Download or read book The Effects of Mechanical Stress Gradients on Irradiation Induced Embrittlement of Pressure Vessel Steel written by John G. Williams and published by . This book was released on 1990 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The role of cracks and locally elevated stress fields in enhancing embrittlement in nuclear pressure vessel steels is assessed. The (elastic) stress field surrounding a crack tip can attract oversized or reject undersized solute atoms. The extent of the attraction or rejection depends on the size difference between the solvent and the solute atom, the temperature, the diffusivity of the solute, and the applied stress intensity. Under certain conditions, it is possible for solute atoms to concentrate near the crack tip and influence its growth. In the present study, a kinetic model for the concentration of solute atoms at crack tips is developed. This model is applied to the examination of the kinetics of enhanced concentrations of copper (Cu), sulfur (S), and phosphorus (P) near crack tips in ferrite. The effects of irradiation on the kinetics of the concentration process are also modeled. Finally, the consequences of such solute concentrations for fracture properties are examined in light of both the potential elevation in yield strength and the lowering of fracture strength. The consequences are found to be significant in pressure vessel steels at typical reactor vessel operating temperatures when irradiation enhanced diffusion accelerates the segregation process.
Download or read book Effects of Nickel on Irradiation Embrittlement of Light Water Reactor Pressure Vessel Steels written by International Atomic Energy Agency and published by IAEA. This book was released on 2005 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication sets out the findings of a co-ordinated research project to determine the influence of the mechanism of the deterioration effect in radiation embrittlement of reactor pressure vessel steels with a high nickel content in nuclear power plants, including procurement of materials, determination of mechanical properties, irradiation and testing of specimens, and microstructural characterisation.
Download or read book Analysis of Radiation Induced Embrittlement Gradients on Fracture Characteristics of Thick Walled Pressure Vessel Steels written by F. J. Loss and published by . This book was released on 1971 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fracture behavior of thick-walled nuclear vessels is considered for the case of a radiation-induced toughness gradient through the wall which characteristically results from neutron attenuation by the wall material itself. Fracture-safe design analyses based on linear elastic formulations or extrapolations of these formulations to the elastic-plastic regime are not sufficiently developed to characterize the integrated behavior of a wall whose toughness can range from brittle at the inner surface to highly ductile at the outer surface. Solutions to the problem in the foreseeable future will be obtained only by experimental means. The present approach uses the Fracture Analysis Diagram (FAD) together with a new interpretative method for fracture extension resistance based on modified dynamic tear specimens as the tools for gradient assessments. With these techniques the significance of the toughness gradient through the wall is assessed in terms of thich section mechanical constraint, and fracture characteristic of the complete wall are predicted. (Author).
Download or read book Radiation Embrittlement of Nuclear Reactor Pressure Vessel Steels written by Lendell E. Steele and published by ASTM International. This book was released on 1986 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deformation Behavior in Reactor Pressure Vessel Steels as a Clue to Understanding Irradiation Hardening written by and published by . This book was released on 1999 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T (less-than or equal to) 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the post-yield hardening rate is clearly greater than that of the unirradiated material, and the flow curves cannot be made to superimpose. The binary iron-base model alloys studied here show a less pronounced difference in flow behavior for neutrons and electrons than exhibited by the steels, implicating the effect of alloy chemistry. Our results are analyzed in the context of classical theories dealing with the interaction between the deformation microstructure, i.e. glide dislocations, and irradiation-produced defects. Our findings provide clues about the way different alloy constituents interact with the different kinds of irradiation damage to strengthen the material differently.
Download or read book Radiation Embrittlement of Nuclear Reactor Pressure Vessel Steels written by Lendell E. Steele and published by ASTM International. This book was released on 1989 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book TID written by and published by . This book was released on 19?? with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microstructural and Mechanical Characterization of Radiation Effects in Model Reactor Pressure Vessel Steels written by H-W Viehrig and published by . This book was released on 2005 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents results of radiation-induced nanoscale microstructural changes measured by Small-Angle Neutron Scattering (SANS) on ASTM-type reactor pressure vessel (RPV) steels. Five different base metals and one weld metal were investigated. The irradiation was performed in a VVER-type power reactor to three different dose levels, maximally 0.14 dpa, at an irradiation temperature of 255°C. The volume content of the micostructural features measured is correlated with the irradiation hardening and embrittlement.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels written by Lendell E. Steele and published by . This book was released on 1975 with total page 252 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 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Irradiation Embrittlement of Reactor Pressure Vessel Steels Due to Mechanisms Other Than Radiation Hardening written by BA. Gurovich and published by . This book was released on 1999 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data on Russian pressure vessel steels in unirradiated, irradiated and annealed conditions are presented. The experimental methods applied included impact testing, fractography, electron microscopy and Auger spectroscopy. Contributions from different mechanisms to radiation embrittlement were evaluated. These studies enabled us to conclude that the major contribution to radiation induced ductile-to-brittle transitions temperature shift in Russian pressure vessel steels is delivered by mechanisms other than radiation hardening.
Download or read book Irradiation Effects in Reactor Pressure Vessel Steels written by CZ. Serpan and published by . This book was released on 1986 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The embrittling effect of neutron irradiation on reactor pressure vessel steel and welds has a significant impact on the regulation of reactors by the U.S. Nuclear Regulatory Commission (NRC). Because the NRC is concerned with the continuing integrity and safety of the reactor's primary system, the neutron-irradiation-induced loss of fracture toughness and ductility must be carefully documented, understood, and controlled to assure that despite such loss, there is always a sufficient reserve of toughness and ductility to preclude crack initiation and uncontrolled propagation in the unlikely event of an accident. Aspects of embrittlement important to the NRC, which are discussed herein, include prediction of the transition temperature and upper-shelf-energy levels at critical vessel locations for the setting of pressure-temperature limits, for analysis of accident loadings such as pressurized thermal shock, and for evaluation of flaws found in inspection. Also discussed are the use of embrittlement-related neutron dosimetry and evaluation of vessel annealing.
Download or read book Radiation Embrittlement of Nuclear Reactor Pressure Vessel Steels written by Lendell E. Steele and published by ASTM International. This book was released on 1986 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation Hardening and Embrittlement in a Reactor Pressure Vessel Steel written by R. G. Berggreen and published by . This book was released on 1969 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relationship between the increase in tensile yield stress (YS) and the increase in the ductile-brittle transition temperature (DBTT) upon irradiation was studied for ASTM A 212-65 Grade B pressure vessel steel. Smooth tension specimens and Charpy V-notch impact specimens were irradiated in the same facility of the Oak Ridge Research Reactor under the same conditions of 60 C irradiation temperature and 1 x 1010 neutrons/cm2 (E > 1 MeV) fluence. The tension tests were carried out at temperatures from 20 to 473 K at two strain rates. The YS increased rapidly with decreasing test temperature, but the radiation-produced increment in YS was largely independent of test temperature. The impact specimens also were tested as a function of temperature and the increase in DBTT was determined based on absorbed energy and fracture appearance. To correlate the changes in YS and DBTT upon irradiation, strain-rate and triaxiality corrections were applied to the tensile yield stresses to approximate the corresponding stresses at the root of the notch of the impact specimens. The results of the tension and impact tests were found to be consistent, based on a critical cleavage stress deduced from the tension tests. No evidence for a decrease in the critical cleavage stress upon irradiation was noted.
Download or read book Report of NRL Progress written by Naval Research Laboratory (U.S.) and published by . This book was released on 1971 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Survey of postirradiation heat treatment as a means to mitigate radiation embrittlement of reactor vessel steels written by J. R. Hawthorne and published by . This book was released on 1979 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
