Resonance Self Shielding Calculation Methods In Nuclear Reactors

Resonance Self-Shielding Calculation Methods in Nuclear Reactors presents the latest progress in resonance self-shielding methods for both deterministic and Mote Carlo methods, including key advances over the last decade such as high-fidelity resonance treatment, resonance interference effect and multi-group equivalence. As the demand for high-fidelity resonance self-shielding treatment is increasing due to the rapid development of advanced nuclear reactor concepts and progression in high performance computational technologies, this practical book guides students and professionals in nuclear engineering and technology through various methods with proven high precision and efficiency. Presents a collection of resonance self-shielding methods, as well as numerical methods and numerical results Includes new topics in resonance self-shielding treatment Provides source codes of key calculations presented

In the simulation of the behavior of neutrons in a nuclear reactor, there has long been a dichotomy in solution techniques. One can use Monte Carlo methods, known to be very accurate and problem agnostic but also very costly, or deterministic methods, known to be more computationally efficient but also requiring tuning to a specific application. As designers rely more and more heavily on predictive simulation, higher fidelity and more problem agnostic deterministic methods are desired. This thesis seeks to push these deterministic methods towards that goal of higher fidelity in the context of multigroup cross section generation and resonance self-shielding. This work has two primary objectives: to quantitatively assess the efficacy of current self-shielding approximations and to propose new self-shielding methods. These objectives are cast primarily in the context of mutual self-shielding, the effect of one nuclide's resonances on the neutron reaction rate with another nuclide. The first objective is accomplished through the development of a framework for the evaluation of self-shielding methods. This framework is analogous to a unit test suite in software engineering, in that specific aspects of physics modeled by a self-shielding method are isolated. The framework is used on numerous existing methods, and highlights the successes and failures of these methods on very simple problems. This objective is also accomplished via an analysis of the consequences of neglecting the angular dependence of multigroup cross sections in the solution to the multigroup neutron transport equation. The second objective is accomplished by proposing two new methods: the subgroup method with interference cross sections and ultrafine with simplified scattering. The former uses a fitting method to find the effect of interfering nuclides on the subgroup levels of a primary nuclide, allowing mutual self-shielding effects to be treated natively inside the subgroup method without increasing algorithmic complexity. The latter is a hybrid of the subgroup method and ultrafine methods, using an ultrafine energy mesh on the left hand side of the transport equation with the scatter source of the subgroup method on the right hand side. These two methods are tested in the context of the evaluation framework alongside classical methods. Although it shows promise on some simple problems, the subgroup method with interference cross sections was seen to exhibit shortcomings on problems with many nuclides. Ultrafine with simplified scattering was found to perform very well on all problems in the test suite.

A nuclear reactor operates in an environment where complex multi-physics and multi-scale phenomena exist, and it requires consideration of coupling among neutronics, thermal hydraulics, fuel performance, chemical dynamics, and coupling between the reactor core and first circuit. Safe, reliable, and economical operation can be achieved by leveraging high-fidelity numerical simulation, and proper considerations for coupling among different physics and required to provide powerful numerical simulation tools. In the past simplistic models for some of the physics phenomena are used, with the recent development of advanced numerical methods, software design, and high-performance computing power, the appeal of multi-physics and multi-scale modeling and simulation has been broadened.

Computational Methods in Reactor Shielding deals with the mathematical processes involved in how to effectively control the dangerous effect of nuclear radiation. Reactor shielding is considered an important aspect in the operation of reactor systems to ensure the safety of personnel and others that can be directly or indirectly affected. Composed of seven chapters, the book discusses ionizing radiation and how it aids in the control and containment of radioactive substances that are considered harmful to all living things. The text also outlines the necessary radiation quantities and units that are needed for a systemic control of shielding and presents an examination of the main sources of nuclear radiation. A discussion of the gamma photon cross sections and an introduction to BMIX, a computer program used in illustrating a technique in identifying the gamma ray build-up factor for a reactor shield, are added. The selection also discusses various mathematical representations and areas of shielding theory that are being used in radiation shielding. The book is of great value to those involved in the development and implementation of systems to minimize and control the dangerous and lethal effect of radiation.

Physics of Nuclear Reactors presents a comprehensive analysis of nuclear reactor physics. Editors P. Mohanakrishnan, Om Pal Singh, and Kannan Umasankari and a team of expert contributors combine their knowledge to guide the reader through a toolkit of methods for solving transport equations, understanding the physics of reactor design principles, and developing reactor safety strategies. The inclusion of experimental and operational reactor physics makes this a unique reference for those working and researching nuclear power and the fuel cycle in existing power generation sites and experimental facilities. The book also includes radiation physics, shielding techniques and an analysis of shield design, neutron monitoring and core operations. Those involved in the development and operation of nuclear reactors and the fuel cycle will gain a thorough understanding of all elements of nuclear reactor physics, thus enabling them to apply the analysis and solution methods provided to their own work and research. This book looks to future reactors in development and analyzes their status and challenges before providing possible worked-through solutions. Cover image: Kaiga Atomic Power Station Units 1 – 4, Karnataka, India. In 2018, Unit 1 of the Kaiga Station surpassed the world record of continuous operation, at 962 days. Image courtesy of DAE, India. Includes methods for solving neutron transport problems, nuclear cross-section data and solutions of transport theory Dedicates a chapter to reactor safety that covers mitigation, probabilistic safety assessment and uncertainty analysis Covers experimental and operational physics with details on noise analysis and failed fuel detection