Disruption Analysis and Response Implication of Passive Plates for the NSTX Upgrade

The National Spherical Torus eXperiment (NSTX) upgrade project requires analysis qualifications of existing vacuum vessel and passive stabilizing plates for increased plasma performance. Vertical stability is critically dependent on the passive conducting structure that surrounds the plasma. In this paper, the passive plate is analyzed for the upgrade condition during plasma disruption to ensure the level of stress in the plate and the fastener is within its design limits. The counter-bore of the passive plate for bolting is evaluated in detail and counter-bore bushing is redesigned to prevent shear failure during disruptions as a result of high pulling and pushing forces, particularly for support at corner bolts.