| The objective of this study is to investigate the effect of hydride precipitates on the distributions of the lattice distortion and stress in CANDU Zr-2.5Nb pressure tube. The three sections taken from CANDU Zr-2.5Nb tube, the longitudinal normal section(LS), the radial normal section(RS) and the transverse normal section(TS) were charged with hydrogen at 530℃ for 15 h. X-ray diffraction analysis was carried out on the sections with or without charged hydrogen using a X-ray diffractometer equipped with a position sensitive detector. The effect of hydride precipitates on the line broadening, the interplanar lattice spacing, and the macro-stress was determined from a change in the peak position and the half width of the diffraction lines ｛12.3｝ on the three sections. The hydride precipitates had an effect of increasing the interplanar lattice spacing of ｛12.3｝ only on the LS, causing tensile stress of as high as 400 ㎫ but decreased the interplanar lattice spacing on the TS causing it subjected to compressive stress. Based on a change in the distribution of line broadening with hydride precipitates on each section depending on the pole density of ｛12.3｝, the preferential site for the precipitation of hydrides is discussed. |
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