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Determination of residual stresses around blisters in Zr-2.5%Nb pressure tubes

Published online by Cambridge University Press:  06 March 2012

Javier R. Santisteban ,
Axel Steuwer ,
Gladys Domizzi  and
Matthew J. Peel
Javier R. Santisteban
Affiliation:
Centro Atómico Bariloche, CONICET e Instituto Balseiro, Bariloche 8400, Argentina
Axel Steuwer
Affiliation:
ESS Scandinavia, Stora Algatan 4, 22350 Lund, Sweden andNMMU, Gardham Avenue, Port Elizabeth, South Africa
Gladys Domizzi
Affiliation:
Centro Atómico Consituyentes, CNEA, Av. Libertador 8250, Buenos Aires 1429, Argentina
Matthew J. Peel
Affiliation:
European Synchrotron Radiation Facility, 6 rue J Horowitz, BP220, 38043 Grenoble, France
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Abstract

We have used synchrotron X-ray diffraction experiments to measure the strain field introduced by a hydride blister grown on a section of a pressure tube from a CANDU nuclear reactor. After charging the tube section with a homogeneous hydrogen concentration of 300 wt ppm, the blister was produced by creating a small cold spot on its surface (∼200 °C), while the bulk was kept at a temperature of 338 °C over a period of 1008 h. The blister studied here is ellipsoidal in shape, with its long axis along the tube axial direction. The experiments were performed on the wiggler beam line ID15 at the European Synchrotron Radiation Facility (ESRF) using a polychromatic beam of high-energy X-rays (60 to 300 keV). Unlike conventional X-ray diffraction, in this mode the scattering angle is fixed and the diffracted beam is discriminated on the basis of the photon energy. The results show that the blister is composed by two crystallographic phases (δ-ZrH and α-Zr), with volume fractions varying with position. The maximum stresses appear at the blister-matrix interfaces. Near the tube outer surface, we found large compressive stresses of (−450±90) MPa along the blister long axis, and tensile stresses (+320±90) MPa along the tube hoop direction. The main uncertainty in these stresses results from the uncertainty in the elastic constants of the hydride phase. Large strains and broad peaks were observed for this phase, which were explained by a rather low Young’s modulus (35 GPa) for the hydride. The results are compared with finite element simulations found in the literature.

Keywords

pressure tubesresidual stresseszirconium hydridehydride blisters
Type
Applications Of Residual Stress Analysis
Information
Powder Diffraction , Volume 24 , Supplement S1 , June 2009 , pp. S72 - S76
Copyright
Copyright © Cambridge University Press 2009

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