NSTX Supported by NSTX Centerstack Upgrade Project Meeting P. Titus April 14, 2010 PF4/5 Terminal Stress Existing PF4/5 Support Weld Algorythm Moment Influence Coefficients Bottom “Lid” Torque with Access Holes

PF5 Terminal Analysis 16.0 kA in PF4 and 31.8kA in PF5

As of Oct CDR: “We are Still Evaluating the Appropriate Loading Design Basis. Present Analyses based on Worst Case Currents Provide Conservatisms That Will Be Translated into Cost Savings During the PDR” For the April 29 Peer Review: Very few areas are being qualified using maximum power supply loads from the design point. Qualification is based on Max and Min loads and load combinations for the 96 scenarios from the Design Point Or Max and min loads, and stresses from an envelope of the Global model results, run for the 96 scenarios. In addition: All calculations will be required to specify an algorithm for computing critical stresses temperatures etc, for the DCPS to limit.

Machine Protection System Algorithms PF1,2,3 supports, welds bolts – At this stage, These are just calculated from influence coefficient matrix loads divided by weld or bolt area. Proposing to add Moment Influence Coefficients PF 4/5 support weldment (see example) PF4/5 Conductor (Titus) OH Preload-Launch-TF temperature dependence PF1a-OH interaction Stress Vertical Loads on pedestal load path (TF Flag Bolts, Pedestal hilti’s), (Ali) TF Strap (T. Willard) – Mostly designed to TF max Current. DCPS should trip if vertical field exceeds limit (.24T?) TF OOP loads are a Special Problem

Addition of Moment Influence Coefficients to DCPS Bolt Loads are calculated from the vertical force and the moment divided by the width of the bolt pattern Bolt Loads are calculated only from the vertical force.

Moment influence Coefficients are calculated about a geometric center of the coil.

Comparison with Ron’s Influence Coefficients

This PF3 support analysis only Included the vertical load on PF3. Moments will add to bolt and weld stress. It is proposed to have the DCPS calculate bolt and weld stresses with the moment applied. AISC Table Minimum weld sizes recommended for joined plate sizes. HM quoted this in his LTX analysis – Why we were concerned with only 1/8 inch structural welds

The torsional moment for design of the lid/flex/diaphragm bolting and the TF steps or keys is 0.3MN-m for the lower lid – Without Holes

PF4UPF5UPF4L PF5L From FEA Weld Pa/Newton Weld psi/lb PF4/5 Weldment Nominal Weld = 5/16 in. QA Effective Weld = 1/4 FEA Weld Model Thick =10mm Weld Stress to FEA Stress = (.01*39.37)/.25 = 1.57 Weld Allowables are: 14 Ksi for Visual Inspection 20 ksi for Penetrant Inspection PF4/5 Support Weldment Strss Algorythm

PF4/5 Weldment Nominal Weld = 5/16 in. QA Effective Weld = 1/4 FEA Weld Model Thick =10mm Weld Stress to FEA Stress = (.01*39.37)/.25 = 1.57 ~25MPa * 1.57 = 39.25MPa = 5629 psi Based on the Corner Peak: 58 MPa*1.57 = psi 14 ksi is allowed with only visual inspection Weique Que told me that the protection system would only allow 18 kA based on my multipliers. I improved the mesh around the corner – Still has a sharp point, but the stresses are lower.

For 30.8kA this is (31.8/20)^2*(~70) = 176 MPa. Satisfies Copper metal Allowable of 233 Low Modulus Insulation Coil Results (Expect Mylar Slip Plane) Is cyclic slippage OK for the Mylar? I would use 12 supports

The torsional moment for design of the lid/flex/diaphragm bolting and the TF steps or keys is 0.28MN-m for the lower lid – With Holes -Only slightly less than without.