A Design Probabilistic Approach to Define Fusion Materials Data Base Requirements

Use of vanadium alloys is contemplated for the ITER blanket and guidance is needed to determine the extent of the data base for qualifying these alloys as structural material. A probabilistic methodology first employed in the fast breeder program is used to provide a preliminary assessment of the data base requirements. This methodology, which is applicable to any structural material, or in general to any design variable, determines the adequacy of the design by considering simultaneously all design affecting uncertainties, such as operational, nuclear, thermal-hydraulic, structural, geometric tolerances and material properties. In this study a thermal-mechanical calculational model of the ITER self cooled lithium blanket design was developed and the effect of design uncertainties on temperature (creep limited) and stress-strain (fatigue limited) were calculated. Based upon the current design, it was concluded that an uncertainty band of ± 30% on vanadium material properties is acceptable. Confirmatory irradiation data are however necessary.