Multiphysics in Nuclear Science and Engineering Books

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Modelling of Nuclear Reactor Multi physics


Modelling of Nuclear Reactor Multi physics
  • Author : Christophe Demazière
  • Publisher : Academic Press
  • Release : 2019-11-19
  • ISBN : 9780128150702
  • Language : En, Es, Fr & De
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Modelling of Nuclear Reactor Multiphysics: From Local Balance Equations to Macroscopic Models in Neutronics and Thermal-Hydraulics is an accessible guide to the advanced methods used to model nuclear reactor systems. The book addresses the frontier discipline of neutronic/thermal-hydraulic modelling of nuclear reactor cores, presenting the main techniques in a generic manner and for practical reactor calculations. The modelling of nuclear reactor systems is one of the most challenging tasks in complex system modelling, due to the many different scales and intertwined physical phenomena involved. The nuclear industry as well as the research institutes and universities heavily rely on the use of complex numerical codes. All the commercial codes are based on using different numerical tools for resolving the various physical fields, and to some extent the different scales, whereas the latest research platforms attempt to adopt a more integrated approach in resolving multiple scales and fields of physics. The book presents the main algorithms used in such codes for neutronic and thermal-hydraulic modelling, providing the details of the underlying methods, together with their assumptions and limitations. Because of the rapidly expanding use of coupled calculations for performing safety analyses, the analysists should be equally knowledgeable in all fields (i.e. neutron transport, fluid dynamics, heat transfer). The first chapter introduces the book’s subject matter and explains how to use its digital resources and interactive features. The following chapter derives the governing equations for neutron transport, fluid transport, and heat transfer, so that readers not familiar with any of these fields can comprehend the book without difficulty. The book thereafter examines the peculiarities of nuclear reactor systems and provides an overview of the relevant modelling strategies. Computational methods for neutron transport, first at the cell and assembly levels, then at the core level, and for one-/two-phase flow transport and heat transfer are treated in depth in respective chapters. The coupling between neutron transport solvers and thermal-hydraulic solvers for coarse mesh macroscopic models is given particular attention in a dedicated chapter. The final chapter summarizes the main techniques presented in the book and their interrelation, then explores beyond state-of-the-art modelling techniques relying on more integrated approaches. Covers neutron transport, fluid dynamics, and heat transfer, and their interdependence, in one reference Analyses the emerging area of multi-physics and multi-scale reactor modelling Contains 71 short videos explaining the key concepts and 77 interactive quizzes allowing the readers to test their understanding

Nuclear Reactor Multiphysics Via Bond Graph Formalism


Nuclear Reactor Multiphysics Via Bond Graph Formalism
  • Author : Eugeny Sosnovsky
  • Publisher :
  • Release : 2014
  • ISBN : OCLC:895647656
  • Language : En, Es, Fr & De
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This work proposes a simple and effective approach to modeling nuclear reactor multiphysics problems using bond graphs. Conventional multiphysics simulation paradigms normally use operator splitting, which treats the individual physics separately and exchanges the information at every time step. This approach has limited accuracy, and so recently, there has been an increased interest in fully coupled physics simulation. The bond graph formalism has recently been suggested as a potential paradigm for reactor multiphysics simulation; this work develops the tools necessary to utilize bond graphs for practical transient reactor analysis. The bond graph formalism was first introduced to solve the multiphysics problem in electromechanical systems. Over the years, it has been used in many fields including nuclear engineering, but with limited scope due to its perceived impracticality in large systems. Bond graph formalism works by first representing a discretized multiphysics system using a group of graph elements, connected with bonds; the bonds transport conserved quantities, and the elements impose the relations between them. The representation can be automatically converted into a state derivative vector, which can be integrated in time. In an earlier work, the bond graph formalism was first applied to neutron diffusion, and coupled to diffusive heat transfer in a 1D slab reactor. In this work, methods are developed to represent, using bond graphs, 2D and 3D multigroup neutron diffusion with precursors, nonlinear point kinetics, and basic nearly-incompressible 1D flow for fully coupled reactor simulation. High-performance, matrix-based bond graph processing methods were developed to support the simulation of medium- and large-scale problems. A pressurized water reactor point kinetics, single-channel rod ejection benchmark problem was used to verify the nonlinear point kinetics representation. 2D and 3D boiling water reactor control blade drop problems were also successfully simulated with the matrix-based bond graph processing code. The code demonstrated 3rd-order convergence in time, a very desirable property of fully coupled time integrators.

BERRU Predictive Modeling


BERRU Predictive Modeling
  • Author : Dan Gabriel Cacuci
  • Publisher : Springer
  • Release : 2018-12-29
  • ISBN : 9783662583951
  • Language : En, Es, Fr & De
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This book addresses the experimental calibration of best-estimate numerical simulation models. The results of measurements and computations are never exact. Therefore, knowing only the nominal values of experimentally measured or computed quantities is insufficient for applications, particularly since the respective experimental and computed nominal values seldom coincide. In the author’s view, the objective of predictive modeling is to extract “best estimate” values for model parameters and predicted results, together with “best estimate” uncertainties for these parameters and results. To achieve this goal, predictive modeling combines imprecisely known experimental and computational data, which calls for reasoning on the basis of incomplete, error-rich, and occasionally discrepant information. The customary methods used for data assimilation combine experimental and computational information by minimizing an a priori, user-chosen, “cost functional” (usually a quadratic functional that represents the weighted errors between measured and computed responses). In contrast to these user-influenced methods, the BERRU (Best Estimate Results with Reduced Uncertainties) Predictive Modeling methodology developed by the author relies on the thermodynamics-based maximum entropy principle to eliminate the need for relying on minimizing user-chosen functionals, thus generalizing the “data adjustment” and/or the “4D-VAR” data assimilation procedures used in the geophysical sciences. The BERRU predictive modeling methodology also provides a “model validation metric” which quantifies the consistency (agreement/disagreement) between measurements and computations. This “model validation metric” (or “consistency indicator”) is constructed from parameter covariance matrices, response covariance matrices (measured and computed), and response sensitivities to model parameters. Traditional methods for computing response sensitivities are hampered by the “curse of dimensionality,” which makes them impractical for applications to large-scale systems that involve many imprecisely known parameters. Reducing the computational effort required for precisely calculating the response sensitivities is paramount, and the comprehensive adjoint sensitivity analysis methodology developed by the author shows great promise in this regard, as shown in this book. After discarding inconsistent data (if any) using the consistency indicator, the BERRU predictive modeling methodology provides best-estimate values for predicted parameters and responses along with best-estimate reduced uncertainties (i.e., smaller predicted standard deviations) for the predicted quantities. Applying the BERRU methodology yields optimal, experimentally validated, “best estimate” predictive modeling tools for designing new technologies and facilities, while also improving on existing ones.

Investigation of Bond Graphs for Nuclear Reactor Simulations


Investigation of Bond Graphs for Nuclear Reactor Simulations
  • Author : Eugeny Sosnovsky
  • Publisher :
  • Release : 2010
  • ISBN : OCLC:714610493
  • Language : En, Es, Fr & De
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This work proposes a simple and effective approach to modeling multiphysics nuclear reactor problems using bond graphs. The conventional method of modeling the coupled multiphysics transients in nuclear reactors is operator splitting, which treats the single physics individually and exchanges the information at every time step. This approach has limited accuracy, and so there is interest in the development of methods for fully coupled physics simulation. The bond graph formalism was first introduced to solve the multiphysics problem in electromechanical systems. Over the years, it has been used in many fields including nuclear engineering, but with limited scope due to its perceived impracticality in large systems. In this work, the bond graph formalism is for the first time applied to neutron transport, and coupled to heat transfer in a nuclear reactor. Fully coupled 1D diffusion reaction model is derived using bond graphs, and the transient solution obtained using a proof-of-concept bond graph processing code. The bond graph-based approach to coupled nuclear reactor simulation was shown to be accurate and stable. Suggestions are made for the expansion of the approach to larger problems and higher fidelity simulations.

Fusion Neutronics


Fusion Neutronics
  • Author : Yican Wu
  • Publisher : Springer
  • Release : 2017-08-16
  • ISBN : 9789811054693
  • Language : En, Es, Fr & De
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This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronic characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics. Further, it introduces readers to the unique principles and procedures of neutronics design, experimental methodologies and methodologies for fusion systems. The book not only highlights the latest advances and trends in the field, but also draws on the experiences and skills collected in the author’s more than 40 years of research. To make it more accessible and enhance its practical value, various representative examples are included to illustrate the application and efficiency of the methods, designs and experimental techniques discussed.