Neutron transport methods for massively parallel computers PDF Download

Author: Ulf Rainer Hanebutte
Publisher:
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Category :
Languages : en
Pages :

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Category :
Languages : en
Pages : 6

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A discrete ordinate response matrix method is formulated for the solution of neutron transport problems on massively parallel computers. The response matrix formulation eliminates iteration on the scattering source. The nodal matrices which result from the diamond-differenced equations are utilized in a factored form which minimizes memory requirements and significantly reduces the required number of algorithm utilizes massive parallelism by assigning each spatial node to a processor. The algorithm is accelerated effectively by a synthetic method in which the low-order diffusion equations are also solved by massively parallel red/black iterations. The method has been implemented on a 16k Connection Machine-2, and S and S16 solutions have been obtained for fixed-source benchmark problems in X--Y geometry.

Author: Salli Moustafa
Publisher:
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Category :
Languages : en
Pages : 0

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High-fidelity nuclear reactor core simulations require a precise knowledge of the neutron flux inside the reactor core. This flux is modeled by the linear Boltzmann equation also called neutron transport equation. In this thesis, we focus on solving this equation using the discrete ordinates method (SN) on Cartesian mesh. This method involves a source iteration scheme including a sweep over the spatial mesh and gathering the vast majority of computations in the SN method. Due to the large amount of computations performed in the resolution of the Boltzmann equation, numerous research works were focused on the optimization of the time to solution by developing parallel algorithms for solving the transport equation. However, these algorithms were designed by considering a super-computer as a collection of independent cores, and therefore do not explicitly take into account the memory hierarchy and multi-level parallelism available inside modern super-computers. Therefore, we first proposed a strategy for designing an efficient parallel implementation of the sweep operation on modern architectures by combining the use of the SIMD paradigm thanks to C++ generic programming techniques and an emerging task-based runtime system: PaRSEC. We demonstrated the need for such an approach using theoretical performance models predicting optimal partitionings. Then we studied the challenge of converging the source iterations scheme in highly diffusive media such as the PWR cores. We have implemented and studied the convergence of a new acceleration scheme (PDSA) that naturally suits our Hybrid parallel implementation. The combination of all these techniques have enabled us to develop a massively parallel version of the SN Domino solver. It is capable of tackling the challenges posed by the neutron transport simulations and compares favorably with state-of-the-art solvers such as Denovo. The performance of the PaRSEC implementation of the sweep operation reaches 6.1 Tflop/s on 768 cores corresponding to 33.9% of the theoretical peak performance of this set of computational resources. For a typical 26-group PWR calculations involving 1.02×1012 DoFs, the time to solution required by the Domino solver is 46 min using 1536 cores.

Author: William Robert Dawson Boyd (III.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 203

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Over the past 20 years, parallel computing has enabled computers to grow ever larger and more powerful while scientific applications have advanced in sophistication and resolution. This trend is being challenged, however, as the power consumption for conventional parallel computing architectures has risen to unsustainable levels and memory limitations have come to dominate compute performance. Multi-core processors and heterogeneous computing platforms, such as Graphics Processing Units (GPUs), are an increasingly popular paradigm for resolving these issues. This thesis explores the applicability of shared memory parallel platforms for solving deterministic neutron transport problems. A 2D method of characteristics code - OpenMOC - has been developed with solvers for shared memory multi-core platforms as well as GPUs. The multi-threading and memory locality methodologies for the multi-core CPU and GPU solvers are presented. Parallel scaling results using OpenMP demonstrate better than ideal weak scaling and nearly perfect strong scaling on both Intel Xeon and IBM Blue Gene/Q architectures. Performance results for the 2D C5G7 benchmark demonstrate up to 50x speedup for MOC on a GPU. The lessons learned from this thesis will provide the basis for further exploration of MOC on many-core platforms and GPUs as well as design decisions for hardware vendors exploring technologies for the next generation of machines for scientific computing.

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Category : Aeronautics
Languages : en
Pages : 700

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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Author:
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Category :
Languages : en
Pages : 5

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The properties of the variational nodal method for neutron transport calculations are investigated. The method is generalized for three-dimensional multigroup criticality problems in both hexagonal-z and Cartesian geometries. The method is implemented as part of the Argonne National Laboratory Code DIF3D, and applied to a series of benchmark reactor calculations. Variational nodal methods are compared of nodal transport methods based on both interface-current and discrete ordinate approximations. Model problems are used to examine the effect of running each of the three classes of nodal transport methods on computers with massively parallel architectures.

Author: MUSA YAVUZ
Publisher:
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Category :
Languages : en
Pages : 530

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performance of the new multigrid method degrades with an increasing number of processors, not because of the degradation in the convergence rate, but because of the domination of communication overhead and unemployment of some processors on the coarse grids.

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Category : Power resources
Languages : en
Pages : 782

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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Book Description
The properties of the variational nodal method for neutron transport calculations are investigated. The method is generalized for three-dimensional multigroup criticality problems in both hexagonal-z and Cartesian geometries. The method is implemented as part of the Argonne National Laboratory Code DIF3D, and applied to a series of benchmark reactor calculations. Variational nodal methods are compared of nodal transport methods based on both interface-current and discrete ordinate approximations. Model problems are used to examine the effect of running each of the three classes of nodal transport methods on computers with massively parallel architectures.

Author: Liangzhi Cao
Publisher: Woodhead Publishing
ISBN: 0128182229
Category : Technology & Engineering
Languages : en
Pages : 294

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Deterministic Numerical Methods for Unstructured-Mesh Neutron Transport Calculation presents the latest deterministic numerical methods for neutron transport equations (NTEs) with complex geometry, which are of great demand in recent years due to the rapid development of advanced nuclear reactor concepts and high-performance computational technologies. This book covers the wellknown methods proposed and used in recent years, not only theoretical modeling but also numerical results. This book provides readers with a very thorough understanding of unstructured neutron transport calculations and enables them to develop their own computational codes. The fundamentals, numerical discretization methods, algorithms, and numerical results are discussed. Researchers and engineers from utilities and research institutes are provided with examples on how to model an advanced nuclear reactor, which they can then apply to their own research projects and lab settings. - Combines the theoretical models with numerical methods and results in one complete resource - Presents the latest progress on the topic in an easy-to-navigate format