices (lysimeters, suction plates, and soil coring) by comparing experimental results with numerical simulations in heterogeneous flow domains. We applied bromide as a small pulse to the bare soil surface (Orthic Luvisol) of the three devices and the displacement of bromide was regurlarly sampled for three years under natural wheather conditions. Based on the mean breakthrough curves we observe experimentally that lysimeters have a lower effective pore-water velocity and exhibit more solute spreading resulting in a larger dispersivity than the suction plates. This can be ascribed to the artefact of the lower boundary. We performed numerical transport simulations in 2-D heterogeneous flow fields (scaling approach) choosing appropriate boundary conditions for the various devices. The simulations allow to follow the temporal evolution of flow and transport processes in the various devices and to gain additional process understanding. We conclude that the model is essentially capable to reproduce the main experimental findings only if we account for the spatial correlation structure of the hydraulic properties, i.e. soil heterogeneity.
Kuroda, Takami; Takiwaki, Tomoya
2012-01-01
We present results from the first generation of multi-dimensional hydrodynamic core-collapse simulations in full general relativity (GR) that include an approximate treatment of neutrino transport. Using a M1 closure scheme with an analytic variable Eddington factor, we solve the energy-independent set of radiation energy and momentum based on the Thorne's momentum formalism. To simplify the source terms of the transport equations, a methodology of multiflavour neutrino leakage scheme is partly employed. Our newly developed code is designed to evolve the Einstein field equation together with the GR radiation hydrodynamic equations. We follow the dynamics starting from the onset of gravitational core-collapse of a 15 $M_{\\odot}$ star, through bounce, up to about 100 ms postbounce in this study to study how the spacial multi-dimensionality and GR would affect the dynamics in the early postbounce phase. Our 3D results support the anticipation in previous 1D results that the neutrino luminosity and average neutri...
Calculation of the transport and relaxation properties of dilute water vapor
Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa
2009-07-01
Transport properties of dilute water vapor have been calculated in the rigid-rotor approximation using four different potential energy hypersurfaces and the classical-trajectory method. Results are reported for shear viscosity, self-diffusion, thermal conductivity, and volume viscosity in the dilute-gas limit for the temperature range of 250-2500 K. Of these four surfaces the CC-pol surface of Bukowski et al. [J. Chem. Phys. 128, 094314 (2008)] is in best accord with the available measurements. Very good agreement is found with the most accurate results for viscosity in the whole temperature range of the experiments. For thermal conductivity the deviations of the calculated values from the experimental data increase systematically with increasing temperature to around 5% at 1100 K. For both self-diffusion and volume viscosity, the much more limited number of available measurements are generally consistent with the calculated values, apart from the lower temperature isotopically labeled diffusion measurements.
Core-scale solute transport model selection using Monte Carlo analysis
Malama, Bwalya; Kuhlman, Kristopher L.; James, Scott C.
2013-06-01
Model applicability to core-scale solute transport is evaluated using breakthrough data from column experiments conducted with conservative tracers tritium (3H) and sodium-22 (22Na ), and the retarding solute uranium-232 (232U). The three models considered are single-porosity, double-porosity with single-rate mobile-immobile mass-exchange, and the multirate model, which is a deterministic model that admits the statistics of a random mobile-immobile mass-exchange rate coefficient. The experiments were conducted on intact Culebra Dolomite core samples. Previously, data were analyzed using single-porosity and double-porosity models although the Culebra Dolomite is known to possess multiple types and scales of porosity, and to exhibit multirate mobile-immobile-domain mass transfer characteristics at field scale. The data are reanalyzed here and null-space Monte Carlo analysis is used to facilitate objective model selection. Prediction (or residual) bias is adopted as a measure of the model structural error. The analysis clearly shows single-porosity and double-porosity models are structurally deficient, yielding late-time residual bias that grows with time. On the other hand, the multirate model yields unbiased predictions consistent with the late-time -5/2 slope diagnostic of multirate mass transfer. The analysis indicates the multirate model is better suited to describing core-scale solute breakthrough in the Culebra Dolomite than the other two models.
Engineered core-shell nanofibers for electron transport study in dye-sensitized solar cells
Shabdan, Y.; Ronasi, A.; Coulibaly, P.; Moniruddin, M.; Nuraje, N.
2017-06-01
In this study, a unique approach was developed to synthesize 1-D core-shell nanofibers of carbon nanotubes (CNTs) and TiO2 using combination of coaxial electrospinning and sol-gel technique. Diameters of the fabricated core-shell single wall carbon nanotube-TiO2 (SWCNT-TiO2) and multi wall carbon nanotube-TiO2 (MWCNT-TiO2) nano-composite fibers were between 50-100nm. Energy dispersive spectroscopy (EDS) and X-ray photon spectroscopy (XPS) were applied to confirm encapsulation of carbon nanotube (CNT) in the core-shell structure. Electron transport properties of both SWCNT-TiO2 and MWCNT-TiO2 in the Dye-sensitized solar cells (DSSCs) were studied for the first time. It was found that SWCNT-TiO2 based DSSC provided higher short circuit current relative to MWCNT-TiO2, which was explained by I-V and bode plots. These findings were further illustrated by semi-conductive properties of SWCNT.
Self-consistent core-pedestal transport simulations with neural network accelerated models
Meneghini, O.; Smith, S. P.; Snyder, P. B.; Staebler, G. M.; Candy, J.; Belli, E.; Lao, L.; Kostuk, M.; Luce, T.; Luda, T.; Park, J. M.; Poli, F.
2017-08-01
Fusion whole device modeling simulations require comprehensive models that are simultaneously physically accurate, fast, robust, and predictive. In this paper we describe the development of two neural-network (NN) based models as a means to perform a snon-linear multivariate regression of theory-based models for the core turbulent transport fluxes, and the pedestal structure. Specifically, we find that a NN-based approach can be used to consistently reproduce the results of the TGLF and EPED1 theory-based models over a broad range of plasma regimes, and with a computational speedup of several orders of magnitudes. These models are then integrated into a predictive workflow that allows prediction with self-consistent core-pedestal coupling of the kinetic profiles within the last closed flux surface of the plasma. The NN paradigm is capable of breaking the speed-accuracy trade-off that is expected of traditional numerical physics models, and can provide the missing link towards self-consistent coupled core-pedestal whole device modeling simulations that are physically accurate and yet take only seconds to run.
Fossgård, Eirik; Ruud, Kenneth
2006-02-01
We describe the implementation of a parallel, in-core, integral-direct Hartree-Fock and density functional theory code for the efficient calculation of Hartree-Fock wave functions and density functional theory. The algorithm is based on a parallel master-slave algorithm, and the two-electron integrals calculated by a slave are stored in available local memory. To ensure the greatest computational savings, the master node keeps track of all integral batches stored on the different slaves. The code can reuse undifferentiated two-electron integrals both in the wave function optimization and in the evaluation of second-, third-, and fourth-order molecular properties. Superlinear scaling is achieved in a series of test examples, with speedups of up to 55 achieved for calculations run on medium-sized molecules on 16 processors with respect to the time used on a single processor.
GUIDE TO CALCULATING TRANSPORT EFFICIENCY OF AEROSOLS IN OCCUPATIONAL AIR SAMPLING SYSTEMS
Energy Technology Data Exchange (ETDEWEB)
Hogue, M.; Hadlock, D.; Thompson, M.; Farfan, E.
2013-11-12
This report will present hand calculations for transport efficiency based on aspiration efficiency and particle deposition losses. Because the hand calculations become long and tedious, especially for lognormal distributions of aerosols, an R script (R 2011) will be provided for each element examined. Calculations are provided for the most common elements in a remote air sampling system, including a thin-walled probe in ambient air, straight tubing, bends and a sample housing. One popular alternative approach would be to put such calculations in a spreadsheet, a thorough version of which is shared by Paul Baron via the Aerocalc spreadsheet (Baron 2012). To provide greater transparency and to avoid common spreadsheet vulnerabilities to errors (Burns 2012), this report uses R. The particle size is based on the concept of activity median aerodynamic diameter (AMAD). The AMAD is a particle size in an aerosol where fifty percent of the activity in the aerosol is associated with particles of aerodynamic diameter greater than the AMAD. This concept allows for the simplification of transport efficiency calculations where all particles are treated as spheres with the density of water (1g cm-3). In reality, particle densities depend on the actual material involved. Particle geometries can be very complicated. Dynamic shape factors are provided by Hinds (Hinds 1999). Some example factors are: 1.00 for a sphere, 1.08 for a cube, 1.68 for a long cylinder (10 times as long as it is wide), 1.05 to 1.11 for bituminous coal, 1.57 for sand and 1.88 for talc. Revision 1 is made to correct an error in the original version of this report. The particle distributions are based on activity weighting of particles rather than based on the number of particles of each size. Therefore, the mass correction made in the original version is removed from the text and the calculations. Results affected by the change are updated.
Measurement and calculation of fast neutron and gamma spectra in well defined cores in LR-0 reactor.
Košťál, Michal; Matěj, Zdeněk; Cvachovec, František; Rypar, Vojtěch; Losa, Evžen; Rejchrt, Jiří; Mravec, Filip; Veškrna, Martin
2017-02-01
A well-defined neutron spectrum is essential for many types of experimental topics and is also important for both calibration and testing of spectrometric and dosimetric detectors. Provided it is well described, such a spectrum can also be employed as a reference neutron field that is suitable for validating selected cross sections. The present paper aims to compare calculations and measurements of such a well-defined spectra in geometrically similar cores of the LR-0 reactor with fuel containing slightly different enrichments (2%, 3.3% and 3.6%). The common feature to all cores is a centrally located dry channel which can be used for the insertion of studied materials. The calculation of neutron and gamma spectra was realized with the MCNP6 code using ENDF/B-VII.0, JEFF-3.1, JENDL-3.3, ROSFOND-2010 and CENDL-3.1 nuclear data libraries. Only minor differences in neutron and gamma spectra were found in the comparison of the presented reactor cores with different fuel enrichments. One exception is the gamma spectrum in the higher energy region (above 8MeV), where more pronounced variations could be observed.
No-Core Shell Model Calculations in Light Nuclei with Three-Nucleon Forces
Energy Technology Data Exchange (ETDEWEB)
Barrett, B R; Vary, J P; Nogga, A; Navratil, P; Ormand, W E
2004-01-08
The ab initio No-Core Shell Model (NCSM) has recently been expanded to include nucleon-nucleon (NN) and three-nucleon (3N) interactions at the three-body cluster level. Here it is used to predict binding energies and spectra of p-shell nuclei based on realistic NN and 3N interactions. It is shown that 3N force (3NF) properties can be studied in these nuclear systems. First results show that interactions based on chiral perturbation theory lead to a realistic description of {sup 6}Li.
A sequential partly iterative approach for multicomponent reactive transport with CORE2D
Energy Technology Data Exchange (ETDEWEB)
Samper, J.; Xu, T.; Yang, C.
2008-11-01
CORE{sup 2D} V4 is a finite element code for modeling partly or fully saturated water flow, heat transport and multicomponent reactive solute transport under both local chemical equilibrium and kinetic conditions. It can handle coupled microbial processes and geochemical reactions such as acid-base, aqueous complexation, redox, mineral dissolution/precipitation, gas dissolution/exsolution, ion exchange, sorption via linear and nonlinear isotherms, sorption via surface complexation. Hydraulic parameters may change due to mineral precipitation/dissolution reactions. Coupled transport and chemical equations are solved by using sequential iterative approaches. A sequential partly-iterative approach (SPIA) is presented which improves the accuracy of the traditional sequential noniterative approach (SNIA) and is more efficient than the general sequential iterative approach (SIA). While SNIA leads to a substantial saving of computing time, it introduces numerical errors which are especially large for cation exchange reactions. SPIA improves the efficiency of SIA because the iteration between transport and chemical equations is only performed in nodes with a large mass transfer between solid and liquid phases. The efficiency and accuracy of SPIA are compared to those of SIA and SNIA using synthetic examples and a case study of reactive transport through the Llobregat Delta aquitard in Spain. SPIA is found to be as accurate as SIA while requiring significantly less CPU time. In addition, SPIA is much more accurate than SNIA with only a minor increase in computing time. A further enhancement of the efficiency of SPIA is achieved by improving the efficiency of the Newton-Raphson method used for solving chemical equations. Such an improvement is obtained by working with increments of log-concentrations and ignoring the terms of the Jacobian matrix containing derivatives of activity coefficients. A proof is given for the symmetry and non-singularity of the Jacobian matrix
Wang, Xiaoming; Zebarjadi, Mona; Esfarjani, Keivan
2016-08-01
This work aims at understanding solid-state energy conversion and transport in layered (van der Waals) heterostructures in contact with metallic electrodes via a first-principles approach. As an illustration, a graphene/phosphorene/graphene heterostructure in contact with gold electrodes is studied by using density functional theory (DFT)-based first principles calculations combined with real space Green's function (GF) formalism. We show that for a monolayer phosphorene, quantum tunneling dominates the transport. By adding more phosphorene layers, one can switch from tunneling-dominated transport to thermionic-dominated transport, resulting in transporting more heat per charge carrier, thus, enhancing the cooling coefficient of performance. The use of layered van der Waals heterostructures has two advantages: (a) thermionic transport barriers can be tuned by changing the number of layers, and (b) thermal conductance across these non-covalent structures is very weak. The phonon thermal conductance of the present van der Waals heterostructure is found to be 4.1 MW m-2 K-1 which is one order of magnitude lower than the lowest value for that of covalently-bonded interfaces. The thermionic coefficient of performance for the proposed device is 18.5 at 600 K corresponding to an equivalent ZT of 0.13, which is significant for nanoscale devices. This study shows that layered van der Waals structures have great potential to be used as solid-state energy-conversion devices.This work aims at understanding solid-state energy conversion and transport in layered (van der Waals) heterostructures in contact with metallic electrodes via a first-principles approach. As an illustration, a graphene/phosphorene/graphene heterostructure in contact with gold electrodes is studied by using density functional theory (DFT)-based first principles calculations combined with real space Green's function (GF) formalism. We show that for a monolayer phosphorene, quantum tunneling dominates the
Considerations of beta and electron transport in internal dose calculations. Progress report
Energy Technology Data Exchange (ETDEWEB)
Bolch, W.E.
1994-11-01
The goal of this particular task is to consider, for the first time, the explicit transport of beta particles and photon-generated electrons in the series of six phantoms developed by Cristy and Eckerman (1987) at the Oak Ridge National Laboratory. In their report, ORNL/TM-8381, specific absorbed fractions of energy are reported for phantoms representing the newborn (3.4 kg), the one-year-old (9.8 kg), the five-year-old (19 kg), the ten-year-old (32 kg), the fifteen-year-old/adult female (55-58 kg), and the adult male (70 kg). Radiation transport calculations were performed with the Monte Carlo code ALGAMP which allows photon transport only. In subsequent calculations of radionuclide S values as is done in the MIRDOSE2 computer program, electron absorbed fractions are thus considered to be either unity or zero depending upon whether the source region does or does not equal the target region, respectively.
Jacob, D; Palacios, J J
2011-01-28
We study the performance of two different electrode models in quantum transport calculations based on density functional theory: parametrized Bethe lattices and quasi-one-dimensional wires or nanowires. A detailed account of implementation details in both the cases is given. From the systematic study of nanocontacts made of representative metallic elements, we can conclude that the parametrized electrode models represent an excellent compromise between computational cost and electronic structure definition as long as the aim is to compare with experiments where the precise atomic structure of the electrodes is not relevant or defined with precision. The results obtained using parametrized Bethe lattices are essentially similar to the ones obtained with quasi-one-dimensional electrodes for large enough cross-sections of these, adding a natural smearing to the transmission curves that mimics the true nature of polycrystalline electrodes. The latter are more demanding from the computational point of view, but present the advantage of expanding the range of applicability of transport calculations to situations where the electrodes have a well-defined atomic structure, as is the case for carbon nanotubes, graphene nanoribbons, or semiconducting nanowires. All the analysis is done with the help of codes developed by the authors which can be found in the quantum transport toolbox ALACANT and are publicly available.
Calculation of effective transport properties of partially saturated gas diffusion layers
Bednarek, Tomasz; Tsotridis, Georgios
2017-02-01
A large number of currently available Computational Fluid Dynamics numerical models of Polymer Electrolyte Membrane Fuel Cells (PEMFC) are based on the assumption that porous structures are mainly considered as thin and homogenous layers, hence the mass transport equations in structures such as Gas Diffusion Layers (GDL) are usually modelled according to the Darcy assumptions. Application of homogenous models implies that the effects of porous structures are taken into consideration via the effective transport properties of porosity, tortuosity, permeability (or flow resistance), diffusivity, electric and thermal conductivity. Therefore, reliable values of those effective properties of GDL play a significant role for PEMFC modelling when employing Computational Fluid Dynamics, since these parameters are required as input values for performing the numerical calculations. The objective of the current study is to calculate the effective transport properties of GDL, namely gas permeability, diffusivity and thermal conductivity, as a function of liquid water saturation by using the Lattice-Boltzmann approach. The study proposes a method of uniform water impregnation of the GDL based on the "Fine-Mist" assumption by taking into account the surface tension of water droplets and the actual shape of GDL pores.
Energy Technology Data Exchange (ETDEWEB)
González-Cataldo, F. [Grupo de NanoMateriales, Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Wilson, Hugh F.; Militzer, B., E-mail: fgonzalez@lpmd.cl [Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA 94720 (United States)
2014-05-20
By combining density functional molecular dynamics simulations with a thermodynamic integration technique, we determine the free energy of metallic hydrogen and silica, SiO{sub 2}, at megabar pressures and thousands of degrees Kelvin. Our ab initio solubility calculations show that silica dissolves into fluid hydrogen above 5000 K for pressures from 10 and 40 Mbars, which has implications for the evolution of rocky cores in giant gas planets like Jupiter, Saturn, and a substantial fraction of known extrasolar planets. Our findings underline the necessity of considering the erosion and redistribution of core materials in giant planet evolution models, but they also demonstrate that hot metallic hydrogen is a good solvent at megabar pressures, which has implications for high-pressure experiments.
Calculations of 3D full-scale VVER fuel assembly and core models using MCU and BIPR-7A codes
Energy Technology Data Exchange (ETDEWEB)
Aleshin, Sergey S.; Bikeev, Artem S.; Bolshagin, Sergey N.; Kalugin, Mikhail A.; Kosourov, Evgeniy K.; Pavlovichev, Aleksandr M.; Pryanichnikov, Aleksandr V.; Sukhino-Khomenko, Evgenia A.; Shcherenko, Anna I.; Shcherenko, Anastasia I.; Shkarovskiy, Denis A. [Nuclear Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation)
2015-09-15
Two types of calculations were made to compare BIPR-7A and MCU results for 3D full-scale models. First EPS (emergency protection system) efficiency and in-core power distributions were analyzed for an equilibrium fuel load of VVER-1000 assuming its operation within an 18-month cycle. Computations were performed without feedbacks and with fuel burnup distributed over the core. After 3D infinite lattices of full-scale VVER-1000 fuel assemblies (A's) with uranium fuel 4.4% enrichment and uranium-erbium fuel 4.4% enrichment and Er{sub 2}O{sub 3} 1 % wt were considered. Computations were performed with feedbacks and fuel burnup at the constant power level. For different time moments effective multiplication factor and power distribution were obtained. EPS efficiency and reactivity effects at chosen time moments were analyzed.
Calculation of PDS-XADS core closed-loop transfer function by using feedback with the lumped-model
Energy Technology Data Exchange (ETDEWEB)
Moghassem, Alireza; Payirandeh, Ali; Abbaspour, Ali [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Nuclear Engineering Dept.
2016-03-15
In this paper, the PDS-XADS LBE-cooled core open-loop transfer function was calculated by considering the source importance in point-kinetic equations. For this purpose, the overall-feedback transfer function was calculated considering the lumped-model for 14-steps of subcritical levels. Following effects were considered in three steps: 1. Doppler broadening, fuel expansion, coolant density and structure expansion, 2. Delayed-reactivity and void-worth inserted to prior step, 3. Severe-accident condition, inserted to prior steps. The linear stability analysis was modeled by using the Bode diagrams, Nyquist stability criterion and Nichols chart in MATLAB for each subcritical level and six groups of delayed neutrons. For optimized subcritical level determination, a conservative severe accident was considered. According to calculation results and analysis, the PDS-XADS core is stable and in optimized subcritical level, has the higher safety margin. The results are in good agreement with SIMMER-III code and main neutronic results. The optimized subcritical level by using the lumped-model is 0.97687.
López, J I; Cáceres, F; Pérez, A; Caamaño, V; Larrinaga, G; Lecumberri, D; Arruza, A
2014-11-01
To evaluate the diagnostic usefulness of the cytological study of the transport buffer in the diagnosis of prostate adenocarcinoma in transrectal core biopsies. A total of 256 consecutively biopsied patients have been included in the analysis, 100 of them diagnosed of prostate adenocarcinoma. The procedure included the cytological analysis of the transport buffer and conventional histology. Cytological evaluation was performed in a blind way by the same pathologist. Overall sensitivity, specificity, and positive and negative predictive values to detect malignancy in the cytological slides were 54%, 98%, 94% and 76%, respectively. When restricted the analysis to cases with Gleason score higher than 8, sensitivity and negative predictive value increased to 85% and 97%, respectively. Similarly, when the analysis focused exclusively to cases with more than 5mm of cancer in the biopsy, sensitivity and positive predictive value increased to 66% and 96%, respectively. This study shows that whilst specificity was maintained in 98%, sensitivity, and positive and negative predictive values significantly improved in high grade and high volume adenocarcinomas. Our findings confirm that the cytological study of the transport buffer may complement the histology in the diagnosis of prostate adenocarcinoma. Copyright © 2014 AEU. Published by Elsevier Espana. All rights reserved.
Leal, Allan; Saar, Martin
2016-04-01
Computational methods for geochemical and reactive transport modeling are essential for the understanding of many natural and industrial processes. Most of these processes involve several phases and components, and quite often requires chemical equilibrium and kinetics calculations. We present an overview of novel methods for multiphase equilibrium calculations, based on both the Gibbs energy minimization (GEM) approach and on the solution of the law of mass-action (LMA) equations. We also employ kinetics calculations, assuming partial equilibrium (e.g., fluid species in equilibrium while minerals are in disequilibrium) using automatic time stepping to improve simulation efficiency and robustness. These methods are developed specifically for applications that are computationally expensive, such as reactive transport simulations. We show how efficient the new methods are, compared to other algorithms, and how easy it is to use them for geochemical modeling via a simple script language. All methods are available in Reaktoro, a unified open-source framework for modeling chemically reactive systems, which we also briefly describe.
Cox, Robert M.; Cogan, James; Sontowski, John; Dougherty, Catherine M.; Fry, Richard N., Jr.; Smith, Thomas J.
2000-12-01
A comparison of atmospheric transport and dispersion calculations over complex terrain was investigated using a mobile profiling system (MPS) versus standard meteorological balloons. Meteorological and sulfur hexafluoride (SF6) concentration data were collected and used to evaluate the performance of a transport and diffusion model coupled with a mass consistency wind field model. Meteorological data were collected throughout April 1995, and parts of August 1995. Both meteorological and concentration data were measured in December 1995. Once the models were validated, the comparison of performance with different upper-air data were accomplished. The models used included the SCIPUFF (Second-order Closure Integrated Puff) transport and diffusion model and the MINERVE mass consistency wind model. Evaluation of the models was focused primarily on their effectiveness as a short-term (one to four hours) predictive tool. These studies showed how the combination of weather and transport models could be used to help direct emergency response following a hazardous material release. The models were used in tandem to direct the deployment of mobile sensors intended to intercept and measure tracer clouds. The MINERVE model was validated for the specific terrain of interest using April 1995 data. The capability of SCIPUFF driven by realistic three-dimensional wind fields generated by MINERVE is demonstrated using data collected in December 1995.
Haskins, Justin; Kinaci, Alper; Sevik, Cem; Cagin, Tahir
2012-01-01
It is widely known that graphene and many of its derivative nanostructures have exceedingly high reported thermal conductivities (up to 4000 W/mK at 300 K). Such attractive thermal properties beg the use of these structures in practical devices; however, to implement these materials while preserving transport quality, the influence of structure on thermal conductivity should be thoroughly understood. For graphene nanostructures, having average phonon mean free paths on the order of one micron, a primary concern is how size influences the potential for heat conduction. To investigate this, we employ a novel technique to evaluate the lattice thermal conductivity from the Green-Kubo relations and equilibrium molecular dynamics in systems where phonon-boundary scattering dominates heat flow. Specifically, the thermal conductivities of graphene nanoribbons and carbon nanotubes are calculated in sizes up to 3 microns, and the relative influence of boundary scattering on thermal transport is determined to be dominant at sizes less than 1 micron, after which the thermal transport largely depends on the quality of the nanostructure interface. The method is also extended to carbon nanostructures (fullerenes) where phonon confinement, as opposed to boundary scattering, dominates, and general trends related to the influence of curvature on thermal transport in these materials are discussed.
Test problem for thermal-hydraulics and neutronic coupled calculation fore ALFREAD reactor core
Filip, A.; Darie, G.; Saldikov, I. S.; Smirnov, A. D.; Tikhomirov, G. V.
2017-01-01
The beginning of a new era of nuclear reactor requires technological advances and also multiples studies. The European Liquid metal cooled Fast breeder Reactor is one of the designs for the generation IV nuclear reactor, selected by ENEA. A pioneer of its time, ELFR needs a demonstrator in order to prove the feasibility of this project and to acquire more data and experience in operating a LFR. For this reason the ALFRED project was started and it is expected to be under operation by the year 2030. This paper has the objective of analyzing the neutronic and thermohydraulics of the ALFRED core by the means of a coupled scheme. The selected code for neutronic simulation is MCNP and the selected code for thermohydraulics is ANSYS.
Ab initio calculations in the symplectic no-core configuration interaction framework
McCoy, Anna; Caprio, Mark; Dytrych, Tomas
2016-09-01
A major challenge in quantitatively predicting nuclear structure directly from realistic nucleon-nucleon interactions, i.e., ab initio, arises due to an explosion in the dimension of the traditional Slater determinant basis as the number of nucleons and included shells increases. The need for including highly excited configurations arises, in large part, because the kinetic energy induces strong coupling across shells. However, the kinetic energy conserves symplectic symmetry. By combining this symplectic symmetry with the no-core configuration interaction (NCCI) framework, we reduce the size of basis necessary to obtain accurate results for p-shell nuclei. Supported by the US DOE under Grants DE-AC05-06OR23100 and DE-FG02-95ER-40934, and the Czech Science Foundation under Grant No. 16-16772S.
CppTransport: a platform to automate calculation of inflationary correlation functions
Seery, David
2016-01-01
CppTransport is a numerical platform that can automatically generate and solve the evolution equations for the 2- and 3-point correlation functions (in field space and for the curvature perturbation) for any inflationary model with canonical kinetic terms. It makes no approximations beyond the applicability of tree-level perturbation theory. Given an input Lagrangian, CppTransport performs symbolic calculations to determine the 'Feynman rules' of the model and generates efficient C++ to integrate the correlation functions of interest. It includes a visualization suite that automates extraction of observable quantities from the raw n-point functions and generates high quality plots with minimal manual intervention. It is intended to be used as a collaborative platform, promoting the rapid investigation of models and systematizing their comparison with observation. This guide describes how to install and use the system, and illustrates its use through some simple examples.
Core calculations for the upgrading of the IEA-R1 research reactor
Energy Technology Data Exchange (ETDEWEB)
Santos, Adimir dos; Perrotta, Jose A.; Bastos, Jose Luis F.; Yamaguchi, Mitsuo; Umbehaun, Pedro E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: asantos@net.ipen.br; perrotta@net.ipen.br; mitsuo@net.ipen.br
1998-07-01
The IEA-R1 Research Reactor is a multipurpose reactor. It has been used for basic and applied research in the nuclear area, training and radioisotopes production since 1957. In 1995, the Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP) took the decision to modernize and upgrade the power from 2 to 5 MW and increase the operational cycle. This work presents the design requirements and the calculations effectuated to reach this goal. (author)
An approximate framework for quantum transport calculation with model order reduction
Energy Technology Data Exchange (ETDEWEB)
Chen, Quan, E-mail: quanchen@eee.hku.hk [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong); Li, Jun [Department of Chemistry, The University of Hong Kong (Hong Kong); Yam, Chiyung [Beijing Computational Science Research Center (China); Zhang, Yu [Department of Chemistry, The University of Hong Kong (Hong Kong); Wong, Ngai [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong); Chen, Guanhua [Department of Chemistry, The University of Hong Kong (Hong Kong)
2015-04-01
A new approximate computational framework is proposed for computing the non-equilibrium charge density in the context of the non-equilibrium Green's function (NEGF) method for quantum mechanical transport problems. The framework consists of a new formulation, called the X-formulation, for single-energy density calculation based on the solution of sparse linear systems, and a projection-based nonlinear model order reduction (MOR) approach to address the large number of energy points required for large applied biases. The advantages of the new methods are confirmed by numerical experiments.
Energy Technology Data Exchange (ETDEWEB)
Kuitto, P.J.
1996-12-31
VTT Energy is compiling a large and versatile calculation program for harvesting and transportation costs of energy wood. The work has been designed and will be carried out in cooperation with Metsaeteho and Finntech Ltd. The program has been realised in Windows surroundings using SQLWindows graphical database application development system, using the SQLBase relational database management system. The objective of the research is to intensify and create new possibilities for comparison of the utilization costs and the profitability of integrated energy wood production chains with each other inside the chains
DEFF Research Database (Denmark)
Fürst, Joachim Alexander; Hashemi, J.; Markussen, Troels
2009-01-01
techniques and tight-binding calculations to illustrate these materials' transmission properties and give physical arguments to interpret the numerical results. Specifically, above the Fermi energy we find a strong reduction in electron transmission due to localized states in certain regions of the structure......Fullerene functionalized carbon nanotubes-NanoBuds-form a novel class of hybrid carbon materials, which possesses many advantageous properties as compared to the pristine components. Here, we report a theoretical study of the electronic transport properties of these compounds. We use both ab initio...
An Approximate Framework for Quantum Transport Calculation with Model Order Reduction
Chen, Quan; Yam, Chiyung; Zhang, Yu; Wong, Ngai; Chen, Guanhua
2014-01-01
A new approximate computational framework is proposed for computing the non-equilibrium charge density in the context of the non-equilibrium Green's function (NEGF) method for quantum mechanical transport problems. The framework consists of a new formulation, called the X-formulation, for single-energy density calculation based on the solution of sparse linear systems, and a projection-based nonlinear model order reduction (MOR) approach to address the large number of energy points required for large applied biases. The advantages of the new methods are confirmed by numerical experiments.
Kendl, Alexander
2014-01-01
Turbulent transport of trace impurities impurities in the edge and scrape-off-layer of tokamak fusion plasmas is modelled by three dimensional electromagnetic gyrofluid computations including evolution of plasma profile gradients. The source function of impurity ions is dynamically computed from pre-determined measured and calculated electron impact ionization cross section data. The simulations describe the generation and further passive turbulent E-cross-B advection of the impurities by intermittent fluctuations and coherent filamentary structures (blobs) across the scrape-off-layer.
Energy Technology Data Exchange (ETDEWEB)
Cliffe, K.A.; Morris, S.T.; Porter, J.D. [AEA Technology, Harwell (United Kingdom)
1998-05-01
NAMMU is a computer program for modelling groundwater flow and transport through porous media. This document provides an overview of the use of the program for geosphere modelling in performance assessment calculations and gives a detailed description of the program itself. The aim of the document is to give an indication of the grounds for having confidence in NAMMU as a performance assessment tool. In order to achieve this the following topics are discussed. The basic premises of the assessment approach and the purpose of and nature of the calculations that can be undertaken using NAMMU are outlined. The concepts of the validation of models and the considerations that can lead to increased confidence in models are described. The physical processes that can be modelled using NAMMU and the mathematical models and numerical techniques that are used to represent them are discussed in some detail. Finally, the grounds that would lead one to have confidence that NAMMU is fit for purpose are summarised.
Genovese, Luigi; Ospici, Matthieu; Deutsch, Thierry; Méhaut, Jean-François; Neelov, Alexey; Goedecker, Stefan
2009-07-21
We present the implementation of a full electronic structure calculation code on a hybrid parallel architecture with graphic processing units (GPUs). This implementation is performed on a free software code based on Daubechies wavelets. Such code shows very good performances, systematic convergence properties, and an excellent efficiency on parallel computers. Our GPU-based acceleration fully preserves all these properties. In particular, the code is able to run on many cores which may or may not have a GPU associated, and thus on parallel and massive parallel hybrid machines. With double precision calculations, we may achieve considerable speedup, between a factor of 20 for some operations and a factor of 6 for the whole density functional theory code.
Kerns, James R; Stingo, Francesco; Followill, David S; Howell, Rebecca M; Melancon, Adam; Kry, Stephen F
2017-08-01
The anthropomorphic phantom program at the Houston branch of the Imaging and Radiation Oncology Core (IROC-Houston) is an end-to-end test that can be used to determine whether an institution can accurately model, calculate, and deliver an intensity modulated radiation therapy dose distribution. Currently, institutions that do not meet IROC-Houston's criteria have no specific information with which to identify and correct problems. In the present study, an independent recalculation system was developed to identify treatment planning system (TPS) calculation errors. A recalculation system was commissioned and customized using IROC-Houston measurement reference dosimetry data for common linear accelerator classes. Using this system, 259 head and neck phantom irradiations were recalculated. Both the recalculation and the institution's TPS calculation were compared with the delivered dose that was measured. In cases in which the recalculation was statistically more accurate by 2% on average or 3% at a single measurement location than was the institution's TPS, the irradiation was flagged as having a "considerable" institutional calculation error. The error rates were also examined according to the linear accelerator vendor and delivery technique. Surprisingly, on average, the reference recalculation system had better accuracy than the institution's TPS. Considerable TPS errors were found in 17% (n=45) of the head and neck irradiations. Also, 68% (n=13) of the irradiations that failed to meet the IROC-Houston criteria were found to have calculation errors. Nearly 1 in 5 institutions were found to have TPS errors in their intensity modulated radiation therapy calculations, highlighting the need for careful beam modeling and calculation in the TPS. An independent recalculation system can help identify the presence of TPS errors and pass on the knowledge to the institution. Copyright © 2017 Elsevier Inc. All rights reserved.
Helium transport in the core and stochastic edge layer in LHD
Ida, K.; Yoshinuma, M.; Goto, M.; Schmitz, O.; Dai, S.; Bader, A.; Kobayashi, M.; Kawamura, G.; Moon, C.; Nakamura, Y.; The LHD Experiment Group
2016-07-01
Radial profiles of the density ratio of helium to hydrogen ions are measured using charge exchange spectroscopy with a two-wavelength spectrometer in the large helical device. Helium transport at the last closed flux surface (LCFS) and stochastic magnetic field layer outside the LCFS as well as in the core plasma is studied for a wide range of helium fractions, i.e. from hydrogen-dominated plasmas up to helium-dominated plasmas. The helium density profile becomes more peaked and inward convection velocity increases in the hydrogen-dominant plasma, while it becomes flat or hollow and the convection velocity is in the outward direction in the helium-dominant plasmas. The density gradient of helium at the LCFS is twice that of hydrogen and becomes steeper as the hydrogen becomes more dominant.
No-Core MCSM calculation for $^{10}$Be and $^{12}$Be low-lying spectra
Liu, Lang; Shimizu, Noritaka; Utsuno, Yutaka; Roth, Robert
2011-01-01
The low-lying excited states of $^{10}$Be and $^{12}$Be are investigated within a no-core Monte Carlo Shell Model (MCSM) framework employing a realistic potential obtained via the Unitary Correlation Operator Method. The excitation energies of the 2$^+_1$ and 2$^+_2$ states and the B(E2; 2$^+_{1}\\rightarrow$ 0$^+_{g.s.}$) for $^{10}$Be in the MCSM with a treatment of spurious center-of-mass motion show good agreement with experimental data. The deformation properties of the 2$^+_1$, 2$^+_2$ states for $^{10}$Be and of the 2$^+_1$ state for $^{12}$Be are studied in terms of quadrupole moments, E2 transitions and the single-particle occupations. The triaxial deformation of $^{10}$Be is tested by the B(E2; 2$^+_{2}\\rightarrow$ 2$^+_{1}$) value. The removal of the spurious center-of-mass motion shifts the 1$^-_1$ level significantly, improving agreement with experiment.
Energy Technology Data Exchange (ETDEWEB)
Pinto, R.M., E-mail: ruipinto@fct.unl.pt [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Dias, A.A. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Coreno, M. [CNR-IMIP, Montelibretti, Rome I-00016 (Italy); Simone, M. de [CNR-IOM, Laboratorio TASC, 34149 Trieste (Italy); Giuliano, B.M. [Departamento de Quimica da Universidade de Coimbra, 3004-535 Coimbra (Portugal); Santos, J.P.; Costa, M.L. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)
2012-03-15
Highlights: Black-Right-Pointing-Pointer High-resolution XPS of 5-aminotetrazole reveals different tautomers. Black-Right-Pointing-Pointer 5ATZ exists mainly in the 2H-form. Black-Right-Pointing-Pointer Results obtained with DSCF are in good agreement with the observed binding energies. - Abstract: The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using synchrotron radiation, with the aim of evaluating 1H/2H tautomer population ratios. The core-electron binding energies (CEBEs) were estimated from computational results, using the delta self-consistent-field ({Delta}SCF) approach. Simulated spectra were generated using these CEBEs and the results from GAUSSIAN-n (Gn, n = 1, 2 and 3) and Complete Basis Set (CBS-4M and CBS-Q) methods. Results reveal the almost exclusive predominance of the 2H-tautomer, with a 1H/2H ratio of ca. 0.12/0.88, taken from a gross analysis of the XPS C 1s spectrum, recorded at 365 K.
Development of a Coolant Analysis Model for the Sodium Reactivity Calculation in the KALIMER Core
Energy Technology Data Exchange (ETDEWEB)
Chang, Won Pyo; Lee, Yong Bum
2006-06-15
The present research concerns about developing a computational algorithm for the analysis of post boiling fuel temperature, based on the sodium boiling model proposed by USNRC. The model selection comes from the fact that the analysis of LMR sodium boiling had already been done using this model being coupled with SSC-L, and therefore its theory is believed to be a quite adequate option for compatibility to SSC-K. Physical phenomena characterizing UTO, ULOF, and ULOHS for KALIMER are analyzed for evaluation of the developed algorithm. The results obtained from the calculation are also compared with those of a previous model to confirm physical consistencies.
Large-scale quantum transport calculations for electronic devices with over ten thousand atoms
Lu, Wenchang; Lu, Yan; Xiao, Zhongcan; Hodak, Miro; Briggs, Emil; Bernholc, Jerry
The non-equilibrium Green's function method (NEGF) has been implemented in our massively parallel DFT software, the real space multigrid (RMG) code suite. Our implementation employs multi-level parallelization strategies and fully utilizes both multi-core CPUs and GPU accelerators. Since the cost of the calculations increases dramatically with the number of orbitals, an optimal basis set is crucial for including a large number of atoms in the ``active device'' part of the simulations. In our implementation, the localized orbitals are separately optimized for each principal layer of the device region, in order to obtain an accurate and optimal basis set. As a large example, we calculated the transmission characteristics of a Si nanowire p-n junction. The nanowire is along (110) direction in order to minimize the number dangling bonds that are saturated by H atoms. Its diameter is 3 nm. The length of 24 nm is necessary because of the long-range screening length in Si. Our calculations clearly show the I-V characteristics of a diode, i.e., the current increases exponentially with forward bias and is near zero with backward bias. Other examples will also be presented, including three-terminal transistors and large sensor structures.
Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa
2004-05-01
The transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory method. Results are reported in the dilute-gas limit for thermal conductivity and thermomagnetic coefficients for temperatures ranging from 200 K to 1000 K. Three recent carbon dioxide potential energy hypersurfaces have been investigated. Since thermal conductivity is influenced by vibrational degrees of freedom, not included in the rigid-rotor classical trajectory calculation, a correction for vibration has also been employed. The calculations indicate that the second-order thermal conductivity corrections due to the angular momentum polarization (Bukowski et al. (1999) are in good agreement with the available experimental data. They underestimate the best experimental data at room temperature by 1% and in the range up to 470 K by 1%-3%, depending on the data source. Outside this range the calculated values, we believe, may be more reliable than the currently available experimental data. Our results are consistent with measurements of the thermomagnetic effect at 300 K only when the vibrational degrees of freedom are considered fully. This excellent agreement for these properties indicates that particularly the potential surface of Bukowski et al. provides a realistic description of the anisotropy of the surface.
Betal, Soutik; Dutta, Moumita; Shrestha, Binita; Saha, Amit; Tang, Liang; Ramasubramanian, Ananad K.; Bhalla, Amar S.; Guo, Ruyan
2016-09-01
Magneto-Elasto-Electroporation (MEEP) is a magnetically controlled acoustic-electroporation observed while core-shell Magneto-electric nanoparticles interact with Biological Cells. The surface polarity change of the piezoelectric coating (BaTiO3) due to absorption of pressure created due magneto-striction of core (CoFe2O4) in AC magnetic field results in electric field (Uext) change at the external vicinity of the cell membrane when nanoparticles are nearby. This results in transmembrane Voltage (Um) change which is basically the difference in Cell's internal potential (Uint) and external potential. The nonlinear permeability change of cell membrane due to change in Um opens the nano-pores on the membrane. The magnetic moment of the nanoparticles further helps in penetration of the Magneto-electric nanoparticles inside the cell through these magneto-electrically controlled newly opened nano-pores on cell's membrane. MEEP is analyzed through in-vitro analysis and Mathematical equations are formulated for numerically expressing its fundamental effect. TEM imaging, XRD analysis, Zeta-potentiometer measurement and AFM imaging are confirming the coating of the piezoelectric layer on Magneto-stricitve nanoparticles, Acoustic measurements confirms the photo-acoustic and magneto-acoustic property of CoFe2O4 nanoparticles and Fluorescence microscopy as well as Confocal microscopy are confirming the penetration of particle inside the Human Epithelial cells (HEP2). Further on application of repulsive magnetic field, nanoparticles are observed to transport a group of cells in controlled boundary conditions in microfluidic chamber. Hence these nanoparticles can be used for accurate and efficient drug delivery as well as cell transport applications
Multi-dimensional Core-Collapse Supernova Simulations with Neutrino Transport
Pan, Kuo-Chuan; Liebendörfer, Matthias; Hempel, Matthias; Thielemann, Friedrich-Karl
We present multi-dimensional core-collapse supernova simulations using the Isotropic Diffusion Source Approximation (IDSA) for the neutrino transport and a modified potential for general relativity in two different supernova codes: FLASH and ELEPHANT. Due to the complexity of the core-collapse supernova explosion mechanism, simulations require not only high-performance computers and the exploitation of GPUs, but also sophisticated approximations to capture the essential microphysics. We demonstrate that the IDSA is an elegant and efficient neutrino radiation transfer scheme, which is portable to multiple hydrodynamics codes and fast enough to investigate long-term evolutions in two and three dimensions. Simulations with a 40 solar mass progenitor are presented in both FLASH (1D and 2D) and ELEPHANT (3D) as an extreme test condition. It is found that the black hole formation time is delayed in multiple dimensions and we argue that the strong standing accretion shock instability before black hole formation will lead to strong gravitational waves.
Energy Technology Data Exchange (ETDEWEB)
Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Méchin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 14050 Caen (France); Hamel, Matthieu [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France)
2016-08-21
Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.
Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane; Méchin, Laurence; Hamel, Matthieu
2016-08-01
Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.
Roscioni, Otello M; Lee, Edmond P F; Dyke, John M
2012-10-05
We present a set of effective core potential (ECP) basis sets for rhodium atoms which are of reasonable size for use in electronic structure calculations. In these ECP basis sets, the Los Alamos ECP is used to simulate the effect of the core electrons while an optimized set of Gaussian functions, which includes polarization and diffuse functions, is used to describe the valence electrons. These basis sets were optimized to reproduce the ionization energy and electron affinity of atomic rhodium. They were also tested by computing the electronic ground state geometry and harmonic frequencies of [Rh(CO)(2) μ-Cl](2) , Rh(CO)(2) ClPy, and RhCO (neutral and its positive, and negative ions) as well as the enthalpy of the reaction of [Rh(CO)(2) μ-Cl](2) with pyridine (Py) to give Rh(CO)(2) ClPy, at different levels of theory. Good agreement with experimental values was obtained. Although the number of basis functions used in our ECP basis sets is smaller than those of other ECP basis sets of comparable quality, we show that the newly developed ECP basis sets provide the flexibility and precision required to reproduce a wide range of chemical and physical properties of rhodium compounds. Therefore, we recommend the use of these compact yet accurate ECP basis sets for electronic structure calculations on molecules involving rhodium atoms. Copyright © 2012 Wiley Periodicals, Inc.
Nguyen van Ye, Romain; Del-Castillo-Negrete, Diego; Spong, D.; Hirshman, S.; Farge, M.
2008-11-01
A limitation of particle-based transport calculations is the noise due to limited statistical sampling. Thus, a key element for the success of these calculations is the development of efficient denoising methods. Here we discuss denoising techniques based on Proper Orthogonal Decomposition (POD) and Wavelet Decomposition (WD). The goal is the reconstruction of smooth (denoised) particle distribution functions from discrete particle data obtained from Monte Carlo simulations. In 2-D, the POD method is based on low rank truncations of the singular value decomposition of the data. For 3-D we propose the use of a generalized low rank approximation of matrices technique. The WD denoising is based on the thresholding of empirical wavelet coefficients [Donoho et al., 1996]. The methods are illustrated and tested with Monte-Carlo particle simulation data of plasma collisional relaxation including pitch angle and energy scattering. As an application we consider guiding-center transport with collisions in a magnetically confined plasma in toroidal geometry. The proposed noise reduction methods allow to achieve high levels of smoothness in the particle distribution function using significantly less particles in the computations.
Kim, T. W.; Yarnell, S. M.; Yager, E.; Leidman, S. Z.
2015-12-01
Caspar Creek is a gravel-bedded stream located in the Jackson Demonstration State Forest in the coast range of California. The Caspar Creek Experimental Watershed has been actively monitored and studied by the Pacific Southwest Research Station and California Department of Forestry and Fire Protection for over five decades. Although total annual sediment yield has been monitored through time, sediment transport during individual storm events is less certain. At a study site on North Fork Caspar Creek, cross-section averaged sediment flux was collected throughout two storm events in December 2014 and February 2015 to determine if two commonly used sediment transport equations—Meyer-Peter-Müller and Wilcock—approximated observed bedload transport. Cross-section averaged bedload samples were collected approximately every hour during each storm event using a Helley-Smith bedload sampler. Five-minute composite samples were collected at five equally spaced locations along a cross-section and then sieved to half-phi sizes to determine the grain size distribution. The measured sediment flux values varied widely throughout the storm hydrographs and were consistently less than two orders of magnitude in value in comparison to the calculated values. Armored bed conditions, changing hydraulic conditions during each storm and variable sediment supply may have contributed to the observed differences.
Preliminary study on CAD-based method of characteristics for neutron transport calculation
Chen, Zhen-Ping; Sun, Guang-Yao; Song, Jing; Hao, Li-Juan; Hu, Li-Qin; Wu, Yi-Can
2013-01-01
The method of characteristics (MOC) is widely used for neutron transport calculation in recent decades. However, the key problem determining whether MOC can be applied in highly heterogeneous geometry is how to combine an effective geometry modeling method with it. Most of the existing MOC codes conventionally describe the geometry model just by lines and arcs with extensive input data. Thus they have difficulty in geometry modeling and ray tracing for complicated geometries. In this study, a new method making use of a CAD-based automatic modeling tool MCAM which is a CAD/Image-based Automatic Modeling Program for Neutronics and Radiation Transport developed by FDS Team in China was introduced for geometry modeling and ray tracing of particle transport to remove those limitations. The diamond -difference scheme was applied to MOC to reduce the spatial discretization errors of the flat flux approximation. Based on MCAM and MOC, a new MOC code was developed and integrated into SuperMC system, whic h is a Super ...
A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom
Energy Technology Data Exchange (ETDEWEB)
Bellezzo, M.; Do Nascimento, E.; Yoriyaz, H., E-mail: mbellezzo@gmail.br [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)
2014-08-15
As the most accurate method to estimate absorbed dose in radiotherapy, Monte Carlo method has been widely used in radiotherapy treatment planning. Nevertheless, its efficiency can be improved for clinical routine applications. In this paper, we present the CUBMC code, a GPU-based Mc photon transport algorithm for dose calculation under the Compute Unified Device Architecture platform. The simulation of physical events is based on the algorithm used in Penelope, and the cross section table used is the one generated by the Material routine, als present in Penelope code. Photons are transported in voxel-based geometries with different compositions. To demonstrate the capabilities of the algorithm developed in the present work four 128 x 128 x 128 voxel phantoms have been considered. One of them is composed by a homogeneous water-based media, the second is composed by bone, the third is composed by lung and the fourth is composed by a heterogeneous bone and vacuum geometry. Simulations were done considering a 6 MeV monoenergetic photon point source. There are two distinct approaches that were used for transport simulation. The first of them forces the photon to stop at every voxel frontier, the second one is the Woodcock method, where the photon stop in the frontier will be considered depending on the material changing across the photon travel line. Dose calculations using these methods are compared for validation with Penelope and MCNP5 codes. Speed-up factors are compared using a NVidia GTX 560-Ti GPU card against a 2.27 GHz Intel Xeon CPU processor. (Author)
Directory of Open Access Journals (Sweden)
I. V. Novash
2015-01-01
Full Text Available This article describes the parameters calculation for the three-phase two-winding power transformer model taken from the SimPowerSystems library, which is the part of the MatLab- Simulink environment. Presented methodology is based on the power transformer nameplate data usage. Particular attention is paid to the power transformer magnetization curve para- meters calculation. The methodology of the three-phase two-winding power transformer model parameters calculation considering the magnetization curve nonlinearity isn’t presented in Russian-and English-language sources. Power transformers demo models described in the SimPowerSystems user’s guide have already calculated parameters, but without reference to the sources of their determination. A power transformer is a nonlinear element of the power system, that’s why for its performance analysis in different modes of operation is necessary to have the magnetization curve parameters.The process analysis during no-load energizing of the power transformer is of special interest. This regime is accompanied by the inrush current on the supply side of the power transformer, which is several times larger than the transformer rated current. Sharp rising of the magnetizing current is explained by the magnetic core saturation. Therefore, magnetiza- tion characteristic accounting during transformer no-load energizing modeling is a mandatory requirement. Article authors attempt to put all calculating formulas in a more convenient form and validate the power transformer nonlinear magnetization characteristics parameters calcu- lation. Inrush current oscillograms obtained during the simulation experiment confirmed the adequacy of the calculated model parameters.
Glamočanin, D.
2017-05-01
In order to maintain the continuity of the telecom operators’ network construction, while monitoring development needs, increasing customers’ demands and application of technological improvements, it is necessary to migrate optical transport core network to the next generation networks - Carrier Grade Ethernet Optical Transport Network (OTN CE). The primary objective of OTN CE is to realize an environment that is based solely on the switching in the optical domain, i.e. the realization of transparent optical networks and optical switching to the second layer of ISO / OSI model. The realization of such a network provides opportunities for further development of existing, but also technologically more demanding, new services. It is also a prerequisite to provide higher scalability, reliability, security and quality of QoS service, as well as prerequisites for the establishment of SLA (Service Level Agreement) for existing services, especially traffic in real time. This study aims to clarify the proposed model, which has the potential to be eventually adjusted in accordance with new scientific knowledge in this field as well as market requirements.
Energy Technology Data Exchange (ETDEWEB)
Serikov, A.; Fischer, U.; Grosse, D.; Leichtle, D.; Majerle, M., E-mail: arkady.serikov@kit.edu [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany)
2011-07-01
The Monte Carlo (MC) method is the most suitable computational technique of radiation transport for shielding applications in fusion neutronics. This paper is intended for sharing the results of long term experience of the fusion neutronics group at Karlsruhe Institute of Technology (KIT) in radiation shielding calculations with the MCNP5 code for the ITER fusion reactor with emphasizing on the use of several ITER project-driven computer programs developed at KIT. Two of them, McCad and R2S, seem to be the most useful in radiation shielding analyses. The McCad computer graphical tool allows to perform automatic conversion of the MCNP models from the underlying CAD (CATIA) data files, while the R2S activation interface couples the MCNP radiation transport with the FISPACT activation allowing to estimate nuclear responses such as dose rate and nuclear heating after the ITER reactor shutdown. The cell-based R2S scheme was applied in shutdown photon dose analysis for the designing of the In-Vessel Viewing System (IVVS) and the Glow Discharge Cleaning (GDC) unit in ITER. Newly developed at KIT mesh-based R2S feature was successfully tested on the shutdown dose rate calculations for the upper port in the Neutral Beam (NB) cell of ITER. The merits of McCad graphical program were broadly acknowledged by the neutronic analysts and its continuous improvement at KIT has introduced its stable and more convenient run with its Graphical User Interface. Detailed 3D ITER neutronic modeling with the MCNP Monte Carlo method requires a lot of computation resources, inevitably leading to parallel calculations on clusters. Performance assessments of the MCNP5 parallel runs on the JUROPA/HPC-FF supercomputer cluster permitted to find the optimal number of processors for ITER-type runs. (author)
Core 2D. A code for non-isothermal water flow and reactive solute transport. Users manual version 2
Energy Technology Data Exchange (ETDEWEB)
Samper, J.; Juncosa, R.; Delgado, J.; Montenegro, L. [Universidad de A Coruna (Spain)
2000-07-01
Understanding natural groundwater quality patterns, quantifying groundwater pollution and assessing the effects of waste disposal, require modeling tools accounting for water flow, and transport of heat and dissolved species as well as their complex interactions with solid and gases phases. This report contains the users manual of CORE ''2D Version V.2.0, a COde for modeling water flow (saturated and unsaturated), heat transport and multicomponent Reactive solute transport under both local chemical equilibrium and kinetic conditions. it is an updated and improved version of CORE-LE-2D V0 (Samper et al., 1988) which in turns is an extended version of TRANQUI, a previous reactive transport code (ENRESA, 1995). All these codes were developed within the context of Research Projects funded by ENRESA and the European Commission. (Author)
National Oceanic and Atmospheric Administration, Department of Commerce — The dataset consists of calculated annual and monthly mean ocean volume transport stream function on 1 degree resolution using the WOA13 (T, S) and corresponding...
Energy Technology Data Exchange (ETDEWEB)
Babeyko, A.Yu.; Sobolev, S.V. [Shmidt Institute of Physics of the Earth, Moscow (Russian Federation)]|[Univ. of Karlsruhe (Germany); Sinelnikov, E.D. [Shmidt Institute of Physics of the Earth, Moscow (Russian Federation)]|[State Univ. of New York, Stony Brook, NY (United States); Smirnov, Yu.P. [Scientific Center SG-3, Zapoliarniy (Russian Federation); Derevschikova, N.A. [Shmidt Institute of Physics of the Earth, Moscow (Russian Federation)
1994-09-01
In-situ elastic properties in deep boreholes are controlled by several factors, mainly by lithology, petrofabric, fluid-filled cracks and pores. In order to separate the effects of different factors it is useful to extract lithology-controlled part from observed in-situ velocities. For that purpose we calculated mineralogical composition and isotropic crack-free elastic properties in the lower part of the Kola borehole from bulk chemical compositions of core samples. We use a new technique of petrophysical modeling based on thermodynamic approach. The reasonable accuracy of the modeling is confirmed by comparison with the observations of mineralogical composition and laboratory measurements of density and elastic wave velocities in upper crustal crystalline rocks at high confining pressure. Calculations were carried out for 896 core samples from the depth segment of 6840-10535m. Using these results we estimate density and crack-free isotropic elastic properties of 554 lithology-defined layers composing this depth segment. Average synthetic P-wave velocity appears to be 2.7% higher than the velocity from Vertical Seismic Profiling (VSP), and 5% higher than sonic log velocity. Average synthetic S-wave velocity is 1.4% higher than that from VSP. These differences can be explained by superposition of effects of fabric-related anisotropy, cracks aligned parallel to the foliation plain, and randomly oriented cracks, with the effects of cracks being the predominant control. Low sonic log velocities are likely caused by drilling-induced cracking (hydrofractures) in the borehole walls. The calculated synthetic density and velocity cross-sections can be used for much more detailed interpretations, for which, however, new, more detailed and reliable seismic data are required.
Energy Technology Data Exchange (ETDEWEB)
Kalin, J., E-mail: jan.kalin@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Petkovsek, B., E-mail: borut.petkovsek@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Montarnal, Ph., E-mail: philippe.montarnal@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Genty, A., E-mail: alain.genty@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Deville, E., E-mail: estelle.deville@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Krivic, J., E-mail: jure.krivic@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia); Ratej, J., E-mail: joze.ratej@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia)
2011-04-15
In the past years the Slovenian Performance Analysis/Safety Assessment team has performed many generic studies for the future Slovenian low and intermediate level waste repository, most recently a Special Safety Analysis for the Krsko site. The modelling approach was to split the problem into three parts: near-field (detailed model of the repository), far-field (i.e., geosphere) and biosphere. In the Special Safety Analysis the code used to perform the near-field calculations was Hydrus2D. Recently the team has begun a cooperation with the French Commisariat al'Energie Atomique/Saclay (CEA/Saclay) and, as a part of this cooperation, began investigations into using the Alliances numerical platform for near-field calculations in order to compare the overall approach and calculated results. The article presents the comparison between these two codes for a silo-type repository that was considered in the Special Safety Analysis. The physical layout and characteristics of the repository are presented and a hydraulic and transport model of the repository is developed and implemented in Alliances. Some analysis of sensitivity to mesh fineness and to simulation timestep has been preformed and is also presented. The compared quantity is the output flux of radionuclides on the boundary of the model. Finally the results from Hydrus2D and Alliances are compared and the differences and similarities are commented.
Transport calculation of thermal and cold neutrons using NMTC/JAERI-MCNP4A code system
Energy Technology Data Exchange (ETDEWEB)
Iga, Kiminori [Kyushu Univ., Fukuoka (Japan); Takada, Hiroshi; Nagao, Tadashi
1998-01-01
In order to investigate the applicability of the NMTC/JAERI-MCNP4A code system to the neutronics design study in the neutron science research project of JAERI, transport calculations of thermal and cold neutrons are performed with the code system on a spallation neutron source composed of light water cooled tantalum target with a moderator and a reflector system. The following neutronic characteristics are studied in the calculation : the variation of the intensity of neutrons emitted from a light water moderator or a liquid hydrogen with/without the B{sub 4}C decoupler, which are installed to produce sharp pulse, and that dependent on the position of external source neutrons in the tantalum target. The calculated neutron energy spectra are reproduced well by the semi-empirical formula with the parameter values reliable in physical meanings. It is found to be necessary to employ proper importance sampling technique in the statistics. It is confirmed from this work that the NMTC/JAERI-MCNP4A code system is applicable to the neutronics design study of spallation neutron sources proposed for the neutron science research project. (author)
Wenzel, Jan; Holzer, Andre; Wormit, Michael; Dreuw, Andreas
2015-06-01
The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of -0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.
DEFF Research Database (Denmark)
Strange, Mikkel; Thygesen, Kristian Sommer
2011-01-01
The calculation of the electronic conductance of nanoscale junctions from first principles is a long-standing problem in the field of charge transport. Here we demonstrate excellent agreement with experiments for the transport properties of the gold/alkanediamine benchmark system when electron-el...
Directory of Open Access Journals (Sweden)
A A Shokri
2013-10-01
Full Text Available In this paper, we have investigated the spin-dependent transport properties and electron entanglement in a mesoscopic system, which consists of two semi-infinite leads (as source and drain separated by a typical quantum wire with a given potential. The properties studied include current-voltage characteristic, electrical conductivity, Fano factor and shot noise, and concurrence. The calculations are based on the transfer matrix method within the effective mass approximation. Using the Landauer formalism and transmission coefficient, the dependence of the considered quantities on type of potential well, length and width of potential well, energy of transmitted electron, temperature and the voltage have been theoretically studied. Also, the effect of the above-mentioned factors has been investigated in the nanostructure. The application of the present results may be useful in designing spintronice devices.
A Transport Equation Approach to Green Functions and Self-force Calculations
Wardell, Barry
2010-01-01
In a recent work, we presented the first application of the Poisson-Wiseman-Anderson method of `matched expansions' to compute the self-force acting on a point particle moving in a curved spacetime. The method employs two expansions for the Green function which are respectively valid in the `quasilocal' and `distant past' regimes, and which may be matched together within the normal neighbourhood. In this article, we introduce the method of matched expansions and discuss transport equation methods for the calculation of the Green function in the quasilocal region. These methods allow the Green function to be evaluated throughout the normal neighborhood and are also relevant to a broad range of problems from radiation reaction to quantum field theory in curved spacetime and quantum gravity.
Choi, Sunghwan; Kwon, Oh-Kyoung; Kim, Jaewook; Kim, Woo Youn
2016-09-15
We investigated the performance of heterogeneous computing with graphics processing units (GPUs) and many integrated core (MIC) with 20 CPU cores (20×CPU). As a practical example toward large scale electronic structure calculations using grid-based methods, we evaluated the Hartree potentials of silver nanoparticles with various sizes (3.1, 3.7, 4.9, 6.1, and 6.9 nm) via a direct integral method supported by the sinc basis set. The so-called work stealing scheduler was used for efficient heterogeneous computing via the balanced dynamic distribution of workloads between all processors on a given architecture without any prior information on their individual performances. 20×CPU + 1GPU was up to ∼1.5 and ∼3.1 times faster than 1GPU and 20×CPU, respectively. 20×CPU + 2GPU was ∼4.3 times faster than 20×CPU. The performance enhancement by CPU + MIC was considerably lower than expected because of the large initialization overhead of MIC, although its theoretical performance is similar with that of CPU + GPU. © 2016 Wiley Periodicals, Inc.
Energy Technology Data Exchange (ETDEWEB)
Andersson, Johan [Golder Grundteknik KB (Sweden)
1999-10-01
This report concerns integration of data and data uncertainties in the radionuclide transport calculations within the SR 97 project. More specifically the present report: establishes a framework for handling data uncertainty within SR 97, explores uncertainties in the different underlying analyses and information such as inventory, canister life time, solubilities, K{sub d}-values, or different flow related migration parameters, which provide input to the radionuclide release and transport models used, suggests and motivates 'reasonable' input values, and 'pessimistic' input values representing conditions at Aaberg (Aespoe), Beberg (Finnsjoen) and Ceberg (Gideaa) when applicable, for the different models used, suggests 'probabilistic' parameter distributions when underlying data support any distribution. The intention of presenting 'reasonable' estimates is one of illustration - to obtain a view on how the repository system would operate without making overly optimistic or pessimistic assumptions. A pessimistic input datum implies a selection of a parameter value (and conceptual model) within the uncertainty range, which maximises the consequence.
Egami, Yoshiyuki; Iwase, Shigeru; Tsukamoto, Shigeru; Ono, Tomoya; Hirose, Kikuji
2015-09-01
We develop a first-principles electron-transport simulator based on the Lippmann-Schwinger (LS) equation within the framework of the real-space finite-difference scheme. In our fully real-space-based LS (grid LS) method, the ratio expression technique for the scattering wave functions and the Green's function elements of the reference system is employed to avoid numerical collapse. Furthermore, we present analytical expressions and/or prominent calculation procedures for the retarded Green's function, which are utilized in the grid LS approach. In order to demonstrate the performance of the grid LS method, we simulate the electron-transport properties of the semiconductor-oxide interfaces sandwiched between semi-infinite jellium electrodes. The results confirm that the leakage current through the (001)Si-SiO_{2} model becomes much larger when the dangling-bond state is induced by a defect in the oxygen layer, while that through the (001)Ge-GeO_{2} model is insensitive to the dangling bond state.
Wang, Y Y; Peng, Xiang; Alharbi, M; Dutin, C Fourcade; Bradley, T D; Gérôme, F; Mielke, Michael; Booth, Timothy; Benabid, F
2012-08-01
We report on the recent design and fabrication of kagome-type hollow-core photonic crystal fibers for the purpose of high-power ultrashort pulse transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all kagome fibers) of 40 dB/km over a broadband transmission centered at 1500 nm. We show that the large core size, low attenuation, broadband transmission, single-mode guidance, and low dispersion make it an ideal host for high-power laser beam transportation. By filling the fiber with helium gas, a 74 μJ, 850 fs, and 40 kHz repetition rate ultrashort pulse at 1550 nm has been faithfully delivered at the fiber output with little propagation pulse distortion. Compression of a 105 μJ laser pulse from 850 fs down to 300 fs has been achieved by operating the fiber in ambient air.
Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.
2012-03-01
We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.
Applying CFD in the Analysis of Heavy-Oil Transportation in Curved Pipes Using Core-Flow Technique
Directory of Open Access Journals (Sweden)
S Conceição
2017-06-01
Full Text Available Multiphase flow of oil, gas and water occurs in the petroleum industry from the reservoir to the processing units. The occurrence of heavy oils in the world is increasing significantly and points to the need for greater investment in the reservoirs exploitation and, consequently, to the development of new technologies for the production and transport of this oil. Therefore, it is interesting improve techniques to ensure an increase in energy efficiency in the transport of this oil. The core-flow technique is one of the most advantageous methods of lifting and transporting of oil. The core-flow technique does not alter the oil viscosity, but change the flow pattern and thus, reducing friction during heavy oil transportation. This flow pattern is characterized by a fine water pellicle that is formed close to the inner wall of the pipe, aging as lubricant of the oil flowing in the core of the pipe. In this sense, the objective of this paper is to study the isothermal flow of heavy oil in curved pipelines, employing the core-flow technique. A three-dimensional, transient and isothermal mathematical model that considers the mixture and k-e turbulence models to address the gas-water-heavy oil three-phase flow in the pipe was applied for analysis. Simulations with different flow patterns of the involved phases (oil-gas-water have been done, in order to optimize the transport of heavy oils. Results of pressure and volumetric fraction distribution of the involved phases are presented and analyzed. It was verified that the oil core lubricated by a fine water layer flowing in the pipe considerably decreases pressure drop.
Moroz, Oleg N
2011-01-01
The shear and the bulk viscosities of the hadron gas at low temperatures are studied in the model with constant elastic cross sections being relativistic generalization of the hard spheres model. One effective radius ${r=0.4 fm}$ is chosen for all elastic collisions. Only elastic collisions are considered which are supposed to be dominant at temperatures ${T\\leq 120-140 MeV}$. The calculations are done in the framework of the Boltzmann equation with the Boltzmann statistics distribution functions and the ideal gas equation of state. The applicability of these approximations is discussed. It's found that the bulk viscosity of the hadron gas is much larger than the bulk viscosity of the pion gas while the shear viscosity is found to be less sensitive to the mass spectrum of hadrons. The constant cross sections and the Boltzmann statistics approximation allows one not only to conduct precise numerical calculations of transport coefficients in the hadron gas but also to obtain some relatively simple relativistic ...
Thermal transport in van der Waals solids from first-principles calculations
Lindroth, Daniel O.; Erhart, Paul
2016-09-01
The lattice thermal expansion and conductivity in bulk Mo and W-based transition metal dichalcogenides are investigated by means of density functional and Boltzmann transport theory calculations. To this end, a recent van der Waals density functional (vdW-DF-CX) is employed, which is shown to yield excellent agreement with reference data for the structural parameters. The calculated in-plane thermal conductivity compares well with experimental room-temperature values, when phonon-phonon and isotopic scattering are included. To explain the behavior over the entire available temperature range one must, however, include additional (temperature independent) scattering mechanisms that limit the mean free path. Generally, the primary heat carrying modes have mean free paths of 1 μ m or more, which makes these materials very susceptible to structural defects. The conductivity of Mo- and W-based transition metal dichalcogenides is primarily determined by the chalcogenide species and increases in the order Te-Se-S. While for the tellurides and selenides the transition metal element has a negligible effect, the conductivity of WS2 is notably higher than for MoS2, which may be traced to the much larger phonon band gap of the former. Overall, the present study provides a consistent set of thermal conductivities that reveal chemical trends and constitute the basis for future investigations of van der Waals solids.
Energy Technology Data Exchange (ETDEWEB)
Madni, I.K. [Brookhaven National Lab., Upton, NY (United States); Cazzoli, E.G.; Khatib-Rahbar, M. [Energy Research, Inc., Rockville, MD (United States)
1995-11-01
During certain hypothetical severe accidents in a nuclear power plant, radionuclides could be released to the environment as a plume. Prediction of the atmospheric dispersion and transport of these radionuclides is important for assessment of the risk to the public from such accidents. A simplified PC-based model was developed that predicts time-integrated air concentration of each radionuclide at any location from release as a function of time integrated source strength using the Gaussian plume model. The solution procedure involves direct analytic integration of air concentration equations over time and position, using simplified meteorology. The formulation allows for dry and wet deposition, radioactive decay and daughter buildup, reactor building wake effects, the inversion lid effect, plume rise due to buoyancy or momentum, release duration, and grass height. Based on air and ground concentrations of the radionuclides, the early dose to an individual is calculated via cloudshine, groundshine, and inhalation. The model also calculates early health effects based on the doses. This paper presents aspects of the model that would be of interest to the prediction of environmental flows and their public consequences.
The spin rate of pre-collapse stellar cores: wave driven angular momentum transport in massive stars
Fuller, Jim; Lecoanet, Daniel; Quataert, Eliot
2015-01-01
The core rotation rates of massive stars have a substantial impact on the nature of core collapse supernovae and their compact remnants. We demonstrate that internal gravity waves (IGW), excited via envelope convection during a red supergiant phase or during vigorous late time burning phases, can have a significant impact on the rotation rate of the pre-SN core. In typical ($10 \\, M_\\odot \\lesssim M \\lesssim 20 \\, M_\\odot$) supernova progenitors, IGW may substantially spin down the core, leading to iron core rotation periods $P_{\\rm min,Fe} \\gtrsim 50 \\, {\\rm s}$. Angular momentum (AM) conservation during the supernova would entail minimum NS rotation periods of $P_{\\rm min,NS} \\gtrsim 3 \\, {\\rm ms}$. In most cases, the combined effects of magnetic torques and IGW AM transport likely lead to substantially longer rotation periods. However, the stochastic influx of AM delivered by IGW during shell burning phases inevitably spin up a slowly rotating stellar core, leading to a maximum possible core rotation perio...
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Aleshin, Sergey S.; Gorodkov, Sergey S.; Shcherenko, Anna I. [National Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2016-09-15
A burn-up calculation of large systems by Monte-Carlo code (MCU) is complex process and it requires large computational costs. Previously prepared isotopic compositions are proposed to be used for the Monte-Carlo code calculations of different system states with burnt fuel. Isotopic compositions are calculated by an approximation method. The approximation method is based on usage of a spectral functionality and reference isotopic compositions, that are calculated by the engineering codes (TVS-M, BIPR-7A and PERMAK-A). The multiplication factors and power distributions of FAs from a 3-D reactor core are calculated in this work by the Monte-Carlo code MCU using earlier prepared isotopic compositions. The separate conditions of the burnt core are observed. The results of MCU calculations were compared with those that were obtained by engineering codes.
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Borodkin, P.G.; Borodkin, G.I.; Khrennikov, N.N. [Scientific and Engineering Centre for Nuclear and Radiation Safety SEC NRS, Malaya Krasnoselskaya ul., 2/8, Bld. 5, 107140 Moscow (Russian Federation); Konheiser, J. [Helmholz Zentrum Dresden-Rossendorf HZDR, Postfach 510119, D-01314 Dresden (Germany)
2011-07-01
This paper deals with calculated and semi-analytical evaluations of VVER-1000 reactor core neutron source distributions and their influence on measurements and calculations of the integral through-vessel neutron leakage. Neutron activation measurements analyzed in the paper were carried out in an ex-vessel air cavity at different nuclear power plant units with VVER-1000 during different fuel cycles. The time-integrated neutron source distributions used for DORT calculations were prepared via two different approaches based on (a) calculated fuel burnup (standard routine procedure) and (b) in-core measurements by means of self-powered detectors (SPDs) and thermocouples (TCs) (new approach). Considering that fuel burnup distributions in operating VVER may be evaluated now by the use of analytical methods (calculations) only, it is necessary to develop new approaches for the testing and correction of calculated evaluations of a neutron source. The results presented in this paper allow one to consider the reverse task of the alternative estimation of fuel burnup distributions. The proposed approach is based on the adjustment (fitting) of time-integrated neutron source distributions, and thus fuel burnup patterns, in some part of the reactor core, taking into account neutron leakage measurements, neutron-physical calculations, and in-core SPD and TC measurement data. (authors)
Transport timescale calculations of sawteeth and helical structures in non-circular tokamak plasmas
Jardin, Stephen; Ferraro, Nate; Breslau, Josh; Chen, Jin
2012-10-01
We present results of using the implicit 3D MHD code M3D-C^1 [1,2] to perform 3D nonlinear magnetohydrodynamics calculations of the internal dynamics of a shaped cross-section tokamak plasma that span the timescales associated with ideal and resistive stability as well as parallel and perpendicular transport. We specify the transport coefficients and apply a ``current controller'' that adjusts the boundary loop-voltage to keep the total plasma current fixed. The 3D 2-fluid plasma model advances the magnetic field, velocities, electron and ion temperatures, and plasma density. We find that the plasma either reaches a stationary quasi-helical state in which the central safety factor is approximately unity, or it periodically undergoes either simple or compound sawtooth oscillations [3] with a period that approaches a constant value. By comparing a dee-shaped cross section with an elliptical shaped cross section, it is shown that the plasma shape has a large effect on determining the sawtooth behavior and the associated mode activity. Application to ITER shaped tokamak plasmas predict the magnitude of the 3D boundary deformation as a result of a stationary quasi-helical state forming in the interior. [4pt] [1] J. Breslau, N. Ferraro, S.C. Jardin, Physics of Plasmas 16 092503 (2009) [0pt] [2] S. C. Jardin, N. Ferraro, J. Breslau, J. Chen, Computational Science and Discovery 5 014002 (2012) [0pt] [3] X. von Goeler, W. Stodiek, and N. Sauthoff, Phys. Rev. Lett. 33, 1201 (1974)
Analytical calculations of neutron slowing down and transport in the constant-cross-section problem
Energy Technology Data Exchange (ETDEWEB)
Cacuci, D.G.
1978-04-01
Aspects of the problem of neutron slowing down and transport in an infinite medium consisting of a single nuclide that scatters elastically and isotropically and has energy-independent cross sections were investigated. The method of singular eigenfunctions was applied to the Boltzmann Equation governing the Laplace transform (with respect to the lethargy variable) of the neutron flux. A new sufficient condition for the convergence of the coefficients of the expansion of the scattering kernel in Legendre polynomials was rigorously derived for this energy-dependent problem. Formulas were obtained for the lethargy-dependent spatial moments of the scalar flux that are valid for medium to large lethargies. Use was made of the well-known connection between the spatial moments of the Laplace-transformed scalar flux and the moments of the flux in the ''eigenvalue space.'' The calculations were aided by the construction of a closed general expression for these ''eigenvalue space'' moments. Extensive use was also made of the methods of combinatorial analysis and of computer evaluation of complicated sequences of manipulations. For the case of no absorption it was possible to obtain for materials of any atomic weight explicit corrections to the age-theory formulas for the spatial moments M/sub 2n/(u) of the scalar flux that are valid through terms of the order of u/sup -5/. The evaluation of the coefficients of the powers of n, as explicit functions of the nuclear mass, represent one of the end products of this investigation. In addition, an exact expression for the second spatial moment, M/sub 2/(u), valid for arbitrary (constant) absorption, was derived. It is now possible to calculate analytically and rigorously the ''age'' for the constant-cross-section problem for arbitrary (constant) absorption and nuclear mass. 5 figures, 1 table.
An approximate calculation of advective gas-phase transport of 14C at Yucca Mountain, Nevada
Knapp, R. B.
1990-01-01
A quasilinear partial differential equation, which describes gas-phase transport of a 14C kinematic wave through a porous medium, is derived, its sensitivity to system variables is analyzed and it is applied to one possible release scenarion at the porposed Yucca Mountain, Nevada high-level radioactive waste repository. Advection, isotope exchange between CO 2 in a flowing gas phase and HCO 3- in a static aqueous phase, and radioactive decay are incorporated. The governing equation is solved analytically by the method of characteristics. The mass fraction of 14C in the gas phase,X 14g, is controlled by radioactive decay. The relatively long half-line of 14C, about 5720 years, and the relatively shallow proposed burial depth of the radioactive waste, about 350m, requires significant retardation of the 14C wave velocity for significant reduction in X 14g. 14C wave velocity is most sensitive to temperature and pH which control the distribution of total carbon between gas and liquid phase; the greater the partitioning of carbon into the liquid phase, the greater the retardation of the 14C wave velocity and the greater the ultimate reduction in X 14g from initial conditions. Partitioning of total carbon into the liquid phase is greatest at low temperatures, 8. Increasing water saturation also tends to retard 14C wave velocity but to a lesser extent. The governing equation has been applied using conditions that may possibly occur at the proposed Yucca Mountain repository. Calculations indicate that the 14C wave takes about 5900 years to reach the surface with a X 14g equal to 25 ppm. Diffusion and dispersion are not of major importance for these conditions. These calculations are approximate due to the number of assumptions involved. Discharge of 14C into the gas before the selected time would accelerate wave arrival and increase the amount of 14C reaching the surface.
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Sugino, Kazuteru [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center; Iwai, Takehiko
1998-07-01
A standard data base for FBR core nuclear design is under development in order to improve the accuracy of FBR design calculation. As a part of the development, we investigated an improved treatment of double-heterogeneity and a method to calculate homogenized control rod cross sections in a commercial reactor geometry, for the betterment of the analytical accuracy of commercial FBR core characteristics. As an improvement in the treatment of double-heterogeneity, we derived a new method (the direct method) and compared both this and conventional methods with continuous energy Monte-Carlo calculations. In addition, we investigated the applicability of the reaction rate ratio preservation method as a advanced method to calculate homogenized control rod cross sections. The present studies gave the following information: (1) An improved treatment of double-heterogeneity: for criticality the conventional method showed good agreement with Monte-Carlo result within one sigma standard deviation; the direct method was consistent with conventional one. Preliminary evaluation of effects in core characteristics other than criticality showed that the effect of sodium void reactivity (coolant reactivity) due to the double-heterogeneity was large. (2) An advanced method to calculate homogenize control rod cross sections: for control rod worths the reaction rate ratio preservation method agreed with those produced by the calculations with the control rod heterogeneity included in the core geometry; in Monju control rod worth analysis, the present method overestimated control rod worths by 1 to 2% compared with the conventional method, but these differences were caused by more accurate model in the present method and it is considered that this method is more reliable than the conventional one. These two methods investigated in this study can be directly applied to core characteristics other than criticality or control rod worth. Thus it is concluded that these methods will
Directory of Open Access Journals (Sweden)
Borodkin Pavel
2016-01-01
Full Text Available Paper describes the new approach of fitting axial fuel burn-up patterns in peripheral fuel assemblies of VVER-1000 type reactors, on the base of ex-core neutron leakage measurements, neutron-physical calculations and in-core SPND measured data. The developed approach uses results of new ex-vessel measurements on different power units through different reactor cycles and their uncertainties to clear the influence of a fitted fuel burn-up profile to the RPV neutron fluence calculations. The new methodology may be recommended to be included in the routine fluence calculations used in RPV lifetime management and may be taken into account during VVER-1000 core burn-up pattern correction.
Borodkin, Pavel; Borodkin, Gennady; Khrennikov, Nikolay
2016-02-01
Paper describes the new approach of fitting axial fuel burn-up patterns in peripheral fuel assemblies of VVER-1000 type reactors, on the base of ex-core neutron leakage measurements, neutron-physical calculations and in-core SPND measured data. The developed approach uses results of new ex-vessel measurements on different power units through different reactor cycles and their uncertainties to clear the influence of a fitted fuel burn-up profile to the RPV neutron fluence calculations. The new methodology may be recommended to be included in the routine fluence calculations used in RPV lifetime management and may be taken into account during VVER-1000 core burn-up pattern correction.
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Fahey, Mark R. [Oak Ridge National Laboratory; Candy, Jeff [General Atomics
2013-11-07
This project initiated the development of TGYRO ? a steady-state Gyrokinetic transport code (SSGKT) that integrates micro-scale GYRO turbulence simulations into a framework for practical multi-scale simulation of conventional tokamaks as well as future reactors. Using a lightweight master transport code, multiple independent (each massively parallel) gyrokinetic simulations are coordinated. The capability to evolve profiles using the TGLF model was also added to TGYRO and represents a more typical use-case for TGYRO. The goal of the project was to develop a steady-state Gyrokinetic transport code (SSGKT) that integrates micro-scale gyrokinetic turbulence simulations into a framework for practical multi-scale simulation of a burning plasma core ? the International Thermonuclear Experimental Reactor (ITER) in particular. This multi-scale simulation capability will be used to predict the performance (the fusion energy gain, Q) given the H-mode pedestal temperature and density. At present, projections of this type rely on transport models like GLF23, which are based on rather approximate fits to the results of linear and nonlinear simulations. Our goal is to make these performance projections with precise nonlinear gyrokinetic simulations. The method of approach is to use a lightweight master transport code to coordinate multiple independent (each massively parallel) gyrokinetic simulations using the GYRO code. This project targets the practical multi-scale simulation of a reactor core plasma in order to predict the core temperature and density profiles given the H-mode pedestal temperature and density. A master transport code will provide feedback to O(16) independent gyrokinetic simulations (each massively parallel). A successful feedback scheme offers a novel approach to predictive modeling of an important national and international problem. Success in this area of fusion simulations will allow US scientists to direct the research path of ITER over the next two
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Beaudoin, B.R.; Beggs, W.J.; Case, C.R.; Wilczynski, R.
1979-02-01
ASBLT is a computer program consisting of DATATRAN MODULES which was used during the manufacturing phase of LWBR to collect and evaluate as-built data. The program was part of the LWBR fuel rod inspection process and produced sections of module assembly certification reports. ASBLT used fuel pellet, fuel rod and module assembly data to compute core inventories and to supply input to nuclear design programs for as-built core calculations.
Thomas, Justin W.
2006-12-01
The Numerical Nuclear Reactor (NNR) is a code suite that is being developed to provide high-fidelity multi-physics capability for the analysis of light water nuclear reactors. The focus of the work here is to extend the capability of the NNR by incorporation of the neutronics module, DeCART, for Boiling Water Reactor (BWR) applications. The DeCART code has been coupled to the NNR fluid mechanics and heat transfer module STAR-CD for light water reactor applications. The coupling has been accomplished via an interface program, which is responsible for mapping the STAR-CD and DeCART meshes, managing communication, and monitoring convergence. DeCART obtains the solution of the 3-D Boltzmann transport equation by performing a series of 2-D modular ray tracing-based method of characteristics problems that are coupled within the framework of 3-D coarse-mesh finite difference. The relatively complex geometry and increased axial heterogeneity found in BWRs are beyond the modeling capability of the original version of DeCART. In this work, DeCART is extended in three primary areas. First, the geometric capability is generalized by extending the modular ray tracing scheme and permitting an unstructured mesh in the global finite difference kernel. Second, numerical instabilities, which arose as a result of the severe axial heterogeneity found in BWR cores, have been resolved. Third, an advanced nodal method has been implemented to improve the accuracy of the axial flux distribution. In this semi-analytic nodal method, the analytic solution to the transverse-integrated neutron diffusion equation is obtained, where the nonhomogeneous neutron source was first approximated by a quartic polynomial. The successful completion of these three tasks has allowed the application of the coupled DeCART/STAR-CD code to practical BWR problems.
Zelovich, Tamar; Kronik, Leeor; Hod, Oded
2014-08-12
We propose a new method for simulating electron dynamics in open quantum systems out of equilibrium, using a finite atomistic model. The proposed method is motivated by the intuitive and practical nature of the driven Liouville-von-Neumann equation approach of Sánchez et al. [J. Chem. Phys. 2006, 124, 214708] and Subotnik et al. [J. Chem. Phys. 2009, 130, 144105]. A key ingredient of our approach is a transformation of the Hamiltonian matrix from an atomistic to a state representation of the molecular junction. This allows us to uniquely define the bias voltage across the system while maintaining a proper thermal electronic distribution within the finite lead models. Furthermore, it allows us to investigate complex molecular junctions, including multilead configurations. A heuristic derivation of our working equation leads to explicit expressions for the damping and driving terms, which serve as appropriate electron sources and sinks that effectively "open" the finite model system. Although the method does not forbid it, in practice we find neither violation of Pauli's exclusion principles nor deviation from density matrix positivity throughout our numerical simulations of various tight-binding model systems. We believe that the new approach offers a practical and physically sound route for performing atomistic time-dependent transport calculations in realistic molecular junction models.
Dinu, Marina; Moiseenko, Tatyana
2016-04-01
An understanding of ability to predict the fate and transport of colloids in soil systems are of great importance in many environmental and industrial applications. Especially, in the case study sizes and zeta potentials of lignin and humus components (as a parameter reflecting the mobility and tread of organic substances). The objects of investigation were water extracts of gleepodzolic soil of European territory of Russia and Western Siberia, as well as humus substances extracted from this soil. In this study, evaluation of size, molecular weight distribution and zeta potential were used to predict the mobility of the organic component fractions of the soil. Fractionation was performed using multistage filtration plant (100 Da) and measuring physic-chemical parameters measured with the Malvern Zetasizer Nano ZSP. Significant differences in the distribution of organic matter on the molecular weight, charge (sign) of the zeta potential and the size of the sample of European Russia in comparison with samples of Western Siberia have been found. Also, laboratory studies have demonstrated of any differences in physicochemical parameters as infrared spectra, ultraviolet spectra, complexing ability of samples of the same soil type but different areas of Russia. The results can be used in the prediction of the migration ability of fractions humus substances and their stability at change physic-chemical conditions (the coefficient of mobility of the organic components by calculated in MathCad). This work was supported by the grant № 14-17-00460 RSF from 07.11.2014
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Slater, C.O.
1990-07-01
Results are reported for two-dimensional discrete ordinates, X-Y geometry calculations performed for seven Halden Heavy Boiling Water Reactor core configurations. The calculations were performed in support of an effort to reassess the neutron fluence received by the reactor vessel. Nickel foil measurement data indicated considerable underprediction of fluences by the previously used multigroup removal- diffusion method. Therefore, calculations by a more accurate method were deemed appropriate. For each core configuration, data are presented for (1) integral fluxes in the core and near the vessel wall, (2) neutron spectra at selected locations, (3) isoflux contours superimposed on the geometry models, (4) plots of the geometry models, and (5) input for the calculations. The initial calculations were performed with several mesh sizes. Comparisons of the results from these calculations indicated that the uncertainty in the calculated fluxes should be less than 10%. However, three-dimensional effects (such as axial asymmetry in the fuel loading) could contribute to much greater uncertainty in the calculated neutron fluxes. 7 refs., 22 figs., 11 tabs.
Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J.
2011-02-01
Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features.
Marchand, Pierre; Chabrier, Gilles; Hennebelle, Patrick; Commerçon, Benoit; Vaytet, Neil
2016-01-01
We develop a detailed chemical network relevant to the conditions characteristic of prestellar core collapse. We solve the system of time-dependent differential equations to calculate the equilibrium abundances of molecules and dust grains, with a size distribution given by size-bins for these latter. These abundances are used to compute the different non-ideal magneto-hydrodynamics resistivities (ambipolar, Ohmic and Hall), needed to carry out simulations of protostellar collapse. For the first time in this context, we take into account the evaporation of the grains, the thermal ionisation of Potassium, Sodium and Hydrogen at high temperature, and the thermionic emission of grains in the chemical network, and we explore the impact of various cosmic ray ionisation rates. All these processes significantly affect the non-ideal magneto-hydrodynamics resistivities, which will modify the dynamics of the collapse. Ambipolar diffusion and Hall effect dominate at low densities, up to n_H = 10^12 cm^-3, after which Oh...
Directory of Open Access Journals (Sweden)
J. Kent
2012-07-01
Full Text Available The accurate modelling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the Western Hemisphere should not pass into the Eastern Hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.
An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the Eastern Hemisphere of the separate cells test.
Directory of Open Access Journals (Sweden)
J. Kent
2012-12-01
Full Text Available The accurate modeling of cascades to unresolved scales is an important part of the tracer transport component of dynamical cores of weather and climate models. This paper aims to investigate the ability of the advection schemes in the National Center for Atmospheric Research's Community Atmosphere Model version 5 (CAM5 to model this cascade. In order to quantify the effects of the different advection schemes in CAM5, four two-dimensional tracer transport test cases are presented. Three of the tests stretch the tracer below the scale of coarse resolution grids to ensure the downscale cascade of tracer variance. These results are compared with a high resolution reference solution, which is simulated on a resolution fine enough to resolve the tracer during the test. The fourth test has two separate flow cells, and is designed so that any tracer in the western hemisphere should not pass into the eastern hemisphere. This is to test whether the diffusion in transport schemes, often in the form of explicit hyper-diffusion terms or implicit through monotonic limiters, contains unphysical mixing.
An intercomparison of three of the dynamical cores of the National Center for Atmospheric Research's Community Atmosphere Model version 5 is performed. The results show that the finite-volume (CAM-FV and spectral element (CAM-SE dynamical cores model the downscale cascade of tracer variance better than the semi-Lagrangian transport scheme of the Eulerian spectral transform core (CAM-EUL. Each scheme tested produces unphysical mass in the eastern hemisphere of the separate cells test.
Energy Technology Data Exchange (ETDEWEB)
Jo, Yu Gwon; Oh, Yoo Min; Park, Hyang Kyu; Park, Kang Soon; Cho, Nam Zin [KAIST, Daejeon (Korea, Republic of)
2016-05-15
In this paper, two issues in the FSS iteration method, i.e., the waiting time for surface source data and the variance biases in local tallies are investigated for the domain decomposed, 3-D continuous-energy whole-core calculation. The fission sources are provided as usual, while the surface sources are provided by banking MC particles crossing local domain boundaries. The surface sources serve as boundary conditions for nonoverlapping local problems, so that each local problem can be solved independently. In this paper, two issues in the FSS iteration are investigated. One is quantifying the waiting time of processors to receive surface source data. By using nonblocking communication, 'time penalty' to wait for the arrival of the surface source data is reduced. The other important issue is underestimation of the sample variance of the tally because of additional inter-iteration correlations in surface sources. From the numerical results on a 3-D whole-core test problem, it is observed that the time penalty is negligible in the FSS iteration method and that the real variances of both pin powers and assembly powers are estimated by the HB method. For those purposes, three cases; Case 1 (1 local domain), Case 2 (4 local domains), Case 3 (16 local domains) are tested. For both Cases 2 and 3, the time penalties for waiting are negligible compared to the source-tracking times. However, for finer divisions of local domains, the loss of parallel efficiency caused by the different number of sources for local domains in symmetric locations becomes larger due to the stochastic errors in source distributions. For all test cases, the HB method very well estimates the real variances of local tallies. However, it is also noted that the real variances of local tallies estimated by the HB method show slightly smaller than the real variances obtained from 30 independent batch runs and the deviations become larger for finer divisions of local domains. The batch size used
Final Report for Project "Framework Application for Core-Edge Transport Simulations (FACETS)"
Energy Technology Data Exchange (ETDEWEB)
Estep, Donald [Colorado State University
2014-01-17
This is the final report for the Colorado State University Component of the FACETS Project. FACETS was focused on the development of a multiphysics, parallel framework application that could provide the capability to enable whole-device fusion reactor modeling and, in the process, the development of the modeling infrastructure and computational understanding needed for ITER. It was intended that FACETS be highly flexible, through the use of modern computational methods, including component technology and object oriented design, to facilitate switching from one model to another for a given aspect of the physics, and making it possible to use simplified models for rapid turnaround or high-fidelity models that will take advantage of the largest supercomputer hardware. FACETS was designed in a heterogeneous parallel context, where different parts of the application can take advantage through parallelism based on task farming, domain decomposition, and/or pipelining as needed and applicable. As with all fusion simulations, an integral part of the FACETS project was treatment of the coupling of different physical processes at different scales interacting closely. A primary example for the FACETS project is the coupling of existing core and edge simulations, with the transport and wall interactions described by reduced models. However, core and edge simulations themselves involve significant coupling of different processes with large scale differences. Numerical treatment of coupling is impacted by a number of factors including, scale differences, form of information transferred between processes, implementation of solvers for different codes, and high performance computing concerns. Operator decomposition involving the computation of the individual processes individually using appropriate simulation codes and then linking/synchronizing the component simulations at regular points in space and time, is the defacto approach to high performance simulation of multiphysics
Huang, Xianli; Morita, Shigeru; Oishi, Tetsutarou; Murakami, Izumi; Goto, Motoshi; Zhang, Hongming; Liu, Yang
2016-10-01
With impurity pellet injection and a one-dimensional transport code, the transport of Al and Fe ions has been analyzed in the Large Helical Device (LHD) based on extreme ultraviolet (EUV) space-resolved spectroscopy. The total density of Fe ions in the plasma core has been analyzed from the radial profiles of the Fe n =3-2 Lα emissions. When the ne profile is peaked or hollow, the Fe density also exhibits a peaked or hollow profile, respectively. Fe transport analysis shows that the convective velocity (V) is outward in the plasma core and inward near the edge when the ne profile is hollow. On the other hand, the V takes negative value over the whole radial range in the peaked ne profile. Therefore, the different Fe density profiles between peaked and hollow ne profiles can be explained by the significant difference in the V profile. Comparison of the transport coefficients between Al and Fe shows the magnitude of V for Al ions seems to be smaller than that for Fe ions while the difference in the diffusion coefficient profile is not significant. The difference in the decay time of line emissions between the two speices is attributed to the weaker convection for the Al.
Iwase, Shigeru; Hoshi, Takeo; Ono, Tomoya
2015-06-01
We propose an efficient procedure to obtain Green's functions by combining the shifted conjugate orthogonal conjugate gradient (shifted COCG) method with the nonequilibrium Green's function (NEGF) method based on a real-space finite-difference (RSFD) approach. The bottleneck of the computation in the NEGF scheme is matrix inversion of the Hamiltonian including the self-energy terms of electrodes to obtain the perturbed Green's function in the transition region. This procedure first computes unperturbed Green's functions and calculates perturbed Green's functions from the unperturbed ones using a mathematically strict relation. Since the matrices to be inverted to obtain the unperturbed Green's functions are sparse, complex-symmetric, and shifted for a given set of sampling energy points, we can use the shifted COCG method, in which once the Green's function for a reference energy point has been calculated the Green's functions for the other energy points can be obtained with a moderate computational cost. We calculate the transport properties of a C(60)@(10,10) carbon nanotube (CNT) peapod suspended by (10,10)CNTs as an example of a large-scale transport calculation. The proposed scheme opens the possibility of performing large-scale RSFD-NEGF transport calculations using massively parallel computers without the loss of accuracy originating from the incompleteness of the localized basis set.
Energy Technology Data Exchange (ETDEWEB)
Duerigen, Susan
2013-05-15
The superior advantage of a nodal method for reactor cores with hexagonal fuel assemblies discretized as cells consisting of equilateral triangles is its mesh refinement capability. In this thesis, a diffusion and a simplified P{sub 3} (or SP{sub 3}) neutron transport nodal method are developed based on trigonal geometry. Both models are implemented in the reactor dynamics code DYN3D. As yet, no other well-established nodal core analysis code comprises an SP{sub 3} transport theory model based on trigonal meshes. The development of two methods based on different neutron transport approximations but using identical underlying spatial trigonal discretization allows a profound comparative analysis of both methods with regard to their mathematical derivations, nodal expansion approaches, solution procedures, and their physical performance. The developed nodal approaches can be regarded as a hybrid NEM/AFEN form. They are based on the transverse-integration procedure, which renders them computationally efficient, and they use a combination of polynomial and exponential functions to represent the neutron flux moments of the SP{sub 3} and diffusion equations, which guarantees high accuracy. The SP{sub 3} equations are derived in within-group form thus being of diffusion type. On this basis, the conventional diffusion solver structure can be retained also for the solution of the SP{sub 3} transport problem. The verification analysis provides proof of the methodological reliability of both trigonal DYN3D models. By means of diverse hexagonal academic benchmark and realistic detailed-geometry full-transport-theory problems, the superiority of the SP{sub 3} transport over the diffusion model is demonstrated in cases with pronounced anisotropy effects, which is, e.g., highly relevant to the modeling of fuel assemblies comprising absorber material.
Tsuchimochi, Takashi; Kobayashi, Masato; Nakata, Ayako; Imamura, Yutaka; Nakai, Hiromi
2008-11-15
The Sakurai-Sugiura projection (SS) method was implemented and numerically assessed for diagonalization of the Hamiltonian in time-dependent density functional theory (TDDFT). Since the SS method can be used to specify the range in which the eigenvalues are computed, it may be an efficient tool for use with eigenvalues in a particular range. In this article, the SS method is applied to core excited calculations for which the eigenvalues are located within a particular range, since the eigenvalues are unique to atomic species in molecules. The numerical assessment of formaldehyde molecule by TDDFT with core-valence Becke's three-parameter exchange (B3) plus Lee-Yang-Parr (LYP) correlation (CV-B3LYP) functional demonstrates that the SS method can be used to selectively obtain highly accurate eigenvalues and eigenvectors. Thus, the SS method is a new and powerful alternative for calculating core-excitation energies without high computation costs.
Directory of Open Access Journals (Sweden)
Hirokazu Takaki
2014-01-01
Full Text Available We present an efficient computation technique for ab-initio electron transport calculations based on density functional theory and the nonequilibrium Green’s function formalism for application to heterostructures with two-dimensional (2D interfaces. The computational load for constructing the Green’s functions, which depends not only on the energy but also on the 2D Bloch wave vector along the interfaces and is thus catastrophically heavy, is circumvented by parallel computational techniques with the message passing interface, which divides the calculations of the Green’s functions with respect to energy and wave vectors. To demonstrate the computational efficiency of the present code, we perform ab-initio electron transport calculations of Al(100-Si(100-Al(100 heterostructures, one of the most typical metal-semiconductor-metal systems, and show their transmission spectra, density of states (DOSs, and dependence on the thickness of the Si layers.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.
Calculation Method of Lamination Plate Types in Frame Type Core of Transformer%变压器框式铁心的片型计算方法
Institute of Scientific and Technical Information of China (English)
王欢; 刘光辉
2012-01-01
The calculation method of types of limb,side limb and yoke in three-phase five-limb four-frame core is presented.%介绍了三相五柱四框式铁心心柱、旁柱及铁轭等片型的计算方法。
Buras, R; Janka, H T; Kifonidis, K
2005-01-01
Supernova models with a full spectral treatment of the neutrino transport are presented, employing the Prometheus/Vertex neutrino-hydrodynamics code with a ``ray-by-ray plus'' approximation for treating two- (or three-) dimensional problems. The method is described in detail and critically assessed with respect to its capabilities, limitations, and inaccuracies in the context of supernova simulations. In this first paper of a series, 1D and 2D core-collapse calculations for a (nonrotating) 15 M_sun star are discussed, uncertainties in the treatment of the equation of state -- numerical and physical -- are tested, Newtonian results are compared with simulations using a general relativistic potential, bremsstrahlung and interactions of neutrinos of different flavors are investigated, and the standard approximation in neutrino-nucleon interactions with zero energy transfer is replaced by rates that include corrections due to nucleon recoil, thermal motions, weak magnetism, and nucleon correlations. Models with t...
Energy Technology Data Exchange (ETDEWEB)
Willmann, P.A.; Hooper, E.B. Jr.
1977-02-01
A computer program was written to calculate the stored energy in a transformer. This result easily yields the inductance and leakage reactance of the transformer and is estimated to be accurate to better than 5 percent. The program was used to calculate the leakage reactance of the main transformer for the LLL neutral beam High Voltage Test Stand.
Mezzacappa, A; Bruenn, S W; Blondin, J M; Guidry, M W; Strayer, M R; Umar, A S
1996-01-01
We investigate neutrino-driven convection in core collapse supernovae and its ramifications for the explosion mechanism. We begin with an ``optimistic'' 15 solar mass precollapse model, which is representative of the class of stars with compact iron cores. This model is evolved through core collapse and bounce in one dimension using multigroup (neutrino-energy--dependent) flux-limited diffusion (MGFLD) neutrino transport and Lagrangian hydrodynamics, providing realistic initial conditions for the postbounce convection and evolution. Our two-dimensional simulation begins at 106 ms after bounce at a time when there is a well-developed gain region, and proceeds for 400 ms. We couple two-dimensional (PPM) hydrodynamics to one-dimensional MGFLD neutrino transport. At 225 ms after bounce we see large-scale convection behind the shock, characterized by high-entropy, mushroom-like, expanding upflows and dense, low-entropy, finger-like downflows. The upflows reach the shock and distort it from sphericity. The radial c...
QmeQ 1.0: An open-source Python package for calculations of transport through quantum dot devices
DEFF Research Database (Denmark)
Kiršanskas, Gediminas; Pedersen, Jonas Nyvold; Karlström, Olov
2017-01-01
QmeQ is an open-source Python package for numerical modeling of transport through quantum dot devices with strong electron–electron interactions using various approximate master equation approaches. The package provides a framework for calculating stationary particle or energy currents driven...... by differences in chemical potentials or temperatures between the leads which are tunnel coupled to the quantum dots. The electronic structures of the quantum dots are described by their single-particle states and the Coulomb matrix elements between the states. When transport is treated perturbatively to lowest...
Liu, Tianyu; Xu, X. George; Carothers, Christopher D.
2014-06-01
Hardware accelerators are currently becoming increasingly important in boosting high performance computing sys- tems. In this study, we tested the performance of two accelerator models, NVIDIA Tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor, using a new Monte Carlo photon transport package called ARCHER-CT we have developed for fast CT imaging dose calculation. The package contains three code variants, ARCHER - CTCPU, ARCHER - CTGPU and ARCHER - CTCOP to run in parallel on the multi-core CPU, GPU and coprocessor architectures respectively. A detailed GE LightSpeed Multi-Detector Computed Tomography (MDCT) scanner model and a family of voxel patient phantoms were included in the code to calculate absorbed dose to radiosensitive organs under specified scan protocols. The results from ARCHER agreed well with those from the production code Monte Carlo N-Particle eXtended (MCNPX). It was found that all the code variants were significantly faster than the parallel MCNPX running on 12 MPI processes, and that the GPU and coprocessor performed equally well, being 2.89~4.49 and 3.01~3.23 times faster than the parallel ARCHER - CTCPU running with 12 hyperthreads.
Kreutz, K.J.; Wake, C.P.; Aizen, V.B.; DeWayne, Cecil L.; Synal, H.-A.
2003-01-01
Stable water isotope (??18O, ??D) data from a high elevation (5100 masl) ice core recovered from the Tien Shan Mountains, Kyrgyzstan, display a seasonal cycle in deuterium excess (d = ??D - 8*??18O) related to changes in the regional hydrologic cycle during 1994-2000. While there is a strong correlation (r2 = 0.98) between ??18O and ??D in the ice core samples, the regression slope (6.9) and mean d value (23.0) are significantly different than the global meteoric water line values. The resulting time-series ice core d profile contains distinct winter maxima and summer minima, with a yearly d amplitude of ???15-20???. Local-scale processes that may affect d values preserved in the ice core are not consistent with the observed seasonal variability. Data from Central Asian monitoring sites in the Global Network of Isotopes in Precipitation (GNIP) have similar seasonal d changes. We suggest that regional-scale hydrological conditions, including seasonal changes in moisture source, transport, and recycling in the Caspian/Aral Sea region, are responsible for the observed spatial and temporal d variability.
THE IMPROVEMENT OF FINANCIAL RESPONSIBILITY IN THE CALCULATIONS FOR INTERNATIONAL FREIGHT TRANSPORT
Directory of Open Access Journals (Sweden)
S. N. Vnukova
2010-01-01
Full Text Available It is suggested to bring in changes into the Rules of Complex Payments applied by the states-participants of the Commonwealth of Independent States and the Baltic States in payments for international freight transportations.
Akie, H.; Sugo, Y.; Okawa, R.
2003-06-01
A rock-like oxide (ROX) fuel - light water reactor (LWR) burning system has been studied for efficient plutonium transmutation. For the improvement of small negative reactivity coefficients and severe transient behaviors of ROX fueled LWRs, a partial loading core of ROX fuel assemblies with conventional UO 2 assemblies was considered. As a result, although the reactivity coefficients could be improved, the power peaking tends to be large in this heterogeneous core configuration. The reactivity initiated accident (RIA) and loss of coolant accident (LOCA) behaviors were not sufficiently improved. In order to reduce the power peaking, the fuel composition and the assembly design of the ROX fuel were modified. Firstly, erbium burnable poison was added as Er 2O 3 in the ROX fuel to reduce the burnup reactivity swing. Then pin-by-pin Pu enrichment and Er content distributions within the ROX fuel assembly were considered. In addition, the Er content distribution was also considered in the axial direction of the ROX fuel pin. With these modifications, a power peaking factor even lower than the one in a conventional UO 2 fueled core can be obtained. The RIA and LOCA analyses of the modified core have also shown the comparable transient behaviors of ROX partial loading core to those of the UO 2 core.
Directory of Open Access Journals (Sweden)
Labarile Antonella
2016-01-01
Full Text Available In nuclear safety research, the quality of the results of simulation codes is widely determined by the reactor design and safe operation, and the description of neutron transport in the reactor core is a feature of particular importance. Moreover, for the long effort that is made, there remain uncertainties in simulation results due to the neutronic data and input specification that need a huge effort to be eliminated. A realistic estimation of these uncertainties is required for finding out the reliability of the results. This explains the increasing demand in recent years for calculations in the nuclear fields with best-estimate codes that proved confidence bounds of simulation results. All this has lead to the Benchmark for Uncertainty Analysis in Modelling (UAM for Design, Operation and Safety Analysis of LWRs of the NEA. The UAM-Benchmark coupling multi-physics and multi-scale analysis using as a basis complete sets of input specifications of boiling water reactors (BWR and pressurized water reactors (PWR. In this study, the results of the transport calculations carried out using the SCALE-6.2 program (TRITON/NEWT and TRITON/KENO modules as well as Monte Carlo SERPENT code, are presented. Additionally, they have been made uncertainties calculation for a PWR 15 × 15 and a BWR 7 × 7 fuel elements, in two different configurations (with and without control rod, and two different states, Hot Full Power (HFP and Hot Zero Power (HZP, using the TSUNAMI module, which uses the Generalized Perturbation Theory (GPT, and SAMPLER, which uses stochastic sampling techniques for cross-sections perturbations. The results obtained and validated are compared with references results and similar studies presented in the exercise I-2 (Lattice Physics of UAM-Benchmark.
Song, Linze; Shi, Qiang
2015-05-07
We present a new non-perturbative method to calculate the charge carrier mobility using the imaginary time path integral approach, which is based on the Kubo formula for the conductivity, and a saddle point approximation to perform the analytic continuation. The new method is first tested using a benchmark calculation from the numerical exact hierarchical equations of motion method. Imaginary time path integral Monte Carlo simulations are then performed to explore the temperature dependence of charge carrier delocalization and mobility in organic molecular crystals (OMCs) within the Holstein and Holstein-Peierls models. The effects of nonlocal electron-phonon interaction on mobility in different charge transport regimes are also investigated.
Energy Technology Data Exchange (ETDEWEB)
Bordy, J.M.; Kodeli, I.; Menard, St.; Bouchet, J.L.; Renard, F.; Martin, E.; Blazy, L.; Voros, S.; Bochud, F.; Laedermann, J.P.; Beaugelin, K.; Makovicka, L.; Quiot, A.; Vermeersch, F.; Roche, H.; Perrin, M.C.; Laye, F.; Bardies, M.; Struelens, L.; Vanhavere, F.; Gschwind, R.; Fernandez, F.; Quesne, B.; Fritsch, P.; Lamart, St.; Crovisier, Ph.; Leservot, A.; Antoni, R.; Huet, Ch.; Thiam, Ch.; Donadille, L.; Monfort, M.; Diop, Ch.; Ricard, M
2006-07-01
The purpose of this conference was to describe the present state of computer codes dedicated to radiation transport or radiation source assessment or dosimetry. The presentations have been parted into 2 sessions: 1) methodology and 2) uses in industrial or medical or research domains. It appears that 2 different calculation strategies are prevailing, both are based on preliminary Monte-Carlo calculations with data storage. First, quick simulations made from a database of particle histories built though a previous Monte-Carlo simulation and secondly, a neuronal approach involving a learning platform generated through a previous Monte-Carlo simulation. This document gathers the slides of the presentations.
Energy Technology Data Exchange (ETDEWEB)
Kanai, Yosuke [Univ. of North Carolina, Chapel Hill, NC (United States); Tang, M [Univ. of North Carolina, Chapel Hill, NC (United States); Wood, B C [Univ. of North Carolina, Chapel Hill, NC (United States)
2013-10-25
We have began the project “Multiscale Capability for Exploring Transport Phenomena in Battery”, which is sponsored by Laboratory Directed Research and Development Program at Lawrence Livermore National Laboratory in February 2012 as the subcontract was approved. We have been performing first-principles quantum-mechanical calculations to first establish the general modeling framework. It was found that it is essential to employ advanced Density Functional Theory (DFT) calculations with Hubbard U correction, in order to describe the battery material, in particular, LiFePO4 (Figure 1). The presence of localized d-electrons at Fe ion sites requires the better treatment of non-local correlation beyond that of standard DFT. As our aim was to first identify and investigate key transport/reaction mechanisms affecting the performance of Lithium-ion based batteries, we have began out work by characterizing the standard structures and how the defects influence the important electronic structure.
Takahashi, F; Shigemori, Y; Seki, A
2009-01-01
A system has been developed to assess radiation dose distribution inside the body of exposed persons in a radiological accident by utilising radiation transport calculation codes-MCNP and MCNPX. The system consists mainly of two parts, pre-processor and post-processor of the radiation transport calculation. Programs for the pre-processor are used to set up a 'problem-dependent' input file, which defines the accident condition and dosimetric quantities to be estimated. The program developed for the post-processor part can effectively indicate dose information based upon the output file of the code. All of the programs in the dosimetry system can be executed with a generally used personal computer and accurately give the dose profile to an exposed person in a radiological accident without complicated procedures. An experiment using a physical phantom was carried out to verify the availability of the dosimetry system with the developed programs in a gamma ray irradiation field.
DEPTH-AVERAGED 2-D CALCULATION OF FLOW AND SEDIMENT TRANSPORT IN CURVED CHANNELS
Institute of Scientific and Technical Information of China (English)
Weiming WU; Sam S. Y. WANG
2004-01-01
The helical flow significantly affects the flow, sediment transport and morphological evolution in curved channels. A semi-empirical formula is proposed to determine the cross-stream distribution of the helical flow intensity in the developed regions of a channel bend. It is then used to evaluate the dispersion terms in the depth-averaged 2-D momentum equations and suspended-load transport equation as well as the bed-load transport angle, thus enhancing the depth-averaged 2-D model to account for the effect of helical flow. The tests in several experimental and field cases show that the enhanced depth-averaged 2-D model can much more reasonably predict the shifting of main flow from inner bank to outer bank, the erosion along outer bank and deposition along inner bank than the depth-averaged 2-D model without considering this effect.
Energy Technology Data Exchange (ETDEWEB)
Freedman, Vicky L.; Zhang, Z. F.; Keller, Jason M.; Chen, Yousu
2007-05-30
This report documents numerical flow and transport simulations performed that establish initial waste acceptance criteria for the potential waste streams that may be safely sequestered in the 221-U Building and similar canyon structures. Specifically, simulations were executed to identify the maximum loading of contaminant mass (without respect to volume) that can be emplaced within the 221-U Building with no more than 1 pCi/m2 of contaminant migrating outside the structure within a 1,000 year time period. The initial scoping simulations were executed in one dimension to assess important processes, and then two dimensions to establish waste acceptance criteria. Two monolithic conditions were assessed: (1) a grouted canyon monolith; and (2) a canyon monolith filled with sand, both assuming no cracks or fissures were present to cause preferential transport. A three-staged approach was taken to account for different processes that may impact the amount of contaminant that can be safely sequestered in canyon structure. In the first stage, flow and transport simulations established waste acceptance criteria based on a linear (Kd) isotherm approach. In the second stage, impacts on thermal loading were examined and the differences in waste acceptance criteria quantified. In the third stage of modeling, precipitation/dissolution reactions were considered on the release and transport of the contaminants, and the subsequent impact on the maximum contaminant loading. The reactive transport modeling is considered a demonstration of the reactive transport capability, and shows the importance of its use for future performance predictions once site-specific data have been obtained.
Non-Equilibrium Green's Function Calculation for Electron Transport through Magnetic Tunnel Junction
Directory of Open Access Journals (Sweden)
Sara Nobakht
2014-06-01
Full Text Available In this paper non-equilibrium Green's function method –dependent electron transport through non magnetic layer (insulator has been studied in one dimension .electron transport in multi-layer (magnetic/non magnetic/ magneticlayers is studied as quantum .the result show increasing the binding strength of the electrical insulator transition probability density case , the electron density , broad levels of disruption increases. Broad band connection increases the levels of disruption to electrical insulation and show non- conductive insulating state to semiconductor stat and even conductor
Imaoka, Haruna; Kinugawa, Kenichi
2017-03-01
Thermal conductivity, shear viscosity, and bulk viscosity of normal liquid 4He at 1.7-4.0 K are calculated using path integral centroid molecular dynamics (CMD) simulations. The calculated thermal conductivity and shear viscosity above lambda transition temperature are on the same order of magnitude as experimental values, while the agreement of shear viscosity is better. Above 2.3 K the CMD well reproduces the temperature dependences of isochoric shear viscosity and of the time integral of the energy current and off-diagonal stress tensor correlation functions. The calculated bulk viscosity, not known in experiments, is several times larger than shear viscosity.
Energy Technology Data Exchange (ETDEWEB)
Gauntt, Randall O.; Powers, Dana Auburn; Ashbaugh, Scott G.; Leonard, Mark Thomas; Longmire, Pamela
2010-04-01
In this study, risk-significant pressurized-water reactor severe accident sequences are examined using MELCOR 1.8.5 to explore the range of fission product releases to the reactor containment building. Advances in the understanding of fission product release and transport behavior and severe accident progression are used to render best estimate analyses of selected accident sequences. Particular emphasis is placed on estimating the effects of high fuel burnup in contrast with low burnup on fission product releases to the containment. Supporting this emphasis, recent data available on fission product release from high-burnup (HBU) fuel from the French VERCOR project are used in this study. The results of these analyses are treated as samples from a population of accident sequences in order to employ approximate order statistics characterization of the results. These trends and tendencies are then compared to the NUREG-1465 alternative source term prescription used today for regulatory applications. In general, greater differences are observed between the state-of-the-art calculations for either HBU or low-burnup (LBU) fuel and the NUREG-1465 containment release fractions than exist between HBU and LBU release fractions. Current analyses suggest that retention of fission products within the vessel and the reactor coolant system (RCS) are greater than contemplated in the NUREG-1465 prescription, and that, overall, release fractions to the containment are therefore lower across the board in the present analyses than suggested in NUREG-1465. The decreased volatility of Cs2MoO4 compared to CsI or CsOH increases the predicted RCS retention of cesium, and as a result, cesium and iodine do not follow identical behaviors with respect to distribution among vessel, RCS, and containment. With respect to the regulatory alternative source term, greater differences are observed between the NUREG-1465 prescription and both HBU and LBU predictions than exist between HBU and LBU
Inelastic Transport through Molecules: Comparing First-Principles Calculations to Experiments
DEFF Research Database (Denmark)
Paulsson, Magnus; Frederiksen, Thomas; Brandbyge, Mads
2006-01-01
We present calculations of the elastic and inelastic conductance through three different hydrocarbon molecules connected to gold electrodes. Our method is based on a combination of the nonequilibrium Green's function method with density functional theory. Vibrational effects in these molecular...
Energy Technology Data Exchange (ETDEWEB)
Frankel, J.I.
1997-09-01
This investigation used sysmbolic manipulation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular integral and integro-differential equations which appear in radiative and mixed-mode energy transport. Contained in this report are seven papers which present the technical results as individual modules.
Krylov subspace method for evaluating the self-energy matrices in electron transport calculations
DEFF Research Database (Denmark)
Sørensen, Hans Henrik Brandenborg; Hansen, Per Christian; Petersen, D. E.;
2008-01-01
We present a Krylov subspace method for evaluating the self-energy matrices used in the Green's function formulation of electron transport in nanoscale devices. A procedure based on the Arnoldi method is employed to obtain solutions of the quadratic eigenvalue problem associated with the infinite...
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2012-02-01
Organic materials form crystals by relatively weak Van der Waals attraction between molecules, and thus differ fundamentally from covalently bonded semiconductors. Carriers in the organic semiconductors induce the drastic lattice deformation, which is called as polaron state. The polaron effect on the transport is a serious problem. Exactly what conduction mechanism applies to organic semiconductors has not been established. Therefore, we have investigated the transport properties using the Time-Dependent Wave-Packet Diffusion (TD-WPD) method [1]. To consider the polaron effect on the transport, in the methodology, we combine the wave-packet dynamics based on the quantum mechanics theory with the molecular dynamics. As the results, we can describe the electron motion modified by (electron-phonon mediated) time-dependent structural change. We investigate the transport property from an atomistic viewpoint and evaluate the mobility of organic semiconductors. We clarify the temperature dependence of mobility from the thermal activated behavior to the power law behavior. I will talk about these results in my presentation. [1] H. Ishii, N. Kobayashi, K. Hirose, Phys. Rev. B, 82 085435 (2010).
Energy Technology Data Exchange (ETDEWEB)
Ono, Shizuca; Vieira, Wilson J.; Garcia, Roberto D.M. [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados
2000-07-01
In this work, the use of multigroup albedo coefficients in Monte Carlo calculations of particle reflection and transmission by ducts is investigated. The procedure consists in modifying the MCNP code so that an albedo matrix computed previously by deterministic methods or Monte Carlo is introduced into the program to describe particle reflection by a surface. This way it becomes possible to avoid the need of considering particle transport in the duct wall explicitly, changing the problem to a problem of transport in the duct interior only and reducing significantly the difficulty of the real problem. The probability of particle reflection at the duct wall is given, for each group, as the sum of the albedo coefficients over the final groups. The calculation is started by sampling a source particle and simulating its reflection on the duct wall by sampling a group for the emerging particle. The particle weight is then reduced by the reflection probability. Next, a new direction and trajectory for the particle is selected. Numerical results obtained for the model are compared with results from a discrete ordinates code and results from Monte Carlo simulations that take particle transport in the wall into account. (author)
Institute of Scientific and Technical Information of China (English)
YAN Yuping; KANG Shichang; SUN Junying; Paul A. Mayewski; QIN Dahe
2005-01-01
Atmospheric circulation reconstruction based on glaciochemical records requires knowledge of chemical concentration controls, such as source, transport pathway and strength. To gain insight into these processes, the relationships between glaciochemical records from two Northern Hemisphere sites (Mt. Logan in Yukon Territory and 20D in southern Greenland) and instrumental sea level pressure (SLP) series are investigated. Calibrations between Mt. Logan sea-salt sodium (ssNa+) concentration and SLP series show that ssNa+ concentrations are closely correlated with the autumntime (SON) Aleutian Low and the summertime (JJA) North Pacific Subtropical High. Both the deepened Aleutian Low and enhanced North Pacific Subtropical High strengthen the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. Calibrations between 20D ssNa+ concentrations and SLP series indicate that ssNa+ concentrations are closely related to the wintertime (Jan.) Icelandic Low. A deepening of the Icelandic Low strengthens winter storms and frequent cyclogenesis over the North Atlantic and pushes more sea-salt laden air masses to the Greenland ice sheet. Therefore, ice core ssNa+ records from the Mt. Logan region can be considered as a proxy for reconstructing the autumntime Aleutian Low and summertime North Pacific Subtropical High, and the ssNa+ records from Greenland ice core (20D) may provide a proxy for reconstructing the wintertime Icelandic Low.
Multidimensional neutrino-transport simulations of the core-collapse supernova central engine
O'Connor, Evan; Couch, Sean
2017-01-01
Core-collapse supernovae (CCSNe) mark the explosive death of a massive star. The explosion itself is triggered by the collapse of the iron core that forms near the end of a massive star's life. The core collapses to nuclear densities where the stiff nuclear equation of state halts the collapse and leads to the formation of the supernova shock. In many cases, this shock will eventually propagate throughout the entire star and produces a bright optical display. However, the path from shock formation to explosion has proven difficult to recreate in simulations. Soon after the shock forms, its outward propagation is stagnated and must be revived in order for the CCSNe to be successful. The leading theory for the mechanism that reenergizes the shock is the deposition of energy by neutrinos. In 1D simulations this mechanism fails. However, there is growing evidence that in 2D and 3D, hydrodynamic instabilities can assist the neutrino heating in reviving the shock. In this talk, I will present new multi-D neutrino-radiation-hydrodynamic simulations of CCSNe performed with the FLASH hydrodynamics package. I will discuss the efficacy of neutrino heating in our simulations and show the impact of the multi-D hydrodynamic instabilities.
Energy Technology Data Exchange (ETDEWEB)
Borges, P. D., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu; Scolfaro, L., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)
2014-12-14
The thermoelectric properties of indium nitride in the most stable wurtzite phase (w-InN) as a function of electron and hole concentrations and temperature were studied by solving the semiclassical Boltzmann transport equations in conjunction with ab initio electronic structure calculations, within Density Functional Theory. Based on maximally localized Wannier function basis set and the ab initio band energies, results for the Seebeck coefficient are presented and compared with available experimental data for n-type as well as p-type systems. Also, theoretical results for electric conductivity and power factor are presented. Most cases showed good agreement between the calculated properties and experimental data for w-InN unintentionally and p-type doped with magnesium. Our predictions for temperature and concentration dependences of electrical conductivity and power factor revealed a promising use of InN for intermediate and high temperature thermoelectric applications. The rigid band approach and constant scattering time approximation were utilized in the calculations.
Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa
2002-08-01
Transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory approach. Results are reported for shear viscosity, viscomagnetic coefficients, and self-diffusion in the dilute-gas limit and in the temperature range of 200-1500 K for the three recently proposed carbon dioxide potential energy hypersurfaces. Agreement with the measurements is, in general, within the experimental error. The calculations indicate that the corrections in the second-order approximation and those due to the angular-momentum polarization for the viscosity are small, Bukowski [et al.] potential energy hypersurface (1999) with the experimental viscosity data is consistent with the rigid-rotor assumption made in the calculations being reasonable for the three properties considered.
Testing of the ABBN-RF multigroup data library in photon transport calculations
Directory of Open Access Journals (Sweden)
Koscheev Vladimir
2017-01-01
Full Text Available Gamma radiation is produced via both of nuclear fuel and shield materials. Photon interaction is known with appropriate accuracy, but secondary gamma ray production known much less. The purpose of this work is studying secondary gamma ray production data from neutron induced reactions in iron and lead by using MCNP code and modern nuclear data as ROSFOND, ENDF/B-7.1, JEFF-3.2 and JENDL-4.0. Results of calculations show that all of these nuclear data have different photon production data from neutron induced reactions and have poor agreement with evaluated benchmark experiment. The ABBN-RF multigroup cross-section library is based on the ROSFOND data. It presented in two forms of micro cross sections: ABBN and MATXS formats. Comparison of group-wise calculations using both ABBN and MATXS data to point-wise calculations with the ROSFOND library shows a good agreement. The discrepancies between calculation and experimental C/E results in neutron spectra are in the limit of experimental errors. For the photon spectrum they are out of experimental errors. Results of calculations using group-wise and point-wise representation of cross sections show a good agreement both for photon and neutron spectra.
Testing of the ABBN-RF multigroup data library in photon transport calculations
Koscheev, Vladimir; Lomakov, Gleb; Manturov, Gennady; Tsiboulia, Anatoly
2017-09-01
Gamma radiation is produced via both of nuclear fuel and shield materials. Photon interaction is known with appropriate accuracy, but secondary gamma ray production known much less. The purpose of this work is studying secondary gamma ray production data from neutron induced reactions in iron and lead by using MCNP code and modern nuclear data as ROSFOND, ENDF/B-7.1, JEFF-3.2 and JENDL-4.0. Results of calculations show that all of these nuclear data have different photon production data from neutron induced reactions and have poor agreement with evaluated benchmark experiment. The ABBN-RF multigroup cross-section library is based on the ROSFOND data. It presented in two forms of micro cross sections: ABBN and MATXS formats. Comparison of group-wise calculations using both ABBN and MATXS data to point-wise calculations with the ROSFOND library shows a good agreement. The discrepancies between calculation and experimental C/E results in neutron spectra are in the limit of experimental errors. For the photon spectrum they are out of experimental errors. Results of calculations using group-wise and point-wise representation of cross sections show a good agreement both for photon and neutron spectra.
Spatially resolved transport data for electrons in gases: Definition, interpretation and calculation
Energy Technology Data Exchange (ETDEWEB)
Dujko, S., E-mail: sasa.dujko@ipb.ac.rs [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, 11080 Belgrade (Serbia); ARC Centre for Antimatter-Matter Studies, School of Engineering and Physical Sciences, James Cook University, Townsville 4810 (Australia); Centrum Wiskunde and Informatica (CWI), P.O. Box 94079, 1090 GB, Amsterdam (Netherlands); White, R.D. [ARC Centre for Antimatter-Matter Studies, School of Engineering and Physical Sciences, James Cook University, Townsville 4810 (Australia); Raspopovic, Z.M.; Petrovic, Z.Lj. [Institute of Physics, University of Belgrade, P.O. Box 68, Pregrevica 118, 11080 Belgrade (Serbia)
2012-05-15
The spatiotemporal evolution of electron swarms in the presence of electric and magnetic fields is investigated to facilitate understanding temporal and spatial non-locality in low-temperature plasmas. Using two independent techniques, a multi-term solution of Boltzmann's equation and a Monte Carlo simulation technique, the synergism of an applied magnetic field and non-conservative collisions (ionization and/or electron attachment) is demonstrated as a means to control the non-locality of relaxation processes. In particular, oscillatory features in the spatial and temporal profiles are demonstrated, and shown to be enhanced or suppressed through the magnetic field strength, the angle between the electric and magnetic fields, and the degree of ionization. Finally we discuss the impact of field configurations and strengths on the transport properties, highlighting the distinctions in the measured transport properties between various experimental configurations when non-conservative processes are present.
Energy Technology Data Exchange (ETDEWEB)
Schloemer, Luc Laurent Alexander
2014-12-17
The compliance with the dose rate limits for transport and storage casks (TLB) for spent nuclear fuel from pressurised water reactors can be proved by calculation. This includes the determination of the radioactive sources and the shielding-capability of the cask. In this thesis the entire computational chain, which extends from the determination of the source terms to the final Monte-Carlo-transport-calculation is analysed and the arising uncertainties are quantified not only by benchmarks but also by variational calculi. The background of these analyses is that the comparison with measured dose rates at different TLBs shows an overestimation by the values calculated. Regarding the studies performed, the overestimation can be mainly explained by the detector characteristics for the measurement of the neutron dose rate and additionally in case of the gamma dose rates by the energy group structure, which the calculation is based on. It turns out that the consideration of the uncertainties occurring along the computational chain can lead to even greater overestimation. Concerning the dose rate calculation at cask loadings with spent uranium fuel assemblies an uncertainty of (({sup +21}{sub -28}) ±2) % (rel.) for the total gamma dose rate and of ({sup +28±23}{sub -55±4}) % (rel.) for the total neutron dose rate are estimated. For mixed-loadings with spent uranium and MOX fuel assemblies an uncertainty of ({sup +24±3}{sub -27±2}) % (rel.) for the total gamma dose rate and of ({sup +28±23}{sub -55±4}) % (rel.) for the total neutron dose rate are quantified. The results show that the computational chain has not to be modified, because the calculations performed lead to conservative dose rate predictions, even if high uncertainties at neutron dose rate measurements arise. Thus at first the uncertainties of the neutron dose rate measurement have to be decreased to enable a reduction of the overestimation of the calculated dose rate afterwards. In the present thesis
Reactive/Adsorptive transport in (partially-) saturated porous media: from pore scale to core scale
Raoof, A.
2011-01-01
Pore-scale modeling provides opportunities to study transport phenomena in fundamental ways because detailed information is available at the microscopic pore scale. This offers the best hope for bridging the traditional gap that exists between pore scale and macro (lab) scale description of the proc
Expression, transport, and axonal sorting of neuronal CCL21 in large dense-core vesicles
de Jong, Eiko K.; Vinet, Jonathan; Stanulovic, Vesna S.; Meijer, Michel; Wesseling, Evelyn; Sjollema, Klaas; Boddeke, Hendrikus W. G. M.; Biber, Knut
2008-01-01
Neurons are highly polarized cells, and neuron-neuron communication is based on directed transport and release of neurotransmitters, neuropeptides, and neurotrophins. Directed communication may also be attributed to neuron-microglia signaling, since neuronal damage can induce a microglia reaction at
Expression, transport, and axonal sorting of neuronal CCL21 in large dense-core vesicles.
Jong, E.K. de; Vinet, J.; Stanulovic, V.S.; Meijer, Michel; Wesseling, E.; Sjollema, K.; Boddeke, H.W.; Biber, K.
2008-01-01
Neurons are highly polarized cells, and neuron-neuron communication is based on directed transport and release of neurotransmitters, neuropeptides, and neurotrophins. Directed communication may also be attributed to neuron-microglia signaling, since neuronal damage can induce a microglia reaction at
Turbulence in edge and core transport barriers: new experimental results and modeling
Tokuzawa, T.
2017-02-01
In this paper, recent progressive studies on experimental analysis and theoretical models for turbulence phenomena around the transport barriers in high-performance magnetic confined fusion plasma are reviewed. The linkage of radial electric fields and turbulence, the importance of radial electric field curvature, and observations of spatiotemporal turbulence structures are described with related theoretical models.
DEFF Research Database (Denmark)
Strange, M.; Rostgaard, Carsten; Hakkinen, H.
2011-01-01
The electronic conductance of a benzene molecule connected to gold electrodes via thiol, thiolate, or amino anchoring groups is calculated using nonequilibrium Green functions in combination with the fully self-consistent GW approximation for exchange and correlation. The calculated conductance...... suggest that more complex gold-thiolate structures where the thiolate anchors are chemically passivated by Au adatoms are responsible for the measured conductance. Analysis of the energy level alignment obtained with DFT, Hartree-Fock, and GW reveals the importance of self-interaction corrections...
Saeed, Yasir
2014-05-11
Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport
Rashidi-Huyeh, M.; Volz, S.; Palpant, B.
2008-09-01
Relaxation dynamics of embedded metal nanoparticles after ultrafast laser pulse excitation is driven by thermal phenomena of different origins, the accurate description of which is crucial for interpreting experimental results: hot electron-gas generation, electron-phonon coupling, heat transfer to the particle environment, and heat propagation in the latter. Regarding this last mechanism, it is well known that heat transport in nanoscale structures and/or at ultrashort timescales may deviate from the predictions of the Fourier law. In these cases heat transport may rather be described by the Boltzmann transport equation. We present a numerical model allowing to determine the electron and lattice temperature dynamics in a spherical gold nanoparticle core under subpicosecond pulsed excitation as well as that in the surrounding shell dielectric medium. For this, we have used the electron-phonon coupling equation in the particle with a source term linked with the laser pulse absorption and the ballistic-diffusive equations for heat conduction in the host medium. Either thermalizing or adiabatic boundary conditions have been considered at the shell external surface. Our results show that the heat transfer rate from the particle to the matrix can be significantly smaller than the prediction of Fourier’s law. Consequently, the particle-temperature rise is larger and its cooling dynamics might be slower than that obtained by using Fourier’s law. This difference is attributed to the nonlocal and nonequilibrium heat conductions in the vicinity of the core nanoparticle. These results are expected to be of great importance for analyzing pump-probe experiments performed on single nanoparticles or nanocomposite media.
DEFF Research Database (Denmark)
Lu, Jing Tao; Christensen, Rasmus Bjerregaard; Foti, Giuseppe;
2014-01-01
We extend the simple and efficient lowest order expansion (LOE) for inelastic electron tunneling spectroscopy (IETS) to include variations in the electronic structure on the scale of the vibration energies. This enables first-principles calculations of IETS line shapes for molecular junctions clo...
DEFF Research Database (Denmark)
Frota, H.O.; Flensberg, Karsten
1992-01-01
We have done a numerical renormalization-group calculation for a Hamiltonian modeling charging effect in ultrasmall tunnel junctions. We find that the conductance is enhanced by the quantum charge fluctuations allowing tunneling below the charging energy gap. However, in all cases the conductance...
Benchmark of Atucha-2 PHWR RELAP5-3D control rod model by Monte Carlo MCNP5 core calculation
Energy Technology Data Exchange (ETDEWEB)
Pecchia, M.; D' Auria, F. [San Piero A Grado Nuclear Research Group GRNSPG, Univ. of Pisa, via Diotisalvi, 2, 56122 - Pisa (Italy); Mazzantini, O. [Nucleo-electrica Argentina Societad Anonima NA-SA, Buenos Aires (Argentina)
2012-07-01
Atucha-2 is a Siemens-designed PHWR reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarities require the adoption of advanced Monte Carlo codes for performing realistic neutronic simulations. Therefore core models of Atucha-2 PHWR were developed using MCNP5. In this work a methodology was set up to collect the flux in the hexagonal mesh by which the Atucha-2 core is represented. The scope of this activity is to evaluate the effect of obliquely inserted control rod on neutron flux in order to validate the RELAP5-3D{sup C}/NESTLE three dimensional neutron kinetic coupled thermal-hydraulic model, applied by GRNSPG/UNIPI for performing selected transients of Chapter 15 FSAR of Atucha-2. (authors)
Energy Technology Data Exchange (ETDEWEB)
Tucker, William C.; Schelling, Patrick K., E-mail: patrick.schelling@ucf.edu [Advanced Material Processing and Analysis Center and Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, Florida 32816 (United States)
2014-07-14
Computation of the heat of transport Q{sub a}{sup *} in monatomic crystalline solids is investigated using the methodology first developed by Gillan [J. Phys. C: Solid State Phys. 11, 4469 (1978)] and further developed by Grout and coworkers [Philos. Mag. Lett. 74, 217 (1996)], referred to as the Grout-Gillan method. In the case of pair potentials, the hopping of a vacancy results in a heat wave that persists for up to 10 ps, consistent with previous studies. This leads to generally positive values for Q{sub a}{sup *} which can be quite large and are strongly dependent on the specific details of the pair potential. By contrast, when the interactions are described using the embedded atom model, there is no evidence of a heat wave, and Q{sub a}{sup *} is found to be negative. This demonstrates that the dynamics of vacancy hopping depends strongly on the details of the empirical potential. However, the results obtained here are in strong disagreement with experiment. Arguments are presented which demonstrate that there is a fundamental error made in the Grout-Gillan method due to the fact that the ensemble of states only includes successful atom hops and hence does not represent an equilibrium ensemble. This places the interpretation of the quantity computed in the Grout-Gillan method as the heat of transport in doubt. It is demonstrated that trajectories which do not yield hopping events are nevertheless relevant to computation of the heat of transport Q{sub a}{sup *}.
Core-flood experiment for transport of reactive fluids in rocks.
Ott, H; de Kloe, K; van Bakel, M; Vos, F; van Pelt, A; Legerstee, P; Bauer, A; Eide, K; van der Linden, A; Berg, S; Makurat, A
2012-08-01
Investigation of the transport of reactive fluids in porous rocks is an intriguing but challenging task and relevant in several areas of science and engineering such as geology, hydrogeology, and petroleum engineering. We designed and constructed an experimental setup to investigate physical and chemical processes caused by the flow of reactive and volatile fluids such as supercritical CO(2) and/or H(2)S in geological formations. Potential applications are geological sequestration of CO(2) in the frame of carbon capture and storage and acid-gas injection for sulfur disposal and/or enhanced oil recovery. The present paper outlines the design criteria and the realization of reactive transport experiments on the laboratory scale. We focus on the spatial and time evolution of rock and fluid composition as a result of chemical rock fluid interaction and the coupling of chemistry and fluid flow in porous rocks.
An OpenCL-based Monte Carlo dose calculation engine (oclMC) for coupled photon-electron transport
Tian, Zhen; Folkerts, Michael; Qin, Nan; Jiang, Steve B; Jia, Xun
2015-01-01
Monte Carlo (MC) method has been recognized the most accurate dose calculation method for radiotherapy. However, its extremely long computation time impedes clinical applications. Recently, a lot of efforts have been made to realize fast MC dose calculation on GPUs. Nonetheless, most of the GPU-based MC dose engines were developed in NVidia CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a fast cross-platform MC dose engine oclMC using OpenCL environment for external beam photon and electron radiotherapy in MeV energy range. Coupled photon-electron MC simulation was implemented with analogue simulations for photon transports and a Class II condensed history scheme for electron transports. To test the accuracy and efficiency of our dose engine oclMC, we compared dose calculation results of oclMC and gDPM, our previously developed GPU-based MC code, for a 15 MeV electron ...
Application of GEANT4 radiation transport toolkit to dose calculations in anthropomorphic phantoms
Rodrigues, P; Peralta, L; Alves, C; Chaves, A; Lopes, M C
2003-01-01
In this paper we present the implementation of a dose calculation application, based on the GEANT4 Monte Carlo toolkit. Validation studies were performed with an homogeneous water phantom and an Alderson--Rando anthropomorphic phantom both irradiated with high--energy photon beams produced by a clinical linear accelerator. As input, this tool requires computer tomography images for automatic codification of voxel based geometries and phase space distributions to characterize the incident radiation field. Simulation results were compared with ionization chamber, thermoluminescent dosimetry data and commercial treatment planning system calculations. In homogeneous water phantom, overall agreement with measurements were within 1--2%. For anthropomorphic simulated setups (thorax and head irradiation) mean differences between GEANT4 and TLD measurements were less than 2%. Significant differences between GEANT4 and a semi--analytical algorithm implemented in the treatment planning system, were found in low density ...
Electron transport in a Pt-CO-Pt nanocontact: Density functional theory calculations
DEFF Research Database (Denmark)
Strange, Mikkel; Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel
2006-01-01
We have performed first-principles calculations for the mechanic and electric properties of pure Pt nanocontacts and a Pt contact with a single CO molecule adsorbed. For the pure Pt contacts we see a clear difference between point contacts and short chains in good agreement with experiments. We i...... of the transmission function for the Pt-CO-Pt contact, and show that the conductance is largely determined by the local d band at the Pt apex atoms....
Phonon transport properties of two-dimensional group-IV materials from ab initio calculations
Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuanfeng; Ni, Gang; Zhang, Rongjun; Zhu, Heyuan
2016-12-01
It has been argued that stanene has lowest lattice thermal conductivity among two-dimensional (2D) group-IV materials because of its largest atomic mass, weakest interatomic bonding, and enhanced ZA phonon scattering due to the breaking of an out-of-plane symmetry selection rule. However, we show that, although the lattice thermal conductivity κ for graphene, silicene, and germanene decreases monotonically with decreasing Debye temperature, unexpected higher κ is observed in stanene. By enforcing all the invariance conditions in 2D materials and including Ge 3 d and Sn 4 d electrons as valence electrons for germanene and stanene, respectively, the lattice dynamics in these materials are accurately described. A large acoustic-optical gap and the bunching of the acoustic-phonon branches significantly reduce phonon scattering in stanene, leading to higher thermal conductivity than germanene. The vibrational origin of the acoustic-optical gap can be attributed to the buckled structure. Interestingly, a buckled system has two competing influences on phonon transport: the breaking of the symmetry selection rule leads to reduced thermal conductivity, and the enlarging of the acoustic-optical gap results in enhanced thermal conductivity. The size dependence of thermal conductivity is investigated as well. In nanoribbons, the κ of silicene, germanene, and stanene is much less sensitive to size effect due to their short intrinsic phonon mean-free paths. This work sheds light on the nature of phonon transport in buckled 2D materials.
Calculation models for prediction of Liquefied Natural Gas (LNG) ageing during ship transportation
Energy Technology Data Exchange (ETDEWEB)
Miana, Mario; Hoyo, Rafael del; Rodrigalvarez, Vega; Valdes, Jose Ramon [Instituto Tecnologico de Aragon, Area de Investigacion, Desarrollo y Servicios Tecnologicos, Maria de Luna 7, 50018 Zaragoza (Spain); Llorens, Raul [ENAGAS SA, Direccion de Ingenieria y Tecnologia del Gas, Autovia A - 2, km. 306.4, 50012 Zaragoza (Spain)
2010-05-15
A group of European gas transportation companies within the European Gas Research Group launched in 2007 the 'MOLAS' Project to provide a software program for the analysis of the Liquefied Natural Gas (LNG) ageing process during ship transportation. This program contains two different modeling approaches: a physical algorithm and an 'intelligent' model. Both models are fed with the same input data, which is composed of the ship characteristics (BOR and capacity), voyage duration, LNG composition, temperature, pressure, and volume occupied by liquid phase at the port of origin, together with pressure at the port of destination. The results obtained are the LNG composition, temperature and liquid volume at the port of destination. Furthermore, the physical model obtains the evolution over time of such variables en route as it is based on unsteady mass balances over the system, while the i-model applies neural networks to obtain regression coefficients from historical data composed only of origin and destination measurements. This paper describes both models and validates them from previous published models and experimental data measured in ENAGAS LNG regasification plants. (author)
Voxel2MCNP: software for handling voxel models for Monte Carlo radiation transport calculations.
Hegenbart, Lars; Pölz, Stefan; Benzler, Andreas; Urban, Manfred
2012-02-01
Voxel2MCNP is a program that sets up radiation protection scenarios with voxel models and generates corresponding input files for the Monte Carlo code MCNPX. Its technology is based on object-oriented programming, and the development is platform-independent. It has a user-friendly graphical interface including a two- and three-dimensional viewer. A row of equipment models is implemented in the program. Various voxel model file formats are supported. Applications include calculation of counting efficiency of in vivo measurement scenarios and calculation of dose coefficients for internal and external radiation scenarios. Moreover, anthropometric parameters of voxel models, for instance chest wall thickness, can be determined. Voxel2MCNP offers several methods for voxel model manipulations including image registration techniques. The authors demonstrate the validity of the program results and provide references for previous successful implementations. The authors illustrate the reliability of calculated dose conversion factors and specific absorbed fractions. Voxel2MCNP is used on a regular basis to generate virtual radiation protection scenarios at Karlsruhe Institute of Technology while further improvements and developments are ongoing.
Energy Technology Data Exchange (ETDEWEB)
Yuan, Y.C. [Square Y, Orchard Park, NY (United States); Chen, S.Y.; LePoire, D.J. [Argonne National Lab., IL (United States). Environmental Assessment and Information Sciences Div.; Rothman, R. [USDOE Idaho Field Office, Idaho Falls, ID (United States)
1993-02-01
This report presents the technical details of RISIUND, a computer code designed to estimate potential radiological consequences and health risks to individuals and the collective population from exposures associated with the transportation of spent nuclear fuel. RISKIND is a user-friendly, semiinteractive program that can be run on an IBM or equivalent personal computer. The program language is FORTRAN-77. Several models are included in RISKIND that have been tailored to calculate the exposure to individuals under various incident-free and accident conditions. The incidentfree models assess exposures from both gamma and neutron radiation and can account for different cask designs. The accident models include accidental release, atmospheric transport, and the environmental pathways of radionuclides from spent fuels; these models also assess health risks to individuals and the collective population. The models are supported by databases that are specific to spent nuclear fuels and include a radionudide inventory and dose conversion factors.
Energy Technology Data Exchange (ETDEWEB)
Tittelbach, S. [Wissenschaftlich-Technische Ingenieurberatung GmbH (WTI), Juelich (Germany); Biedermann, R. [GNS Gesellschaft fuer Nuklear-Service mbH, Essen (Germany); Schmidt-Wohlfarth, Y.; Louia, A. [EnBW Kernkraft GmbH, Philippsburg (Germany)
2011-07-01
The transport rack for the internal transport of loaded CASTOR {sup registered} casks before the storage in the intermediate storage facility at the site of the NPP Philippsburg is exposed to neutron irradiation from the cask inventory. Using the Monte Carlo code MCNP the activation rates of the transport rack materials are calculated for typical storage times of the casks in the rack. The long-term activation was also calculated for the continuous use of the transport rack over 10 years. Further topics were the dose rate in the near surrounding of the transport rack after long-term activation and finally the disposability of rack components according to the legal regulations. The maximum contact dose rate was calculated to be below 1 micro Sv/h after 10 years of application. The transport rack can be disposed with large safety margins to the radiation protection limits.
Energy Technology Data Exchange (ETDEWEB)
Lautard, J.J.; Magnaud, C.; Moreau, F.; Baudron, A.M. [CEA Saclay, Dept. de Mecanique et de Technologie (DMT/SERMA), 91 - Gif-sur-Yvette (France)
1999-07-01
The CRONOS2 software is that part of the SAPHYR code system dedicated to neutronic core calculations. CRONOS2 is a powerful tool for reactor design, fuel management and safety studies. Its modular structure and great flexibility make CRONOS2 an unique simulation tool for research and development for a wide variety of reactor systems. CRONOS2 is a versatile tool that covers a large range of applications from very fast calculations used in training simulators to time and memory consuming reference calculations needed to understand complex physical phenomena. CRONOS2 has a procedure library named CPROC that allows the user to create its own application environment fitted to a specific industrial use. (authors)
Energy Technology Data Exchange (ETDEWEB)
Lee, Y.S.
1977-11-01
The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed in detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials.
Directory of Open Access Journals (Sweden)
Petr Rada
Full Text Available Trichomonas vaginalis is a parasitic protist of the Excavata group. It contains an anaerobic form of mitochondria called hydrogenosomes, which produce hydrogen and ATP; the majority of mitochondrial pathways and the organellar genome were lost during the mitochondrion-to-hydrogenosome transition. Consequently, all hydrogenosomal proteins are encoded in the nucleus and imported into the organelles. However, little is known about the membrane machineries required for biogenesis of the organelle and metabolite exchange. Using a combination of mass spectrometry, immunofluorescence microscopy, in vitro import assays and reverse genetics, we characterized the membrane proteins of the hydrogenosome. We identified components of the outer membrane (TOM and inner membrane (TIM protein translocases include multiple paralogs of the core Tom40-type porins and Tim17/22/23 channel proteins, respectively, and uniquely modified small Tim chaperones. The inner membrane proteins TvTim17/22/23-1 and Pam18 were shown to possess conserved information for targeting to mitochondrial inner membranes, but too divergent in sequence to support the growth of yeast strains lacking Tim17, Tim22, Tim23 or Pam18. Full complementation was seen only when the J-domain of hydrogenosomal Pam18 was fused with N-terminal region and transmembrane segment of the yeast homolog. Candidates for metabolite exchange across the outer membrane were identified including multiple isoforms of the β-barrel proteins, Hmp35 and Hmp36; inner membrane MCF-type metabolite carriers were limited to five homologs of the ATP/ADP carrier, Hmp31. Lastly, hydrogenosomes possess a pathway for the assembly of C-tail-anchored proteins into their outer membrane with several new tail-anchored proteins being identified. These results show that hydrogenosomes and mitochondria share common core membrane components required for protein import and metabolite exchange; however, they also reveal remarkable differences
Keul, Christine; Köhler, Patrick; Hampe, Rüdiger; Roos, Malgorzata; Stawarczyk, Bogna
Pull-out testing was used to determine the tensile load (TL) and tensile strength (TS) of five different fiber post systems bonded to human intracanal dentin. 120 caries-free premolars, canines, and maxillary central incisors were divided into 5 different groups for 5 fiber post systems (n = 24): 1. RelyX Fiber Post 3D (RX3D); 2. RelyX Fiber Post (RX); 3. Luxa- Post (LP); 4. FibreKleer 4X Tapered Post (FK); 5. ParaPost Taper Lux (PP). The teeth were prepared and posts inserted. Core buildups were performed with the corresponding product's resin composite. All specimens were stored in water for 24 h at 37°C. TL and TS were tested on half of the specimens (n = 12/group). The remaining samples were thermocycled (10,000 x 5°C/55°C) before testing. TL was directly measured and TS was calculated using the bonding surface. Failure modes were identified using a stereomicroscope. Data were analyzed using twoway ANOVA with the post-hoc Scheffé test, as well as the chi-squared test (p core buildup from the tooth; all other systems mainly demonstrated detachment of the core from the posts. PP, RX, and RX3D together with an adhesive core buildup yielded the highest bond strength to human dentin. Parameters TL and TS showed the same tendencies and statistical evidence.
Electron transport calculations in warm dense matter using scattering cross sections
Burrill, D J; Charest, M R J; Starrett, C E
2015-01-01
The Ziman formulation of electrical conductivity is tested in warm and hot dense matter using the pseudo-atom molecular dynamics method. Several implementation options that have been widely used in the literature are systematically tested through a comparison to accurate but expensive Kohn-Sham density functional theory molecular dynamics (KS-DFT-MD) calculations. The comparison is made for several elements and mixtures and for a wide range of temperatures and densities, and reveals a preferred method that generally gives very good agreement with the KSDFT-MD results, but at a fraction of the computational cost.
A FIRST APPROXIMATION CALCULATION OF AIR CUSHION CHASSIS WEIGHT OF TRANSPORT AIRPLANE
Directory of Open Access Journals (Sweden)
2016-01-01
Full Text Available This article describes a first approximation of a weighted estimate of air cushion chassis. The algorithm for calculating the weight of air cushion chassis allows not only to estimate the mass of the chassis to a first approximation, but also to conduct a preliminary analysis of the influence of various parameters of the aircraft and the chassis on the weight of the aircraft at the stage of before designing. The algorithm can be expanded to include additional design decisions, such as the transformation of the fuselage, increasing the air cushion chassis canopy due to extensions, center of gravity, etc.
Energy Technology Data Exchange (ETDEWEB)
Mendenhall, Marcus H., E-mail: marcus.h.mendenhall@vanderbilt.edu [Vanderbilt University, Department of Electrical Engineering, P.O. Box 351824B, Nashville, TN 37235 (United States); Weller, Robert A., E-mail: robert.a.weller@vanderbilt.edu [Vanderbilt University, Department of Electrical Engineering, P.O. Box 351824B, Nashville, TN 37235 (United States)
2012-03-01
In Monte Carlo particle transport codes, it is often important to adjust reaction cross-sections to reduce the variance of calculations of relatively rare events, in a technique known as non-analog Monte Carlo. We present the theory and sample code for a Geant4 process which allows the cross-section of a G4VDiscreteProcess to be scaled, while adjusting track weights so as to mitigate the effects of altered primary beam depletion induced by the cross-section change. This makes it possible to increase the cross-section of nuclear reactions by factors exceeding 10{sup 4} (in appropriate cases), without distorting the results of energy deposition calculations or coincidence rates. The procedure is also valid for bias factors less than unity, which is useful in problems that involve the computation of particle penetration deep into a target (e.g. atmospheric showers or shielding studies).
Scheck, L; Foglizzo, T; Kifonidis, K
2007-01-01
By 2D hydrodynamic simulations including a detailed equation of state and neutrino transport, we investigate the interplay between different non-radial hydrodynamic instabilities that play a role during the postbounce accretion phase of collapsing stellar cores. The convective mode of instability, which is driven by negative entropy gradients caused by neutrino heating or by time variations of the shock strength, can be identified clearly by the development of typical Rayleigh-Taylor mushrooms. However, in cases where the gas in the postshock region is rapidly advected towards the gain radius, the growth of such a buoyancy instability can be suppressed. In such a situation the shocked flow nevertheless can develop non-radial asymmetry with an oscillatory growth of the amplitude. This phenomenon was previously termed ``standing accretion shock instability'' (SASI) by Blondin et al. (2003). It is shown here that the oscillation period of the SASI observed in our simulations agrees well with the one estimated fo...
Regulated Transport into the Nucleus of Herpesviridae DNA Replication Core Proteins
Directory of Open Access Journals (Sweden)
Alessandro Ripalti
2013-09-01
Full Text Available The Herpesvirdae family comprises several major human pathogens belonging to three distinct subfamilies. Their double stranded DNA genome is replicated in the nuclei of infected cells by a number of host and viral products. Among the latter the viral replication complex, whose activity is strictly required for viral replication, is composed of six different polypeptides, including a two-subunit DNA polymerase holoenzyme, a trimeric primase/helicase complex and a single stranded DNA binding protein. The study of herpesviral DNA replication machinery is extremely important, both because it provides an excellent model to understand processes related to eukaryotic DNA replication and it has important implications for the development of highly needed antiviral agents. Even though all known herpesviruses utilize very similar mechanisms for amplification of their genomes, the nuclear import of the replication complex components appears to be a heterogeneous and highly regulated process to ensure the correct spatiotemporal localization of each protein. The nuclear transport process of these enzymes is controlled by three mechanisms, typifying the main processes through which protein nuclear import is generally regulated in eukaryotic cells. These include cargo post-translational modification-based recognition by the intracellular transporters, piggy-back events allowing coordinated nuclear import of multimeric holoenzymes, and chaperone-assisted nuclear import of specific subunits. In this review we summarize these mechanisms and discuss potential implications for the development of antiviral compounds aimed at inhibiting the Herpesvirus life cycle by targeting nuclear import of the Herpesvirus DNA replicating enzymes.
Energy Technology Data Exchange (ETDEWEB)
1993-12-01
The long-range goal of the Numerical Tokamak Project (NTP) is the reliable prediction of tokamak performance using physics-based numerical tools describing tokamak physics. The NTP is accomplishing the development of the most advanced particle and extended fluid model`s on massively parallel processing (MPP) environments as part of a multi-institutional, multi-disciplinary numerical study of tokamak core fluctuations. The NTP is a continuing focus of the Office of Fusion Energy`s theory and computation program. Near-term HPCC work concentrates on developing a predictive numerical description of the core plasma transport in tokamaks driven by low-frequency collective fluctuations. This work addresses one of the greatest intellectual challenges to our understanding of the physics of tokamak performance and needs the most advanced computational resources to progress. We are conducting detailed comparisons of kinetic and fluid numerical models of tokamak turbulence. These comparisons are stimulating the improvement of each and the development of hybrid models which embody aspects of both. The combination of emerging massively parallel processing hardware and algorithmic improvements will result in an estimated 10**2--10**6 performance increase. Development of information processing and visualization tools is accelerating our comparison of computational models to one another, to experimental data, and to analytical theory, providing a bootstrap effect in our understanding of the target physics. The measure of success is the degree to which the experimentally observed scaling of fluctuation-driven transport may be predicted numerically. The NTP is advancing the HPCC Initiative through its state-of-the-art computational work. We are pushing the capability of high performance computing through our efforts which are strongly leveraged by OFE support.
Imanaka, T
2001-09-01
A transport calculation of the neutrons leaked to the environment by the JCO criticality accident was carried out based on three-dimensional geometrical models of the buildings within the JCO territory. Our work started from an initial step to simulate the leakage process of neutrons from the precipitation tank, and proceeded to a step to calculate the neutron propagation throughout the JCO facilities. The total fission number during the accident in the precipitation tank was evaluated to be 2.5 x 10(18) by comparing the calculated neutron-induced activities per 235U fission with the measured values in a stainless-steel net sample taken 2 m from the precipitation tank. Shield effects by various structures within the JCO facilities were evaluated by comparing the present results with a previous calculation using two-dimensional models which suppose a point source of the fission spectrum in the air above the ground without any shield structures. The shield effect by the precipitation tank, itself, was obtained to be a factor of 3. The shield factor by the conversion building varied between 1.1 and 2, depending on the direction from the building. The shield effect by the surrounding buildings within the JCO territory was between I and 5, also depending on the direction.
Pressure Vessel Calculations for VVER-440 Reactors
Hordósy, G.; Hegyi, Gy.; Keresztúri, A.; Maráczy, Cs.; Temesvári, E.; Vértes, P.; Zsolnay, É.
2003-06-01
Monte Carlo calculations were performed for a selected cycle of the Paks NPP Unit II to test a computational model. In the model the source term was calculated by the core design code KARATE and the neutron transport calculations were performed by the MCNP. Different forms of the source specification were examined. The calculated results were compared with measurements and in most cases fairly good agreement was found.
Plessis, Sylvain; Mandt, Kathy; Greathouse, Thomas; Luspay-Kuti, Adrienn
2015-01-01
Bimolecular diffusion coefficients are important parameters used by atmospheric models to calculate altitude profiles of minor constituents in an atmosphere. Unfortunately, laboratory measurements of these coefficients were never conducted at temperature conditions relevant to the atmosphere of Titan. Here we conduct a detailed uncertainty analysis of the bimolecular diffusion coefficient parameters as applied to Titan's upper atmosphere to provide a better understanding of the impact of uncertainty for this parameter on models. Because temperature and pressure conditions are much lower than the laboratory conditions in which bimolecular diffusion parameters were measured, we apply a Bayesian framework, a problem-agnostic framework, to determine parameter estimates and associated uncertainties. We solve the Bayesian calibration problem using the open-source QUESO library which also performs a propagation of uncertainties in the calibrated parameters to temperature and pressure conditions observed in Titan's u...
Energy Technology Data Exchange (ETDEWEB)
Mitenkova, E. F.; Novikov, N. V. [Nuclear Safety Inst. of Russian Academy of Sciences, B. Tulskaya 52, Moscow, 115119 (Russian Federation); Blokhin, A. I. [State Scientific Center of Russian Federation, Inst. of Physics and Power Engineering Named after A.I. Leypunsky, Bondarenko Square 1, Obninsk, Kaluga Region, 249030 (Russian Federation)
2012-07-01
The different (U-Pu) fuel compositions are considered for next generation of sodium fast breeder reactors. The considerable discrepancies in axial and radial neutron spectra for hybrid reactor systems compared to the cores with UO{sub 2} fuel cause increasing uncertainty of generating the group nuclear constants in those reactor systems. The calculation results of BFS-62-3A critical assembly which is considered as full-scale model of BN-600 hybrid core with steel reflector specify quite different spectra in local areas. For those systems the MCNP 5 calculations demonstrate significant sensitivity of effective multiplication factor K{sub eff} and spectral indices to nuclear data libraries. For {sup 235}U, {sup 238}U, {sup 239}Pu the results of calculated radial fission rate distributions against the reconstructed ones are analyzed. Comparative analysis of spectral indices, neutron spectra and radial fission rate distributions are performed using the different versions of ENDF/B, JENDL-3.3, JENDL-4, JEFF-3.1.1 libraries and BROND-3 for Fe, Cr isotopes. For analyzing the fission rate sensitivity to the plutonium presence in the fuel {sup 239}Pu is substituted for {sup 235}U (enrichment 90%) in the FA areas containing the plutonium. For {sup 235}U, {sup 238}U, {sup 239}Pu radial fission rate distributions the explanation of pick values discrepancies is based on the group fission constants analyses and possible underestimation of some features at the experimental data recovery method (Westcott factors, temperature dependence). (authors)
A new, coupled transport-diffusion method for radiative transfer calculations
Energy Technology Data Exchange (ETDEWEB)
Wollaber, A. B.; Warsa, J. S. [Los Alamos National Laboratory, MS D409, P.O. Box 1663, Los Alamos NM, 87545 (United States)
2013-07-01
We derive and present a new frequency- and angle-integrated low-order system of equations designed to enhance the accuracy of a coupled, high-order (transport) solution of the thermal radiative transfer equations. In particular, our new low-order system is designed to use intensity-weighted opacities and anisotropic diffusion coefficients generated by a solution of the Implicit Monte Carlo (IMC) equations in order to predict the spatial dependence of the material temperature and radiation energies in the ensuing time cycle. The predicted temperature solution can then be exploited to generate appropriately time-centered opacities, specific heats, and Planck emission spectra for the upcoming IMC solution. Additionally, the relatively inexpensive solution of the low-order system can be iteratively solved to recommend an adaptive time step size before the IMC solution is computed. A test implementation has been implemented using existing software available from the Jayenne and Capsaicin projects at Los Alamos National Laboratory. We present initial results from a new driver code that has integrated these stochastic and deterministic software packages. (authors)
First-principles calculation of transport property in nano-devices under an external magnetic field
Institute of Scientific and Technical Information of China (English)
Chen Jing-Zhe; Zhang Jin; Han Ru-Shan
2008-01-01
The mesoscopic quantum interference phenomenon (QIP) can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green's function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP: universal conductance fluctuation (UCF) and Aharonov-Bohm effect (A-B effect). We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states (DOSs). We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A-B effect is observed and the origin of the oscillation is also discussed.
Sweepless time-dependent transport calculations using the staggered block Jacobi method
Energy Technology Data Exchange (ETDEWEB)
Davidson, G [Los Alamos National Laboratory; Larsen, E W [Los Alamos National Laboratory
2009-01-01
The Staggered-Block Jacobi (SBJ) method is a new numerical SN transport method for solving time-dependent problems without sweeps or low-order acceleration. Because it is a Jacobian method, it is trivial to parallelize and will scale linearly with the number of processors, It is highly accurate in thick-diffusive problems and unconditionally stable when combined with the lumped linear discontinuous finite element spatial discretization. In this way, the SBJ method is complementary to sweep-based methods, which are accurate and efficient in thin, streaming regions but inefficient in thick, diffusive problems without acceleration. We have extended previous work by demonstrating how sweep-based methods and the SBJ method may be combined to produce a method which is accurate and efficient without acceleration in all optical thicknesses while still retaining good parallel efficiency. Furthermore, iterations may also be added to the SBJ method. This is particularly useful for improving the accuracy of the SBJ method in intermediate-thickness problems.
Energy Technology Data Exchange (ETDEWEB)
Goluoglu, S.
2001-01-11
Transportation of low-enriched uranium (LEU) and mixed-oxide (MOX) assemblies to and within the VVER-1000-type Balakovo Nuclear Power Plant is investigated. Effective multiplication factors for fresh fuel assemblies on the railroad platform, fresh fuel assemblies in the fuel transportation vehicle, and fresh fuel assemblies in the spent fuel storage pool are calculated. If there is no absorber between the units, the configurations with all MOX assemblies result in higher effective multiplication factors than the configurations with all LEU assemblies when the system is dry. When the system is flooded, the configurations with all LEU assemblies result in higher effective multiplication factors. For normal operating conditions, effective multiplication factors for all configurations are below the presumed upper subcritical limit of 0.95. For an accident condition of a fully loaded fuel transportation vehicle that is flooded with low-density water (possibly from a fire suppression system), the presumed upper subcritical limit is exceeded by configurations containing LEU assemblies.
DEPTH-AVERAGED 2-D CALCULATION OF TIDAL FLOW,SALINITY AND COHESIVE SEDIMENT TRANSPORT IN ESTUARIES
Institute of Scientific and Technical Information of China (English)
Weiming WU; Sam S.Y. WANG
2004-01-01
A depth-averaged 2-D numerical model for unsteady flow, salinity and cohesive sediment transport in estuaries is established using the finite volume method on the non-staggered, curvilinear grid. The convection terms are discretized by upwind schemes, the diffusion terms are by the central difference scheme, and the time derivative terms are by the three-time-level implicit scheme. The coupling of flow velocity and water level in the 2-D shallow water equations is achieved by the SIMPLEC algorithm with the Rhie and Chow's momentum interpolation method. The sediment model calculates the settling, deposition, erosion and transport of cohesive sediment, taking into account the influence of sediment size, sediment concentration, salinity and turbulence intensity on the flocculation of cohesive sediment. The flow model is first tested against the measurement data in the Tokyo Bay and San Francisco Bay, showing good agreements. And then, the entire model of flow, salinity and sediment transport is verified in the Gironde Estuary. The water elevation, flow velocity, salinity and sediment concentration are well predicted.
Energy Technology Data Exchange (ETDEWEB)
White, Morgan C. [Univ. of Florida, Gainesville, FL (United States)
2000-07-01
The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron transport simulations. The dissertation includes details of the model development and implementation necessary to use the new photonuclear data within MCNP simulations. A new data format has been developed to include tabular photonuclear data. Data are processed from the Evaluated Nuclear Data Format (ENDF) to the new class ''u'' A Compact ENDF (ACE) format using a standalone processing code. MCNP modifications have been completed to enable Monte Carlo sampling of photonuclear reactions. Note that both neutron and gamma production are included in the present model. The new capability has been subjected to extensive verification and validation (V&V) testing. Verification testing has established the expected basic functionality. Two validation projects were undertaken. First, comparisons were made to benchmark data from literature. These calculations demonstrate the accuracy of the new data and transport routines to better than 25 percent. Second
Pantillon, Florian P; Charbonnel, Corinne
2007-01-01
This is the third in a series of papers that deal with angular momentum transport by internal gravity waves. We concentrate on the waves excited by core convection in a 3Msun, Pop I main sequence star. Here, we want to examine the role of the Coriolis acceleration in the equations of motion that describe the behavior of waves and to evaluate its impact on angular momentum transport. We use the so-called traditional approximation of geophysics, which allows variable separation in radial and horizontal components. In the presence of rotation, the horizontal structure is described by Hough functions instead of spherical harmonics. The Coriolis acceleration has two main effects on waves. It transforms pure gravity waves into gravito-inertial waves that have a larger amplitude closer to the equator, and it introduces new waves whose restoring force is mainly the conservation of vorticity. Taking the Coriolis acceleration into account changes the subtle balance between prograde and retrograde waves in non-rotating ...
Kobayashi, Yoshihiko; Koike, Tsuyoshi; Okawa, Mario; Takayanagi, Ryohei; Takei, Shohei; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Yasui, Akira; Ikenaga, Eiji; Saitoh, Tomohiko; Asai, Kichizo
2016-11-01
We have investigated the Ce and Co core level spectroscopy, and the magnetic and electrical transport properties of lightly Ce-doped YCoO3. We have successfully synthesized single-phase Y1-xCexCoO3 for 0.0 ≤ x ≤ 0.1 by the sol-gel method. Hard X-ray photoelectron and X-ray absorption spectroscopy experiments reveal that the introduced Ce ions are tetravalent, which is considered to be the first case of electron doping into bulk trivalent Co oxides with perovskite RECoO3 (RE: rare-earth element or Y) caused by RE site substitution. The magnitude of the effective magnetic moment peff obtained from the temperature dependence of magnetic susceptibility χ(T) at higher temperatures is close to that for high-spin Co2+ introduced by the Ce doping, implying that the electrons doped into the Co site induce Co2+ with a high-spin state. For x = 0.1, ferromagnetic ordering is observed below about 7 K. Electrical transport properties such as resistivity and thermoelectric power show that negative electron-like carriers are introduced by Ce substitution.
Energy Technology Data Exchange (ETDEWEB)
Yuan, Y.C. [Square Y Consultants, Orchard Park, NY (US); Chen, S.Y.; Biwer, B.M.; LePoire, D.J. [Argonne National Lab., IL (US)
1995-11-01
This report presents the technical details of RISKIND, a computer code designed to estimate potential radiological consequences and health risks to individuals and the collective population from exposures associated with the transportation of spent nuclear fuel. RISKIND is a user-friendly, interactive program that can be run on an IBM or equivalent personal computer under the Windows{trademark} environment. Several models are included in RISKIND that have been tailored to calculate the exposure to individuals under various incident-free and accident conditions. The incident-free models assess exposures from both gamma and neutron radiation and can account for different cask designs. The accident models include accidental release, atmospheric transport, and the environmental pathways of radionuclides from spent fuels; these models also assess health risks to individuals and the collective population. The models are supported by databases that are specific to spent nuclear fuels and include a radionuclide inventory and dose conversion factors. In addition, the flexibility of the models allows them to be used for assessing any accidental release involving radioactive materials. The RISKIND code allows for user-specified accident scenarios as well as receptor locations under various exposure conditions, thereby facilitating the estimation of radiological consequences and health risks for individuals. Median (50% probability) and typical worst-case (less than 5% probability of being exceeded) doses and health consequences from potential accidental releases can be calculated by constructing a cumulative dose/probability distribution curve for a complete matrix of site joint-wind-frequency data. These consequence results, together with the estimated probability of the entire spectrum of potential accidents, form a comprehensive, probabilistic risk assessment of a spent nuclear fuel transportation accident.
Energy Technology Data Exchange (ETDEWEB)
Hanson A. L.; Diamond D.
2014-06-30
A plan is being developed for the conversion of the NIST research reactor (NBSR) from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. The LEU fuel may be a monolithic foil (LEUm) of U10Mo (10% molybdenum by weight in an alloy with uranium) or a dispersion of U7Mo in aluminum (LEUd). A previous report provided neutronic calculations for the LEUm fuel and this report presents the neutronics parameters for the LEUd fuel. The neutronics parameters for the LEUd fuel are compared to those previously obtained for the present HEU fuel and the proposed LEUm fuel. The results show no significant differences between the LEUm and the LEUd other than the LEUd fuel requires slightly less uranium than the LEUm fuel due to less molybdenum being present. The calculations include kinetics parameters, reactivity coefficients, reactivity worths of control elements and abnormal configurations, and power distributions under normal operation and with misloaded fuel elements.
CONDOR-CITVAP-MCNP calculation line description
Energy Technology Data Exchange (ETDEWEB)
Villarino, Eduardo Anibal [INVAP S.E., San Carlos de Bariloche (Argentina)
2002-07-01
A general description of the CONDOR-CITVAP-MCNP calculation line is given. This calculation line starts at cross section library and allows burnup dependent detailed calculation using MCNP. This calculation line is divided in two main methodologies: CONDOR-CITVAP that allows the 3-Dimensional core burnup calculation and MCNP that performs detailed transport calculations, both methodologies are coupled using the NDDUMP code. A short description of the used codes are given: CONDOR code performs the cell calculation, generating burnup dependent macroscopic cross section and burnup dependent numerical densities per material. CITVAP codes perform the burnup dependent core calculation, including the fuel management and calculates the burnup distribution per material. NDDUMP code generates materials burnup dependent numerical densities to be used by MCNP code. This paper presents a detailed description of the CONDOR-CITVAP-MCNP calculation line and a numerical comparison of the proposed methodology. (author)
Mitin, Alexander V; van Wüllen, Christoph
2006-02-14
A two-component quasirelativistic Hamiltonian based on spin-dependent effective core potentials is used to calculate ionization energies and electron affinities of the heavy halogen atom bromine through the superheavy element 117 (eka-astatine) as well as spectroscopic constants of the homonuclear dimers of these atoms. We describe a two-component Hartree-Fock and density-functional program that treats spin-orbit coupling self-consistently within the orbital optimization procedure. A comparison with results from high-order Douglas-Kroll calculations--for the superheavy systems also with zeroth-order regular approximation and four-component Dirac results--demonstrates the validity of the pseudopotential approximation. The density-functional (but not the Hartree-Fock) results show very satisfactory agreement with theoretical coupled cluster as well as experimental data where available, such that the theoretical results can serve as an estimate for the hitherto unknown properties of astatine, element 117, and their dimers.
Energy Technology Data Exchange (ETDEWEB)
Ranta, T. [VTT Energy, Jyvaeskylae (Finland)
1997-12-01
A computer based model has been developed for calculating the production costs of industrial wood and wood fuel. Several calculation situations, which might be useful for decision-making in energy wood supply, are included into this software. The model will be easy to use for practical purposes and flexible so that different new model and changes in the basis of calculations are easy to implement. Model will offer open interfaces for importing and exporting information. Model includes selected wood delivery chains and open interfaces for adding data from different procurement sources. The cost analysis model is built on Windows-based software, SQLWindows, using different sources of data (ODBC). With the model it is possible to manage these SQLBase databases with SQL-queries. The data included in the databases origins from various energy wood sources (local communities or part of them, forestry boards planning areas or even stands ready for cutting). By knowing the planned share of first thinnings, final cuttings and other harvesting operations it is possible to estimate the potential amount of wood fuel from each area. Also databases from energy wood users, forest and transportation machinery and distances are available in the system. Using the information it is possible to find out the fuel demand of power and heating plants in each moment (e.g., amount and quality), costs of various machines (harvesters, forwarders, trucks) as well as distances between energy wood sources and users. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Pinchedez, K
1999-06-01
Parallel computing meets the ever-increasing requirements for neutronic computer code speed and accuracy. In this work, two different approaches have been considered. We first parallelized the sequential algorithm used by the neutronics code CRONOS developed at the French Atomic Energy Commission. The algorithm computes the dominant eigenvalue associated with PN simplified transport equations by a mixed finite element method. Several parallel algorithms have been developed on distributed memory machines. The performances of the parallel algorithms have been studied experimentally by implementation on a T3D Cray and theoretically by complexity models. A comparison of various parallel algorithms has confirmed the chosen implementations. We next applied a domain sub-division technique to the two-group diffusion Eigen problem. In the modal synthesis-based method, the global spectrum is determined from the partial spectra associated with sub-domains. Then the Eigen problem is expanded on a family composed, on the one hand, from eigenfunctions associated with the sub-domains and, on the other hand, from functions corresponding to the contribution from the interface between the sub-domains. For a 2-D homogeneous core, this modal method has been validated and its accuracy has been measured. (author)
Energy Technology Data Exchange (ETDEWEB)
Kruse, Philipp [GNS Gesellschaft fuer Nuklear-Service mbH, Essen (Germany); Huettner, Frank [Vattenfall Europe Nuclear, Hamburg (Germany); Phlippen, Peter-Wilhelm [WTI GmbH, Juelich (Germany)
2015-10-15
For the final repository Konrad during operating and decommissioning phase, ten radionuclides and two radionuclide groups are restricted regarding their maximum storable activity quantities. One of the ten relevant radionuclides is C-14. The determination of the C-14 activities within activation calculations is currently performed with conservative assumptions. With the results of the presented analysis a method for a realistic determination of representative C-14 contents of irradiated steels is available now. The relevant N-14 contents as a source for the C-14 amount are lower than previously estimated.
Energy Technology Data Exchange (ETDEWEB)
Devan, K.; Gopalakrishnan, V.; Lee, S.M. [Nuclear Data Section Indira Ganhi Centre for Atomic Research, Tamilnadu (India)
1994-12-31
We have created a 25 group neutron cross section set (IGCJENDL) for nuclides of interest to LMFBRs from the Japanese Evaluated Nuclear Data Library - Version 2 (JENDL-2) in the format of French adjusted Cadarache Version 2 set (1969). The integral validation of IGCJENDL set was done by analyzing nine fast critical assemblies proposed by Cross Section Evaluation Working Group (CSEWG). The calculated integral parameters agreed reasonably well with the reported measured values. It is found that this set predicts the integral parameters, k-eff in particular, close to that predicted by adjusted CARNAVAL IV (French) or BNAB-78 (Russian) sets, for a 1200 MWe theoretical benchmark, representing a large power reactor.
Takiwaki, Tomoya; Suwa, Yudai
2011-01-01
We present numerical results on three-dimensional (3D) hydrodynamic core-collapse simulations of an $11.2 M_{\\odot}$ star. By comparing one-(1D) and two-dimensional(2D) results with those of 3D, we study how the increasing spacial multi-dimensionality affects the postbounce supernova dynamics. The calculations were performed with an energy-dependent treatment of the neutrino transport that is solved by the isotropic diffusion source approximation scheme. By performing a tracer-particle analysis, we show that the maximum residency time of material in the gain region is shown to be longer for 3D due to non-axisymmetric flow motions than 2D, which is one of advantageous aspects of 3D models to obtain neutrino-driven explosions. Our results show that convective matter motions below the gain radius become much more violent in 3D than 2D, making the neutrino luminosity larger for 3D. Nevertheless the emitted neutrino energies are made smaller due to the enhanced cooling. Our results indicate whether these advantage...
Energy Technology Data Exchange (ETDEWEB)
VOOGD, J.A.
1999-04-19
An analysis of three software proposals is performed to recommend a computer code for immobilized low activity waste flow and transport modeling. The document uses criteria restablished in HNF-1839, ''Computer Code Selection Criteria for Flow and Transport Codes to be Used in Undisturbed Vadose Zone Calculation for TWRS Environmental Analyses'' as the basis for this analysis.
Mandrekas, John
2004-08-01
GTNEUT is a two-dimensional code for the calculation of the transport of neutral particles in fusion plasmas. It is based on the Transmission and Escape Probabilities (TEP) method and can be considered a computationally efficient alternative to traditional Monte Carlo methods. The code has been benchmarked extensively against Monte Carlo and has been used to model the distribution of neutrals in fusion experiments. Program summaryTitle of program: GTNEUT Catalogue identifier: ADTX Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTX Computer for which the program is designed and others on which it has been tested: The program was developed on a SUN Ultra 10 workstation and has been tested on other Unix workstations and PCs. Operating systems or monitors under which the program has been tested: Solaris 8, 9, HP-UX 11i, Linux Red Hat v8.0, Windows NT/2000/XP. Programming language used: Fortran 77 Memory required to execute with typical data: 6 219 388 bytes No. of bits in a word: 32 No. of processors used: 1 Has the code been vectorized or parallelized?: No No. of bytes in distributed program, including test data, etc.: 300 709 No. of lines in distributed program, including test data, etc.: 17 365 Distribution format: compressed tar gzip file Keywords: Neutral transport in plasmas, Escape probability methods Nature of physical problem: This code calculates the transport of neutral particles in thermonuclear plasmas in two-dimensional geometric configurations. Method of solution: The code is based on the Transmission and Escape Probability (TEP) methodology [1], which is part of the family of integral transport methods for neutral particles and neutrons. The resulting linear system of equations is solved by standard direct linear system solvers (sparse and non-sparse versions are included). Restrictions on the complexity of the problem: The current version of the code can
Haerle, Rainer; Riedo, Elisa; Pasquarello, Alfredo; Baldereschi, Alfonso
2002-01-01
Using a combined experimental and theoretical approach, we address C 1s core-level shifts in amorphous carbon. Experimental results are obtained by x-ray photoelectron spectroscopy (XPS) and electron-energy-loss spectroscopy (EELS) on thin-film samples of different atomic density, obtained by a pulsed-laser deposition growth process. The XPS spectra are deconvoluted into two contributions, which are attributed to sp2- and sp3-hybridized atoms, respectively, separated by 0.9 eV, independent of atomic density. The sp3 hybridization content extracted from XPS is consistent with the atomic density derived from the plasmon energy in the EELS spectrum. In our theoretical study, we generate several periodic model structures of amorphous carbon of different densities applying two schemes of increasing accuracy in sequence. We first use a molecular-dynamics approach, based on an environmental-dependent tight-binding Hamiltonian to quench the systems from the liquid phase. The final model structures are then obtained by further atomic relaxation using a first-principles pseudopotential plane-wave approach within density-functional theory. Within the latter framework, we also calculate carbon 1s core-level shifts for our disordered model structures. We find that the shifts associated to threefold- and fourfold- coordinated carbon atoms give rise to two distinct peaks separated by about 1.0 eV, independent of density, in close agreement with experimental observations. This provides strong support for decomposing the XPS spectra into two peaks resulting from sp2- and sp3-hybridized atoms. Core-hole relaxations effects account for about 30% of the calculated shifts.
Bencs, László; Laczai, Nikoletta; Ajtony, Zsolt
2015-07-01
A combination of former convective-diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass - m0) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m0 values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm3 min- 1) of the internal sheath gas during atomization. The theoretical and experimental ratios of m0(mini-flow)-to-m0(stop-flow) were closely similar for each study analyte. Likewise, the calculated m0 data gave a fairly good agreement with the corresponding experimental m0 values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology.
Wurster, James
2016-09-01
In this paper, we introduce Nicil: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library. Nicil is a stand-alone Fortran90 module that calculates the ionisation values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. The module is fully parameterised such that the user can decide which processes to include and decide upon the values of the free parameters, making this a versatile and customisable code. The module includes both cosmic ray and thermal ionisation; the former includes two ion species and three species of dust grains (positively charged, negatively charged, and neutral), and the latter includes five elements which can be doubly ionised. We demonstrate tests of the module, and then describe how to implement it into an existing numerical code.
Wurster, James
2016-01-01
In this paper, we introduce Nicil: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library. Nicil is a stand-alone Fortran90 module that calculates the ionisation values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. The module is fully parameterised such that the user can decide which processes to include and decide upon the values of the free parameters, making this a versatile and customisable code. The module includes both cosmic ray and thermal ionisation; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionised. We demonstrate tests of the module, and then describe how to implement it into an existing numerical code.
Burkatzki, M; Filippi, Claudia; Dolg, M
2008-10-28
We extend our recently published set of energy-consistent scalar-relativistic Hartree-Fock pseudopotentials by the 3d-transition metal elements, scandium through zinc. The pseudopotentials do not exhibit a singularity at the nucleus and are therefore suitable for quantum Monte Carlo (QMC) calculations. The pseudopotentials and the accompanying basis sets (VnZ with n=T,Q) are given in standard Gaussian representation and their parameter sets are presented. Coupled cluster, configuration interaction, and QMC studies are carried out for the scandium and titanium atoms and their oxides, demonstrating the good performance of the pseudopotentials. Even though the choice of pseudopotential form is motivated by QMC, these pseudopotentials can also be employed in other quantum chemical approaches.
Energy Technology Data Exchange (ETDEWEB)
Bencs, László, E-mail: bencs.laszlo@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Laczai, Nikoletta [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Ajtony, Zsolt [Institute of Food Science, University of West Hungary, H-9200 Mosonmagyaróvár, Lucsony utca 15–17 (Hungary)
2015-07-01
A combination of former convective–diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass — m{sub 0}) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m{sub 0} values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm{sup 3} min{sup −1}) of the internal sheath gas during atomization. The theoretical and experimental ratios of m{sub 0}(mini-flow)-to-m{sub 0}(stop-flow) were closely similar for each study analyte. Likewise, the calculated m{sub 0} data gave a fairly good agreement with the corresponding experimental m{sub 0} values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology. - Highlights: • A calculation scheme for convective–diffusive vapor loss in GFAAS is described. • Residence time (τ) formulas were compared for sensitivity (m{sub 0}) in a THGA furnace. • Effects of the sample/platform dimension and dosing hole on τ were assessed. • Theoretical m{sub 0} of 18 analytes were
Ji, Xianghai; Yang, Xiaoguang; Du, Wenna; Pan, Huayong; Yang, Tao
2016-12-14
We report the first selective-area growth of high quality InAs(Sb)/GaSb core-shell nanowires on Si substrates using metal-organic chemical vapor deposition (MOCVD) without foreign catalysts. Transmission electron microscopy (TEM) analysis reveals that the overgrowth of the GaSb shell is highly uniform and coherent with the InAs(Sb) core without any misfit dislocations. To control the structural properties and reduce the planar defect density in the self-catalyzed InAs core nanowires, a trace amount of Sb was introduced during their growth. As the Sb content increases from 0 to 9.4%, the crystal structure of the nanowires changes from a mixed wurtzite (WZ)/zinc-blende (ZB) structure to a perfect ZB phase. Electrical measurements reveal that both the n-type InAsSb core and p-type GaSb shell can work as active carrier transport channels, and the transport type of core-shell nanowires can be tuned by the GaSb shell thickness and back-gate voltage. This study furthers our understanding of the Sb-induced crystal-phase control of nanowires. Furthermore, the high quality InAs(Sb)/GaSb core-shell nanowire arrays obtained here pave the foundation for the fabrication of the vertical nanowire-based devices on a large scale and for the study of fundamental quantum physics.
Knyazev, D V
2014-01-01
This work is devoted to the investigation of transport and optical properties of liquid aluminum in the two-temperature case. At first optical properties, static electrical and thermal conductivities were obtained in the \\textit{ab initio} calculation. The \\textit{ab initio} calculation is based on the quantum molecular dynamics, density functional theory and the Kubo-Greenwood formula. The semiempirical approximation was constructed based on the results of the \\textit{ab initio} caculation. The approximation yields the dependences $\\sigma_{1_\\mathrm{DC}}\\propto1/T_i^{0.25}$ and $K\\propto T_e/T_i^{0.25}$ for the static electrical conductivity and thermal conductivity, respectively. The approximation is valid for liquid aluminum at $\\rho=2.70$~g/cm$^3$, 3~kK~$\\leq T_i\\leq T_e\\leq20$~kK. Our results are well described by the Drude model with the effective relaxation time $\\tau\\propto T_i^{-0.25}$. We have compared our results with a number of other models. They are all reduced in the low-temperature limit to th...
Photogenerated carriers transport behaviors in L-cysteine capped ZnSe core-shell quantum dots
Energy Technology Data Exchange (ETDEWEB)
Shan, Qingsong; Li, Kuiying, E-mail: kuiyingli@ysu.edu.cn; Lin, Yingying; Yin, Hua; Zhu, Ruiping [State Key Laboratory of Metastable Materials Manufacture Technology and Science, Yanshan University, Qinhuangdao 066004 (China); Xue, Zhenjie [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
2016-02-07
The photoexcited carrier transport behavior of zinc selenide (ZnSe) quantum dots (QDs) with core–shell structure is studied because of their unique photoelectronic characteristics. The surface photovoltaic (SPV) properties of self-assembled ZnSe/ZnS/L-Cys core–shell QDs were probed via electric field induced surface photovoltage and transient photovoltage (TPV) measurements supplemented by Fourier transform infrared, laser Raman, absorption, and photoluminescence spectroscopies. The ZnSe QDs displayed p-type SPV characteristics with a broader stronger SPV response over the whole ultraviolet-to-near-infrared range compared with those of other core–shell QDs in the same group. The relationship between the SPV phase value of the QDs and external bias was revealed in their SPV phase spectrum. The wide transient photovoltage response region from 3.3 × 10{sup −8} to 2 × 10{sup −3} s was closely related to the long diffusion distance of photoexcited free charge carriers in the interfacial space–charge region of the QDs. The strong SPV response corresponding to the ZnSe core mainly originated from an obvious quantum tunneling effect in the QDs.
Xue, Yuyuan; Wu, Ying; Li, Yuan
2017-03-01
With the dramatic development of the power conversion efficiency (PCE) of perovskite solar cells (PVSCs), device lifetime has become one of the extensive research interests and concerns. To enhance the device durability, developing high performance dopant-free hole transport materials (HTMs) is a promising strategy. Herein, two new C3-symmetric HTMs with phenol core, TCP-OH and TCP-OC8 are readily prepared and show ultra-wide energy band-gap and excellent film-formation property. PCEs of 16.97% and 15.28% are achieved with pristine TCP-OH and TCP-OC8 film as HTMs, respectively, even though their hole mobilities are as low as 10-6 cm2 V-1 s-1. Phenol acts as hole trap in traditional concept, however, TCP-OH shows higher hole mobility than that of TCP-OC8. Moreover, TCP-OH shows higher glass transition temperature and better matching band alignment than those of TCP-OC8. Phenol shows great potential as building block for HTMs as it is beneficial to enhance hole mobility of HTMs. Moreover, our study demonstrates an interesting viewpoint to design HTMs with the balance of hole mobility and electron blocking effect.
Observations on the flow structures and transport in a warm-core ring in the Gulf of Mexico
Lipinski, Doug
2013-01-01
This study presents several new observations from the study of a warm-core ring (WCR) in the Gulf of Mexico based on the ECCO2 global ocean simulation. Using Lagrangian coherent structures (LCS) techniques to investigate this flow reveals a pattern of transversely intersecting LCS in the mixed layer of the WCR which experiences consistent stretching behavior over a large region of space and time. A detailed analysis of this flow region leads to an analytical model velocity field which captures the essential elements that generate the transversely intersecting LCS. The model parameters are determined from the WCR and the resulting LCS show excellent agreement with those observed in the WCR. The three-dimensional transport behavior which creates these structures relies on the small radial outflow which is present in the mixed layer and is not seen below the pycnocline, leading to a sharp change in the character of the LCS at the bottom of the mixed layer. The flow behavior revealed by the LCS limits fluid excha...
Leukauf, Daniel; Gohm, Alexander; Rotach, Mathias W.; Posch, Christian
2016-04-01
Slope winds provide a mechanism for the vertical exchange of air between the valley and the free atmosphere aloft. By this means, heat, moisture and pollutants are exported or imported. However, it the static stability of the valley atmosphere is strong, one part of the up-slope flow is redirected towards the valley center and pollutants are recirculated within the valley. This may limit the venting potential of slope winds severely. The main objective of this study is to quantify the horizontal transport of pollutants from the slope wind layer into the stable valley core and to determine the dependency of this flux as a function of the initial stability of the atmosphere. For this purpose, we conducted large eddy simulations with the Weather Research and Forecasting (WRF) model for a quasi-two-dimensional valley. The valley geometry consists of two slopes with constant slope angle rising to a crest height of 1500 m and a 4 km wide flat valley floor in between. The valley is 20 km long and homogeneous in along-valley direction. Hence, only slope winds but no valley winds can evolve. The surface sensible heat flux is prescribed by a sine function with an amplitude of 125 W m-2. The initial sounding characterized by an atmosphere at rest and by a constant Brunt-Väisälä frequency which is varied between 0.006 s-1 and 0.02 s-1. A passive tracer is released with an arbitrary but constant rate at the valley floor. As expected, the atmospheric stability has a strong impact on the vertical and horizontal transport of tracer mass. A horizontal intrusion forms at the top of the mixed layer due to outflow from the slope wind layer. Tracer mass is transported from the slope towards the center of the valley. The efficiency of this mechanism increases with increasing stability N. For the lowest value of N, about 70% of the tracer mass released at the valley bottom is exported out of the valley. This value drops to about 12% in the case of the strongest stability. Hence, most
Energy Technology Data Exchange (ETDEWEB)
Akherraz, B.; Lautard, J.J. [CEA Saclay, Dept. Modelisation de Systemes et Structures, Serv. d' Etudes des Reacteurs et de Modelisation Avancee (DMSS/SERMA), 91 - Gif sur Yvette (France); Erhard, P. [Electricite de France (EDF), Dir. de Recherche et Developpement, Dept. Sinetics, 92 - Clamart (France)
2003-07-01
In this paper we present two applications of the Nodal finite elements developed by Hennart and del Valle, first to three-dimensional Cartesian meshes and then to two-dimensional Hexagonal meshes. This work has been achieved within the framework of the DESCARTES project, which is a co-development effort by the 'Commissariat a l'Energie Atomique' (CEA) and 'Electricite de France' (EDF) for the development of a toolbox for reactor core calculations based on object oriented programming. The general structure of this project is based on the object oriented method. By using a mapping technique proposed in Schneider's thesis and del Valle, Mund, we show how this structuration allows us an easy implementation of the hexagonal case from the Cartesian case. The main attractiveness of this methodology is the possibility of a pin-by-pin representation by division of each lozenge into smaller ones. Furthermore, we will explore the use of non structured quadrangles to treat the circular geometry within a hexagon. It remains nevertheless, in the hexagonal case, the implementation of the acceleration of the internal iterations by the DSA (Diffusion Synthetic Acceleration) or the TSA. (authors)
BlueCore2型模块及其HCI传输驱动的实现%BlueCore2 module and implementation of bluetooth HCI transport driver
Institute of Scientific and Technical Information of China (English)
李义军
2006-01-01
BlueCore2-external是英国CSR公司生产的蓝牙收发电路.具有功耗低、外围器件少等特点,广泛应用在笔记本电脑、蓝牙手机和个人数字助理(PDA)等产品中.文中着重介绍BlueCore2的特点及其在计算机中的应用并给出软件流程.
Directory of Open Access Journals (Sweden)
Marina ZHURAVSKAYA
2014-12-01
Full Text Available In the modern world the alternative energy sources, which considerably depend on a region, play more and more significant role. However, the transition of regions to new energy sources lead to the change of transport and logistic network configuration. The formation of optimal core transport network today is a guarantee of the successful economic development of a region tomorrow. The present article studies the issue of advanced core transport network development in a region based on the experience of European and Asian countries and the opportunity to adapt the best foreign experience to Russian conditions. On the basis of artificial intelligence methods for forest industry complex of Sverdlovskaya Oblast the algorithm of problem solution of an optimal logistic infrastructure allocation is offered and some results of a regional transport network are presented. These methods allowed to solve the set task in the conditions of information uncertainty. There are suggestions on the improvement of transport and logistic network in the territory of Sverdlovskaya Oblast. Traditionally the logistics of mineral fuel plays main role in regions development. Actually it is required to develop logistic strategic plans to be able to provide different possibilities of power-supply, flexible enough to change with the population density, transport infrastructure and demographics of different regions. The problem of logistic centers allocation was studied by many authors. The approach, offered by the authors of this paper is to solve the set of tasks by applying artificial intelligence methods, such as fuzzy set theory and genetic algorithms.
Calculation of Linear Dichroism in the Ce 4d-Core XAS and 4f Electronic State of CeRh3B2
Jo, Takeo; Imada, Shin
1990-07-01
Linear dichroism in Ce 4d-core photoabsorption for CeRh3B2 with a hexagonal structure is discussed on the basis of an impurity Anderson model. The model takes into account the hybridization between the 4f orbit and conduction band states, multiplets arising from electrostatic interactions between electrons and crystalline anisotropy. In the paramagnetic state of the compound, the difference in the multiplet structure of 4d XAS is calculated between two incident beams with polarizations parallel and perpendicular to the c-axis with varying the crystalline field to increase the occupancy of the 4f state with the azimuthal quantum number m{=}0. The result shows that the dichroism is a promising characteristic to check recent theoretical predictions on the occupancy of the 4f state with m{=}0 in CeRh3B2 and therefore, to measure the crystal anisotropy.
Energy Technology Data Exchange (ETDEWEB)
Dorado, B.
2010-09-15
Uranium dioxide UO{sub 2} is the standard nuclear fuel used in pressurized water reactors. During in-reactor operation, the fission of uranium atoms yields a wide variety of fission products (FP) which create numerous point defects while slowing down in the material. Point defects and FP govern in turn the evolution of the fuel physical properties under irradiation. In this study, we use electronic structure calculations in order to better understand the fuel behavior under irradiation. In particular, we investigate point defect behavior, as well as the stability of three volatile FP: iodine, krypton and xenon. In order to take into account the strong correlations of uranium 5f electrons in UO{sub 2}, we use the DFT+U approximation, based on the density functional theory. This approximation, however, creates numerous metastable states which trap the system and induce discrepancies in the results reported in the literature. To solve this issue and to ensure the ground state is systematically approached as much as possible, we use a method based on electronic occupancy control of the correlated orbitals. We show that the DFT+U approximation, when used with electronic occupancy control, can describe accurately point defect and fission product behavior in UO{sub 2} and provide quantitative information regarding point defect transport properties in the oxide fuel. (author)
Ott, Lesley E.
2010-02-18
A three-dimensional (3-D) cloud-scale chemical transport model that includes a parameterized source of lightning NOx on the basis of observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (PIC) and cloud-to-ground (PCG) flash is estimated by assuming various values of PIC and PCG for each storm and determining which production scenario yields NOx mixing ratios that compare most favorably with in-cloud aircraft observations. We obtain a mean PCG value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, PIC may be nearly equal to PCG, which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud-to-ground flashes. This study also presents vertical profiles of the mass of lightning NOx after convection based on 3-D cloud-scale model simulations. The results suggest that following convection, a large percentage of lightning NOx remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2-D cloud-scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a “C-shaped” profile). The new model results (a backward C-shaped profile) suggest that chemical transport models that assume a C-shaped vertical profile of lightning NOx mass may place too much mass near the surface and too little in the middle troposphere.
Kalantzis, Georgios; Tachibana, Hidenobu
2014-01-01
For microdosimetric calculations event-by-event Monte Carlo (MC) methods are considered the most accurate. The main shortcoming of those methods is the extensive requirement for computational time. In this work we present an event-by-event MC code of low projectile energy electron and proton tracks for accelerated microdosimetric MC simulations on a graphic processing unit (GPU). Additionally, a hybrid implementation scheme was realized by employing OpenMP and CUDA in such a way that both GPU and multi-core CPU were utilized simultaneously. The two implementation schemes have been tested and compared with the sequential single threaded MC code on the CPU. Performance comparison was established on the speed-up for a set of benchmarking cases of electron and proton tracks. A maximum speedup of 67.2 was achieved for the GPU-based MC code, while a further improvement of the speedup up to 20% was achieved for the hybrid approach. The results indicate the capability of our CPU-GPU implementation for accelerated MC microdosimetric calculations of both electron and proton tracks without loss of accuracy. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Crawford, James (Kemakta Konsult AB, Stockholm (Sweden))
2010-12-15
The safety assessment SR-Site is undertaken to assess the safety of a potential geologic repository for spent nuclear fuel at the Forsmark and Laxemar sites. The present report is one of several reports that form the data input to SR-Site and contains a compilation of recommended K{sub d} data (i.e. linear partitioning coefficients) for safety assessment modelling of geosphere radionuclide transport. The data are derived for rock types and groundwater compositions distinctive of the site investigation areas at Forsmark and Laxemar. Data have been derived for all elements and redox states considered of importance for far-field dose estimates as described in /SKB 2010d/. The K{sub d} data are given in the form of lognormal distributions characterised by a mean (mu) and standard deviation (sigma). Upper and lower limits for the uncertainty range of the recommended data are defined by the 2.5% and 97.5% percentiles of the empirical data sets. The best estimate K{sub d} value for use in deterministic calculations is given as the median of the K{sub d} distribution
Pressure vessel calculations for VVER-440 reactors.
Hordósy, G; Hegyi, Gy; Keresztúri, A; Maráczy, Cs; Temesvári, E; Vértes, P; Zsolnay, E
2005-01-01
For the determination of the fast neutron load of the reactor pressure vessel a mixed calculational procedure was developed. The procedure was applied to the Unit II of Paks NPP, Hungary. The neutron source on the outer surfaces of the reactor was determined by a core design code, and the neutron transport calculations outside the core were performed by the Monte Carlo code MCNP. The reaction rate in the activation detectors at surveillance positions and at the cavity were calculated and compared with measurements. In most cases, fairly good agreement was found.
Kotake, Kei; Yamada, Shoichi; Takiwaki, Tomoya; Kuroda, Takami; Suwa, Yudai; Nagakura, Hiroki
2012-01-01
This is a status report on our endeavor to reveal the mechanism of core-collapse supernovae (CCSNe) by large-scale numerical simulations. Multi-dimensionality of the supernova engine, general relativisitic magnetohydrodynamics, energy and lepton number transport by neutrinos emitted from the forming neutron star as well as nuclear interactions there, are all believed to play crucial roles in repelling infalling matter and producing energetic explosions. These ingredients are nonlinearly coupled with one another in the dynamics of core-collapse, bounce, and shock expansion. Serious quantitative studies of CCSNe hence make extensive numerical computations mandatory. Since neutrinos are neither in thermal nor in chemical equilibrium in general, their distributions in the phase space should be computed. This is a six dimensional (6D) neutrino transport problem and quite a challenge even for those with an access to the most advanced numerical resources such as the "K computer". To tackle this problem, we have emba...
Niu, Chunping; Chen, Zhexin; Rong, Mingzhe; Wang, Chunlin; Wu, Yi; Yang, Fei; Wang, Xiaohua; Pang, Qingping
2016-10-01
The transport coefficients, namely thermal conductivity, viscosity and electrical conductivity, of CO2-CH4 mixture in and out of LTE are calculated in this paper. The calculation was based on local chemical equilibrium (LCE) and local phase equilibrium assumption. The 2-temperature composition results obtained with consideration of condensed phase in the previous paper (Part I) of this series were used in this calculation. The transport coefficients were calculated by classical Chapman-Enskog method simplified by Devoto. The results are presented for different temperatures (300-30 000 K), pressures (0.1-10 atm), non-equilibrium degrees (1-5), and CH4 molar proportions (0-100%). The influence of condensed graphite, non-LTE effect, mixture ratio and pressure on the composition and thermodynamic properties has been discussed. The results will serve as reliable reference data for computational simulation of CO2-CH4 plasmas.
Kholod, N; Evans, M; Gusev, E; Yu, S; Malyshev, V; Tretyakova, S; Barinov, A
2016-03-15
This paper presents a methodology for calculating exhaust emissions from on-road transport in cities with low-quality traffic data and outdated vehicle registries. The methodology consists of data collection approaches and emission calculation methods. For data collection, the paper suggests using video survey and parking lot survey methods developed for the International Vehicular Emissions model. Additional sources of information include data from the largest transportation companies, vehicle inspection stations, and official vehicle registries. The paper suggests using the European Computer Programme to Calculate Emissions from Road Transport (COPERT) 4 model to calculate emissions, especially in countries that implemented European emissions standards. If available, the local emission factors should be used instead of the default COPERT emission factors. The paper also suggests additional steps in the methodology to calculate emissions only from diesel vehicles. We applied this methodology to calculate black carbon emissions from diesel on-road vehicles in Murmansk, Russia. The results from Murmansk show that diesel vehicles emitted 11.7 tons of black carbon in 2014. The main factors determining the level of emissions are the structure of the vehicle fleet and the level of vehicle emission controls. Vehicles without controls emit about 55% of black carbon emissions. Copyright © 2015 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Sanchez-Cervera, S.; Hueso, C.; Herrero, J. J.
2011-07-01
This paper contains the work developed to study the dependencies of the nodal parameters with local variables. After entering the parameter space of operation, are obtained constants homogenized through calculations with deterministic code of transport NEWT with SCALE system codes.
Ehrler, V.; Engel, A. van den; Davydenko, I.; Diekmann, D.; Kiel, J.; Lewis, A.; Seidel, S.
2015-01-01
The transport industry, consumers, shippers and political bodies are all pressing for a global standard for the calculation of emissions along supply chains. Comparability of the chains’ efficiency, reduction of energy consumption, transparency of the carbon footprint of products and identification
Wann, E. T. H.; Vočadlo, L.; Wood, I. G.
2017-02-01
The Fe-Ni-Si system is potentially a very important component of terrestrial planetary cores. However, at present, even the behaviour of the FeSi and NiSi end members is poorly understood, especially at low to moderate pressures—the data for FeSi are contradictory and NiSi has been little studied. For FeSi, there is general agreement that there is a phase transition from the ɛ-FeSi to the CsCl structure with increasing pressure, but, in experiments, there is disagreement as to the position and slope of the phase boundary and the range of coexistence of the two phases. In this paper we have used ab initio lattice dynamics calculations to determine the phase boundary between the ɛ-FeSi and CsCl structures as a function of pressure and temperature in both FeSi and NiSi. For FeSi, we find that the transition pressure at zero Kelvin is 11 GPa and that the boundary between the ɛ-FeSi and CsCl phases varies little with temperature, having a slight negative Clapeyron slope, going from 11 GPa at 300 K to 3 GPa at 2000 K. For NiSi, there is much greater variation of the transition pressure with temperature, with a much shallower negative Clapeyron slope, going from 156 GPa at 300 K to 94 GPa at 2000 K.
Bouazza, Safa; Palmeri, Patrick; Quinet, Pascal
2017-09-01
We present a semi-empirical determination of Mo II radiative parameters in a wide wavelength range 1716-8789 Å. Our fitting procedure to experimental oscillator strengths available in the literature permits us to provide reliable values for a large number of Mo II lines, predicting previously unmeasured oscillator strengths of lines involving 4d45p and 4d35s5p odd-parity configurations. The extracted transition radial integral values are compared with ab-initio calculations: on average they are 0.88 times the values obtained with the basic pseudo-relativistic Hartree Fock method and they agree well when core polarization effects are included. When making a survey of our present and previous studies and including also those given in the literature we observe as general trends a decreasing of transition radial integral values with filling nd shells of the same principal quantum numbers for ndk(n + 1)s → ndk(n + 1)p transitions.
Delucia, Angela M; Six, David A; Caughlan, Ruth E; Gee, Patricia; Hunt, Ian; Lam, Joseph S; Dean, Charles R
2011-01-01
Gram-negative outer membrane (OM) integrity is maintained in part by Mg(2+) cross-links between phosphates on lipid A and on core sugars of adjacent lipopolysaccharide (LPS) molecules. In contrast to other Gram-negative bacteria, waaP, encoding an inner-core kinase, could not be inactivated in Pseudomonas aeruginosa. To examine this further, expression of the kinases WaaP or WapP/WapQ/PA5006 was placed under the control of the arabinose-regulated pBAD promoter. Growth of these strains was arabinose dependent, confirming that core phosphorylation is essential in P. aeruginosa. Transmission electron micrographs of kinase-depleted cells revealed marked invaginations of the inner membrane. SDS-PAGE of total LPS from WaaP-depleted cells showed accumulation of a fast-migrating band. Mass spectrometry (MS) analysis revealed that LPS from these cells exhibits a unique truncated core consisting of two 3-deoxy-d-manno-octulosonic acids (Kdo), two l-glycero-d-manno-heptoses (Hep), and one hexose but completely devoid of phosphates, indicating that phosphorylation by WaaP is necessary for subsequent core phosphorylations. MS analysis of lipid A from WaaP-depleted cells revealed extensive 4-amino-4-deoxy-l-arabinose modification. OM prepared from these cells by Sarkosyl extraction of total membranes or by sucrose density gradient centrifugation lacked truncated LPS. Instead, truncated LPS was detected in the inner membrane fractions, consistent with impaired transport/assembly of this species into the OM. IMPORTANCE Gram-negative bacteria have an outer membrane (OM) comprised of a phospholipid inner leaflet and a lipopolysaccharide (LPS) outer leaflet. The OM protects cells from toxic molecules and is important for survival during infection. The LPS core kinase gene waaP can be deleted in several Gram-negative bacteria but not in Pseudomonas aeruginosa. We used a controlled-expression system to deplete WaaP directly in P. aeruginosa cells, which halted growth. WaaP depletion
Miller, J J; Beasley, B W; Drury, C F; Hao, X; Larney, F J
2013-11-01
The environmental impact of using wood chips instead of straw bedding with feedlot manure on transport and leaching potential from feedlot manure is unknown. Our main objective was to determine if transport of total N, total organic N, NO-N, and nonpurgeable organic C (NPOC) to subsurface soil was lower for soils amended with feedlot manure if combined with wood chips compared with straw. A secondary objective was to compare transport of N and NPOC with organic amendments versus inorganic fertilizer. Stockpiled feedlot manure (SM) with wood chip (SM-WD) or barley straw (SM-ST) bedding at 39 Mg (dry wt.) ha, and inorganic fertilizer (IN) at 100 kg N ha, was applied annually for 13 yr to a clay loam soil in a replicated field experiment in southern Alberta, Canada. Intact soil cores were taken in fall 2011 (0-30 cm depth) from the three treatments, and the residual N and NPOC were eluted from the soil cores. Total N, total organic N, and NPOC were determined on filtered (1.0 μm) effluent samples that are primarily dissolved fraction but may contain some small particulate N and C. Peak concentrations, flow-weighted mean concentrations, and mass loss of total N, total organic N, NO-N, and NPOC were significantly ( ≤ 0.05) lower by 35 to 86% for SM-WD compared with SM-ST. Mean recoveries were also significantly lower for SM-WD than SM-ST by 0.07 to 8% (absolute difference). The transport behavior was similar for SM-WD and IN treatment, but solute transport was greater for SM-ST than for IN. Application of stockpiled feedlot manure with wood chips instead of straw bedding may be a beneficial management practice to reduce transport and leaching potential of N fractions and NPOC.
Transport simulation for EBT reactor
Energy Technology Data Exchange (ETDEWEB)
Uckan, T.; Uckan, N.A.; Jaeger, E.F.
1983-08-01
Transport simulation and modeling studies for the ELMO Bumpy Torus (EBT) reactor are carried out by using zero-dimensional (0-D) and one-and-one-half-dimensional (1 1/2-D) transport calculations. The time-dependent 0-D model is used for global analysis, whereas the 1 1/2-D radial transport code is used for accurate determination of density, temperature, and ambipolar potential profiles and of the role of these profiles in reactor plasma performance. Analysis with the 1 1/2-D transport code shows that profile effects near the outer edge of the hot electron ring lead to enhanced confinement by at least a factor of 2 to 5 beyond the simple scaling that is obtained from the global analysis. The radial profiles of core plasma density and temperatures (or core pressure) obtained from 1 1/2-D transport calculations are found to be similar to those theoretically required for stability.
Kim, Hyun-Tae; Romanelli, M.; Voitsekhovitch, I.; Koskela, T.; Conboy, J.; Giroud, C.; Maddison, G.; Joffrin, E.; contributors, JET
2015-06-01
A consistent deterioration of global confinement in H-mode experiments has been observed in JET [1] following the replacement of all carbon plasma facing components (PFCs) with an all metal (‘ITER-like’) wall (ILW). This has been correlated to the observed degradation of the pedestal confinement, as lower electron temperature (Te) values are routinely measured at the top of the edge barrier region. A comparative investigation of core heat transport in JET-ILW and JET-CW (carbon wall) discharges has been performed, to assess whether core confinement has also been affected by the wall change. The results presented here have been obtained by analysing a set of discharges consisting of high density JET-ILW H-mode plasmas and comparing them against their counterpart discharges in JET-CW having similar global operational parameters. The set contains 10 baseline ({βN}=1.5∼ 2 ) discharge-pairs with 2.7 T toroidal magnetic field, 2.5 MA plasma current, and 14 to 17 MW of neutral beam injection (NBI) heating. Based on a Te profile analysis using high resolution Thomson scattering (HRTS) data, the Te profile peaking (i.e. core Te (ρ = 0.3) / edge Te (ρ = 0.7)) is found to be similar, and weakly dependent on edge Te, for both JET-ILW and JET-CW discharges. When ILW discharges are seeded with N2, core and edge Te both increase to maintain a similar peaking factor. The change in core confinement is addressed with interpretative TRANSP simulations. It is found that JET-ILW H-mode plasmas have higher NBI power deposition to electrons and lower NBI power deposition to ions as compared to the JET-CW counterparts. This is an effect of the lower electron temperature at the top of the pedestal. As a result, the core electron energy confinement time is reduced in JET-ILW discharges, but the core ion energy confinement time is not decreased. Overall, the core energy confinement is found to be the same in the JET-ILW discharges compared to the JET-CW counterparts.
Energy Technology Data Exchange (ETDEWEB)
Kuroishi, Takeshi; Hoang, Anh Tuan; Nomura, Yasushi; Okuno, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2003-03-01
The reactivity effect of the asymmetry of axial burnup profile in burnup credit criticality safety is studied for a realistic PWR spent fuel transport cask proposed in the current OECD/NEA Phase II-C benchmark problem. The axial burnup profiles are simulated in 21 material zones based on in-core flux measurements varying from strong asymmetry to more or less no asymmetry. Criticality calculations in a 3-D model have been performed using the continuous energy Monte Carlo code MCNP-4B2 and the nuclear data library JENDL-3.2. Calculation conditions are determined with consideration of the axial fission source convergence. Calculations are carried out not only for cases proposed in the benchmark but also for additional cases assuming symmetric burnup profile. The actinide-only approach supposed for first domestic introduction of burnup credit into criticality evaluation is also considered in addition to the actinide plus fission product approach adopted in the benchmark. The calculated results show that k{sub eff} and the end effect increase almost linearly with increasing burnup axial offset that is defined as one of typical parameters showing the intensity of axial burnup asymmetry. The end effect is more sensitive to the asymmetry of burnup profile for the higher burnup. For an axially distributed burnup, the axial fission source distribution becomes strongly asymmetric as its peak shifts toward the top end of the fuel's active zone where the local burnup is less than that of the bottom end. The peak of fission source distribution becomes higher with the increase of either the asymmetry of burnup profile or the assembly-averaged burnup. The conservatism of the assumption of uniform axial burnup based on the actinide-only approach is estimated quantitatively in comparison with the k{sub eff} result calculated with experiment-based strongest asymmetric axial burnup profile with the actinide plus fission product approach. (author)
Energy Technology Data Exchange (ETDEWEB)
Kuroishi, Takeshi; Hoang, Anh Tuan; Nomura, Yasushi; Okuno, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2003-03-01
The reactivity effect of the asymmetry of axial burnup profile in burnup credit criticality safety is studied for a realistic PWR spent fuel transport cask proposed in the current OECD/NEA Phase II-C benchmark problem. The axial burnup profiles are simulated in 21 material zones based on in-core flux measurements varying from strong asymmetry to more or less no asymmetry. Criticality calculations in a 3-D model have been performed using the continuous energy Monte Carlo code MCNP-4B2 and the nuclear data library JENDL-3.2. Calculation conditions are determined with consideration of the axial fission source convergence. Calculations are carried out not only for cases proposed in the benchmark but also for additional cases assuming symmetric burnup profile. The actinide-only approach supposed for first domestic introduction of burnup credit into criticality evaluation is also considered in addition to the actinide plus fission product approach adopted in the benchmark. The calculated results show that k{sub eff} and the end effect increase almost linearly with increasing burnup axial offset that is defined as one of typical parameters showing the intensity of axial burnup asymmetry. The end effect is more sensitive to the asymmetry of burnup profile for the higher burnup. For an axially distributed burnup, the axial fission source distribution becomes strongly asymmetric as its peak shifts toward the top end of the fuel's active zone where the local burnup is less than that of the bottom end. The peak of fission source distribution becomes higher with the increase of either the asymmetry of burnup profile or the assembly-averaged burnup. The conservatism of the assumption of uniform axial burnup based on the actinide-only approach is estimated quantitatively in comparison with the k{sub eff} result calculated with experiment-based strongest asymmetric axial burnup profile with the actinide plus fission product approach. (author)
DEFF Research Database (Denmark)
Holmslykke, Hanne D.; Kjøller, Claus; Fabricius, Ida Lykke
2017-01-01
Seasonal storage of excess heat in hot deep aquifers is considered to optimize the usage of commonly available energy sources. The chemical effects of heating the Gassum Sandstone Formation to up to 150 degrees C is investigated by combining laboratory core flooding experiments with petrographic...
Energy Technology Data Exchange (ETDEWEB)
Petzoldt, R.W.; Perkins, L.J.
1995-06-16
The authors performed 1-D coupled, neutron-gamma transport calculations for lithium-vanadium blankets and lithium-sodium cauldron pot blankets in cylindrical and spherical geometries. Parametric fits to the data are supplied for subsequent use in systems code models. Scaling relationships are given for various neutronics parameters of interest, including: tritium breeding ratio, neutron energy multiplication, magnet dose rates, magnet heating rates, and integrated magnet fluence.
Institute of Scientific and Technical Information of China (English)
杨佳; 刘寿康
2012-01-01
对目前广泛应用于乳化炸药混装车上的水环输送乳胶基质的减阻机理进行了理论分析,分别推导出层流同心水环、湍流同心水环的速度分布与流量计算公式,并得到了从层流到湍流的转捩判据.此外,优化了水环润滑装置结构参数,提出了稳定水环输送的相关措施.%The mechanism of drag reduction by core-annular flow in transportation of emulsion matrix was widely used in the existing mixing-loading truck for emulsion explosive. After theoretical analysis, formulas were deduced respectively to calculate the velocity distribution, flow rate of annular water flow in laminar and turbulent flows. The criterion of transition from laminar flow to turbulent flow was obtained. Furthermore, the optimized parameters and some stabilizing measures are also proposed for core-annular flow device.
Application of MCNP for neutronic calculations at VR-1 training reactor
Huml, Ondřej; Rataj, Jan; Bílý, Tomáš
2014-06-01
The paper presents utilization of Monte Carlo MCNP transport code for neutronic calculations of training reactor VR-1. Results of calculations are compared with results of measurements realized during last few critical experiments with various reactor core configurations. Very good agreement between calculations and measurements is observed.
Triner, J. E.
1979-01-01
The basic magnetic properties under various operating conditions encountered in the state-of-the-art DC-AC/DC converters are examined. Using a novel core excitation circuit, the basic B-H and loss characteristics of various core materials may be observed as a function of circuit configuration, frequency of operation, input voltage, and pulse-width modulation conditions. From this empirical data, a mathematical loss characteristics equation is developed to analytically predict the specific core loss of several magnetic materials under various waveform excitation conditions.
Directory of Open Access Journals (Sweden)
Valery Anatolyevich Tsvetkov
2017-03-01
Full Text Available The article discusses the theory and practice of the implementation and development of transport and transit potential (TTP of Russia. This could be an effective way to replace the natural resource rent as the main source of income for the state and economic actors. For the modernization of national economic system the key importance are innovative technologies in the development of transport and transit potential through the organization of the production of goods and services with the highest added value in Russia. We proposed and substantiated the hypothesis about the necessity of creation of a Federal company responsible for the financing and implementation of Russia’s transport and transit potential development projects on the principles of public-private partnership (PPP. The authors have revealed the economic, institutional and organizational prerequisites for the establishment of such a public-private partnership company. We have provided the opinions of scientists and experts showing the urgent need to create in one form or another a single operator to transport goods on the territory of Russia and the Eurasian economic Union. To prove the hypothesis, we presented a description and analysis of the factors affecting the value of transit freight transport on Euro-Asian routes. We paid the special attention to identify the reasons of the increasing competitive advantage of Maritime transport in the world’s goods movement system. The authors based the main conclusion that, first of all, the created publicprivate partnership company should be large due to tough competition of developing transit freight by land routes with the global Maritime container services. Secondly, it needs a significant state participation since the management of the world’s cargo flows requires the effort of foreign policy and geo-economic nature. We emphasized that this business entity would become an active proponent and lobbyist of the most effective
Belikov, D.A.; Maksyutov, S.; Krol, M.C.; Fraser, A.; Rigby, M.; Bian, H.; Agusti-Panareda, A.; Bergmann, D.; Bousquet, P.; Cameron-Smith, P.; Chipperfield, M.P.; Fortems-Cheiney, A.; Gloor, E.; Haynes, K.; Hess, P.; Houweling, S.; Kawa, S.R.; Law, R.M.; Loh, Z.; Meng, L.; Palmer, P.I.; Patra, P.K.; Prinn, R.G.; Saito, R.; Wilson, C.
2013-01-01
A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical
Directory of Open Access Journals (Sweden)
D. A. Belikov
2012-08-01
Full Text Available A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transport within the scheme includes entrainment and detrainment processes in convective updrafts and downdrafts. Output from the proposed parametrisation scheme is employed in the National Institute for Environmental Studies (NIES global chemical transport model driven by JRA-25/JCDAS reanalysis. The simulated convective precipitation rate and mass fluxes are compared with observations and reanalysis data. A simulation of the short-lived tracer ^{222}Rn is used to further evaluate the performance of the cumulus convection scheme. Simulated distributions of ^{222}Rn are validated against observations at the surface and in the free troposphere, and compared with output from models that participated in the TransCom-CH_{4} Transport Model Intercomparison. From this comparison, we demonstrate that the proposed convective scheme can successfully reproduce deep cloud convection.
Directory of Open Access Journals (Sweden)
D. A. Belikov
2013-02-01
Full Text Available A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transport within the scheme includes entrainment and detrainment processes in convective updrafts and downdrafts. Output from the proposed parametrisation scheme is employed in the National Institute for Environmental Studies (NIES global chemical transport model driven by JRA-25/JCDAS reanalysis. The simulated convective precipitation rate and mass fluxes are compared with observations and reanalysis data. A simulation of the short-lived tracer ^{222}Rn is used to further evaluate the performance of the cumulus convection scheme. Simulated distributions of ^{222}Rn are evaluated against observations at the surface and in the free troposphere, and compared with output from models that participated in the TransCom-CH_{4} Transport Model Intercomparison. From this comparison, we demonstrate that the proposed convective scheme in general is consistent with observed and modeled results.
Belikov, D.A.; Maksyutov, S.; Krol, M.C.; Fraser, A.; Rigby, M.; Bian, H.; Agusti-Panareda, A.; Bergmann, D.; Bousquet, P.; Cameron-Smith, P.; Chipperfield, M.P.; Fortems-Cheiney, A.; Gloor, E.; Haynes, K.; Hess, P.; Houweling, S.; Kawa, S.R.; Law, R.M.; Loh, Z.; Meng, L.; Palmer, P.I.; Patra, P.K.; Prinn, R.G.; Saito, R.; Wilson, C.
2013-01-01
A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transpo
Energy Technology Data Exchange (ETDEWEB)
Kueppers, Christian; Ustohalova, Veronika; Steinhoff, Mathias
2012-05-21
The long-term release of radioactivity into the ground water path cannot be excluded for the radioactive waste repository Asse II. The possible radiological consequences were analyzed using a radio-ecological scenario developed by GRS. A second scenario was developed considering the solubility of radionuclides in salt saturated solutions and retarding/retention effects during the radionuclide transport through the cap rock layers. The modeling of possible radiation exposure was based on the lifestyle habits of reference persons. In Germany the calculation procedure for the prediction of radionuclide release from final repositories is not defined by national standards, the used procedures are based on analogue methods from other radiation protection calculations.
Energy Technology Data Exchange (ETDEWEB)
Martinez C, E.
2011-07-01
One of the main objectives related to the safety of any nuclear power plant, including the nuclear power plant of Laguna Verde is to ensure the structural integrity of reactor pressure vessel. To identify and quantify the damage caused by neutron irradiation in the vessel of any nuclear reactor, it is necessary to know both the neutron flux and the neutron fluence that the vessel has been receiving during its operation lifetime, and that the damage observed by mechanical testing are products of microstructural effects induced by neutron irradiation; therefore, it is important the study and prediction of the neutron flux in order to have a better understanding of the damage that these materials are receiving. The calculation here described uses the DORT code, which solves the neutron transport equation in discrete ordinates in two dimensions (x-y, r-{theta} and r-z), according to a regulatory guide, it should make an approximation of the neutron flux in three dimensions by the so called synthesis method. It is called in that way because it achieves a representation of 3 Dimensional neutron flux combining or summarizing the fluxes calculated by DORT r-{theta}, r-z and r. This work presents the application of synthesis method, according to Regulatory Guide 1190, to determine the 3 Dimensional fluxes in internal BWR reactor using three different spatial meshes. The results of the neutron flux and fluence, using three different meshes in the directions r, {theta} and z were compared with results reported in the literature obtaining a difference not larger than 9.61%, neutron flux reached its maximum, 1.58 E + 12 n/cm{sup 2}s, at a height H 4 (239.07 cm) and angle 32.236{sup o} in the core shroud and 4.00 E + 09 n/cm{sup 2}s at a height H 4 and angle 35.27{sup o} in the inner wall of the reactor vessel, positions that are consistent to within {+-}10% over the ones reported in the literature. (Author)
Energy Technology Data Exchange (ETDEWEB)
Wagner, John C [ORNL; Peplow, Douglas E. [ORNL; Mosher, Scott W [ORNL
2014-01-01
This paper presents a new hybrid (Monte Carlo/deterministic) method for increasing the efficiency of Monte Carlo calculations of distributions, such as flux or dose rate distributions (e.g., mesh tallies), as well as responses at multiple localized detectors and spectra. This method, referred to as Forward-Weighted CADIS (FW-CADIS), is an extension of the Consistent Adjoint Driven Importance Sampling (CADIS) method, which has been used for more than a decade to very effectively improve the efficiency of Monte Carlo calculations of localized quantities, e.g., flux, dose, or reaction rate at a specific location. The basis of this method is the development of an importance function that represents the importance of particles to the objective of uniform Monte Carlo particle density in the desired tally regions. Implementation of this method utilizes the results from a forward deterministic calculation to develop a forward-weighted source for a deterministic adjoint calculation. The resulting adjoint function is then used to generate consistent space- and energy-dependent source biasing parameters and weight windows that are used in a forward Monte Carlo calculation to obtain more uniform statistical uncertainties in the desired tally regions. The FW-CADIS method has been implemented and demonstrated within the MAVRIC sequence of SCALE and the ADVANTG/MCNP framework. Application of the method to representative, real-world problems, including calculation of dose rate and energy dependent flux throughout the problem space, dose rates in specific areas, and energy spectra at multiple detectors, is presented and discussed. Results of the FW-CADIS method and other recently developed global variance reduction approaches are also compared, and the FW-CADIS method outperformed the other methods in all cases considered.
Czerny, Daniel D; Padmanaban, Senthilkumar; Anishkin, Andriy; Venema, Kees; Riaz, Zoya; Sze, Heven
2016-09-01
Using Arabidopsis thaliana AtCHX17 as an example, we combine structural modeling and mutagenesis to provide insights on its protein architecture and transport function which is poorly characterized. This approach is based on the observation that protein structures are significantly more conserved in evolution than linear sequences, and mechanistic similarities among diverse transporters are emerging. Two homology models of AtCHX17 were obtained that show a protein fold similar to known structures of bacterial Na(+)/H(+) antiporters, EcNhaA and TtNapA. The distinct secondary and tertiary structure models highlighted residues at positions potentially important for CHX17 activity. Mutagenesis showed that asparagine-N200 and aspartate-D201 inside transmembrane5 (TM5), and lysine-K355 inside TM10 are critical for AtCHX17 activity. We reveal previously unrecognized threonine-T170 and lysine-K383 as key residues at unwound regions in the middle of TM4 and TM11 α-helices, respectively. Mutation of glutamate-E111 located near the membrane surface inhibited AtCHX17 activity, suggesting a role in pH sensing. The long carboxylic tail of unknown purpose has an alternating β-sheet and α-helix secondary structure that is conserved in prokaryote universal stress proteins. These results support the overall architecture of AtCHX17 and identify D201, N200 and novel residues T170 and K383 at the functional core which likely participates in ion recognition, coordination and/or translocation, similar to characterized cation/H(+) exchangers. The core of AtCHX17 models according to EcNhaA and TtNapA templates faces inward and outward, respectively, which may reflect two conformational states of the alternating access transport mode for proteins belonging to the plant CHX family.
Energy Technology Data Exchange (ETDEWEB)
Okuno, Hiroshi; Naito, Yoshitaka [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ando, Yoshihira [Toshiba Corp., Kawasaki, Kanagawa (Japan)
2000-09-01
The report describes the final results of Phase IIIA Benchmarks conducted by the Burnup Credit Criticality Calculation Working Group under the auspices of the Nuclear Energy Agency of the Organization for Economic Cooperation and Development (OECD/NEA). The benchmarks are intended to confirm the predictive capability of the current computer code and data library combinations for the neutron multiplication factor (k{sub eff}) of a layer of irradiated BWR fuel assembly array model. In total 22 benchmark problems are proposed for calculations of k{sub eff}. The effects of following parameters are investigated: cooling time, inclusion/exclusion of FP nuclides and axial burnup profile, and inclusion of axial profile of void fraction or constant void fractions during burnup. Axial profiles of fractional fission rates are further requested for five cases out of the 22 problems. Twenty-one sets of results are presented, contributed by 17 institutes from 9 countries. The relative dispersion of k{sub eff} values calculated by the participants from the mean value is almost within the band of {+-}1%{delta}k/k. The deviations from the averaged calculated fission rate profiles are found to be within {+-}5% for most cases. (author)
White, M C
2000-01-01
The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron tran...
Chekli, L; Brunetti, G; Marzouk, E R; Maoz-Shen, A; Smith, E; Naidu, R; Shon, H K; Lombi, E; Donner, E
2016-09-01
The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials; mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an individual soil basis suitable for site specific risk assessment prior to nZVI remediation.
Ness, H; Stella, L; Lorenz, C D; Kantorovich, L
2017-04-28
We use a generalised Langevin equation scheme to study the thermal transport of low dimensional systems. In this approach, the central classical region is connected to two realistic thermal baths kept at two different temperatures [H. Ness et al., Phys. Rev. B 93, 174303 (2016)]. We consider model Al systems, i.e., one-dimensional atomic chains connected to three-dimensional baths. The thermal transport properties are studied as a function of the chain length N and the temperature difference ΔT between the baths. We calculate the transport properties both in the linear response regime and in the non-linear regime. Two different laws are obtained for the linear conductance versus the length of the chains. For large temperatures (T≳500 K) and temperature differences (ΔT≳500 K), the chains, with N>18 atoms, present a diffusive transport regime with the presence of a temperature gradient across the system. For lower temperatures (T≲500 K) and temperature differences (ΔT≲400 K), a regime similar to the ballistic regime is observed. Such a ballistic-like regime is also obtained for shorter chains (N≤15). Our detailed analysis suggests that the behaviour at higher temperatures and temperature differences is mainly due to anharmonic effects within the long chains.
Su, Lin; Du, Xining; Liu, Tianyu; Xu, X. George
2014-06-01
An electron-photon coupled Monte Carlo code ARCHER - Accelerated Radiation-transport Computations in Heterogeneous EnviRonments - is being developed at Rensselaer Polytechnic Institute as a software testbed for emerging heterogeneous high performance computers that utilize accelerators such as GPUs. This paper presents the preliminary code development and the testing involving radiation dose related problems. In particular, the paper discusses the electron transport simulations using the class-II condensed history method. The considered electron energy ranges from a few hundreds of keV to 30 MeV. For photon part, photoelectric effect, Compton scattering and pair production were modeled. Voxelized geometry was supported. A serial CPU code was first written in C++. The code was then transplanted to the GPU using the CUDA C 5.0 standards. The hardware involved a desktop PC with an Intel Xeon X5660 CPU and six NVIDIA Tesla™ M2090 GPUs. The code was tested for a case of 20 MeV electron beam incident perpendicularly on a water-aluminum-water phantom. The depth and later dose profiles were found to agree with results obtained from well tested MC codes. Using six GPU cards, 6x106 electron histories were simulated within 2 seconds. In comparison, the same case running the EGSnrc and MCNPX codes required 1645 seconds and 9213 seconds, respectively. On-going work continues to test the code for different medical applications such as radiotherapy and brachytherapy.
Yang, Jia-Yue; Yue, Sheng-Ying; Hu, Ming
2016-12-01
Considerable discussions have occurred about the critical role played by free electrons in the transport of heat in pure metals. In principle, any environment that can influence the dynamical behaviors of electrons would have impact on electronic thermal conductivity (κel) of metals. Over the past decades, significant progress and comprehensive understanding have been gained from theoretical, as well as experimental, investigations by taking into account the effects of various conditions, typically temperature, impurities, strain, dimensionality, interface, etc. However, the effect of external magnetic field has received less attention. In this paper, the magnetic-field dependence of electron-phonon scattering, the electron's lifetime, and κel of representative metals (Al, Ni, and Nb) are investigated within the framework of all-electron spin-density functional theory. For Al and Ni, the induced magnetization vector field and difference in electron density under external magnetic-field aggregate toward the center of unit cell, leading to the enhanced electron-phonon scattering, the damped electron's lifetime, and thus the reduced κel. On the contrary, for Nb with strong intrinsic electron-phonon interaction, the electron's lifetime and κel slightly increase as external magnetic field is enhanced. This is mainly attributed to the separately distributed magnetization vector field and difference in electron density along the corner of unit cell. This paper sheds light on the origin of influence of external magnetic field on κel for pure metals and offers a new route for robust manipulation of electronic thermal transport via applying external magnetic field.
Desjarlais, Michael P.; Scullard, Christian R.; Benedict, Lorin X.; Whitley, Heather D.; Redmer, Ronald
2017-03-01
We compute electrical and thermal conductivities of hydrogen plasmas in the nondegenerate regime using Kohn-Sham density functional theory (DFT) and an application of the Kubo-Greenwood response formula, and demonstrate that for thermal conductivity, the mean-field treatment of the electron-electron (e-e) interaction therein is insufficient to reproduce the weak-coupling limit obtained by plasma kinetic theories. An explicit e-e scattering correction to the DFT is posited by appealing to Matthiessen's Rule and the results of our computations of conductivities with the quantum Lenard-Balescu (QLB) equation. Further motivation of our correction is provided by an argument arising from the Zubarev quantum kinetic theory approach. Significant emphasis is placed on our efforts to produce properly converged results for plasma transport using Kohn-Sham DFT, so that an accurate assessment of the importance and efficacy of our e-e scattering corrections to the thermal conductivity can be made.
Li, Fushan; Ick Son, Dong; Kim, Tae Whan; Ryu, Euidock; Kim, Sang Wook
2009-02-01
Transmission electron microscopy images showed that conjugation between single core-shell CdSe/ZnSe quantum dots (QDs) and oxidized multi-walled carbon nanotubes (MWCNTs) was achieved through the complexation reaction. Current-voltage (I-V) measurements on Al/CdSe:MWCNT conjugated nanocomposite/indium-tin-oxide devices at 300 K showed that the on/off ratio of the current bistability was as large as about 104, which was significantly increased due to an enhancement of the carrier transfer efficiency between the CdSe/ZnSe QDs and the MWCNTs. Carrier transport mechanisms of the bistable memory devices fabricated utilizing CdSe/ZnSe QD/MWCNT hybrid nanocomposite are described on the basis of the I-V results.
Mezzacappa, A; Liebendörfer, M; Messer, O E; Hix, W R; Thielemann, F K; Bruenn, S W
2001-03-05
With exact three-flavor Boltzmann neutrino transport, we simulate the stellar core collapse, bounce, and postbounce evolution of a 13M star in spherical symmetry, the Newtonian limit, without invoking convection. In the absence of convection, prior spherically symmetric models, which implemented approximations to Boltzmann transport, failed to produce explosions. We consider exact transport to determine if these failures were due to the transport approximations made and to answer remaining fundamental questions in supernova theory. The model presented here is the first in a sequence of models beginning with different progenitors. In this model, a supernova explosion is not obtained.
Osterberg, E. C.; Kreutz, K. J.; Mayewski, P. A.; Fisher, D. A.; Wake, C. P.; Handley, M.
2009-12-01
The Aleutian Low (ALOW) is a semi-permanent low pressure center that dominates the wintertime climate of the North Pacific, and is an integral component of major ocean-atmosphere climate oscillations including the Pacific Decadal Oscillation and the extra-tropical response to the El Niño-Southern Oscillation. Previous research has suggested that the trans-Pacific transport of dust and pollution from Asia to the North Pacific is enhanced under conditions with a strong ALOW and strong Pacific High, increasing average mid-latitude westerly wind velocities. Here we investigate the influence of annual ALOW intensity fluctuations on the trans-Pacific transport of lead (Pb) pollution as recorded in ice cores collected from the Mt. Logan summit plateau (5300 m asl) and Eclipse Icefield (3017 m asl). These two ice core sites are well suited to investigate vertical gradients in climate and pollution because they are situated Mt. Logan summit and Eclipse Icefield receive significant trans-Pacific Pb pollution, the Mt. Logan summit Pb concentration is positively correlated with ALOW strength (r=0.40, pMt. Logan and Eclipse. Occluded cyclones are stratified by the warm front, with lower elevation sites like Eclipse situated in a cold-air zone sourced by a relatively clean local airmass from the Gulf of Alaska, whereas higher elevation sites like the Mt. Logan summit plateau are situated above the warm front where moisture and airmasses (and their pollutants) originate from more distant locations in the North Pacific and Asia. The relative proportion of local vs distant moisture feeding Eclipse and the Mt. Logan summit has previously been hypothesized to account for the observed stable water isotope “step” in the St. Elias range.
Energy Technology Data Exchange (ETDEWEB)
Martens, Reinhard; Bruecher, Wenzel; Richter, Cornelia; Sentuc, Florence; Sogalla, Martin; Thielen, Harald
2012-02-15
In the medium-term time scale the Gaussian plume model used so far for atmospheric dispersion calculations in the General Administrative Provision (AVV) relating to Section 47 of the Radiation Protection Ordinance (StrISchV) as well as in the Incident Calculation Bases (SGB) relating to Section 49 StrISchV is to be replaced by a Lagrangian particle model. Meanwhile the Atmospheric Radionuclide Transportation Model (ARTM) is available, which allows the simulation of the atmospheric dispersion of operational releases from nuclear installations. ARTM is based on the program package AUSTAL2000 which is designed for the simulation of atmospheric dispersion of nonradioactive operational releases from industrial plants and was adapted to the application of airborne radioactive releases. In the context of the research project 3608S05005 possibilities for an upgrade of ARTM were investigated and implemented as far as possible to the program system. The work program comprises the validation and evaluation of ARTM, the implementation of technical-scientific extensions of the model system and the continuation of experience exchange between developers and users. In particular, the suitability of the model approach for simulations of radiological consequences according to the German SBG and the representation of the influence of buildings typical for nuclear power stations have been validated and further evaluated. Moreover, post-processing modules for calculation of dose-relevant decay products and for dose calculations have been developed and implemented. In order to continue the experience feedback and exchange, a web page has been established and maintained. Questions by users and other feedback have been dealt with and a common workshop has been held. The continued development and validation of ARTM has strengthened the basis for applications of this model system in line with the German regulations AVV and SBG. Further activity in this field can contribute to maintain and
Nakano, H.; Tsujino, H.; Sakamoto, K.
2013-10-01
Using an eddy-resolving ocean general circulation model, we examine the cold-core rings pinched off from the Kuroshio Extension (KE), focusing on their tracer transport. The origin of the tracers in the rings and how they are trapped are directly investigated by releasing two passive tracers, corresponding to the KE water and the water in the Mixed-Water Region (MWR) to the north of the KE. The cold-core rings carry the tracer in the MWR wrapped by the KE water from the surface to the bottom at the pinch-off. In and above the upper thermocline (σθ estimations are compared with the indirect diagnoses using PV, the ratio of drift velocity of ring to its tangential velocity (nonlinear parameter), and the largest closed contour of stream function in the comoving frame of the ring. These indirect diagnoses are consistent with the direct estimation in the upper thermocline, but are not good indicators below the lower thermocline. The cause of their insufficient performance is discussed.
Energy Technology Data Exchange (ETDEWEB)
Renner, Franziska [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany)
2016-11-01
Monte Carlo simulations are regarded as the most accurate method of solving complex problems in the field of dosimetry and radiation transport. In (external) radiation therapy they are increasingly used for the calculation of dose distributions during treatment planning. In comparison to other algorithms for the calculation of dose distributions, Monte Carlo methods have the capability of improving the accuracy of dose calculations - especially under complex circumstances (e.g. consideration of inhomogeneities). However, there is a lack of knowledge of how accurate the results of Monte Carlo calculations are on an absolute basis. A practical verification of the calculations can be performed by direct comparison with the results of a benchmark experiment. This work presents such a benchmark experiment and compares its results (with detailed consideration of measurement uncertainty) with the results of Monte Carlo calculations using the well-established Monte Carlo code EGSnrc. The experiment was designed to have parallels to external beam radiation therapy with respect to the type and energy of the radiation, the materials used and the kind of dose measurement. Because the properties of the beam have to be well known in order to compare the results of the experiment and the simulation on an absolute basis, the benchmark experiment was performed using the research electron accelerator of the Physikalisch-Technische Bundesanstalt (PTB), whose beam was accurately characterized in advance. The benchmark experiment and the corresponding Monte Carlo simulations were carried out for two different types of ionization chambers and the results were compared. Considering the uncertainty, which is about 0.7 % for the experimental values and about 1.0 % for the Monte Carlo simulation, the results of the simulation and the experiment coincide.
Parkhurst, David L.; Appelo, C.A.J.
2013-01-01
PHREEQC version 3 is a computer program written in the C and C++ programming languages that is designed to perform a wide variety of aqueous geochemical calculations. PHREEQC implements several types of aqueous models: two ion-association aqueous models (the Lawrence Livermore National Laboratory model and WATEQ4F), a Pitzer specific-ion-interaction aqueous model, and the SIT (Specific ion Interaction Theory) aqueous model. Using any of these aqueous models, PHREEQC has capabilities for (1) speciation and saturation-index calculations; (2) batch-reaction and one-dimensional (1D) transport calculations with reversible and irreversible reactions, which include aqueous, mineral, gas, solid-solution, surface-complexation, and ion-exchange equilibria, and specified mole transfers of reactants, kinetically controlled reactions, mixing of solutions, and pressure and temperature changes; and (3) inverse modeling, which finds sets of mineral and gas mole transfers that account for differences in composition between waters within specified compositional uncertainty limits. Many new modeling features were added to PHREEQC version 3 relative to version 2. The Pitzer aqueous model (pitzer.dat database, with keyword PITZER) can be used for high-salinity waters that are beyond the range of application for the Debye-Hückel theory. The Peng-Robinson equation of state has been implemented for calculating the solubility of gases at high pressure. Specific volumes of aqueous species are calculated as a function of the dielectric properties of water and the ionic strength of the solution, which allows calculation of pressure effects on chemical reactions and the density of a solution. The specific conductance and the density of a solution are calculated and printed in the output file. In addition to Runge-Kutta integration, a stiff ordinary differential equation solver (CVODE) has been included for kinetic calculations with multiple rates that occur at widely different time scales
Energy Technology Data Exchange (ETDEWEB)
Tres, Anderson [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Matematica Aplicada; Becker Picoloto, Camila [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Prolo Filho, Joao Francisco [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Inst de Matematica, Estatistica e Fisica; Dias da Cunha, Rudnei; Basso Barichello, Liliane [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Inst de Matematica
2014-04-15
In this work a study of two-dimensional fixed-source neutron transport problems, in Cartesian geometry, is reported. The approach reduces the complexity of the multidimensional problem using a combination of nodal schemes and the Analytical Discrete Ordinates Method (ADO). The unknown leakage terms on the boundaries that appear from the use of the derivation of the nodal scheme are incorporated to the problem source term, such as to couple the one-dimensional integrated solutions, made explicit in terms of the x and y spatial variables. The formulation leads to a considerable reduction of the order of the associated eigenvalue problems when combined with the usual symmetric quadratures, thereby providing solutions that have a higher degree of computational efficiency. Reflective-type boundary conditions are introduced to represent the domain on a simpler form than that previously considered in connection with the ADO method. Numerical results obtained with the technique are provided and compared to those present in the literature. (orig.)
The application of the Monte-Carlo neutron transport code MCNP to a small "nuclear battery" system
Puigdellívol Sadurní, Roger
2009-01-01
The project consist in calculate the keff to a small nuclear battery. The code Monte- Carlo neutron transport code MCNP is used to calculate the keff. The calculations are done at the beginning of life to know the capacity of the core becomes critical in different conditions. These conditions are the study parameters that determine the criticality of the core. These parameters are the uranium enrichment, the coated particles (TRISO) packing factor and the size of the core. More...
Institute of Scientific and Technical Information of China (English)
杨伟焱; 汤春桃; 毕光文; 杨波
2016-01-01
少群截面模型为堆芯三维扩散计算提供实时的节块均匀少群截面,是堆芯计算程序的关键模型之一.CYCAS程序是上海核工程研究设计院最新开发的堆芯三维核设计程序.本文在详细解析影响节块截面的各种因素的基础上,提出应用于CYCAS程序的少群截面的模型.该模型采用能谱修正方法处理由于能谱变化所引入的二次效应,采用微观燃耗修正方法处理燃耗历史效应.单组件和A P1000核电厂的数值验证计算表明,该模型具有很高的计算精度.%The few group cross section calculation model generates node homogeneous few group cross section for core 3D diffusion calculation ,w hich is one of the key models of core calculation code .CYCAS is the new core 3D nuclear design code developed by Shanghai Nuclear Engineering Research & Design Institute (SNERDI) .A new model based on detail analysis of the factors affecting node cross section was developed for CYCAS .In the model ,the energy spectrum correction method was used to process the second order effect introduced by energy spectrum change , and the micro-depletion correction method was utilized to treat depletion history effect .The numerical results of unit assembly and AP1000 core validate the high accuracy of the new model within CYCAS .
Directory of Open Access Journals (Sweden)
Sabine Thuens
2014-05-01
Full Text Available Multimedia fate and transport models are used to evaluate the long range transport potential (LRTP of organic pollutants, often by calculating their characteristic travel distance (CTD. We calculated the CTD of several polycyclic aromatic hydrocarbons (PAHs and metals using two models: the OECD POV& LRTP Screening Tool (The Tool, and ELPOS. The absolute CTDs of PAHs estimated with the two models agree reasonably well for predominantly particle-bound congeners, while discrepancies are observed for more volatile congeners. We test the performance of the models by comparing the relative ranking of CTDs with the one of experimentally determined travel distances (ETDs. ETDs were estimated from historical deposition rates of pollutants to peat bogs in Eastern Canada. CTDs and ETDs of PAHs indicate a low LRTP. To eliminate the high influence on specific model assumptions and to emphasize the difference between the travel distances of single PAHs, ETDs and CTDs were analyzed relative to the travel distances of particle-bound compounds. The ETDs determined for PAHs, Cu, and Zn ranged from 173 to 321 km with relative uncertainties between 26% and 46%. The ETDs of two metals were shorter than those of the PAHs. For particle-bound PAHs the relative ETDs and CTDs were similar, while they differed for Chrysene.
重庆市交通运输投资乘数的测算及分析%Calculation and Analysis of Transportation Investment Multiplier of Chongqing
Institute of Scientific and Technical Information of China (English)
郭建国; 陈正伟
2012-01-01
Based on Chongqing input-output table in 2007, this paper uses input-output model to quantitatively calculate the size of output multiplier and investment multiplier of Chongqing transportation investment, measures economic growth driving coefficient of Chongqing transportation investment and its contribution rate to GDP during 2005-2009 and,based on this,further analyzes the contribution of transportation investment to economic growth of Chongqing.%以重庆市2007年投入产出表为基础，运用投入产出模型定量测算出了重庆市交通运输投资的产出乘数与投资乘数的大小，测算出了2005—2009年交通运输投资对重庆市经济增长的拉动系数与GDP总量贡献率，并依此进一步分析了交通运输投资对重庆市经济增长的贡献。
Directory of Open Access Journals (Sweden)
Tien Anh Tran
2017-03-01
Full Text Available Nowadays, the development of science and technology brings the innovations and resolutions in aims with increasing the benefits and incomes for companies and producers. Additionally, the development of nation's economic associates with environmental protection. In the field of shipping transportation, the increasing in a number of ships operates then International Maritime Organization IMO's regulations become gradually more tightly about the environmental protection. EEOI – Energy Efficiency Operational Indicator is an operational measure tool for assessing the ship energy efficiency and CO2 emission to the environment. Furthermore, the research status is about ships energy efficiency management also has the optimistic trends and more effective. In the world, there are a lot of ships energy efficiency researches in aim with enhancing the energy efficiency and environmental protection. For instance, the voyage optimization, increasing the propulsion efficiency of ships, reducing the resistances, etc. However, in Vietnam, there are a lot of shipping transportation companies with different types of ship but the number of research about ships energy efficiency management also restrict. Since this research was carried out and applied the energy efficiency measure tool of International Maritime Organization (IMO for assessing all ships in Vietnam. The above workings were conducted by EEOI calculation tool for a certain ship with name M/V NSU JUSTICE 250,000 DWT of the VINIC Shipping Transportation Company, Vietnam.
Bracher, Susanne; Schmidt, Claudia C; Dittmer, Sophie I; Jung, Heinrich
2016-12-09
Crystal structures of transporters with a LeuT-type structural fold assign core transmembrane domain 6 (TM6') a central role in substrate binding and translocation. Here, the function of TM6' in the sodium/proline symporter PutP, a member of the solute/sodium symporter family, was investigated. A complete scan of TM6' identified eight amino acids as particularly important for PutP function. Of these residues, Tyr-248, His-253, and Arg-257 impact sodium binding, whereas Arg-257 and Ala-260 may participate in interactions leading to closure of the inner gate. Furthermore, the previous suggestion of an involvement of Trp-244, Tyr-248, and Pro-252 in proline binding is further supported. In addition, substitution of Gly-245, Gly-247, and Gly-250 affects the amount of PutP in the membrane. A Cys accessibility analysis suggests an involvement of the inner half of TM6' in the formation of a hydrophilic pathway that is open to the inside in the absence of ligands and closed in the presence of sodium and proline. In conclusion, the results demonstrate that TM6' plays a central role in substrate binding and release on the inner side of the membrane also in PutP and extend the knowledge on functionally relevant amino acids in transporters with a LeuT-type structural fold.
Leal, Allan M. M.; Kulik, Dmitrii A.; Kosakowski, Georg; Saar, Martin O.
2016-10-01
We present an extended law of mass-action (xLMA) method for multiphase equilibrium calculations and apply it in the context of reactive transport modeling. This extended LMA formulation differs from its conventional counterpart in that (i) it is directly derived from the Gibbs energy minimization (GEM) problem (i.e., the fundamental problem that describes the state of equilibrium of a chemical system under constant temperature and pressure); and (ii) it extends the conventional mass-action equations with Lagrange multipliers from the Gibbs energy minimization problem, which can be interpreted as stability indices of the chemical species. Accounting for these multipliers enables the method to determine all stable phases without presuming their types (e.g., aqueous, gaseous) or their presence in the equilibrium state. Therefore, the here proposed xLMA method inherits traits of Gibbs energy minimization algorithms that allow it to naturally detect the phases present in equilibrium, which can be single-component phases (e.g., pure solids or liquids) or non-ideal multi-component phases (e.g., aqueous, melts, gaseous, solid solutions, adsorption, or ion exchange). Moreover, our xLMA method requires no technique that tentatively adds or removes reactions based on phase stability indices (e.g., saturation indices for minerals), since the extended mass-action equations are valid even when their corresponding reactions involve unstable species. We successfully apply the proposed method to a reactive transport modeling problem in which we use PHREEQC and GEMS as alternative backends for the calculation of thermodynamic properties such as equilibrium constants of reactions, standard chemical potentials of species, and activity coefficients. Our tests show that our algorithm is efficient and robust for demanding applications, such as reactive transport modeling, where it converges within 1-3 iterations in most cases. The proposed xLMA method is implemented in Reaktoro, a
Alexander L. Wolman
2011-01-01
K-core inflation is a new class of underlying inflation measures. The two most popular measures of underlying inflation are core inflation and trimmed mean inflation. The former removes fixed categories of goods and services (food and energy) from the inflation calculation, and the latter removes fixed percentiles of the weighted distribution of price changes. In contrast, k-core inflation specifies a size of relative price change to be removed from the inflation calculation. Thus, the catego...
Saito, Kazuo; Shimbori, Toshiki; Draxler, Roland
2015-01-01
The World Meteorological Organization (WMO) convened a small technical task team of experts to produce a set of meteorological analyses to drive atmospheric transport, dispersion and deposition models (ATDMs) for the United Nations Scientific Committee on the Effects of Atomic Radiation's assessment of the Fukushima Daiichi Nuclear Power Plant (DNPP) accident. The Japan Meteorological Agency (JMA) collaborated with the WMO task team as the regional specialized meteorological center of the country where the accident occurred, and provided its operational 5-km resolution mesoscale (MESO) analysis and its 1-km resolution radar/rain gauge-analyzed precipitation (RAP) data. The JMA's mesoscale tracer transport model was modified to a regional ATDM for radionuclides (RATM), which included newly implemented algorithms for dry deposition, wet scavenging, and gravitational settling of radionuclide aerosol particles. Preliminary and revised calculations of the JMA-RATM were conducted according to the task team's protocol. Verification against Cesium 137 ((137)Cs) deposition measurements and observed air concentration time series showed that the performance of RATM with MESO data was significantly improved by the revisions to the model. The use of RAP data improved the (137)Cs deposition pattern but not the time series of air concentrations at Tokai-mura compared with calculations just using the MESO data. Sensitivity tests of some of the more uncertain parameters were conducted to determine their impacts on ATDM calculations, and the dispersion and deposition of radionuclides on 15 March 2011, the period of some of the largest emissions and deposition to the land areas of Japan. The area with high deposition in the northwest of Fukushima DNPP and the hotspot in the central part of Fukushima prefecture were primarily formed by wet scavenging influenced by the orographic effect of the mountainous area in the west of the Fukushima prefecture.
Santoso, R. K.; Rachmat, S.; Putra, W. D. K.; Resha, A. H.; Hartowo, H.
2017-07-01
Understanding the transport and retention of iron oxide nanoparticles is critical in optimizing electromagnetic heating well stimulation. If the injected concentration or injection rate is too big, nanoparticles can build-up inside the pore throat, which can reduce the permeability of the reservoir. A numerical model has been created to describe the behavior of iron oxide nanoparticles in porous media. The model is coupling material balance equation and fluid flow in porous media equations. There are six parameters to be estimated through matching with experimental data: irreversible attachment rate, reversible attachment rate, irreversible attachment capacity, reversible attachment capacity, reversible detachment rate and permeability. All parameters were obtained directly through coreflooding result in previous study. We add Langmuir static isotherm test to limit the maximum adsorption capacity to provide a better estimation of concentration distribution. We use 1% NaCl solution as the base fluid and 45-50 mesh sand as the porous media. From the Langmuir static isotherm test, the maximum adsorption concentration is determined. Then, coreflooding is conducted using 10 ppm nanofluid and 12 cc/min injection rate. The proposed model is matched with the experimental data and its parameters are consistent with the maximum adsorption capacity provided from the test.
Institute of Scientific and Technical Information of China (English)
刘一哲; 薛秀丽; 许义军; 冯预恒; 侯志峰
2012-01-01
Based on the core and primary circuit design of China Experimental Fast Reactor(CEFR), a multiple-channel thermal-hydraulic analysis code DAEMON was developed to calculate the core flow rate distribution and unsymmetric coefficient in different conditions. In the commissioning stage, a series of full-scale tests for reactor core were performed in CEFR with a permanent-magnet sodium flow meter. The numerical results of code DAEMON showed a good agreement with test data. The core hydraulic design was also validated with a view to the requirements of design criteria, commissioning and operation specifications.%针对中国实验快堆(CEFR)堆芯和一回路的设计特点,开发水力特性计算程序DAEMON,完成不同工况下的全堆芯流量分配计算,给出流量分配不均匀性等参数.在反应堆调试阶段,进行全堆芯流量分配试验.结果表明,程序计算值与试验值符合较好.在此基础上,验证了CEFR堆芯的流体力学设计,并为反应堆调试和运行提供了基础数据.
Church, Stanley E.; Rice, Cyndi A.; Marot, Marci E.
2008-01-01
The U.S. Departments of Agriculture and Interior Abandoned Mine Lands (AML) Initiative is focused on the evaluation of the effect of past mining practices on the water quality and the riparian and aquatic habitats of impacted stream reaches downstream from historical mining districts located primarily on Federal lands. This problem is manifest in the eleven western states (west of longitude 102 degrees) where the majority of hardrock mines that had past production are located on Federal lands. In areas of temperate climate and moderate to heavy precipitation, the effects of rapid chemical and physical weathering of sulfides exposed on mine-waste dumps and acidic drainage from mines have resulted in elevated metal concentrations in the stream water and stream-bed sediment. The result of these mineral weathering processes has an unquantified impact on the quality of the water and the aquatic and riparian habitats that may limit their recreational resource value. One of the confounding factors in these studies is the determination of the component of metals derived from hydrothermally altered but unmined portions of these drainage basins. Several watersheds have been studied to evaluate the effects of acid mine drainage and acid rock drainage on the near-surface environment. The Animas River watershed in southwestern Colorado contains a large number of past-producing metal mines that have affected the watershed. Beginning in October 1996, the U.S. Geological Survey (USGS) began a collaborative study of these effects under the USGS-AML Initiative. In this report, we present the radionuclide and geochemical analytical results of sediment coring during 1997-1999 from two cores from oxbow lakes 0.5 mi. upstream from the 32nd Street Bridge near Durango, Colo., and from three cores from beaver ponds within the Mineral Creek drainage basin near Silverton, Colo.
Akiyama, Toru; Komoda, Takato; Nakamura, Kohji; Ito, Tomonori
2017-08-01
The effects of polytypism on thermoelectric properties of Si and Ge nanowires (NWs) are systematically investigated by using a combination of density functional theory and Boltzmann transport calculations. The calculations for NWs with various polytypes demonstrate that the thermoelectric figure of merit Z T of Si and Ge NWs can be tuned by changing different stacking sequences along the growth direction. In particular, the Z T values of n -type Si and Ge NWs with hexagonal (2 H ) structure at 300 K are significantly larger than Z T of Si and Ge NWs with a cubic (3 C ) structure. The underlying mechanism for the enhanced Z T value in Si NWs with a 2 H structure compared with a 3 C structure is attributed by the different Seebeck coefficient depending on the structure, while that in Ge NWs is due to the difference in both the Seebeck coefficient and electrical conductivity. The calculated results offer a way to design high-performance thermoelectric materials by controlling the polytype of NWs.
Development of core design technology for LMR
Energy Technology Data Exchange (ETDEWEB)
Kim, Young Jin; Kim Young In; Kim, Young Il; Kim, Y. G.; Kim, S. J.; Song, H.; Kim, T. K.; Kim, W. S.; Hwang, W.; Lee, B. O.; Park, C. K.; Joo, H. K.; Yoo, J. W.; Kang, H. Y.; Park, W. S
2000-05-01
For the development of KALIMER (150 MWe) core conceptual design, design evolution and optimization for improved economics and safety enhancement was performed in the uranium metallic fueled equilibrium core design which uses U-Zr binary fuel not in excess of 20 percent enrichment. Utilizing results of the uranium ,metallic fueled core design, the breeder equilibrium core design with breeding ratio being over 1.1 was developed. In addition, utilizing LMR's excellent neutron economy, various core concepts for minor actinide burnup, inherent safety, economics and non-proliferation were realized and its optimization studies were performed. A code system for the LMR core conceptual design has been established through the implementation of needed functions into the existing codes and development of codes. To improve the accuracy of the core design, a multi-dimensional nodal transport code SOLTRAN, a three-dimensional transient code analysis code STEP, MATRA-LMR and ASSY-P for T/H analysis are under development. Through the automation of design calculations for efficient core design, an input generator and several interface codes have been developed. (author)
Zhou, Shiqi; Solana, J. R.
2013-06-01
The first four perturbation coefficients in the expansion of the Helmholtz free energy in power series of the inverse of the reduced temperature for a number of potential models with hard-sphere cores plus core-softened and discontinuous tails are obtained from Monte Carlo simulations. The potential models considered include square-well, double square-well, and square-shoulder plus square-well, with different potential parameters. These simulation data are used to evaluate the performance of a traditional macroscopic compressibility approximation (MCA) for the second order coefficient and a recent coupling parameter series expansion (CPSE) for the first four coefficients. Comprehensive comparison indicates the incapability of the MCA for the second order coefficient in most non-stringent situations, and significance of the CPSE in accurately calculating these four coefficients.
DEFF Research Database (Denmark)
Aldén, M.; Abrikosov, I. A.; Johansson, B.
1994-01-01
We have implemented an efficient self-consistent Green's-function technique, based on the tight-binding linear-muffin-tin-orbitals method, for calculating the electronic structure and total energy of a substitutional impurity located either in the bulk or at the surface. The technique makes use...
Gifford, Kent A; Price, Michael J; Horton, John L; Wareing, Todd A; Mourtada, Firas
2008-06-01
The goal of this work was to calculate the dose distribution around a high dose-rate 192Ir brachytherapy source using a multi-group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila version 6.1.1 was used to calculate the photon kerma rate distribution in water around the Nucletron microSelectron mHDRv2 source. MCNPX 2.5.c was used to compute the Monte Carlo water photon kerma rate distribution. Two hundred million histories were simulated, resulting in standard errors of the mean of less than 3% overall. The number of energy groups, S(n) (angular order), P(n) (scattering order), and mesh elements were varied in addition to the method of analytic ray tracing to assess their effects on the deterministic solution. Water photon kerma rate matrices were exported from both codes into an in-house data analysis software. This software quantified the percent dose difference distribution, the number of points within +/- 3% and +/- 5%, and the mean percent difference between the two codes. The data demonstrated that a 5 energy-group cross-section set calculated results to within 0.5% of a 15 group cross-section set. S12 was sufficient to resolve the solution in angle. P2 expansion of the scattering cross-section was necessary to compute accurate distributions. A computational mesh with 55 064 tetrahedral elements in a 30 cm diameter phantom resolved the solution spatially. An efficiency factor of 110 with the above parameters was realized in comparison to MC methods. The Attila code provided an accurate and efficient solution of the Boltzmann transport equation for the mHDRv2 source.
Sputtering Yield Calculation of Some Candidate PFC Materials
Institute of Scientific and Technical Information of China (English)
DENGBaiquan; YANJiancheng; HUANGJinhua
2001-01-01
In order to estimate the erosion rates of some plasma facing component materials, the sputtering yields of Mo, W and Li bombarded by charged particles H+, D+, T+ and He+ are calculated by application of sputtering theory based on bipartition model of ion transport. The comparisons with Monte-Carlo calculation results are made. These data might be useful to estimate the lifetime of plasma facing components and to analyze the impurity level in core plasma of fusion reactors.
Directory of Open Access Journals (Sweden)
Jonathan Leitner
2015-08-01
Full Text Available The Calumet & Hecla Copper Company was a firm funded by core capital, but operating in an internal periphery (Michigans Upper Peninsula, and eventually subject to peripheral constraints, along with the constraints of the physical environment, the physical characteristics of copper, and a concentrating industrial structure itself due largely to the physical characteristics of other types of copper mined elsewhere in the world. I focus on the firms efforts to maintain market access in the face of both a restructuring copper industry, driven by the coming online of much larger, lower-grade deposits that required much larger aggregations of capital to extract and process; and a restructuring transport system, driven by coppers industrial restructuring, but also by the politics of core and periphery within the U.S., including the imperatives of transport capital that tied peripheral resources to core manufacturing industry. A number of world-systems works over the past decade have examined periphery-core resource transport, exploring its importance to historical capitalism via increasing the speed and scope of circulation, improving access to raw materials, and being a leading sector for rising hegemons, due to the ever-increasing need for raw materials entailed by economic ascent. The case examined here was part of the United States own core emergence and eventual hegemonic ascendance, which was largely based on its domestic raw materials and the internal transport lines that enabled core industry to gain cheap access to those resources.
The compactness of presupernova stellar cores
Energy Technology Data Exchange (ETDEWEB)
Sukhbold, Tuguldur; Woosley, S. E., E-mail: sukhbold@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2014-03-01
The success or failure of the neutrino-transport mechanism for producing a supernova in an evolved massive star is known to be sensitive not only to the mass of the iron core that collapses, but also to the density gradient in the silicon and oxygen shells surrounding that core. Here we study the systematics of a presupernova core's 'compactness' as a function of the mass of the star and the physics used in its calculation. Fine-meshed surveys of presupernova evolution are calculated for stars from 15 to 65 M {sub ☉}. The metallicity and the efficiency of semiconvection and overshoot mixing are both varied and bare carbon-oxygen cores are explored as well as full hydrogenic stars. Two different codes, KEPLER and MESA, are used for the study. A complex interplay of carbon and oxygen burning, especially in shells, can cause rapid variations in the compactness for stars of very nearly the same mass. On larger scales, the distribution of compactness with main sequence mass is found to be robustly non-monotonic, implying islands of 'explodabilty,' particularly around 8-20 M {sub ☉} and 25-30 M {sub ☉}. The carbon-oxygen (CO) core mass of a presupernova star is a better, (though still ambiguous) discriminant of its core structure than the main sequence mass.
Harmoko, Rikno; Yoo, Jae Yong; Ko, Ki Seong; Ramasamy, Nirmal Kumar; Hwang, Bo Young; Lee, Eun Ji; Kim, Ho Soo; Lee, Kyung Jin; Oh, Doo-Byoung; Kim, Dool-Yi; Lee, Sanghun; Li, Yang; Lee, Sang Yeol; Lee, Kyun Oh
2016-10-01
In plants, α1,3-fucosyltransferase (FucT) catalyzes the transfer of fucose from GDP-fucose to asparagine-linked GlcNAc of the N-glycan core in the medial Golgi. To explore the physiological significance of this processing, we isolated two Oryza sativa (rice) mutants (fuct-1 and fuct-2) with loss of FucT function. Biochemical analyses of the N-glycan structure confirmed that α1,3-fucose is missing from the N-glycans of allelic fuct-1 and fuct-2. Compared with the wild-type cv Kitaake, fuct-1 displayed a larger tiller angle, shorter internode and panicle lengths, and decreased grain filling as well as an increase in chalky grains with abnormal shape. The mutant allele fuct-2 gave rise to similar developmental abnormalities, although they were milder than those of fuct-1. Restoration of a normal tiller angle in fuct-1 by complementation demonstrated that the phenotype is caused by the loss of FucT function. Both fuct-1 and fuct-2 plants exhibited reduced gravitropic responses. Expression of the genes involved in tiller and leaf angle control was also affected in the mutants. We demonstrate that reduced basipetal auxin transport and low auxin accumulation at the base of the shoot in fuct-1 account for both the reduced gravitropic response and the increased tiller angle.
Institute of Scientific and Technical Information of China (English)
潘昕怿; 兰兵; 张春明; 靖剑平; 攸国顺
2016-01-01
Background: The uncertainty of nuclear data is one of the key factors resulting in the uncertainty of reactor physics calculation. Purpose: The influence of multigroup nuclear data uncertainties on the reactor core physics calculation was studied in this paper. Methods:The stochastic sampling modular SAMP based on covariance matrix of nuclear data was developed, and the hybrid method and stochastic sampling method were realized using SCALE (Standardized Computer Analyses for Licensing Evaluation) software package. The two methods were validated using 3×3 hypothetical core and then applied to the first cycle of Almaraz pressurized-water reactor (PWR) in the IAEA (International Atomic Energy Agency) fuel management benchmark. Results: Results of the two methods are in good agreement. The uncertainty of core effective multiplication factor is about 0.5%, and the maximum uncertainties of the radial and axial power are about 1.9% and 0.45% respectively in Almaraz PWR. Conclusion:The two-step method and stochastic sampling method can both be used for the uncertainty analysis of reactor core calculation.%核数据不确定性是造成反应堆物理计算结果不确定性的重要因素之一。基于所需抽样核数据的协方差矩阵开发了随机抽样模块(Stochastic Sampling, SAMP)，在此基础上利用SCALE (Standardized Computer Analyses for Licensing Evaluation)软件包实现了混合法和随机抽样法两种不确定性分析方法，以研究多群核数据不确定性对堆芯物理计算的影响。以3×3假想堆芯为对象，对两种方法进行了验证，然后应用于国际原子能机构(International Atomic Energy Agency, IAEA)燃料管理基准题中的Almaraz核电厂首循环堆芯。分析结果表明，两种方法结果符合良好，Almaraz核电厂堆芯kef 不确定性约为0.5%，堆芯径向和轴向功率的最大不确定性分别为1.9%和0.45%。
Osmera, B; Cvachovec, F; Kyncl, J; Smutný, V
2005-01-01
The fast-neutron and photon space-energy distributions have been measured in an axially (1.25 m active height) and azimuthally (60 degree symmetry sector) shortened model of the WWER-1000 reactor assembled in the LR-0 experimental reactor. The space-energy distributions have been calculated with the stochastic code MCNP and the deterministic three-dimensional code TORT. Selected results are presented and discussed in the paper. This work has been done in the frame of the EU 5th FW project REDOS REDOS, Reactor Dosimetry: Accurate determination and benchmarking of radiation field parameters, relevant for reactor pressure vessel monitoring. EURATOM Programme, Call 2000/C 294/04). All geometry and material composition data of the model as well as the available experimental data were carefully checked and revised.
Energy Technology Data Exchange (ETDEWEB)
Gomez T, A. M.; Xolocostli M, V. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Lopez M, R.; Filio L, C.; Mugica R, C. A. [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico); Royl, P., E-mail: armando.gomez@inin.gob.mx [Karlsruhe Institute of Technology, Consultor, Hermann-von-Helmholtz-Platz, D-76344 Eggenstein -Leopoldshafen, Karlsruhe (Germany)
2013-10-15
The scenario of electric power total loss in the nuclear power plant of Laguna Verde (NPP-L V) has been analyzed using the code MELCOR previously, until reaching fault conditions of the primary container. A mitigation measure to avoid the loss of the primary contention is the realization of a venting toward the secondary contention (reactor building), however this measure bears the potential explosions occurrence risk when the hydrogen accumulated in the primary container with the oxygen of the reactor building atmosphere reacting. In this work a scenario has been supposed that considers the mentioned venting when the pressure of 4.5 kg/cm{sup 2} is reached in the primary container. The information for the hydrogen like an entrance fact is obtained of the MELCOR results and the hydrogen transport in both contentions is analyzed with the code CFD GASFLOW that allows predicting the detailed distribution of the hydrogen volumetric concentration and the possible detonation of flammability conditions in the reactor building. The results show that the venting will produce detonation conditions in the venting level (level 33) and flammability in the level of the recharge floor. The methodology here described constitutes the base of a detailed calculation system of this type of phenomena that can use to make safety evaluations in the NPP-L V on scenarios that include gases transport. (Author)
Baumgarten, Werner; Thiele, Holger; Ruprecht, Benjamin; Phlippen, Peter-W.; Schlömer, Luc
2017-09-01
Dose rate calculations are important for judging the shielding performance of transport casks for radioactive material. Therefore it is important to have reliable calculation tools. We report on measured and calculated dose rates near a thick-walled transport and storage cask of ductile cast iron with lead inserts and a Co-60 source inside. In a series of experiments the thickness of the inserts was varied, and measured dose rates near the cask were compared with SCALE/MAVRIC 6.1.3 and SCALE/MAVRIC 6.2 calculation results. Deviations from the measurements were found to be higher for increased lead thicknesses. Furthermore, it is shown how the shielding material density, air scattering and accounting for the floor influence the quality of the calculation.
Parallel plasma fluid turbulence calculations
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Leboeuf, J.N.; Carreras, B.A.; Charlton, L.A.; Drake, J.B.; Lynch, V.E.; Newman, D.E.; Sidikman, K.L.; Spong, D.A.
1994-12-31
The study of plasma turbulence and transport is a complex problem of critical importance for fusion-relevant plasmas. To this day, the fluid treatment of plasma dynamics is the best approach to realistic physics at the high resolution required for certain experimentally relevant calculations. Core and edge turbulence in a magnetic fusion device have been modeled using state-of-the-art, nonlinear, three-dimensional, initial-value fluid and gyrofluid codes. Parallel implementation of these models on diverse platforms--vector parallel (National Energy Research Supercomputer Center`s CRAY Y-MP C90), massively parallel (Intel Paragon XP/S 35), and serial parallel (clusters of high-performance workstations using the Parallel Virtual Machine protocol)--offers a variety of paths to high resolution and significant improvements in real-time efficiency, each with its own advantages. The largest and most efficient calculations have been performed at the 200 Mword memory limit on the C90 in dedicated mode, where an overlap of 12 to 13 out of a maximum of 16 processors has been achieved with a gyrofluid model of core fluctuations. The richness of the physics captured by these calculations is commensurate with the increased resolution and efficiency and is limited only by the ingenuity brought to the analysis of the massive amounts of data generated.
Directory of Open Access Journals (Sweden)
Weiling Yin
Full Text Available The pulsatile release of GnRH is crucial for normal reproductive physiology across the life cycle, a process that is regulated by hypothalamic neurotransmitters. GnRH terminals co-express the vesicular glutamate transporter 2 (vGluT2 as a marker of a glutamatergic phenotype. The current study sought to elucidate the relationship between glutamate and GnRH nerve terminals in the median eminence--the site of GnRH release into the portal capillary vasculature. We also determined whether this co-expression may change during reproductive senescence, and if steroid hormones, which affect responsiveness of GnRH neurons to glutamate, may alter the co-expression pattern. Female Sprague-Dawley rats were ovariectomized at young adult, middle-aged and old ages (~4, 11, and 22 months, respectively and treated four weeks later with sequential vehicle + vehicle (VEH + VEH, estradiol + vehicle (E2 + VEH, or estradiol + progesterone (E2+P4. Rats were perfused 24 hours after the second hormone treatment. Confocal microscopy was used to determine colocalization of GnRH and vGluT2 immunofluorescence in the median eminence. Post-embedding immunogold labeling of GnRH and vGluT2, and a serial electron microscopy (EM technique were used to determine the cellular interaction between GnRH terminals and glutamate signaling. Confocal analysis showed that GnRH and vGluT2 immunofluorescent puncta were extensively colocalized in the median eminence and that their density declined with age but was unaffected by short-term hormone treatment. EM results showed that vGluT2 immunoreactivity was extensively associated with large dense-core vesicles, suggesting a unique glutamatergic signaling pathway in GnRH terminals. Our results provide novel subcellular information about the intimate relationship between GnRH terminals and glutamate in the median eminence.
van Roon, André; Parsons, John R; Krap, Lenny; Govers, Harrie A J
2005-09-01
This theoretical study was performed to investigate the influence of soil temperature, soil water content and soil organic carbon fraction on the mobility of monoterpenes (C10HnOn') applied as pesticides to a top soil layer. This mobility was expressed as the amount volatilized and leached from the contaminated soil layer after a certain amount of time. For this, (slightly modified) published analytical solutions to a one dimensional, homogeneous medium, diffusion/advection/biodegradation mass balance equation were used. The required input-parameters were determined in a preceding study. Because the monoterpenes studied differ widely in the values for their physico-chemical properties, the relative importance of the various determinants also differed widely. Increasing soil water saturation reduced monoterpene vaporization and leaching losses although a modest increase was usually observed at high soil water contents. Organic matter served as the major retention domain, reducing volatilization and leaching losses. Increasing temperature resulted in higher volatilization and leaching losses. Monoterpene mobility was influenced by vertical water flow. Volatilization losses could be reduced by adding a clean soil layer on top of the contaminated soil. Detailed insight into the specific behaviour of different monoterpenes was obtained by discussing intermediate calculation results; the transport retardation factors and effective soil diffusion coefficients. One insight was that the air-water interface compartment is probably not an important partitioning domain for monoterpenes in most circumstances. The results further indicated that biodegradation is an important process for monoterpenes in soil.
Errandonea, D.; Segura, A.; Manjón, F. J.; Chevy, A.; Machado, E.; Tobias, G.; Ordejón, P.; Canadell, E.
2005-03-01
This paper reports on Hall effect and resistivity measurements under high pressure up to 3-4 GPa in p -type γ -indium selenide (InSe) (doped with As, Cd, or Zn) and ɛ -gallium selenide (GaSe) (doped with N or Sn). The pressure behavior of the hole concentration and mobility exhibits dramatic differences between the two layered compounds. While the hole concentration and mobility increase moderately and monotonously in ɛ -GaSe, a large increase of the hole concentration near 0.8 GPa and a large continuous increase of the hole mobility, which doubled its ambient pressure value by 3.2 GPa, is observed in γ -InSe. Electronic structure calculations show that the different pressure behavior of hole transport parameters can be accounted for by the evolution of the valence-band maximum in each material under compression. While the shape of the valence band maximum is virtually pressure-insensitive in ɛ -GaSe, it changes dramatically in γ -InSe, with the emergence of a ring-shaped subsidiary maximum that becomes the absolute valence-band maximum as pressure increases. These differences are shown to be a consequence of the presence or absence of a symmetry element (mirror plane perpendicular to the anisotropy axis) in the point group of each polytype ( D3h for the ɛ -polytype and C3v for the γ -polytype), resulting in different selection rules that affect the k⃗•p⃗ interaction between valence bands.
Energy Technology Data Exchange (ETDEWEB)
Beckert, C.
2007-12-19
Conventionally the data preparation of the neutron cross sections for reactor-core calculations pursues with 2D cell codes. Aim of this thesis was, to develop a 3D cell code, to study with this code 3D effects, and to evaluate the necessarity of a 3D data preparation of the neutron cross sections. For the calculation of the neutron transport the method of the first-collision probabilities, which are calculated with the ray-tracing method, was chosen. The mathematical algorithms were implemented in the 2D/3D cell code TransRay. For the geometry part of the program the geometry module of a Monte Carlo code was used.The ray tracing in 3D was parallelized because of the high computational time. The program TransRay was verified on 2D test problems. For a reference pressured-water reactor following 3D problems were studied: A partly immersed control rod and void (vacuum or steam) around a fuel rod as model of a steam void. All problems were for comparison calculated also with the programs HELIOS(2D) and MCNP(3D). The dependence of the multiplication factor and the averaged two-group cross section on the immersion depth of the control rod respectively of the height of the steam void were studied. The 3D-calculated two-group cross sections were compared with three conventional approximations: Linear interpolation, interpolation with flux weighting, and homogenization, At the 3D problem of the control rod it was shown that the interpolation with flux weighting is a good approximation. Therefore here a 3D data preparation is not necessary. At the test case of the single control rod, which is surrounded by the void, the three approximation for the two-group cross sections were proved as unsufficient. Therefore a 3D data preparation is necessary. The single fuel-rod cell with void can be considered as the limiting case of a reactor, in which a phase interface has been formed. [German] Standardmaessig erfolgt die Datenaufbereitung der Neutronenwirkungsquerschnitte fuer
Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...
Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in...
Analyzing the thermionic reactor critical experiments. [thermal spectrum of uranium 235 core
Niederauer, G. F.
1973-01-01
The Thermionic Reactor Critical Experiments (TRCE) consisted of fast spectrum highly enriched U-235 cores reflected by different thicknesses of beryllium or beryllium oxide with a transition zone of stainless steel between the core and reflector. The mixed fast-thermal spectrum at the core reflector interface region poses a difficult neutron transport calculation. Calculations of TRCE using ENDF/B fast spectrum data and GATHER library thermal spectrum data agreed within about 1 percent for the multiplication factor and within 6 to 8 percent for the power peaks. Use of GAM library fast spectrum data yielded larger deviations. The results were obtained from DOT R Theta calculations with leakage cross sections, by region and by group, extracted from DOT RZ calculations. Delineation of the power peaks required extraordinarily fine mesh size at the core reflector interface.
Directory of Open Access Journals (Sweden)
L Otero Pereiro
1998-01-01
.____________________________________________________________________AbstractThe Finite Elements Method (FEM developed until the present time is a powerful computerized calculation system applied inthe tensions and deformations analysis of solids and structures and much literature has been published on FEM as calculationmethod,The need of solving the problems of passengers transportation, mainly in Havana City, in the difficult conditions of Cubanspecial period, conducted to the development of a semi - trailer with the necessary characteristics to fulfil this function , whichby their attributes constitutes the only one in his gender for this purpose.It is, the first time that in our country is executed the calculation of a self - potable reticulated structure of similar magnitude,with satisfactory concrete results.It is approached the creation of a physic - mathematical model that simulates the real structure, conditioned to the limitations ofthe calculation program, offering a similar behavior in the efforts and deformations that are produced, with a study of thedifferent variants of results.In the work are obtained some results on the possible consequences the calculation of the complete structure or separating it bysections, being necessary the establishment of a methodical for the definition of those sections that they can be analyzedseparately, as well as the order of importance of this analysis.It was accomplished the experimental determination of the dynamic load coefficient, as well as the establishment of the physic- mathematical model adapted for the calculation of the structure of a semi - trailer for passengers transportation applying theFinite Elements Method.It was effected a test to statics load del frame to corroborate the validity of the physic - mathematical model of the structure.Additionally, It is proposed a technical solution within the technological possibilities of the constructing company to avoid thestructure breakage of the equipment.
Energy Technology Data Exchange (ETDEWEB)
Reynolds, J. M.; Lopez-Bruna, D.
2009-12-11
This report is the first of a series dedicated to the numerical calculation of the evolution of fusion plasmas in general toroidal geometry, including TJ-II plasmas. A kinetic treatment has been chosen: the evolution equation of the distribution function of one or several plasma species is solved in guiding center coordinates. The distribution function is written as a Maxwellian one modulated by polynomial series in the kinetic coordinates with no other approximations than those of the guiding center itself and the computation capabilities. The code allows also for the inclusion of the three-dimensional electrostatic potential in a self-consistent manner, but the initial objective has been set to solving only the neoclassical transport. A high order conservative method (Spectral Difference Method) has been chosen in order to discretized the equation for its numerical solution. In this first report, in addition to justifying the work, the evolution equation and its approximations are described, as well as the baseline of the numerical procedures. (Author) 28 refs.
Webber, W R
2010-01-01
Using new calculations of 10Be production in the Earths atmosphere which are based on direct measurements of the 11-year solar modulation effects on galactic cosmic rays and spacecraft measurements of the cosmic ray energy spectrum, we have calculated the yearly average production of 10Be in the Earths atmosphere by galactic and solar cosmic rays since 1939. During the last six 11-year cycles the average amplitude of these production changes is 36%. These predictions are compared with measurements of 10Be concentration in polar ice cores in both the Northern and Southern hemisphere over the same time period. We find a large scatter between the predicted and measured yearly average data sets and a low cross correlation ~0.30. Also the normalized regression line slope between 10Be production changes and 10Be concentration changes is found to be only 0.4-0.6; much less than the value of 1.0 expected for a simple proportionality between these quantities, as is typically used for historical projections of the rela...
Isaev, S. A.; Baranov, P. A.; Sudakov, A. G.; Popov, I. A.
2016-08-01
A modification of the popular model of shear stress transport aimed at calculating the separation flow of an incompressible viscous liquid is justified. The modification eliminates the nonphysical pumping of the vortex viscosity in the cores of large-scale vortices. It has been verified with regard to the influence of the streamline curvature on the vortex viscosity by introducing a reciprocal linear function of the turbulent Richardson number with the Isaev-Kharchenko-Usachov constant equal to 0.02.Verification is based on solving the test problem an axisymmetric steady flow about a disk-cylinder tandem with an optimally configured nose, which has an ultralow profile drag for a Reynolds number of 5 × 105. It has been shown that the Menter combined boundary conditions are valid if y + y of the wall does not exceed two.
Institute of Scientific and Technical Information of China (English)
迟利华; 刘杰; 龚春叶; 徐涵; 蒋杰; 胡庆丰
2009-01-01
The parallel performance of solving the multi-group particle transport equations on the unstructure meshes is analyzed Adapting to the characteristics of multi-core cluster systems, this paper desgins a MPI/OpenMP hybrid parallel code. For the meshes, the space domain decomposition is adopted, and MPI between the computations of multi-core CPU nodes is used. When each MPI process begin to compute the variables of the energy groups, several OpenMP threads will be forked, and the threads start to compute simultaneously in the same mutli-core CPU node. Using the MPI/OpenMP hybrid parallel code, we solve a 2D mutli-group particle transport equation on a cluster with mutli-core CPU nodes, and the results show that the code has good scalability and can be scaled to 1024 CPU cores.%本文分析了非结构网格多群粒子输运Sn方程求解的并行性,拟合多核机群系统的特点,设计了MPI/OpenMP混合程序,针对空间网格点采用区域分解划分,计算结点间基于消息传递MPI编程,每个MPI计算进程在计算过程中碰到关于能群的计算,就生成多个OpenMP线程,计算结点内针对能群进行多线程并行计算.数值测试结果表明,非结构网格上的粒子输运问题的混合并行计算能较好地匹配多核机群系统的硬件结构,具有良好的可扩展性,可以扩展到1 024个CPU核.
Copeland, Kyle; Parker, Donald E; Friedberg, Wallace
2010-03-01
Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult male and an adult female to (56)Fe(26+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Calculations using ICRP 2007 recommendations result in fluence-to-effective dose conversion coefficients that are almost identical at most energies to those calculated using ICRP 1990 recommendations.
Energy Technology Data Exchange (ETDEWEB)
Mann, F.M.
1998-01-26
The Tank Waste Remediation System (TWRS) is responsible for the safe storage, retrieval, and disposal of waste currently being held in 177 underground tanks at the Hanford Site. In order to successfully carry out its mission, TWRS must perform environmental analyses describing the consequences of tank contents leaking from tanks and associated facilities during the storage, retrieval, or closure periods and immobilized low-activity tank waste contaminants leaving disposal facilities. Because of the large size of the facilities and the great depth of the dry zone (known as the vadose zone) underneath the facilities, sophisticated computer codes are needed to model the transport of the tank contents or contaminants. This document presents the code selection criteria for those vadose zone analyses (a subset of the above analyses) where the hydraulic properties of the vadose zone are constant in time the geochemical behavior of the contaminant-soil interaction can be described by simple models, and the geologic or engineered structures are complicated enough to require a two-or three dimensional model. Thus, simple analyses would not need to use the fairly sophisticated codes which would meet the selection criteria in this document. Similarly, those analyses which involve complex chemical modeling (such as those analyses involving large tank leaks or those analyses involving the modeling of contaminant release from glass waste forms) are excluded. The analyses covered here are those where the movement of contaminants can be relatively simply calculated from the moisture flow. These code selection criteria are based on the information from the low-level waste programs of the US Department of Energy (DOE) and of the US Nuclear Regulatory Commission as well as experience gained in the DOE Complex in applying these criteria. Appendix table A-1 provides a comparison between the criteria in these documents and those used here. This document does not define the models (that
Institute of Scientific and Technical Information of China (English)
姜志鹏; 文习山; 王羽; 陈瑞珍; 曹继丰; 陈图腾
2015-01-01
为了研究特高压干式空心平波电抗器的温升分布特性,该文基于计算流体力学和传热学理论,建立了电抗器稳态流体与固体耦合温度场的数学计算模型.采用有限容积法对三维模型进行稳态流体场与温度场直接求解,获得其温度场分布特性,研究了包封轴向及径向温度分布规律.最后采用光纤测温法对自然对流下的电抗器进行温升测量.对比分析表明,计算与试验结果吻合较好,验证温度场数值计算的合理性和准确性,为特高压干式空心平波电抗器温升监测提供参考.%To research the distribution characteristics of temperature rise for UHV dry-type air-core smoothing reactor, according to computational fluid dynamics and heat transfer theory, this paper presented the mathematical model of temperature field coupling steady fluid and solid for the reactor. The finite volume method was employed to solve the steady flow and temperature fields of 3D model directly, and the temperature distribution characteristics of the reactor were obtained. Then the axial and radial temperature distributions of encapsulations were studied separately. Finally, optical fiber temperature measurement method was used to test temperature rise for the reactor under natural convection condition. Comparative analysis shows that the calculated results are in good agreement with the experiment, which verifies the rationality and accuracy of the temperature field numerical calculation. And it can provide references for the temperature rise monitoring of UHV dry-type air-core smoothing reactor.
Institute of Scientific and Technical Information of China (English)
李文静; 龙亮
2014-01-01
Calculation of containment radionuclide concentration is an important part of estimating containment radiation dose rate ,and the latter is a primary parameter for core damage assessment .This paper provides the calculation of concentration of three typical nuclides within containment post-accident in both simplified analyt-ical method and indirect method with ORIGEN 2 code .The results show that the indirect method can simulate the release and decay of radionuclides and the transformation among them ,and suggests it can be used in the early core damage assessment .But if the containment radionuclide concentration is evaluated after a long time since the accident ,when the nuclides with short half-lives have little effects on the result ,the simplified meth-od is appropriate .%安全壳内放射性核素浓度的计算是确定安全壳辐射剂量率的重要环节，而安全壳辐射剂量率是堆芯损伤评价的重要参数之一。本文利用ORIGEN2程序，采用简化分析法和间接计算法分别对事故后3种典型核素在安全壳内的浓度进行分析计算，并对两种方法的可用性进行了讨论。根据分析可知，间接计算法能够更好的模拟核素的释放、衰变以及相互转化过程，建议在事故早期堆芯损伤评价过程中使用。但是若考虑事故发生较长时间后的安全壳内核素浓度，短半衰期核素影响已经很小，简化分析法是可用的。
DEFF Research Database (Denmark)
Svensson, Anders
2014-01-01
Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...
DEFF Research Database (Denmark)
Svensson, Anders
2014-01-01
Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...
Copeland, Kyle; Parker, Donald E; Friedberg, Wallace
2010-03-01
Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective dose and fluence to gray equivalent, for isotropic exposure to alpha particles in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for effective dose are within 30 % of those calculated using ICRP 1990 recommendations.
Calculation of reactivity changes due to bubble collapse. [LMFBR
Energy Technology Data Exchange (ETDEWEB)
Hoffman, T.J.; Petrie, L.M.
1977-01-01
Calculations based on Behrens' method indicate that a substantial increase in reactivity may accompany the collapse of a large number of small bubbles in an LMFBR core. More sophisticated transport approaches to this problem have encountered several difficulties: the large number of bubbles requires many mesh points; the desired effect can easily be masked by the movement of fuel to regions of greater (or lesser) importance; the reactivity is desired for a random distribution of spherical bubbles. This paper describes a transport approach to this problem which avoids the above difficulties by using the ''sub-group'' or ''probability table'' method.
Energy Technology Data Exchange (ETDEWEB)
Baggemann, Johannes
2015-05-22
Generation IV of reactor design is supposed to include inherent safety systems that allow accident management using passive processes (without external energy). The VTR (very high temperature reactor) is graphite moderated with helium cooling. The design concept assumes that in any operational situation the after heat is removed by thermal conduction and radiation. Air ingress is beyond-design accident assuming a leak in the primary circuit triggering oxygen reaction with the hot graphite that could damage the barriers for fission product release. Using 3D CFD (computational fluid dynamics) codes the air ingress scenario is simulated, the flow and transport processes in the reactor core are analyzed. For validation of the modeling heat transport processes were investigated in specific test facilities.
Energy Technology Data Exchange (ETDEWEB)
Both, J.P.; Lee, Y.K.; Mazzolo, A.; Peneliau, Y.; Petit, O.; Roesslinger, B. [CEA Saclay, Dir. de l' Energie Nucleaire (DEN), Service d' Etudes de Reacteurs et de Modelisation Avancee, 91 - Gif sur Yvette (France)
2003-07-01
Tripoli-4 is a three dimensional calculations code using the Monte Carlo method to simulate the transport of neutrons, photons, electrons and positrons. This code is used in four application fields: the protection studies, the criticality studies, the core studies and the instrumentation studies. Geometry, cross sections, description of sources, principle. (N.C.)
Millennium Challenge Corporation — The evaluation examines impacts of the Transportation Project in three ways. First, we calculate economic rates of return associated with reduced user costs for each...
Establishment and Verification of MCNP Neutron Transport Model About Tianwan Nuclear Power Plant
Institute of Scientific and Technical Information of China (English)
ZHOU; Qi
2012-01-01
<正>In order to calculating the neutron flux in the surveillance box and reactor pressure vessel of the Tianwan NPP, we need to build up the neutron transport model by using the Monte Carlo code MCNP. The core of the NPP is very complicated for modeling so we put forward some assumptions that can simplify the neutron transport model. A lot of calculation works have been done to prove that the assumptions are right and suitable.
Paulius, D; Torres, D; Illas, F; Archibald, W E
2014-11-14
Self-assembled monolayers on Au(111) have outstanding chemical, electrical, and optical properties, and Au adatoms seem to play a key role in these properties. Still, the fundamental understanding of adatom transport inside the self-assembled structure is very thin. In this paper we use first-principles calculations to reveal new details about the migration mechanism of Au adatoms in the presence of a CH3S self-assembled structure on Au(111). We study the inclusion of Au adatoms inside a well-packed (√3 × √3)-R30°-CH3S self-assembled lattice and present atomistic models supporting adatom migration by means of a hopping mechanism between pairs of CH3S species. Our calculations reveal that the transport of Au adatoms is slowed down inside the molecular network where the kinetic barrier for adatom migration is larger than on the clean Au surface. We attribute the hindered mobility of Au adatoms to the fact that adatom transport involves the breaking and making of Au-S bonds. Our results form a basis for further understanding the role played by defect transport in the properties of molecular assemblies.
On the Calculation of Reactor Time Constants Using the Monte Carlo Method
Energy Technology Data Exchange (ETDEWEB)
Leppaenen, Jaakko [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT (Finland)
2008-07-01
Full-core reactor dynamics calculation involves the coupled modelling of thermal hydraulics and the time-dependent behaviour of core neutronics. The reactor time constants include prompt neutron lifetimes, neutron reproduction times, effective delayed neutron fractions and the corresponding decay constants, typically divided into six or eight precursor groups. The calculation of these parameters is traditionally carried out using deterministic lattice transport codes, which also produce the homogenised few-group constants needed for resolving the spatial dependence of neutron flux. In recent years, there has been a growing interest in the production of simulator input parameters using the stochastic Monte Carlo method, which has several advantages over deterministic transport calculation. This paper reviews the methodology used for the calculation of reactor time constants. The calculation techniques are put to practice using two codes, the PSG continuous-energy Monte Carlo reactor physics code and MORA, a new full-core Monte Carlo neutron transport code entirely based on homogenisation. Both codes are being developed at the VTT Technical Research Centre of Finland. The results are compared to other codes and experimental reference data in the CROCUS reactor kinetics benchmark calculation. (author)
Visible and IR photoluminescence of c-FeSi@a-Si core-shell nano-fibres produced by vapour transport
CSIR Research Space (South Africa)
Thabethe, S
2013-11-01
Full Text Available The procedures for the synthesis of amorphous e-FeSi/Si core–shell nanofibres by vapour transport in a CVD configuration are reported. Crystallite studies by the Williamson-Hall method show the sizes to be typically about 8.0 nm which agrees...