Download or read book Oxide Characteristics and Corrosion and Hydrogen Uptake in Zr 2 5 Nb CANDU Pressure Tubes written by MA. Maguire and published by . This book was released on 1996 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxides on removed pressure tubes from Pickering Unit 3 after 13.4 effective full power years (EFPY) have been examined to investigate the cause of variability in bulk alloy deuterium contents in outlet regions in order to improve predictions and minimize deuterium uptake in operating CANDU reactors. Secondary ion mass spectroscopy (SIMS) and electrochemical impedance spectrometry (EIS) were used for characterization with minimal sample preparation and modification. Two SIMS techniques were used for quantification: (1) the relative sensitivity factor (RSF) method, which requires a reference material and is subject to matrix effects as a result of variation in the secondary ion intensities of a species when different materials are sputtered; and (2) the SIMS infinite velocity (IV) method, which circumvents matrix effects by extrapolating all secondary ion intensity data to infinite velocity. A novel 13C oxide dating technique was used to determine oxide growth kinetics and ensure that oxide spalling had not occurred in the regions examined.
Download or read book Oxide Characteristics and Their Relationship to Hydrogen Uptake in Zirconium Alloys written by BD. Warr and published by . This book was released on 1991 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) have been used to investigate composition and structure of oxides on pure zirconium and Zr-2.5Nb following both in and out-reactor exposures in aqueous and gaseous environments. Thin oxides formed in steam at 400°C on Zr-2.5Nb act as excellent hydrogen permeation barriers for CANadian Deuterium Uranium (CANDU) pressure tubes. Following up to 4350 effective full power days (EFPD) exposure in-reactor in the annulus gas, and out-reactor elevated exposures to deuterium gas, these oxides generally continue to show diffusional-type through-thickness deuterium concentration profiles, with negligible deuterium contents at the metal/oxide interface. Diffusion coefficients inferred from these profiles are as low as ~2 x 10-22m2/s at 300°C. The structure of these thin oxides on Zr-2.5Nb consists of columnar grains with amorphous regions at grain boundaries and at the metal oxide interface, and non-interconnected porosity, which implies that deuterium permeation is likely controlled by solid state diffusion through the bulk oxide. At regions containing relatively high deuterium contents in the bulk metal of removed pressure tubes, outside surface oxides showed several regions with flat deuterium concentration profiles with higher deuterium concentrations at the metal/oxide interface. Examination of thicker oxides with interconnected porosity, on pure Zr, following exposures to pure deuterium gas, also showed the presence of flat deuterium concentration profiles. This would tend to suggest that regions of high deuterium concentration dissolved in the base metal of pressure tubes may also contain oxides with interconnected porosity.
Download or read book Zirconium in the Nuclear Industry written by George P. Sabol and published by ASTM International. This book was released on 1996 with total page 907 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Long Term Corrosion and Deuterium Uptake in CANDU PHW Pressure Tubes written by B. Cox and published by . This book was released on 1987 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent examinations of cold-worked Zircaloy-2 and cold-worked Zr-2.5Nb pressure tubes from CANDU-PHW reactors have extended the corrosion and deuteriding data for these materials up to 5600 effective full power days (efpd), the longest published exposure for these materials in reactor. The examinations have demonstrated that short-term tests to investigate irradiation and water chemistry effects must be supplemented by extended exposures in order to better understand the long-term corrosion and deuteriding behavior of zirconium alloy components with thick oxide films.
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 The Development of Zr 2 5Nb Pressure Tubes for CANDU Reactors written by B. A. Cheadle and published by . This book was released on 2010 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first reactor to use zirconium alloy tubes to contain hot pressurized water as a heat transport medium was the Hanford N reactor in 1962. For this reactor, three companies that had suitable extrusion and cold working equipment were given contracts to produce Zircaloy-2 tubes. All the companies were successful, and tubes from each company were installed in the reactor. When Canada decided to design and build a power reactor (nuclear power demonstration (NPD)), it elected to use the pressure tube concept and gave a contract to one of the companies (Chase Bass) to fabricate the Zircaloy-2 tubes. Douglas Point and Pickering Units 1 and 2 followed NPD, and all used similar Zircaloy-2 pressure tubes. A stronger tube was desired in order to thin the wall and improve the neutron economy. An alloy development program in the USSR had shown that the alloy Zr-2.5Nb looked very promising as a stronger alloy than Zircaloy-2, and both the USSR and Canada developed this alloy and subsequently used Zr-2.5Nb pressure tubes in their reactors. When both the Zircaloy-2 and Zr-2.5Nb pressure tubes were first installed in the reactors, several important properties and characteristics such as hydrogen ingress into the metal from corrosion in water, the enhancement of creep by neutron irradiation, shape change by neutron irradiation, reduction in fracture toughness by neutron irradiation, and delayed hydride cracking were not appreciated. These properties all led to problems during the service lives of the early tubes. Large research programs investigated these properties and showed that the ?-grain size, shape, and crystallographic texture, the distribution of the ?-phase, the dislocation type, and density as well as the micro-chemistry controlled the in-reactor properties of the tubes. This information enabled the design and operation of the reactors to be changed so that the tubes had satisfactory service lives. In addition, the information was used to fabricate tubes that had much improved properties and service lives. The original paper was published by ASTM International in the Journal of ASTM International, August 2010.
Download or read book Zirconium in the Nuclear Industry written by Leo F. P. Van Swam and published by ASTM International. This book was released on 1989 with total page 781 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxidation and Deuterium Uptake of Zr 2 5Nb Pressure Tubes in CANDU PHW Reactors written by CK. Chow and published by . This book was released on 1989 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxidation and deuterium uptake in Zr-2.5Nb pressure tubes are being monitored by destructive examination of tubes removed from commercial Canadian Deuterium Uranium Pressurized Heavy-Water (CANDU-PHW) stations and by analyses of microsamples, obtained in-situ, from the inside surface of tubes in the reactor. Unlike Zircaloy-2, there is no evidence for any acceleration in the oxidation rate for exposures up to about 4500 effective full power days. Changes towards a more equilibrium microstructure during irradiation may be partly responsible for maintaining the low oxidation rate, since thermal aging treatments, producing similar microstructural changes in initially cold worked tubes, were found to improve out-reactor corrosion resistance in 589 K water.
Download or read book Oxidation and deuterium uptake of zr 2 5 nb pressure tubes in CANDU phw reactors written by V. F. Urbanic and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Hydrogen Uptake Mechanism in Zirconium Alloys written by MB. Elmoselhi and published by . This book was released on 1994 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen uptake in zirconium alloy CANDU (CANada Deuterium Uranium) pressure tubes and other core components is controlled by the rate of transport of atomic/ionic species across the oxide film. The importance of understanding the mechanism of transport stems from the need to predict and control the rate of uptake. Samples of Zr-2.5Nb and Zircaloy-2 were prefilmed in steam (H2O, 400°C at 2 MPa) and subsequently exposed to D2O (10-3 Pa to 18 MPa) and D2 (10-3 Pa) at a temperature range of 250 to 380°C in the laboratory. Samples from Zr-2.5Nb pressure tubes removed from CANDU power reactors were also examined. Hydrogen mobility in oxides was investigated by secondary ion mass spectroscopy (SIMS) following these exposures. Diffusional-type through-oxide-thickness deuterium profiles have been observed adjacent to the oxide-metal interface for samples exposed to environments containing D2O for 4 h out-reactor and up to 10 years in-reactor. These profiles probably represent the density of accessible sites on surfaces of intergranular porosity through-thickness. Although, in small regions observed by transmission electron microscopy (TEM) such porosity has not been found. Nevertheless, from observations of grain size, sufficient sites would be available to produce deuterium concentration observed near oxide surfaces. The observed deuterium concentration profiles appear to result predominantly from deuteroxyl groups bonded to such sites. Deuterium content at the oxide-metal interface provides an indication of the extent of interfacial intergranular porosity. High deuterium contents at the interface may imply local regions with absent oxide barrier at the interface. In the presence of sufficient D2O, the oxide is continually healed, and deuterium uptake is relatively low where short-circuit routes such as intermetallics in Zircaloy-2 are not present. In environments with relatively high D2:D2O ratios, deuterium atoms may diffuse through the oxide to the interface and react directly with the metal resulting in high deuterium uptake rates. It is proposed that observed deuterium profiles may be the sum of mainly two components. The predominant component is due to deuteroxyl groups residing on accessible sites on surfaces of intergranular porosity with no direct link to hydrogen uptake by the bulk alloy. The second masked component would be due to another mobile hydrogen species (for example, H) that is diffusing to the bulk alloy. Further work is needed to substantiate the proposed hypothesis that would include exposures with varying D2:D2O ratios and further TEM examination.
Download or read book Reducing hydrogen ingress during aqueous corrosion of CANDU zr 2 5nb pressure tubes using inhibitors status report written by M. B. Elmoselhi and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Zirconium in the Nuclear Industry written by and published by . This book was released on 1996 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inhibitors for reducing hydrogen ingress during aqueous corrosion of CANDU zr 2 5nb pressure tube material status report written by M. B. Elmoselhi and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Zirconium in the Nuclear Industry written by Craig M. Eucken and published by ASTM International. This book was released on 1991 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the Ninth International Symposium on [title], held in Kobe, Japan, November 1990, address current trends in the development, performance, and fabrication of zirconium alloys for nuclear power reactors. the bulk of the most recent work on zirconium alloy behavior has concerned corr
Download or read book Microstructural Aspects of Corrosion and Hydrogen Ingress in Zr 2 5Nb written by VF. Urbanic and published by . This book was released on 2000 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zr-2.5Nb alloy pressure tubes for CANDU® reactors are nominally extruded at 815°C, cold-worked about 27%, and stress-relieved at 400°C for 24 h. The resulting structure consists of elongated ?-Zr grains interspersed with a network of thin ?-Zr filaments. Corrosion tests on unirradiated and preirradiated material have investigated the effects of microstructure and microchemistry on corrosion and hydrogen ingress. In two-phase (?-Zr+?-Zr) structures, the corrosion and hydrogen pickup increases with increasing volume fraction of ?-Zr. Corrosion is highest for single ?-phase material although hydrogen pickup reverts to a minimum value. Tests on alloys with low Nb concentration show that the optimum corrosion resistance occurs at a Nb content of about 0.1 wt% Nb. Thermal aging the metastable two-phase structure reduces corrosion and is consistent with a lower ?-phase volume fraction and a lower concentration of Nb in the ?-phase.
Download or read book Investigations of the alloy and oxide microstructures of zr 2 5nb pressure tube specimens subsequent to long term out reactor corrosion in simulated primary heat transport coolant at 310 degrees celcius and 360 degrees celcius written by V. Perovic and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigations of the alloy and oxide microstructures of zr 2 5nb pressure tube specimens subsequent to long term out reactor corrosion in simulated primary heat transport coolant at 250 degrees celcius and 310 degrees celcius written by V. Perovic and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
