In order to develop the small-scale specimen technology in Charpy impact testing for ferritic steels, the effects of specimen size and notch geometry on the upper shelf energy (USE) and ductile-to-brittle transition temperature (DBTT) were investigated for Japanese Ferrite/Martensite Dual Phase Steel (JFMS). Miniaturized specimens with different sizes and notch geometry, together with full size specimens, were irradiated to 3x10^n/m^2 in the Japan Materials Testing Reactor (JMTR) and were Charpy impact tested. The USE for miniaturized specimens, normalized by Bb^2 or (Bb)^ (B is the specimen thickness, b the ligament size), was essentially independent of specimen size and notch geometry and decreased by the irradiation, but the decrease was larger in full size specimens than in miniaturized specimens; the normalized USE for miniaturized specimens was distinctly higher than that for full size specimens . The DBTT of miniaturized specimens was strongly dependent on notch geometry, but its dependence decreased as compared with that for unirradiated JFMS . It is shown that these results may be useful in determining the USE and DBTT for full size specimens from those for miniaturized specimens
