Compact Ignition Tokamak Vacuum Vessel Material Selection^a

The Compact Ignition Tokamak (CIT) vacuum vessel is envisioned to be a thick wall torus with a Dee shaped cross section. It must withstand violent impact forces from plasma disruptions. Operating conditions include a base pressure of 10⁻⁸ torr and a 350°C base temperature. A suitable vacuum vessel material of construction must combine adequate elevated temperature strength and desired physical properties compatible with the operating service conditions. CIT performance and design requirements also dictate that fabricability and availability critically influence selection. Similarly, a requirement that the vessel shall have a low level waste activation further affects the appropriate choice. Based upon these selection criteria two materials were identified, that used in a unique hybrid design, satisfy both performance and decommissioning requirements.