Transmutation of Tungsten in Fusion and Fission Nuclear Environments

The amount and type of gaseous and metallic transmutants produced in tungsten (W) when used as a plasma-facing armor in magnetic (MFE) and inertial (IFE) confinement fusion systems were determined and compared to those obtained following irradiation in fission reactors. Up to ∽8% metallic transmutants are generated at the expected lifetime of the fusion blanket. Irradiation in fission reactors to the same fast neutron fluence yields a much larger amount of metallic transmutation products than in fusion systems. While the dominant component in fusion systems is rhenium (Re), osmium (Os) is the main transmutation product in fission reactors. The impact on the W properties needs to be assessed. The results of this work will help guide irradiation experiments in fission reactors to properly simulate the conditions in fusion systems by possible direct implantation of transmutation products in irradiated samples. In addition, the results represent a necessary input for modeling activities aimed at understanding the expected effects on properties.