Dynamic Bolting Analysis of Centerstack Casing G10 Ring for NSTX-U

A new dynamic bolting analysis has been conducted to verify the design quality of a G10 ring for the National Spherical Torus Experiment Upgrade (NSTX-U). The G10 ring under the centerstack casing and lower skirt plays a critical role in NSTX-U with large electromagnetic forces during plasma drifts, quench, and halo currents. Inspections of the installed condition of the G10 ring showed a poorly shimmed interface between the ring and the toroidal field flags. This paper will describe how to define the bolt preload to resolve this underperformance issue with the G10 ring by transient bolting analysis. The simulation results of transient bolt reaction forces show that the loads imposed on the G10 ring are within the tested capacity of the Keenserts and G10 ring.