USE OF TITANIUM IN THE TOKAMAK PHYSICS EXPERIMENT (TPX)

The titanium alloy Ti-6A1-4V is currently the reference alloy for the vacuum vessel of the tokamak physics experiment (TPX), which will use D-D as fuel. Titanium was selected because it satisfies the requiremen t of reduced radioactivation of the TPX vacuum vessel. Reduced activat ion allows the hands-on maintenance of components inside the vacuum ve ssel during the first two years of operation, with a gradual transitio n to fully remote maintenance required during the latter phases of TPX 's experimental program when the neutron yields are expected to be muc h higher. It also reduces the eventual waste storage requirements. As part of the R&D program on TPX, two issues on titanium were studied: t he impact of the plasma hydrogen absorption on titanium and the weldin g of thick sections. Based on preliminary analysis, no critical issues were encountered.