Author: A. R. Causey
Publisher: Chalk River, Ont. : Reactor Materials Research Branch, Chalk River Laboratories
ISBN:
Category : Anisotropy
Languages : en
Pages : 34
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This report investigates the anistrophy of irradiation-enhanced creep of cold-worked Zr-2.5Nb at 548-563 K using internally-pressurized capsules and axially loaded helical-springs. The test specimens were machined from small diameter extruded and cold-worked tubing that had crystallographic texture and microstructure similar to that of CANDU power reactor pressure tubes. The biaxial creep capsules and the helical-springs were irradiated for 9,525 and 16,670 hours, respectively, in a fast neutron flux.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Author: AR. Causey
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 20
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The anisotropy of irradiation creep of Zr-2.5Nb alloy tubes at 570 K has been investigated using creep of helical springs and stress relaxation of twisted rods and bent beams. These tests measure creep rate directly since strains associated with irradiation growth are absent. Creep rates from these tests and from results on creep of pressurized tubes reported in the literature can be correlated through consideration of the crystallographic texture, slip systems, and dislocation density of the Zr-2.5Nb tubing. A creep model based on glide of 1/311 ̄20 type dislocations on prismatic planes in combination with secondary glide of 1/311 ̄22 dislocations on {10 ̄11} pyramidal planes provides a consistent correlation. The creep rate is only slightly dependent on dislocation density as measured by X-ray diffraction.
Author: D. G. Franklin
Publisher: ASTM International
ISBN: 9780803102590
Category : Science
Languages : en
Pages : 322
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Author: R. J. Klassen
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author:
Publisher: ASTM International
ISBN:
Category :
Languages : en
Pages : 308
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Author: L. Walters
Publisher:
ISBN:
Category : In-reactor deformation
Languages : en
Pages : 33
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Book Description
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.
Author: DS. Wood
Publisher:
ISBN:
Category : Irradiation
Languages : en
Pages : 18
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High creep strain experiments have been carried out under irradiation using cold worked Zircaloy-2, cold-worked Zr-Nb, and heat treated Zr-Nb 0.6-in.-diameter tubes in DFR, DMTR, and PLUTO reactor. The tests in PLUTO were found to be the most useful since full creep curves were obtained using neutron radiography techniques. Creep strains of up to 9 percent were obtained on cold-worked Zircaloy-2 tubes without failure, thus substantiating the recommended pressure tube creep strain limit of 3 percent. Up to 5 percent creep strain was observed with cold-worked Zr-Nb tubing, but since one tube failed at only 1.8 percent strain it is not yet possible to specify a realistic yet safe creep limit for this material.
Author: Robert F. DeAbreu
Publisher:
ISBN:
Category : Nuclear activation analysis
Languages : en
Pages : 27
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Book Description
Over the past 10 years, internally pressurized capsules made from Zr-2.5Nb tubing have been irradiated in the National Research Universal (NRU) reactor at Chalk River Laboratories at temperatures of 280, 320, and 340°C and dose rates between 3 x 1015 n . m-2 . s-1 and 2 x 1017 n . m-2 . s-1 (E > 1 MeV). Periodic gaging has been used to assess the primary and secondary (steady-state) creep behavior. The objective of this detailed and controlled experiment was to determine, for the first time, the creep and microstructure evolution in Zr-2.5Nb tubing over a wide range of irradiation conditions for fast neutron fluxes applicable to a CANDU pressure tube. Similar but "accelerated" creep experiments have been conducted in the Osiris test reactor at fast neutron fluxes of approximately 1.8 x 1018 n . m-2 . s-1 (E > 1 MeV), much greater than the neutron fluxes in the NRU reactor. Although accelerated tests in high-flux reactors such as Osiris provide information on irradiation creep, they do not represent the neutron flux conditions applicable to a power reactor. Tests covering power reactor operating conditions are needed to develop models for in-reactor creep of pressure tubes under the appropriate conditions. The data from the NRU reactor are compared with results from creep capsules with similar starting microstructures but irradiated in the Osiris reactor. The results show that the steady-state diametral and axial creep rates have a complex dependence on stress, temperature, and fast neutron flux. Data from out-reactor creep tests on unirradiated and pre-irradiated creep capsules that show the effect of prior irradiation on creep are also reported. The results are discussed in terms of a combination of creep mechanisms involving dislocation glide and mass transport.
Author: E. F. Ibrahim
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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