Download or read book Inhibition of Oxidation in Nuclear Graphite written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphite is a fundamental material of high temperature gas cooled nuclear reactors, providing both structure and neutron moderation. Its high thermal conductivity, chemical inertness, thermal heat capacity, and high thermal structural stability under normal and off normal conditions contribute to the inherent safety of these reactor designs. One of the primary safety issues for a high temperature graphite reactor core is the possibility of rapid oxidation of the carbon structure during an off normal design basis event where an oxidizing atmosphere (air ingress) can be introduced to the hot core. Although the current Generation IV high temperature reactor designs attempt to mitigate any damage caused by a postualed air ingress event, the use of graphite components that inhibit oxidation is a logical step to increase the safety of these reactors. Recent experimental studies of graphite containing between 5.5 and 7 wt% boron carbide (B4C) indicate that oxidation is dramatically reduced even at prolonged exposures at temperatures up to 900°C. The proposed addition of B4C to graphite components in the nuclear core would necessarily be enriched in B-11 isotope in order to minimize B-10 neutron absorption and graphite swelling. The enriched boron can be added to the graphite during billet fabrication. Experimental oxidation rate results and potential applications for borated graphite in nuclear reactor components will be discussed.
Download or read book Evaluation of Chlorine Inhibition of Graphite Oxidation as a Gas cooled Reactor Safeguard written by R. E. Dahl and published by . This book was released on 1961 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Graphite written by R. E. Nightingale and published by Academic Press. This book was released on 2013-10-02 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear Graphite focuses on the development and uses of nuclear graphite, including machining practices, manufacture, nuclear properties and structure, radiation, and electrical resistance. The selection first discusses the applications of graphite in the nuclear industry, machining practices, and manufacture. Discussions focus on early, current, and future applications of graphite, impregnation, graphitization, purification, general machining techniques, and equipment and methods in the nuclear industry. The book then examines the structure and nuclear and properties of graphite. The text evaluates radiation-induced structural and dimensional changes; radiation effects on electrical and thermal properties; and radiation effects on mechanical properties. Topics include radiation effects on crystal structure, electrical resistance, thermoelectric power, magnetoresistance, coefficient of friction, irradiation under stress, and elastic moduli of nuclear graphite. The book also ponders on stored energy, annealing radiation effects, and gas-graphite systems. The selection is a dependable source of data for readers interested in the applications of nuclear graphite.
Download or read book The Radiolytic Oxidation of Graphite in Carbon Dioxide cooled Nuclear Reactors written by P. Campion and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation Damage in Graphite written by J. H. W. Simmons and published by Elsevier. This book was released on 2013-10-22 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear Energy, Volume 102: Radiation Damage in Graphite provides a general account of the effects of irradiation on graphite. This book presents valuable work on the structure of the defects produced in graphite crystals by irradiation. Organized into eight chapters, this volume begins with an overview of the description of the methods of manufacturing graphite and of its physical properties. This text then presents details of the method of setting up a scale of irradiation dose. Other chapters consider the effect of irradiation at a given temperature on a physical property of graphite. This book discusses as well the changes in dimensions produced by irradiation and the effects of irradiation on the mechanical properties of graphite. The final chapter deals with the accumulation of stored energy, which is one of the main problems caused by the irradiation of graphite in nuclear reactors. This book is a valuable resource for physicists and chemical physicists.
Download or read book Oxidation Resistant Graphite Studies written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.
Download or read book Effects of Oxidation on Oxidation Resistant Graphite written by and published by . This book was released on 2015 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.
Download or read book Nuclear Safety written by and published by . This book was released on 1959 with total page 1750 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975-06 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxidation of Graphite Under High Temperature Reactor Conditions written by R. E. Dahl and published by . This book was released on 1961 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1982 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Reacting Surface Density on the Overall Graphite Oxidation Rate written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphite oxidation in an air-ingress accident is presently a very important issue for the reactor safety of the very high temperature gas cooled-reactor (VHTR), the concept of the next generation nuclear plant (NGNP) because of its potential problems such as mechanical degradation of the supporting graphite in the lower plenum of the VHTR might lead to core collapse if the countermeasure is taken carefully. The oxidation process of graphite has known to be affected by various factors, including temperature, pressure, oxygen concentration, types of graphite, graphite shape and size, flow distribution, etc. However, our recent study reveals that the internal pore characteristics play very important roles in the overall graphite oxidation rate. One of the main issues regarding graphite oxidation is the potential core collapse problem that may occur following the degradation of graphite mechanical strength. In analyzing this phenomenon, it is very important to understand the relationship between the degree of oxidization and strength degradation. In addition, the change of oxidation rate by graphite oxidation degree characterization by burn-off (ratio of the oxidized graphite density to the original density) should be quantified because graphite strength degradation is followed by graphite density decrease, which highly affects oxidation rates and patterns. Because the density change is proportional to the internal pore surface area, they should be quantified in advance. In order to understand the above issues, the following experiments were performed: (1)Experiment on the fracture of the oxidized graphite and validation of the previous correlations, (2) Experiment on the change of oxidation rate using graphite density and data collection, (3) Measure the BET surface area of the graphite. The experiments were performed using H451 (Great Lakes Carbon Corporation) and IG-110 (Toyo Tanso Co., Ltd) graphite. The reason for the use of those graphite materials is because their chemical and mechanical characteristics are well identified by the previous investigations, and therefore it was convenient for us to access the published data, and to apply and validate our new methodologies. This paper presents preliminary results of compressive strength vs. burn-off and surface area density vs. burn-off, which can be used for the nuclear graphite selection for the NGNP.
Download or read book Effect of Prestress and Stress on the Strength and Oxidation Rate of Nuclear Graphite written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of prestress or stress during oxidation on the reactivities and strengths of PGX and H451 graphites were examined at oxidation temperatures of 450 to 600°C in air and 550 to 750°C in 2% H2O/He. Little or no effect of compressive prestress at stress levels of up to 75% of the mean fracture strengths, was found. A small effect on the reactivity of H451 graphite was observed in the case of 2% H2O/He, i.e., the rate was enhanced by no more than 30% for compressive prestress levels of up to 90% of the fracture strength. Tensile and compressive stresses during oxidation did not affect the reactivities of these graphites at stress levels of up to 28% of the mean compressive strength and 35% of the mean tensile strength for H451 graphite, and 44% and 56% for PGX graphite, respectively. 13 refs., 18 figs.
Download or read book A Study of the Effects of Irradiation and Radiolytic Oxidation of the Pore level Structure of Gilsocarbon Nuclear Graphite written by Katie Jones and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1970 with total page 1338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Nuclear Materials written by and published by Elsevier. This book was released on 2020-07-22 with total page 4871 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials in a nuclear environment are exposed to extreme conditions of radiation, temperature and/or corrosion, and in many cases the combination of these makes the material behavior very different from conventional materials. This is evident for the four major technological challenges the nuclear technology domain is facing currently: (i) long-term operation of existing Generation II nuclear power plants, (ii) the design of the next generation reactors (Generation IV), (iii) the construction of the ITER fusion reactor in Cadarache (France), (iv) and the intermediate and final disposal of nuclear waste. In order to address these challenges, engineers and designers need to know the properties of a wide variety of materials under these conditions and to understand the underlying processes affecting changes in their behavior, in order to assess their performance and to determine the limits of operation. Comprehensive Nuclear Materials, Second Edition, Seven Volume Set provides broad ranging, validated summaries of all the major topics in the field of nuclear material research for fission as well as fusion reactor systems. Attention is given to the fundamental scientific aspects of nuclear materials: fuel and structural materials for fission reactors, waste materials, and materials for fusion reactors. The articles are written at a level that allows undergraduate students to understand the material, while providing active researchers with a ready reference resource of information. Most of the chapters from the first Edition have been revised and updated and a significant number of new topics are covered in completely new material. During the ten years between the two editions, the challenge for applications of nuclear materials has been significantly impacted by world events, public awareness, and technological innovation. Materials play a key role as enablers of new technologies, and we trust that this new edition of Comprehensive Nuclear Materials has captured the key recent developments. Critically reviews the major classes and functions of materials, supporting the selection, assessment, validation and engineering of materials in extreme nuclear environments Comprehensive resource for up-to-date and authoritative information which is not always available elsewhere, even in journals Provides an in-depth treatment of materials modeling and simulation, with a specific focus on nuclear issues Serves as an excellent entry point for students and researchers new to the field
Download or read book Introduction to Carbon Science written by Ian A. S. Edwards and published by Butterworth-Heinemann. This book was released on 2013-10-22 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Carbon Science deals with various aspects of carbon science, from polymer science and prosthetics to crystallography, carbonization, spectroscopy, and surface science. Topics covered include the mechanisms of formation of isotropic and anisotropic carbons, physical properties of pitch relevant to the fabrication of carbon materials; kinetics and catalysis of carbon gasification; and porosity in carbons and graphites. Carbon fibers, cokes and composites, and coal to coke transformations are also discussed. This book is comprised of nine chapters and begins with an overview of the basic structural features of carbon materials, along with definitions of the various carbon forms encountered in carbon science. The principal techniques for studying the structure of solid carbons are also considered. The reader is then introduced to the mechanisms underlying the formation of isotropic and anisotropic carbons; the physicochemical changes that take place when pitch is pyrolyzed to carbon; and kinetics and catalysis of carbon gasification reactions. The following chapters explore various types of porosity in carbons and graphites; manufacture, properties, structure, and applications of carbon fibers; and mechanical properties of cokes and composites. This text concludes by describing the conversion of coal to coke. This monograph will be of interest to carbon scientists, technologists, and engineers, as well as those entering the field of carbon science for the first time.
