Download or read book Development of the Random Ray Method of Neutral Particle Transport for High fidelity Nuclear Reactor Simulation written by John Robert Tramm and published by . This book was released on 2018 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: A central goal in computational nuclear engineering is the high-fidelity simulation of a full nuclear reactor core by way of a general simulation method. General full core simulations can potentially reduce design and construction costs, increase reactor performance and safety, reduce the amount of nuclear waste generated, and allow for much more complex and novel designs. To date, however, the time to solution and memory requirements for a general full core high fidelity 3D simulation have rendered such calculations impractical, even using leadership class supercomputers. Reactor designers have instead relied on calibrated methods that are accurate only within a narrow design space, greatly limiting the exploration of innovative concepts. One numerical simulation approach, the Method of Characteristics (MOC), has the potential for fast and efficient performance on a variety of next generation computing systems, including CPU, GPU, and Intel Xeon Phi architectures. While 2D MOC has long been used in reactor design and engineering as an efficient simulation method for smaller problems, the transition to 3D has only begun recently, and to our knowledge no 3D MOC based codes are currently used in industry. The delay of the onset of full 3D MOC codes can be attributed to the impossibility of “naively” scaling current 2D codes into 3D due to prohibitively high memory requirements. To facilitate transition of MOC based methods to 3D, we have developed a fundamentally new computational algorithm. This new algorithm, known as The Random Ray Method (TRRM), can be viewed as a hybrid between the Monte Carlo (MC) and MOC methods. Its three largest advantages compared to MOC are that it can handle arbitrary 3D geometries, it offers extreme improvements in memory efficiency, and it allows for significant reductions in algorithmic complexity on some simulation problems. It also offers a much lower time to solution as compared to MC methods. In this thesis, we will introduce the TRRM algorithm and a parallel implementation of it known as the Advanced Random Ray Code (ARRC). Then, we will evaluate its capabilities using a series of benchmark problems and compare the results to traditional deterministic MOC methods. A full core simulation will be run to assess the performance characteristics of the algorithm at massive scale. We will also discuss the various methods to parallelize the algorithm, including domain decomposition, and will investigate the new method’s scaling characteristics on two current supercomputers, the IBM Blue Gene/Q Mira and the Cray XC40 Theta. The results of these studies show that TRRM is capable of breakthrough performance and accuracy gains compared to existing methods which we demonstrate to enable general, full core 3D high-fidelity simulations that were previously out of reach.

Download or read book Parallel Asynchronous Ray tracing for Scalable 3D Full core Method of Characteristics Neutron Transport on Unstructured Mesh written by Derek Ray Gaston and published by . This book was released on 2020 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: One important goal in nuclear reactor core simulations is the computation of detailed 3D power distributions that will enable higher confidence in licensing of next-generation reactors and lifetime extensions/power up-rates for current-generation reactors. To date, there have been only a few demonstrations of such high-fidelity deterministic neutron transport calculations. However, as computational power continues to grow, such capabilities continue to move closer to being practically realized. Predictive reactor physics needs both neutronics calculations and full-core, 3D coupled multiphysics simulations (e.g., neutronics, fuel performance, fluid mechanics, structural mechanics). Therefore, new reactor physics tools should harness supercomputers to enable full-core reactor simulations and be capable of coupling for multiphysics feedback. One candidate for full-core nuclear reactor neutronics is the method of characteristics (MOC). Recent advancements have seen a pellet-resolved 3D MOC solution for the BEAVRS benchmark. However, MOC is traditionally implemented using constructive solid geometry (CSG) that makes it difficult (if not impossible) to accurately deform material to capture physical feedback effects such as fuel pin thermal expansions, assembly bowings, or core flowering. An alternative to CSG is to use unstructured, finite-element mesh for spatial discretization of MOC. Such mesh-based geometries permit directly linking to unstructured mesh-based multiphysics tools, such as fuels performance. Utilizing unstructured mesh has been attempted in the past, but those attempts have fallen short of producing usable 3D reactor simulators. Several key issues have hindered these attempts: lack of fuel volume preservation, approximations of boundary conditions, inefficient spatial domain decompositions, excessive memory requirements, ineffective parallel load balancing, and lack of scalability on massively parallel modern computer clusters. This thesis resolves these issues by developing a massively parallel, 3D, full-core MOC code, called MOCkingbird, using unstructured meshes. Underpinning MOCkingbird is a new algorithm for parallel ray tracing: the Scalable Massively Asynchronous Ray Tracing (SMART) algorithm. This algorithm enables efficient parallel ray-tracing across the full reactor domain, alleviating issues of reduced convergence associated with standard parallel MOC algorithms. In addition, to enable full-core simulation using unstructured mesh MOC, several new algorithms are developed, including reactor mesh generation, sparse parallel communication, parallel cyclic track generation, and weighted partitioning. Within this work MOCkingbird and SMART are tested for scalability from 10 to 20,000 cores on the Lemhi supercomputer at Idaho National Laboratory. Accuracy is tested using a suite of benchmarks that ultimately culminate in a first-of-a-kind, 3D, full-core, simulation of the BEAVRS benchmark using unstructured mesh MOC.

Download or read book Reactor Physics For Developing Countries And Nuclear Spectroscopy Research written by Klaus-peter Lieb and published by World Scientific. This book was released on 1986-12-01 with total page 777 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Editors' Foreword (G Medrano & K P Lieb)Introduction (G Violini)Principles of Nuclear Reactor Physics (R Caro)Lectures on Neutron Transport Theory (P Benoist)Reactor Physics in India (B P Rastogi)On the Solution of Some Nuclear and Energy Problems Using Optimal Control Theory (E Rofman)A Teaching, Training and Research Reactor: Argentine Reactor No 6(J Lokch)The Modular High Temperature Gas Cooled Reactor: A New Approach in Reactor Design (G Lohnert)A Nuclear Power Reactor Concept for Developing Countries (F Sefidvash)Nuclear Physics with Neutrons (K Schreokenbaoh)Electromagnetic Moments of High-Spin States in Medium-Mass Nuclei (K P Lieb)Hypernuclei (Jr Bevtini)Round Table on Nuclear Reactors and Developing Countries (G Medrano) Readership: Graduate students and researchers in nuclear physics, and nuclear engineers.

Download or read book Random Processes in Nuclear Reactors written by M. M. R. Williams and published by Elsevier. This book was released on 2013-10-22 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Random Processes in Nuclear Reactors describes the problems that a nuclear engineer may meet which involve random fluctuations and sets out in detail how they may be interpreted in terms of various models of the reactor system. Chapters set out to discuss topics on the origins of random processes and sources; the general technique to zero-power problems and bring out the basic effect of fission, and fluctuations in the lifetime of neutrons, on the measured response; the interpretation of power reactor noise; and associated problems connected with mechanical, hydraulic and thermal noise sources. The book will be very useful to nuclear engineers.

Download or read book Fractional order Modeling of Nuclear Reactor From Subdiffusive Neutron Transport to Control oriented Models written by Vishwesh Vyawahare and published by Springer. This book was released on 2018-02-03 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the topic of fractional-order modeling of nuclear reactors. Approaching neutron transport in the reactor core as anomalous diffusion, specifically subdiffusion, it starts with the development of fractional-order neutron telegraph equations. Using a systematic approach, the book then examines the development and analysis of various fractional-order models representing nuclear reactor dynamics, ultimately leading to the fractional-order linear and nonlinear control-oriented models. The book utilizes the mathematical tool of fractional calculus, the calculus of derivatives and integrals with arbitrary non-integer orders (real or complex), which has recently been found to provide a more compact and realistic representation to the dynamics of diverse physical systems. Including extensive simulation results and discussing important issues related to the fractional-order modeling of nuclear reactors, the book offers a valuable resource for students and researchers working in the areas of fractional-order modeling and control and nuclear reactor modeling.

Download or read book Investigation of Stochastic Radiation Transport Methods in Random Heterogeneous Mixtures written by Dustin Ray Reinert and published by . This book was released on 2008 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the most formidable challenges facing our world is the need for safe, clean, affordable energy sources. Growing concerns over global warming induced climate change and the rising costs of fossil fuels threaten conventional means of electricity production and are driving the current nuclear renaissance. One concept at the forefront of international development efforts is the High Temperature Gas-Cooled Reactor (HTGR). With numerous passive safety features and a meltdown-proof design capable of attaining high thermodynamic efficiencies for electricity generation as well as high temperatures useful for the burgeoning hydrogen economy, the HTGR is an extremely promising technology. Unfortunately, the fundamental understanding of neutron behavior within HTGR fuels lags far behind that of more conventional watercooled reactors. HTGRs utilize a unique heterogeneous fuel element design consisting of thousands of tiny fissile fuel kernels randomly mixed with a non-fissile graphite matrix. Monte Carlo neutron transport simulations of the HTGR fuel element geometry in its full complexity are infeasible and this has motivated the development of more approximate computational techniques. A series of MATLAB codes was written to perform Monte Carlo simulations within HTGR fuel pebbles to establish a comprehensive understanding of the parameters under which the accuracy of the approximate techniques diminishes. This research identified the accuracy of the chord length sampling method to be a function of the matrix scattering optical thickness, the kernel optical thickness, and the kernel packing density. Two new Monte Carlo methods designed to focus the computational effort upon the parameter conditions shown to contribute most strongly to the overall computational error were implemented and evaluated. An extended memory chord length sampling routine that recalls a neutron's prior material traversals was demonstrated to be effective in fixed source calculations containing densely packed, optically thick kernels. A hybrid continuous energy Monte Carlo algorithm that combines homogeneous and explicit geometry models according to the energy dependent optical thickness was also developed. This resonance switch approach exhibited a remarkably high degree of accuracy in performing criticality calculations. The versatility of this hybrid modeling approach makes it an attractive acceleration strategy for a vast array of Monte Carlo radiation transport applications.

Download or read book Selected basic techniques v 3 The physics of intermediate spectrum reactors Ed J R Stehn written by U.S. Atomic Energy Commission. Division of Reactor Development and published by . This book was released on 1959 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Random Noise Techniques in Nuclear Reactor Systems written by Robert E. Uhrig and published by . This book was released on 1970 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variational Methods in Nuclear Reactor Physics written by Weston M. Jr. Stacey and published by Elsevier. This book was released on 2012-12-02 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear Science and Technology, Volume 10: Variational Methods in Nuclear Reactor Physics presents the mathematical methods of a variational origin that are useful in obtaining approximate solutions to science and engineering problems. This book is composed of five chapters and begins with a discussion on the variation principles for physical systems described by both inhomogeneous and homogeneous equations to develop a generalized perturbation theory. Chapter 2 deals with the applications of variational estimates and generalized perturbation theory to neutron transport problems. Chapter 3 covers the variation principles of the Lagrangian form that are constructed for a general, linear- time-dependent process and for the specific case of the P1 neutron kinetics equations. Chapter 4 presents the general procedure for the variational derivation of synthesis approximations and their applications to problems in reactor physics. This chapter also examines the relationship of the spatial synthesis and finite-element method and a hybrid method that combines features of both methods. Chapter 5 describes the relationship of variation theory with the Hamilton-Jacobi theory and with the optimization theories of the maximum principle and dynamic programming. Nuclear physicists and researchers will find this text invaluable.

Download or read book Computing Methods in Reactor Physics written by Harold Greenspan and published by . This book was released on 1968 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced High Fidelity Reactor Simulators Based on Neutron Transport and Subchannel Methodologies written by Miriam Knebel and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Progress in Reactor Physics written by Virgil W. Lower and published by . This book was released on 1969 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimal Shutdown Control of Nuclear Reactors by Milton Ash written by and published by Elsevier. This book was released on 1966-01-01 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;methods for low-rank matrix approximations; hybrid methods based on a combination of iterative procedures and best operator approximation; andmethods for information compression and filtering under condition that a filter model should satisfy restrictions associated with causality and different types of memory.As a result, the book represents a blend of new methods in general computational analysis,and specific, but also generic, techniques for study of systems theory ant its particularbranches, such as optimal filtering and information compression. - Best operator approximation,- Non-Lagrange interpolation,- Generic Karhunen-Loeve transform- Generalised low-rank matrix approximation- Optimal data compression- Optimal nonlinear filtering

Download or read book Mathematical methods in Nuclear reactor Dynamics written by Ziya Akcasuh and published by Elsevier. This book was released on 2012-12-02 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical Methods in Nuclear Reactor Dynamics covers the practical and theoretical aspects of point-reactor kinetics and linear and nonlinear reactor dynamics. The book, which is a result of the lectures given at the University of Michigan, is composed of seven chapters. The opening chapter of the book describes various physical phenomena influencing the temporal behavior of neutrons to provide insights into the physics of reactor dynamics and the interrelationships between various diverse phenomena. The text then presents a set of equations, called point kinetic equation, which describes the time behavior of the total power generated in the medium. The book also provides a short discussion on Gyftopoulos modification and Becker’s formulation. The next chapters explore the exact methods for solving the feedback-free point kinetic equations for a number of reactivity insertions and the validity of the various approximate methods of solution. The book also examines the derivation of models for a certain reactor type and briefly discusses the validity of these models in certain cases against experimental data. A chapter focuses on a concise presentation of the stability theory of linear systems with feedback. Lastly, the concepts of stability in nonlinear reactor systems and the criteria for asymptotic stability in the large as well as in a finite domain of initial disturbances are covered in the concluding chapter. The text is an ideal source for nuclear engineers and for those who have adequate background in reactor physics and operational and applied mathematics.

Download or read book Simulation Studies of Recombination Kinetics and Spin Dynamics in Radiation Chemistry written by Amit Agarwal and published by Springer Science & Business. This book was released on 2014-04-23 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amit Agarwal’s thesis reports a substantial contribution to the microscopic simulation of radiation chemical reactions. In his research Agarwal extends existing models to further understand scavenging, spin and relaxation effects. This research has advanced the development of both the Monte Carlo Random Flights and the Independent Reaction Times (IRT) simulation tools. Particular highlights are the extension of these tools to include both the spin-exchange interaction and spin relaxation, both of which are influential in radiolytic systems where many reactions are spin-controlled. In addition, the study has led to the discovery of a novel correlation of the scavenging rate with the recombination time in low permittivity solvents. This finding goes against existing assumptions underlying the theory of diffusion kinetics while still being accommodated in the IRT method which demonstrates the power of this unconventional approach. The work in this thesis can be applied to a wide number of fields including the nuclear industry, medicine, food treatment, polymer curing, the preparation of nano-colloids, power generation and waste disposal.

Download or read book Reactor Physics Calculations For Applications In Nuclear Technology Proceedings Of The Workshop written by Dermott E Cullen and published by World Scientific. This book was released on 1991-01-30 with total page 757 pages. Available in PDF, EPUB and Kindle. Book excerpt: This workshop was designed to meet the needs of those currently involved in or are planning a nuclear programme involving research and/or power fission reactors. The workshop had a broad scope including not only fission reactor core calculations, but also safety, fuel management, waste disposal reactor licensing. The lectures and computer exercises covered almost all aspects of the operation of fission reactors.This workshop introduced participants to the methods currently used in fission reactor calculations and to some computer codes in which these methods are used.