Download or read book Effect of stress on hydride reorientation in zirconium alloys written by M. P. Puls and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components written by Manfred P. Puls and published by Springer Science & Business Media. This book was released on 2012-08-04 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the emphasis lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals. This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing how our understanding of DHC is supported by progress in general understanding of such broad fields as the study of hysteresis associated with first order phase transformations, phase relationships in coherent crystalline metallic solids, the physics of point and line defects, diffusion of substitutional and interstitial atoms in crystalline solids, and continuum fracture and solid mechanics. Furthermore, an account of current methodologies is given illustrating how such understanding of hydrogen, hydrides and DHC in zirconium alloys underpins these methodologies for assessments of real life cases in the Canadian nuclear industry. The all-encompassing approach makes The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Component: Delayed Hydride Cracking an ideal reference source for students, researchers and industry professionals alike.

Download or read book written by and published by . This book was released on 19?? with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Statistical Analysis of Hydride Reorientation Properties in Irradiated Zircaloy 2 written by S. Valance and published by . This book was released on 2011 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The orientation of hydrides in fuel cladding determines the anisotropic fracture behavior of Zircaloy and the failure modes of cladding tubes. Approach coupling experiments using the cladding tube deformation test and finite element analysis have successfully led to the quantification of the stress influencing reorientation of hydrides in unirradiated samples. An improved version of this procedure was applied to six samples of irradiated Zircaloy-2 from two different rods with three classes of thermo-mechanical loading. It was found that at medium maximum temperature, when no more than half of the hydrides were dissolved, the mechanical loading showed no measurable effect. When most of the hydrides were dissolved, the orientation and location of the hydrides depended strongly on the mechanical loading: The hydrides spatial location followed the hoop tensile stress. When the number of loading cycles was raised, the fraction of radial hydrides increased even for very low hoop tensile stress. The inner side of the cladding showed a marked depletion of hydrides whatever the size of the hoop stress. Since our test setup involved a tri-axial stress state, the possible influence of the other components of the stress tensor was evaluated. Through the use of a classical nucleation law, it was shown that for our test setup, the hoop stress was the important mechanical quantity. Therefore, the inner side depletion of hydrides may be attributed to three other factors: Residual stress, a memory effect, and a pumping effect by the inner liner.

Download or read book The Effect of Stress and Texture on the Morphology of Hydrides in Zirconium Alloys written by Douglas Enrique Cortes and published by . This book was released on 1985 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The stress reorientation of zirconium hydride in zircaloy 2 written by M. Farrow and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydride Reorientation and Fracture in Zirconium Alloys written by CJ. Simpson and published by . This book was released on 1977 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Under conditions of high tensile stress, the Zr-2.5Nb alloy has been shown to he susceptible to a very slow crack propagation failure mechanism. This failure mechanism, hydride cracking, has been studied extensively since leaks developed in the pressure tubes of Reactor Units 3 and 4 at Ontario Hydro's Pickering Nuclear Generating Station in Aug. 1974. The failures have been attributed to reorientation and preferential redistribution of hydrides under high tensile stresses, followed by progressive fracture of these hydrides. Mechanical tests, acoustic emission data, and metallographic studies relevant to this mechanism will be presented and related to the occurrence of cracks in the Zr-2.5Nb reactor pressure tubes.

Download or read book Mechanisms of Hydride Reorientation in Zircaloy 4 Studied in Situ written by Arthur Motta and published by . This book was released on 2014 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium hydride platelet reorientation in fuel cladding during dry storage and transportation of spent nuclear fuel is an important technological issue. Using an in situ x-ray synchrotron diffraction technique, the detailed kinetics of hydride precipitation and reorientation can be directly determined while the specimen is under stress and at temperature. Hydrided Zircaloy-4 dogbone sheet samples were submitted to various thermo-mechanical schedules, while x-ray diffraction data was continuously recorded. Post-test metallography showed that nearly full hydride reorientation was achieved when the applied stress was above 210 MPa. In general, repeated thermal cycling above the terminal solid solubility temperature increased both the reoriented hydride fraction and the connectivity of the reoriented hydrides. The dissolution and precipitation temperatures were determined directly from the hydride diffraction signal. The diffraction signature of reoriented hydrides is different than that of in-plane hydrides. During cooling under stress, the precipitation of reoriented hydrides occurs at lower temperatures than the precipitation of in-plane hydrides, suggesting that applied stress suppresses the precipitation of in-plane hydrides. The analysis of the elastic strains determined by the shift in position of hydride and zirconium diffraction peaks allowed following of the early stages of hydride precipitation. Hydride particles were observed to start to nucleate with highly compressive strain. These compressive strains quickly relax to smaller compressive strains within 30°C of the onset of precipitation. After about half of the overall hydride volume fraction is precipitated, hydride strains follow the thermal contraction of the zirconium matrix. In the case of hydrides precipitating under stress, the strains in the hydrides are different in direction and trend. Analyses performed on the broadening of hydride diffraction peaks yielded information on the distribution of strains in hydride population during precipitation and cooldown. These results are discussed in light of existing models and experiments on hydride reorientation.

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 Zirconium in the Nuclear Industry written by D. Franklin and published by ASTM International. This book was released on 1982 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Hydrogen and Hydride Morphology on the Tensile Properties of Zircaloy 2 written by W. J. Babyak and published by . This book was released on 1963 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ORNL Interim Progress Report on Hydride Reorientation CIRFT Tests written by and published by . This book was released on 2016 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic study of H.B. Robinson (HBR) high burnup spent nuclear fuel (SNF) vibration integrity was performed in Phase I project under simulated transportation environments, using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) hot cell testing technology developed at Oak Ridge National Laboratory in 2013-14. The data analysis on the as-irradiated HBR SNF rods demonstrated that the load amplitude is the dominant factor that controls the fatigue life of bending rods. However, previous studies have shown that the hydrogen content and hydride morphology has an important effect on zirconium alloy mechanical properties. To address the effect of radial hydrides in SNF rods, in Phase II a test procedure was developed to simulate the effects of elevated temperatures, pressures, and stresses during transfer-drying operations. Pressurized and sealed fuel segments were heated to the target temperature for a preset hold time and slow-cooled at a controlled rate. The procedure was applied to both non-irradiated/prehydrided and high-burnup Zircaloy-4 fueled cladding segments using the Nuclear Regulatory Commission-recommended 400°C maximum temperature limit at various cooling rates. Before testing high-burnup cladding, four out-of-cell tests were conducted to optimize the hydride reorientation (R) test condition with pre-hydride Zircaloy-4 cladding, which has the same geometry as the high burnup fuel samples. Test HR-HBR#1 was conducted at the maximum hoop stress of 145 MPa, at a 400°C maximum temperature and a 5°C/h cooling rate. On the other hand, thermal cycling was performed for tests HR-HBR#2, HR-HBR#3, and HR-HBR#4 to generate more radial hydrides. It is clear that thermal cycling increases the ratio of the radial hydride to circumferential hydrides. The internal pressure also has a significant effect on the radial hydride morphology. This report describes a procedure and experimental results of the four out-of-cell hydride reorientation tests of hydrided Zircaloy-4 cladding, which served as a guideline to prepare in-cell hydride reorientation samples with high burnup HBR fuel segments. This report also provides the Phase II CIRFT test data for the hydride reorientation irradiated samples. The variations in fatigue life are provided in terms of moment, equivalent stress, curvature, and equivalent strain for the tested SNFs. The CIRFT results appear to indicate that hydride reoriented treatment (HRT) have a negative effect on fatigue life, in addition to hydride reorientation effect. For HR4 specimen that had no pressurization procedure applied, the thermal annealing treatment alone showed a negative impact on the fatigue life compared to the HBR rod.

Download or read book Characterization of Zirconium Hydrides and Phase Field Approach to a Mesoscopic Scale Modeling of Their Precipitation written by Z. Zhao and published by . This book was released on 2008 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium alloys are currently used in nuclear power plants where they are submitted to hydrogen pick-up. Hydrogen in solid solution or hydride precipitation can affect the behavior of zirconium alloys during service but also in long term storage and in accidental conditions. Numerical modeling at mesoscopic scale using a "phase field" approach has been launched to describe hydride precipitation and its consequences on the mechanical properties of zirconium alloys. To obtain realistic results, it should take into account an accurate kinetic, thermodynamic, and structural database in order to properly describe hydride nucleation, growth, and coalescence as well as hydride interaction with external stresses. Therefore, an accurate structural characterization was performed on Zircaloy-4 plates and it allowed us to identify a new zirconium hydride phase called ?. The ? phase has a trigonal symmetry and is fully coherent with hcp ?Zr. The consequences of this new zirconium hydride phase on hydride transformation process and stress-reorientation phenomenon are discussed. A first attempt to numerically model the precipitation of this new zirconium hydride phase has been undertaken using the phase field approach.

Download or read book Phase Field Modeling and Quantification of Zirconium Hydride Morphology written by Pierre Clement Simon and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In light water nuclear reactors, waterside corrosion of the cladding material leads to the production of hydrogen, a fraction of which is picked up by the zirconium cladding. Once the hydrogen concentration reaches its solid solubility limit in zirconium, it precipitates into brittle hydride particles. These nanoscale hydride particles aggregate into mesoscale hydride clusters. Depending on the material's texture and the thermomechanical treatment imposed on the cladding, these mesoscale hydride clusters exhibit different morphologies. In particular, the principal orientation of the hydride platelets in the cladding tube can be circumferential or radial. Because hydrides are usually more brittle than the zirconium matrix, the morphology of the mesoscale hydride clusters can affect cladding integrity. This is in part because radial hydrides can ease crack propagation through the cladding thickness and because the concentration of hydrides in specific locations driven by temperature, hydrogen concentration, and stress gradients can create local weak points in the cladding. This dissertation work investigates the link between precipitation conditions, hydride morphology, and hydride embrittlement in zirconium cladding material. The first part focuses on understanding which physics and mechanisms govern the formation of specific hydride microstructures. A quantitative phase field model has been developed to predict the hydride morphology observed experimentally and identify which mechanisms are responsible for circumferential and radial hydride precipitation. The model accurately predicts the elongated nanoscale hydride shape and the stacking of hydrides along the basal plane of the hexagonal zirconium matrix. When investigating the role of applied stress on hydride morphology, the model challenges some of the mechanisms proposed in previous studies to explain hydride reorientation. Although hydride reorientation has been hypothesized to be caused by a change in nanoscale hydride shape and orientation, the current model shows that these mechanisms are unlikely. This study focuses on the precipitation of nanoscale hydrides in polycrystalline zirconium to understand the physics and mechanisms responsible for the change in hydride microstructure from circumferential to radial under applied stress. It proposes a new mechanism where the presence of an applied stress promotes hydride precipitation in grains with circumferentially aligned basal poles. Nanoscale hydrides, even though they still grow along the basal plane of the hexagonal matrix, now grow and stack radially, thus leading to radial mesoscale hydrides. This mechanism is consistent with experimental observations performed in other studies. The second part of this dissertation focuses on the link between hydride morphology and hydride embrittlement. Although hydride microstructure can significantly influence Zr alloy nuclear fuel cladding's ductility, quantifying hydride microstructure is challenging and several of the metrics currently being used have significant shortcomings. A new metric has been developed to quantify hydride microstructure in 2D micrographs and relate it to crack propagation. As cladding failure usually results from a hoop stress, this new metric, called the Radial Hydride Continuous Path (RHCP), is based on quantifying the continuity of brittle hydride particles along the radial direction of the cladding tube. Compared to previous metrics, this approach more closely relates to the propensity of a crack to propagate radially through the cladding tube thickness. The RHCP takes into account hydride length, orientation, and connectivity to choose the optimal path for crack propagation through the cladding thickness. The RHCP can therefore be more closely linked to hydride embrittlement of the Zr alloy material, thus creating a relationship between material structure, properties, and performance. The new definition, along with previously proposed metrics such as the Radial Hydride Fraction (RHF), the Hydride Continuity Coefficient (HCC), and the Radial Hydride Continuity Factor (RHCF), have been implemented and automated in MATLAB. These metrics were verified by comparing their predictions of hydride morphology against expected values in simple cases, and the implementation of the new metric was validated by comparing its predictions with manual measurements of hydride microstructure performed on ImageJ. The RHCP was also validated against experimental measurements of fracture behavior and it was shown to correlate with cladding failure better than previous metrics. The information provided by these metrics will help accurately assess cladding integrity during operation, transportation, and storage.

Download or read book Development of a Phase Field Model of Hydride Morphology in Zirconium Alloy Nuclear Fuel Cladding written by Pierre Simon and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium alloys are widely used in the nuclear industry as fuel cladding due to their particular properties. During normal operation conditions, hydrogen enters the cladding and forms brittle hydride precipitates. The effect of the presence of hydrides on the deformation behavior of the cladding largely depends on the orientation and the morphology of the hydrides. Because of the zirconium texture and the thermo-mechanical conditions, hydrides usually precipitate circumferentially in the cladding. However, temperature cycling and the application of additional stress can lead to hydride reorientation in the radial direction, which eases crack propagation through the cladding, and thus threatens the integrity of the fuel rod. In an effort to understand the mechanisms governing the orientation and the morphology of the hydrides, two different phase field models were developed using the Multi-physics Object Oriented Simulation Environment MOOSE. The first model was first proposed by Wheeler, Boettinger, and McFadden and is known as the WBM model. The second model, called the grand potential model, has the advantage of allowing the definition of the interfacial thickness independently of the bulk free energy of the different phases of the system. It thus allows the use of thicker interfaces, which means coarser mesh, making the simulations computationally less expensive. Because of the importance of the mechanical contributions in the nucleation and growth of hydride precipitates, both phase field models have then been coupled with elastic schemes. The first scheme, called the Voight-Taylor scheme (VTS), was shown to strongly overestimate the elastic free energy contribution at the interface, while the Khachaturya's scheme (KHS) performed better with just a small underestimation of the elastic free energy at the interface. In the project presented in this thesis, the multi-phase models simulated the alpha phase of the zirconium as well as the zeta, the gamma, and the delta phase of the hydrides. The models are dimensional, use the Gibbs free energy of formation of the different phases and the mechanical properties found in the literature. In this study, the phase field models have been carefully verified, meaning that their implementations have been successfully tested by comparing their results to widely accepted solutions. Once the models were applied to the zirconium hydride system, the first steps towards the validation of the code were promising. Simulated hydrides grew preferentially in the direction of the basal plane of the zirconium matrix, thus reproducing experimental observations.

Download or read book Hydride Reorientation in Zircaloy 4 Under Different States of Stress as Studied with In Situ X Ray Diffraction written by M. Nedim Cinbiz and published by . This book was released on 2018 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydride Reorientation in Zirconium Alloy Nuclear Fuel Cladding Studied Using Synchrotron Radiation written by Jennifer Anne Jarvis and published by . This book was released on 2010 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: During reactor operation, waterside corrosion of Zirconium alloy fuel cladding leads to hydrogen pickup. Hydrides platelets will normally precipitate circumferentially in the cladding. However, under temperature and load, the hydrides can reorient in the radial direction. These brittle radial hydrides can drastically reduce the ductility and the fracture toughness of the cladding. This work contains an in-situ study of hydride reorientation. Using synchrotron radiation from the Advanced Photon Source (APS) at Argonne National Laboratory, x-ray diffraction in transmission geometry was used to study a hydrogen-charged sample under mechanical and thermal load. The sample was rolled Zircaloy-2 with a hydrogen content of 96 wt.ppm. It was studied under a loading cycle with temperature cycling from 25 to 400°C and with an applied tensile stress of 100 MPa. Under two cycles of loading, partial reorientation was achieved. This diffraction data was used to perform an evaluation of the intensity, peak broadening, and peak shift of hydride peaks, in order to characterize the kinetics of reorientation. Additionally, the dissolution and precipitation temperatures were studied. Optical microscopy was used to compare the microstructure and hydride orientation before and after the experiment.