Download or read book Role of Iron for Hydrogen Absorption Mechanism in Zirconium Alloys written by K. Kakiuchi and published by . This book was released on 2004 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD (Contact Potential Difference) and FBP (Flat-band Potential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi.

Download or read book Oxidation and the Testing of Turbine Oils written by Cyril A. Migdal and published by ASTM International. This book was released on 2008 with total page 929 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents papers from a December 2005 symposium held in Norfolk, Virginia, and sponsored by ASTM Committee D2 on Petroleum Products and Lubricants and its Subcommittees D02.09 on Oxidation and D02.C0 on Turbine Oils. Contributors include equipment manufacturers, end users, lubricant producers, lubricant additive suppliers, test equipment manufacturers, and standard test method developers. They share information on industry trends, evolving technologies, and changing equipment designs and operating conditions, with a focus on how these factors impact oxidation. Some topics covered include turbine oil performance limits, a new form of the rotating pressure vessel oxidation test, and degradation mechanisms leading to sludge and varnish in modern turbine oil formulations. B&w photos are included. There is no subject index. Migdal is affiliated with Chemtura Corporation.

Download or read book The Role of Nickel in Hydrogen Pick up During In reactor Corrosion of Zirconium Alloys written by Aditya Shivprasad and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen pick-up of zirconium-based fuel cladding and structural materials duringin-reactor corrosion can degrade fuel component performance in existing light waterreactors (LWRs) and advanced nuclear reactors, such as the LWR-like supercriticalwater reactors (SCWRs), as the ingress of corrosion hydrogen can lead to the formationof brittle hydrides. In the boiling water reactor (BWR) environment, Zircaloy-2 fuelcladding and reactor core components, such as water rods and channel boxes, canexperience accelerated hydrogen pick-up (higher pickup fraction) at high burnup whenexposed for one extra 24-month cycle, while Zircaloy-4 components under similarconditions do not. Because the principal difference between the two alloys is thatZircaloy-2 contains nickel, this accelerated hydrogen pick-up has been hypothesizedto result from the presence of nickel and its role in the corrosion process whenincorporated into the protective oxide layer.Zircaloy-2 and Zircaloy-4 sister samples were corroded in 360 _C water and anadditional set of Zircaloy-2 samples was corroded in 400 _C steam. Total weightgain, assumed to be due mostly to oxygen, and hydrogen content were measured asfunctions of exposure time. The results indicate that Zircaloy-2 samples absorbed morehydrogen than did Zircaloy-4 samples on the basis of total weight gain (hydrogen pickupfraction), though both exhibited similar corrosion kinetics parameters. Microbeamsynchrotron radiation X-ray absorption near-edge spectroscopy (XANES) of selectedZircaloy-2 samples at the Advanced Photon Source (APS) was used to probe theoxidation states of nickel and iron in these materials and understand the evolutionof the oxidation states of these alloying elements as functions of distance from theoxide/metal interface. Result showed that a significant fraction of nickel atomsremained metallic upon incorporation in the oxide layer. In contrast, iron atomsoxidized much earlier than did nickel atoms and, in most cases, fully oxidized withinseveral micrometers from the oxide/metal interface. A general hypothesis was madethat metallic nickel in contact with the coolant may catalyze the surface reactionsinvolved in the hydrogen pick-up mechanism.To understand accelerated hydrogen pick-up of certain Zircaloy-2 samples at highburn-up, additional XANES examinations were performed on Zircaloy-2 water rodsexposed in-reactor to high burn-up in commercial BWRs. The first set of samples wascorroded in the Limerick-1 reactor, while the second set was corroded in the Dresden-2reactor. Within each set of samples, fluences, oxide thicknesses, and sample elevationswere similar, but hydrogen pick-up fractions were vastly different. In the first setof samples, oxide thicknesses ranged from 28 - 35 m, but hydrogen pick-up rangedbetween 15 and 51%. In the second set of samples, oxide thicknesses ranged between3.5 m and 16 m, but hydrogen pick-up ranged from 28 - 69%. All samples wereirradiated to fluences between 9.4 and 13.1 1021 n/cm2 for neutron energies above1 MeV. Results of XANES examinations showed a similar correlation between thedelayed oxidation of nickel and higher hydrogen pick-up of Zircaloy-2 at high burn-up.A significant fraction (greater than 30%) of nickel atoms were found to be in themetallic state in the porous oxide layer. It was hypothesized that this metallic nickelis responsible for enhancing hydrogen pick-up by catalyzing the surface reactions thataffect the overall hydrogen pick-up reaction. This would allow for easier absorptionof hydrogen into the protective oxide layer from the coolant. Ab initio modeling ofXANES of selected iron- and nickel-containing compounds was also performed andcompared to experimental results to help understand how different populations ofalloying elements oxidized upon incorporation into the oxide layer.A concurrent study of the microstructure of oxide layers formed on these sameirradiated water rods was performed to understand if there was a characteristicmicrostructure associated with accelerated hydrogen pick-up. Microbeam X-raydiffraction (XRD) at the APS was performed on water rod samples to study oxidetexture, phase content, and grain size. A similar examination was performed onsteam-corroded Zircaloy-2 to serve as a comparison. Results showed that the oxidelayers formed on these samples consisted primarily of highly-oriented monoclinic phasezirconium oxide with a small fraction of tetragonal phase oxide. Monoclinic phasegrains were shown to grow as a function of distance from the oxide/metal interface,while tetragonal phase grains remained a constant size, indicating a tetragonal-to-monoclinic phase transformation above a critical grain size of approximately 10 nm.The tetragonal phase fraction was also calculated and observed to maximize nearthe oxide/metal interface, coinciding with the appearance of the (002)-tetragonalphase diffraction reflection, which appeared to be highly-oriented and strained, butdisappeared away from the oxide/metal interface. Findings were consistent withprevious microbeam XRD examinations of oxide layers formed on Zircaloy-4 underautoclave conditions. Transmission XRD examinations were also performed on aselected steam-corroded sample to serve as an additional comparison.The observations presented in this study helped to propose a mechanism foroxidation of different populations of iron and nickel upon incorporation into theZircaloy-2 oxide layer and the effect on the hydrogen pick-up mechanism.

Download or read book Hydrogen Absorption Mechanism of Zirconium Alloys Based on Characterization of Oxide Layer written by K. Une and published by . This book was released on 2011 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of the Hydrogen Damage Mechanism in the Corrosion of Zirconium written by R. D. Misch and published by . This book was released on 1961 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: In complex alloys, cathodes may arise in a variety of ways and the corrosion resistance of the intermetallics may be of importance.

Download or read book Zirconium in the Nuclear Industry written by and published by . This book was released on 1998 with total page 976 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrogen Absorption in Zircaloy During Aqueous Corrosion written by E. Hillner and published by . This book was released on 1964 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Hydrogen Absorption by Zirconium Alloys written by Atomic Energy of Canada Limited and published by Chalk River, Ont. : Chalk River Nuclear Laboratories. This book was released on 1985 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrogen Pickup During Corrosion of Zirconium Alloys written by Warren E. Berry and published by . This book was released on 1959 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydriding of Zircaloy 2 written by Myra S. Feldman and published by . This book was released on 1963 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrogen Pickup Mechanism of Zirconium Alloys written by Adrien Couet and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the optimization of zirconium based alloys has led to significant improvements in hydrogen pickup and corrosion resistance, the mechanisms by which such alloy improvements occur are still not well understood. In an effort to understand such mechanisms, a systematic study of the alloy effect on hydrogen pickup is conducted, using advanced characterization techniques to rationalize precise measurements of hydrogen pickup. The hydrogen pick-up fraction is accurately measured for a specially designed set of commercial and model alloys to investigate the effects of alloying elements, microstructure and corrosion kinetics on hydrogen uptake. Two different techniques to measure hydrogen concentrations were used: a destructive technique, Vacuum Hot Extraction, and a non-destructive one, Cold Neutron Prompt Gamma Activation Analysis. The results indicate that hydrogen pickup varies not only from alloy to alloy but also during the corrosion process for a given alloy. For instance Zircaloy type alloys show high hydrogen pickup fraction and sub-parabolic oxidation kinetics whereas ZrNb alloys show lower hydrogen pickup fraction and close to parabolic oxidation kinetics. Hypothesis is made that hydrogen pickup result from the need to balance charge during the corrosion reaction, such that the pickup of hydrogen is directly related to (and indivisible of) the corrosion mechanism and decreases when the rate of electron transport or oxide electronic conductivity through the protective oxide increases. According to this hypothesis, alloying elements (either in solid solution or in precipitates) embedded in the oxide as well as space charge variations in the oxide would impact the hydrogen pick-up fraction by modifying electron transport, which drives oxidation and hydriding kinetics. Dedicated experiments and modelling were performed to assess and validate these hypotheses.In-situ electrochemical impedance spectroscopy (EIS) experiments were performed on Zircaloy-4 tubes to directly measure the evolution of oxide electronic conductivity as function of exposure time. The results show that oxide electronic conductivty decreases as function of exposure time and that its variations are directly correlated to the instantaneous hydrogen pickup fraction variations. The electron transport through the oxide layer is thus altered as the oxide grows, reasons for which are yet to be exactly determined. Preliminary results also show that oxide electronic conductivty of ZrNb alloys would be much higher compared with Zircaloy-4. Thus, it is confirmed that oxide electronic conductivity is a key parameter in the hydrogen and oxidation mechanism.Because the mechanism whereby alloying elements are incorporated into the oxide layer is critical to changing [sigma]_(e^-)^ox, the evolution of the oxidation state of two common alloying elements, Fe and Nb, when incorporated into the growing oxide layers is investigated using X-Ray Absorption Near-Edge Spectroscopy (XANES) using micro-beam synchrotron radiation on cross sectional oxide samples. The results show that the oxidation of both Fe and Nb is delayed in the oxide layer compared to that of Zr, and that this oxidation delay is related to the variations of the instantaneous hydrogen pick-up fraction with exposure time. The evolution of Nb oxidation as function of oxide depth is also compatible with space charge compensation in the oxide and with an increase in oxide electronic conductivity of ZrNb alloys compared to Zircaloys.Finally, various successively complex models from the well-known Wagner oxidation theory to the more complex effect of space charge on oxidation kinetics have been developed. The general purpose of the modeling effort is to provide a rationale for the sub-parabolic oxidation kinetics and demonstrate the correlation with hydrogen pickup fraction. It is directly demonstrated that parabolic oxidation kinetics is associated with high oxide electronic conductivity and low space charges in the oxide whereas sub-parabolic oxidation kinetics is associated with lower oxide electronic conductivity and higher space charge in the oxide.All these observations helped us to propose a general corrosion mechanism of zirconium alloys involving both oxidation and hydrogen pickup mechanism to better understand and predict the effect of alloying additions on the behavior of zirconium alloys.

Download or read book Proceedings of the USAEC Symposium on Zirconium Alloy Development Castlewood Pleasanton California November 12 14 1962 written by and published by . This book was released on 1962 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Zirconium in the Nuclear Industry written by Gerry D. Moan and published by ASTM International. This book was released on 2002 with total page 891 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation The 41 papers of this proceedings volume were first presented at the 13th symposium on Zirconium in the Nuclear Industry held in Annecy, France in June of 2001. Many of the papers are devoted to material related issues, corrosion and hydriding behavior, in-reactor studies, and the behavior and properties of Zr alloys used in storing spent fuel. Some papers report on studies of second phase particles, irradiation creep and growth, and material performance during loss of coolant and reactivity initiated accidents. Annotation copyrighted by Book News, Inc., Portland, OR.

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 Zirconium in the Nuclear Industry written by George P. Sabol and published by ASTM International. This book was released on 2000 with total page 953 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detrimental Role of Hydrogen on the Corrosion Rate of Zirconium Alloys written by M. Blat and published by . This book was released on 1996 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies have suggested that hydride precipitation at the metal/oxide interface could play a detrimental role on the waterside corrosion rate. Nevertheless, the mechanism of that detrimental role is not completely understood, and two hypotheses were investigated to understand the mechanism that controls the role of the hydrides. The first hypothesis is based on a mechanical effect: the hydrides precipitate at the metal/oxide interface and destroy the physical integrity of the "barrier" oxide layer. The second hypothesis is a modification of the transport properties of the oxide grown on the hydrided metal.

Download or read book Effects of Silicon Nitrogen and Oxygen on the Corrosion and Hydrogen Absorption Performance of Zircaloy 2 written by S. Kass and published by . This book was released on 1963 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: