[en] Mod.9Cr-1Mo steel (G91) is the currently favored structural material for several high temperature components of a Sodium-cooled Fast Reactor and it became a registered material for ASME Section III, Subsection NH in 2004. However, the material properties for Mod.9Cr-1Mo at elevated temperatures are not enough at this stage. In particular, it is not feasible to conduct a high temperature leak before break and flaw assessment for Mod.9Cr-1Mo structures due to the lack of material data concerning its fracture toughness, fatigue crack growth, creep crack growth, and creep-fatigue crack growth at elevated temperature conditions and the assessment technologies are not accomplished yet. In this study, a creep-fatigue crack initiation and growth test facility was established and corresponding tests for Mod.9Cr-1Mo tubular specimen were carried out