Experimental validation of tensile properties measured with thick samples taken from MEGAPIE target

Abstract

A post-irradiation examination (PIE) was performed on samples from the MEGAPIE (MEGAwatt Pilot Experiment) project allotted to the Japan Atomic Energy Agency. The specimens for the tensile tests were prepared from components of the MEGAPIE target, such as the beam window and the flow guide tube, which were irradiated in flowing lead–bismuth eutectic (LBE). The specimens contained curvatures and their thicknesses were over two times larger than that of the standard specimen. The PIE revealed that there was no LBE effect on the tensile properties of the 316-stainless-steel (SS316L) and T91 samples within the dose range from 0.16 dpa to 1.74 dpa at room temperature, 250 °C, and 300 °C. However, the T91 specimens showed a 1.5–2.0 times larger total elongation (TE) compared to the literature values for a specimen with standard t/w (ratio of thickness to width). It could be suggested that the t/w and TE were strongly correlated. Then, we tried to investigate the effects of the curvature and the t/w on the TE by comparing unirradiated specimens. We found that there was no curvature effect on the tensile properties and no t/w dependence on the strength and uniform elongation. On the other hand, the TE increases with increasing t/w. Based on the experimental data, we correlated the TE with various specimens t/w to estimate appropriate TE values, including that for the standard specimen.