Download or read book Effect of Irradiation on the Fracture Properties of Zr 2 5Nb Pressure Tubes at the End of Design Life written by S. St Lawrence and published by . This book was released on 2005 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: To determine the fracture properties of Zr-2.5Nb pressure tubes irradiated until the end of design life, cantilever beam, curved compact toughness, and transverse tensile samples were prepared from a typical pressure tube and irradiated in the high flux reactor OSIRIS at CEA, Saclay, France. Experiments were conducted on two batches of samples mounted in two irradiation inserts. Each insert held sixteen samples of each type of specimen. The first insert was irradiated to a fluence corresponding to approximately half of the design life in a CANDU3 reactor. The experimental results were reported in [1]. Samples in the second insert were irradiated for 10.5 years in OSIRIS and received a maximum neutron fluence of 2.61 x 1026 n/m2 (E > 1 MeV), being equivalent to 2.98 x 1026 n/m2 (E > 1 MeV) in a CANDU reactor, i.e., corresponding to ~30 years operation in CANDU reactors at 80 % capacity factor. The present report describes the results of tensile, fracture toughness, and Delayed Hydride Cracking (DHC) tests and XRD microstructure analysis from the second batch of specimens. A continuous and gradual evolution in tensile, fracture, DHC properties, and dislocation densities is demonstrated without any evidence of a sudden change following the initial transitient at very low fluence. In the whole high fluence range, there is a very slow rate of increase in c-component dislocation density, strength, and DHC velocity and a slow reduction in elongation and Nb concentration in the ?-phase. The a-type dislocation density and fracture toughness remain approximately constant. The results from the second insert of specimens confirm that, following the initial transient at very low fluence, there is little further change in the fracture properties of Zr-2.5Nb pressure tube material. Therefore, material properties behave in a stable and predicable manner to the end of a 30 years design life for CANDU reactor pressure tubes.

Download or read book Effect of Long Term Irradiation on the Fracture Properties of Zr 2 5Nb Pressure Tubes written by S. Sagat and published by . This book was released on 2000 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results from fracture toughness and tensile and delayed hydride cracking (DHC) tests on Zr-2.5Nb pressure tubes removed from CANDU power reactors in the 1970s and 80s for surveillance showed considerable scatter. At that time, the cause of the scatter was unknown and prediction of fracture toughness to the end of the design life of a CANDU reactor using the surveillance data was difficult. To eliminate the heat-to-heat variability and to determine end-of-life mechanical properties, a program was undertaken to irradiate, in a high-flux reactor, fracture toughness, DHC, and transverse tensile specimens from a single "typical" pressure tube. Two inserts were placed in the OSIRIS reactor at CEA, Saclay, in 1988. Each insert held 16 of each type of specimen. The first insert, ERABLE 1, was designed so that half the specimens could be replaced at intervals and the properties could be measured as a function of fluence. All the specimens would be removed after a total fluence of 15 x 1025 n . m-2, E > 1 MeV. The second insert, ERABLE 2, was designed to run without interruption to a fluence of 30 x 1025 n . m-2, the fluence corresponding to 30 years' operation of a CANDU reactor at 90% capacity factor. The irradiation temperature was chosen to be 250°C, the inlet temperature of early CANDU reactors. The irradiation of ERABLE 1 has been completed and sets of specimens have been removed and tested with maximum fluences of approximately 0.7, 1.7, 2.8, 12, and 17 x 1025 n . m-2, E > 1 MeV. X-ray and TEM examinations have been performed on the material from fractured specimens to characterize the irradiation damage. Results showed that there is, initially, a large change in the mechanical properties before a fluence of 0.6 x 1025 n . m-2, E > 1 MeV (corresponding to an initial rapid increase in a-type dislocation density), followed by a gradual change. As expected, the fracture toughness decreased with fluence, whereas the yield strength, UTS, and DHC crack velocities all increased. Z-ray analysis showed that, although the a-type dislocation density remained constant after the initial increase, the number of c-component dislocations showed a steady increase, agreeing with the behavior seen in the mechanical specimens. Because the flux in OSIRIS is different from that in a CANDU reactor, specimens were also irradiated in NRU, a heavy water moderated test reactor with approximately the same flux as a CANDU reactor, to fluences of 0.3, 0.6, and 1.0 x 1025 n.m-2, E > 1 MeV for comparison. These initial results show that, once past the initial transient, one can have confidence that there will be little further degradation with fluence, with the results from the NRU specimens being similar to those from OSIRIS.

Download or read book Effect of Irradiation Damage on the Deformation Properties of Zr 2 5Nb Pressure Tubes written by M. Griffiths and published by . This book was released on 2008 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The diametral expansion, elongation, and sag rates of Zr-2.5Nb pressure tubes in CANDU® (CANada Deuterium Uranium) nuclear reactors are important properties that limit their useful life and the maximum power level for reactor operation. As a result irradiation creep models are needed to predict the deformation behavior of the core components over the reactor life. It is important to know the creep behavior as a function of neutron flux in order to develop creep models over the range of operating conditions in the reactor core. At the edge of the reactor core, the neutron flux is decreasing very rapidly and there is a complex transition in creep behavior from irradiation-dominated creep to thermal-dominated creep. Also, mechanical properties such as tensile strength, fracture toughness, and delayed hydride-cracking are changing in the transition from thermal to irradiation conditions at the edge of the reactor core. Detailed studies have been completed on a Zr-2.5Nb tube irradiated in the NRU materials test reactor at Chalk River Laboratories. Pressure tube 601 was operating for a period of 66 950 h at temperatures ranging from about 547 K at the inlet and 571 K at the outlet. After the tube was removed in 1988 samples were taken for retrospective dosimetry to determine the fast neutron flux along the assembly. It was determined that the tube had been irradiated to a peak fluence of about 6x1025 n.m-2 corresponding to a fast neutron flux of about 2x1017 n.m-2.s-1. The flux profile was mapped and it was clear that the flux dropped rapidly to negligible values at about 0.5 m from the ends of the fueled zone. Samples of pressure tubes were taken for hardness testing and characterization by TEM and XRD analysis at various locations corresponding with different operating conditions (neutron flux and temperature) but at the same time. The creep behavior during operation was obtained by periodic gaging of the pressure tube internal diameter. The results of the microstructure characterization are presented and discussed in relation to the measured mechanical properties (creep and hardness). The microstructure and mechanical properties change significantly in the transition from the unirradiated state up to fluxes of about 1x1017 n.m-2.s-1.

Download or read book Correlation Between Irradiated and Unirradiated Fracture Toughness of Zr 2 5Nb Pressure Tubes written by CK. Chow and published by . This book was released on 1994 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three coordinated research programs were undertaken on the fracture toughness of Zr-2.5Nb pressure tubes to determine relationships between irradiated and unirradiated values, the effect of long-term irradiation, and the causes of the variation in toughness. The present paper describes results from these programs and their implications.

Download or read book Effect of thickness on the fracture toughness of irradiated zr 2 5nb pressure tubes written by C. K. Chow and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture toughness of hydrided zr 2 5nb pressure tube material irradiated in the NRU test reactor written by P. H. Davies and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was completed on hydrided specimens of zr-2.5 nb pressure tube material irradiated in the nru test reactor to fluences up to 5 x 10 sup(24) n.m. sup(-2). material with three different mixed hydride morphologies (m1, m2 and m3 with hydrogen concentrations in the range of 42 to 61 wt ppm, 62 to 75 wt ppm and 183 to 216 wt ppm, respectively, and hydride continuity coefficients (hccs) in the range 0.1 to 0.3) was supplied by ontario hydro technologies for irradiation. the morphologies consisted of mixed hydrides of different orientations (m1/m2) as well as predominantly circumferential hydrides (m3). the joint effect of irradiation and zirconium hydride significantly reduces the toughness of the material at all test temperatures up to the operating temperature range, 240 degrees c, and results in an increased incidence of discontinuous crack growth (crack jumping) and unstable fracture. after irradiation the transition temperature for upper shelf fracture behaviour is above 240 degrees c for all three hydride morphologies. the reduction in the maximum load toughness, k sub(ml), at 240 degrees c is about 30 mpa square root of m due to irradiation and up to a further 18 mpa square root of m (m2) and 22 mpa square root of m (m3) due to the zirconium hydride. fractographic evidence is presented which shows that the increased incidence of discontinuous crack growth and unstable fracture after irradiation is due not only to an increase in the number of hydride sites activated close to the radial-axial plane but also to changes in the ability of the remaining material to arrest the crack. in particular, material containing a high concentration of microsegregated species (zr-cl-c complex) promotes unstable fracture due to the reduced area and width of dimpled rupture zones (between fissures) available for crack arrest.

Download or read book Size geometry and material effects in fracture toughness testing of irradiated zr 2 5nb pressure tube material written by P. H. Davies and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Properties of an Irradiated Heat Treated Zr 2 5Nb Pressure Tube Removed From the NPD Reactor written by AR. Causey and published by . This book was released on 1996 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some pressure tubes in reactors moderated by heavy water have been made from heat-treated (HT) Zr-2.5Nb. One such tube was removed from the NPD nuclear reactor after 20 years of operation. An extensive program was carried out jointly by AECL and PNC to evaluate the condition and properties of this pressure tube. The investigations include irradiation creep, tensile, corrosion, delayed hydride cracking (DHC), fatigue, and fracture properties.

Download or read book The effect of irradiation and irradiation temperature on the fracture toughness of zircaloy 2 pressure tubing containing radial hydrides written by L. A. Simpson 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 A survey of the effect of irradiation on the tensile properties of zr 2 5 percent nb pressure tubes written by G. D. Moan and published by . This book was released on 1983 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Toughness of Irradiated Zr 2 5Nb Pressure Tubes from CANDU Reactors written by R. Choubey and published by . This book was released on 1991 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: About 400 pressure-tubes made of cold-worked Zr-2.5Nb are used in a CANDU power reactor to contain the nuclear fuel and the heat transport fluid, heavy water, at between 250 to 310°C at a pressure of about 10 MPa. The fracture toughness of these tubes is needed to determine if they are fit for service. We have measured the fracture toughness by bursting 450 mm long tube sections and using 17 mm curved compact toughness (C(T)) specimens, employing the J-integral resistance curve method in both cases. The burst test is expensive but it simulates the stress state under which the pressure tubes operate, while the small specimen method is more economical although the interpretation of data is more difficult.

Download or read book Radial fracture toughness of irradiated zr 2 5nb pressure tube material written by D. D. Himbeault and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Microstructure and Operating Conditions on Irradiation Creep of Zr 2 5Nb Pressure Tubing written by L. Walters and published by . This book was released on 2014 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Creep experiments have been performed on biaxially stressed 10 mm diameter Zr-2.5Nb capsules. As the pressurized capsules were obtained from micro-pressure tubes, which were fabricated by the same process as CANDU power reactor pressure tubes, they have a similar microstructure to that of the full-size tubes. The experiments were performed in the OSIRIS test reactor at nominal operating temperatures ranging from 553 and 613 K in fast neutron fluxes up to 2 x 1018 n.m-2.s-1 (E > 1 MeV). Diametral and axial strains are reported as functions of fluence for specimens internally pressurized to hoop stresses from 0 to 160 MPa and irradiated to 26.5 dpa. The effects of microstructure, temperature, and cold work on irradiation creep are shown. The analysis of OSIRIS data combined with data from in-service CANDU tubes has revealed some significant observations regarding pressure tube deformation: (i) that irradiation creep anisotropy varies with temperature, (ii) texture appears to have a more significant effect on axial creep than on diametral creep, (iii) diametral strain appears to be strongly dependent on grain size and aspect ratio, and (iv) that whereas cold-work correlates with the axial creep of the capsules, there appears to be no statistically significant dependence of diametral creep on cold-work.

Download or read book Implications of Embrittlement During the Life of a Zirconium Pressure Tube Reactor written by R.W. Nichols and published by . This book was released on 1966 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Irradiation and Irridiation Temperature on the Fracture Toughness of Cold worked Zr 2 5 Wt Percent Nb written by Atomic Energy of Canada Limited and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Change of Mechanical Properties by Irradiation and Evaluation of the Heat Treated Zr 2 5Nb Pressure Tube written by T. Akiyama and published by . This book was released on 1994 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prototype advanced thermal reactor, Fugen (165MWe), is a heavy-water-moderated, boiling-light-water-cooled, pressure tube type reactor. A Zr-2.5 Nb alloy, in the heat-treated condition to improve its high-temperature strength, is used for the pressure tubes in the Fugen. Pressure tube surveillance specimens were assembled in the inside of the special fuel assemblies from the initial stage of the operation and were exposed to irradiation. The post-irradiation examinations of the first and second surveillance specimens were performed. The tensile strength increased by 30% when fast neutron fluence was >2 x 1025 n/m2. The decreasing rate of the fracture toughness was large over the initial period of the irradiation and became smaller when fast neutron fluence was >2 x 1025 n/m2. The corrosion rate was measured as -1 ?m/year and the hydrogen pickup rate was measured as 1 ppm/year. Based on the results, a predictive capability for each respective property for 30 years was established, which demonstrated the integrity of the pressure tube for 30 years.

Download or read book The effect of irradiation and irradiation temperature on the fracture toughness of cold worked zr 2 5 wt percent nb written by L. A. Simpson and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: