NSTX-U_Center_Stack_Casing_Description.pdf

Figure 1: (a) Cross sectional view of NSTXU (b) Center Stack Case Assembly.

Design Description

CSC Assembly The Center Stack Casing (CSC) assembly (CSCA) is a precision machined weldment made from the four different types of parts show in Figure 2. Both the upper and lower regions (opposite ends of the structure) have similar parts. The assembled CSCA consists of 1 CSC weldment, 2 bellows with flanges, 2 collar supports and 34 organ pipes. All of the parts are made from Inconel 625 with the exception of the vacuum sealing flanges on the end of the organ pipes which are stainless steel.

The CSCA main functions are forming part of the vacuum vessel boundary along with providing structural support to the Plasma Facing Components (PFCs) and the Inner PF coils. The CSC assembly also provides vacuum ports for various diagnostics, instrumentation, and the gas injection system. The CSCA must also facilitate heat up and cool down of PFCs during bakeout and operations respectively. The heating and cooling functions are achieved through various interfaces. Refer to the interface section of this document for these details.

Figure 2 Center Stack Casing Assembly

Center Stack Casing Weldment Figure 3 shows the CSC weldment constituent parts. The CSC weldment consists of 4 types of parts, 7 individual parts in total, welded together and then post-weld machined to high precision. These parts are welded together with full penetration welds as shown in Figure 4 and also detailed in the drawings. As seen in the image, bevels are used on both sides of the weld joint, with a 1/16 inch mating region between the parts to be welded. When the weld is completed the full wall thickness and full strength of the material is available to ensure structural integrity. Interface with the PFC tiles is achieved via welded studs installed on the First Wall and the Angled, and Vertical sections of the divertor. Mounting features for the Heat transfer plate and passage holes for organ pipes are provided in the horizontal divertor flange. Note, the organ pipes are welded to the horizontal divertor flange. Grooves on the inner diameter of the vertical section are provided for mounting the heat transfer tubing.

Figure 3 (a) Center Stack Case Weldment – Section Labels (b) Weldment Parts

Figure 4 Full Penetration Weld Details

Divertor Flange

Figure 5 Divertor Flange Details

Vertical Section

Figure 6 Divertor Vertical Section Details

Angled Section

Figure 7 Angled Section Details

First Wall Region

Figure 8 First Wall Region Details

Organ Pipe:

There are 34 total organ pipes installed into the CSC assembly. 17 organ pipes are installed on each upper / lower region of the CSC assembly. The organ pipes are weldments made from 2 pieces: (1) In625 tubing and (2) 304 stainless steel vacuum flange. Refer to Figure 5 for the organ pipe details. The organ pipes provide a vacuum interface for various diagnostics, instrumentation and the gas injection system.

Figure 9 (a) Organ Pipe CAD model (b) Sample Drawing

CSC Collar Support.

The collar support is a precision machined structure made from In625. The average wall thickness is 3/8 inch with an inner diameter of XX and an outer diameter of XX and a height of XX . Refer to Figure 6 for the Collar support details. There are two collar supports installed on the CSC assembly. One each is installed on the upper / lower ends of the CSC assembly and is connected to the divertor flange with full penetration welds. The collar interfaces with the machine core structure (Polar Region) Pf1AB coil support assembly via a bolted frictional connection as shown in Figure 6. The collar has access ports to aid installation of the cooling tube connections.

Figure 10 CSC Collar Support (Ref. Drawing E-DC11418)

Bellows Assembly The bellows and the associated flanges are a 3 part welded assembly and are made from In625. Refer to Figure 7 for an image of the bellows assembly. The bellows is a custom part made through cold forming. Refer to Figure 11 and drawing E-DC11167 for the bellows geometric details. The flanges were designed in-house to provide allow full penetration welded connections between flanges and the bellows. One end of this assembly interfaces with the Polar Region PF1C o-ring flange forming a vacuum seal via a bolted connection. The other end of the bellows assembly is welded and bolted to the divertor flange. Refer to Figure 8 for the welded-bolted connection.

Figure 11 (a) Bellows and Flanges (b) Cross Sectional View

Figure 12 Bellows Flange Welded-Bolted Connection to the Divertor Flange.

Drawings The drawings colored yellow pertain to the HTT and HTP which from the design validation perspective are out of scope for the CSC FDR. But, HTT and HTP installation into the CSC (fabrication phase) is within scope for the review.

E-DC11165 DIAGNOSTIC ORGAN PIPE WELDMENT

E-DC11206 BLANK, CS VERTICAL SLEEVE

E-DC11208 FORGING, CS ANGLED SECTION ADAPTER

E-DC11209 BLANK, CS FIRST WALL SLEEVE

E-DC11213 FORGING, CS COLLAR SUPPORT

E-DC11210 CENTER CASE WELDMENT, CENTERSTACK

E-DC11124 HTT COOLING PLATE ASSEMBLY, UPPER

E-DC11125 HTT COOLING PLATE ASSEMBLY, LOWER

E-DC11073 HEAT TRANSFER COIL ASSEMBLY

E-DC11074 COOLING COIL VERTICAL CLAMPS

E-DC11174HTT AND HTP CLAMPS

E-EB1089 DIVERTOR COOLANT TUBE STUB WELDMENT

E-DC11173 GASKET, HTP

E-DC11211 CENTER CASE WELDMENT, HEAT TRANSFER PARTS

E-DC1428 ECN CENTERSTACK BELLOWS

E-DC11204 CENTER CASE ASSEMBLY, PROTECTIVE TILE WELD STUD LOCATIONS

E-DC11212 CENTER CASE WELDMENT, BELLOWS

E-DC11167 BELLOWS WELDMENT