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Book Initiation of Delayed Hydride Cracking in Zr 2 5Nb Micro Pressure Tubes

Download or read book Initiation of Delayed Hydride Cracking in Zr 2 5Nb Micro Pressure Tubes written by Ravi Kumar Sundaramoorthy and published by . This book was released on 2009 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pressure tubes pick up hydrogen while they are in service within CANDU reactors. Sufficiently high hydrogen concentration can lead to hydride precipitation during reactor shutdown/repair at flaws, resulting in the potential for eventual rupture of the pressure tubes by a process called Delayed Hydride Cracking (DHC). The threshold stress intensity factor (KIH) below which the cracks will not grow by delayed hydride cracking of Zr-2.5Nb micro pressure tubes (MPTs) has been determined using a load increasing mode (LIM) method at different temperatures. MPTs have been used to allow easy study of the impact of properties like texture and grain size on DHC. Previous studies on MPTs have focused on creep and effects of stress on hydride orientation; here the use of MPTs for DHC studies is confirmed for the first time. Micro pressure tube samples were hydrided to a target hydrogen content of 100 ppm using an electrolytic method. For DHC testing, 3 mm thick half ring samples were cut out from the tubes using Electrical Discharge Machining (EDM) with a notch at the center. A sharp notch with a root radius of 15 mu m was introduced by broaching to facilitate crack initiation. The direct current potential drop method was used to monitor crack growth during the DHC tests. For the temperature range tested the threshold stress intensity factors for the micro pressure tube used were found to be 6.5-10.5 MPa.m1/2 with the value increasing with increasing temperature. The average DHC velocities obtained for the three different test temperatures 180, 230 and 250oC were 2.64, 10.87 and 8.45 x 10-8 m/s, respectively. The DHC data obtained from the MPTs are comparable to the data published in the literature for full sized CANDU pressure tubes.

Book The Initiation of Delayed Hydride Cracking in Zirconium 2 5 Niobium

Download or read book The Initiation of Delayed Hydride Cracking in Zirconium 2 5 Niobium written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Initiation of Delayed Hydride Cracking in Zirconium 2 5 Niobium

Download or read book Initiation of Delayed Hydride Cracking in Zirconium 2 5 Niobium written by Douglas Keith Rodgers and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Delayed Hydride Cracking (DHC) occurs in Zr-2.5Nb when certain requirements are met. The mechanism of DHC consists of diffusion of hydrogen to a stress concentrator, such as a crack-tip, precipitation then fracture of a hydride at the crack-tip, and repetition of the process; the crack advances in steps. Incubation times, to the start of cracking and crack-tip hydride morphologies have been measured in pre-cracked cantilever beam specimens tested at applied K$\rm\sb I$'s up to 20 MPam$\sp{1/2}$ and temperatures ranging from 100 to 250$\sp\circ$C. The incubation time for DHC was found to vary inversely with DHC velocity. Contrary to previous research, the incubation time is highly variable, even for a given temperature and applied K$\rm\sb I,$ and the crack-tip hydride morphology is much more complicated than the simple model of a single hydride at a crack-tip.

Book Delayed Hydride Cracking in Zirconium Alloys in Pressure Tube Nuclear Reactors

Download or read book Delayed Hydride Cracking in Zirconium Alloys in Pressure Tube Nuclear Reactors written by International Atomic Energy Agency and published by IAEA. This book was released on 2004 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dated October 2004. With CD-ROM containing additional information inside back cover

Book Crack initiation at long radial hydrides in zr 2 5 nb pressure tube material at elevated temperatures

Download or read book Crack initiation at long radial hydrides in zr 2 5 nb pressure tube material at elevated temperatures written by R. Choubey and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deuterium buildup in pressure tubes arises as a consequence of corrosion on pressure tube surfaces exposed to both the primary coolant and annulus gas. because there is a potential for pressure tube failure by delayed hydride cracking once the solubility limit for hydrogen isotopes in the pressure tube material is exceeded, there is a need to develop a predictive capability for corrosion and deuterium ingress in candu pressure tubes. this predictive capability is being set up through the development of a design equation, beginning with simple empirical correlations but evolving as a model with an increasingly more mechanistic basis as our understanding of the physical processes involved improves. the preliminary version of the design equation described here attempts to account for the observed effects of temperature, neutron flux and water chemistry on corrosion in the primary coolant. functional relationships describing how corrosion varies with temperature, oxide thickness, dissolved oxygen in the water and irradiation are derived using data from out-reactor autoclave tests, in-reactor loop tests and out-reactor autoclave tests using pre-irradiated pressure tube material. deuterium uptake by the pressure tube is accounted for as a percentage of the total amount of deuterium released through the corrosion process. reasonable agreement between predictions of oxide thickness and deuterium concentrations in pressure tubes with actual measurements from bruce pressure tube surveillance examinations is encouraging. the current model predicts that the rate of deuterium ingress in pressure tubes is not constant but increasing with time.

Book Delayed hydride cracking in russian rbmk zr 2 5 nb pressure tubes

Download or read book Delayed hydride cracking in russian rbmk zr 2 5 nb pressure tubes written by B. A. Cheadle and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components

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.

Book Initiation of Delayed Hydride Cracking in Zr 2 5Nb

Download or read book Initiation of Delayed Hydride Cracking in Zr 2 5Nb written by Douglas Keith Rodgers and published by . This book was released on 1992 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Delayed Hydride Cracking (DHC) occurs in Zr-2.5Nb when certain requirements are met. The mechanism of DHC consists of diffusion of hydrogen to a stress concentrator, such as a crack-tip, precipitation then fracture of a hydride at the crack-tip, and repetition of the process; the crack advances in steps. Incubation times, to the start of cracking and crack-tip hydride morphologies have been measured in pre-cracked cantilever beam specimens tested at applied K$\rm\sb I$'s up to 20 MPam$\sp{1/2}$ and temperatures ranging from 100 to 250$\sp\circ$C. The incubation time for DHC was found to vary inversely with DHC velocity. Contrary to previous research, the incubation time is highly variable, even for a given temperature and applied K$\rm\sb I,$ and the crack-tip hydride morphology is much more complicated than the simple model of a single hydride at a crack-tip.

Book Measurement of Rates of Delayed Hydride Cracking DHC in Zr 2 5Nb Alloys An IAEA Coordinated Research Project

Download or read book Measurement of Rates of Delayed Hydride Cracking DHC in Zr 2 5Nb Alloys An IAEA Coordinated Research Project written by Christopher E. Coleman and published by . This book was released on 2008 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Values of DHC rates in Zr alloys are sensitive to measurement procedures. A standard method has been developed at the laboratories of AECL and evaluated in a round-robin involving ten IAEA member states. Two test materials were used--Zr-2.5Nb pressure tubes in the cold-worked (CANDUTM) and heat-treated (RBMK) conditions. Cracks were grown from fatigued starter cracks in the axial direction on the axial-radial plane of the original tubes. To obtain the maximum value of Vc, specimens were heated to dissolve all their hydrogen, then cooled at 1 to 3°C/min to the test temperature before loading at 15 MPa?m. Although the start of cracking was detected by potential drop, the extent of cracking was measured directly on the crack faces. The values of incubation time to the start of cracking were highly variable but Vc was well behaved. The values of Vc were normally distributed with a range varying from a factor of 1.2 to 5.2. At 250°C the mean value of Vc from 80 specimens of cold-worked material was 8.9(±1.12)x10-8 m/s and from 41 specimens of heat-treated material the mean value of Vc was3.3(±0.64)x10-8 m/s. Tests were also done at six other temperatures between 144 and 283°C, using up to 22 specimens at each temperature. Both materials had an Arrhenius-type temperature dependence, Vc=Aexp(-Q/RT). The use of strictly defined and coordinated experimental procedures gave a consistent set of Vc values, allowing effective comparison of results obtained in different national laboratories and resulting in good correlations between the DHC velocity values and differences in strength, crystallographic texture, and distribution of ?-phase in the test materials.

Book Hydride banding in experimental zirconium 2 5 wt per cent niobium pressure tubes

Download or read book Hydride banding in experimental zirconium 2 5 wt per cent niobium pressure tubes written by S. A. Aldridge and published by . This book was released on 1969 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: