# Presentation: 936723

## Magnet Structure Engineering

***Presented by C. H. Choi***
***National Fusion R&D Center***
***Korea Basic Science Institute***

**Magnet Structure Engineering**
**and Mechanical Test of Incoloy908**

## KSTAR Magnet system

**KSTAR Magnet system**

**PF5U str.**

**PF6U str.**

**PF7U str. **

**CS magnet system**

**TF magnet system**

**Gravity Support**

## Features of TF Coil Structure

**Functions**
**Supporting TF magnet system**
**Supporting CS & PF magnet system**
**Supporting in-cryostat components (bus-line, helium-line, and signal-line, etc)**
**Sustaining In-Plane Force (IPF) & Out-of-Plane Force (OPF)**
**Reducing heat transfer to coil**
**Parameters**
**Number of structure                           ****   ****             16**
**Weight / a structure             ****    ****                          6.4 tons**
**Total weight                                                  102.4 tons**
**Dimension                           (r/********/z) 3.0 m/22.5 ****°****/4.2 m**
**Main structural material        Strengthened Austenitic Steel**
**Shape**
**Wedged D-shape structure**
**Components **
**TF case, Intercoil structures, Joint box, PF coil structure basements, Toroidal ring basement, and Cooling lines**

## Configuration of TF structure

**Inner Intercoil **
**Structure (IIS)**

**TF coil case**
**(Inboard leg)**

**Joint box**

**TF coil case**
**(Outboard leg)**

**3-D View of TF coil structure**

**PF5U structure**
**basement**

**Outer Intercoil **
**Structure (OIS)**

**PF6U structure**
**basement**

**PF7U structure**
**basement**

**Toroidal ring **
**basement**

**Configuration of TF structure**

## Cross section of TF coil case

**Filler in gap between TF coil and case**

**Test system for final VPI**

## Cooling line of TF coil case

- 7 mm

**U-type seamless tube ****(316L)**

- 7 mm

- Φ 4 mm

**Drawing of TF case cooling line**

## Structural analysis results

- Max. stress intensities of TF structure                           Unit : MPa

-  **Allowable stress = ****1059**** MPa (1.5 K Sm) for base metal of strengthened austenitic steel**

## Thermo-hydraulic analysis results

**TF & PF structures : 133 ton**
**Criteria**
**ΔTmax = 50 K**
**Gaseous He (300 K ******** 50 K)**
**Supercritical He ( 50 K ******** 4.5 K)**

**Thermo-hydraulic analysis results**

## Fabrication of prototype

**Outer intercoil str. (OIS)**

**PF basements**

**Upper & lower blocks**

**Inboard leg**

**Inner intercoil str.**

**Connection plate of OIS**

## Features of CS structure

**Providing pre-compression on segmented CS coil stack**
**Sustaining axial repulsive force between CS coils**
**Absorbing relative radial displacement between CS & TF structures**
**Sustaining gravity and vertical launching force of CS magnet system**
**Minimizing eddy current heating on structure **
**Parameters**
**Toroidal segmentation ****	****	****	****     ****	****                8**
**Overall dimension of CS structure     ****	****   (H/ ******** ) 4.3 m/1.7 m **
**Weight of CS structure****	****	****	****                   ~ 8 tons**
**Main structural material****	****            ****	****strengthened austenitic steel**
**Shape**
**Wedge and shell type****	**

**Features of CS structure**

## Configuration of CS structure

**Configuration of CS structure**

**Support lug**

**3-D View of CS structure**

**Flexible joint**

**Top block**

**Wedge**

**Upper bearing plate**

**CS coils**

**Outer shell**

**Lower bearing plate**

**Inner shell**

**Stopper**

**Bottom block**

## Wedge and stopper

**Wedge**
**Function : Providing additional pre-compression                that is for preventing separation of coils from repulsive force.**
**Sliding angle : tan******** = 0.1**
**Max. vertical pitch : ~ 5.5 mm**
**Max. vertical force : ~ 15 MN**

**Adjustable head**

**Limiter**

**Springs**

**Stopper**
**To limit lateral movement of CS system (seismic loads and lateral forces)**
** ****Re-centering of CS system**

**Wedge and stopper**

## Structural analysis results

**Structural analysis results**

- Max. stress intensities of CS structure      Unit : MPa

-  **Allowable stress = ****1059**** MPa (1.5 K Sm) for base metal of strengthened austenitic steel**

## Features of PF coil structure

**Features**
**Rigid in vertical & tangential direction**
**(Max. vertical force on PF5 coil : -10.1 MN)**
**Flexible in radial direction**
**(Hinged pin connection)**
**Hinged pin connection**** : PF5 structure**
**Flexible plate : PF6 & PF7 structures**
**Main structural material : strengthened austenitic steel**
**Parameters**

## PF coil structures

**PF5U structure**

**PF6U structure**

**PF7U structure **

**Prototype of PF5U str.**

## Design issues of PF coil structure

** ****Components : **
** ****Cover plate : pre-compression **
** ****Connection block : radial flexibility **
** ****Pin connection : accurate machining & assembly, low friction material**
** ****Spacer between coil and structure : about 5 mm (for alignment)**
** ****Structure cooling lines : connected to TF structure cooling lines**

## Structural analysis results

- PF5

**Note) * The displacements include the initial deformation due to assembly load.**

**Structural analysis results**

**Case **

**Link **

**Cover **

## Benchmarking of magnet system design

**Purpose**
**Benchmarking of magnet system design**
**Collaborator**
**Efremov institute in Russia**
**Period**
**1****st**** period : Jul. 2001 ~ Dec. 2001**
**2****nd**** period : Oct. 2001 ~ Jan. 2002**
**3****rd**** period : May. 2002 ~ Dec. 2002**

**Items**
**3D global analysis of the KSTAR TF Magnet**
**3D EM analysis of the KSTAR PF 5 coil and structures**
**3D structural analysis of the KSTAR PF5 Coil and structure**** **
**2D local analysis of aligned and mis-aligned conductor layers of CS**** **
**3D local analysis of CS CICC with He inlet tube**** **
**3D detail analysis of the conical bolt / 2D detail analysis of the shear key**** **
**Fault analysis**** **
**Calculation of more realistic waveforms of PF coils during plasma disruption.**** **
**Transient heat load calculation**** **
**Thermo-hydraulic analysis**
**Structural analysis of TF00 coil and structure**
**Mechanical test of incoloy 908 jacket**** **

## Mechanical test of Incoloy908 jacket

**Tensile property measurement**
**Sample size : 6.0 ******** 2.4 ******** 40**

**Temperature**
**(K)**

**Yield strength**
**(MPa)**

**T1**

**Ultimate strength**
**(MPa)**

**Type of specimen**

**Specimen**

**δ**
**(%)**

**WT3**

**WT2**

**T2**

**T3**

**T4**

**T5**

**T6**

**WT1**

**Base**

**Base**

**Base**

**Base**

**Base**

**Base**

**Weld**

**Weld**

**Weld**

**295**

**295**

**295**

**295**

**295**

**295**

**4.2**

**4.2**

**4.2**

**1215**

**1163**

**1244**

**1292**

**1313**

**1220**

**1188**

**1286**

**1204**

**1878**

**1962**

**1966**

**1463**

**1470**

**1485**

**19**

**19**

**21**

**14**

**14**

**14**

**-**

**-**

**-**

**-**

**-**

**-**

**ITER**

**Weld**

**4**

**1150**

**1000**

**3**

**ITER**

**Base**

**4**

**1650**

**1130**

**15**

## Mechanical test of Incoloy908 jacket

**Fracture toughness measurement **
**    ****at 4.2 K**

**Inductive extensometer **
**Attached to specimen**

**F1 specimen after testing**

**Specimen for Fracture toughness test**

## Mechanical test of Incoloy908 jacket

**FCGR measurement at 4.2 K**
**Base metal : R=0.1, *****0.4, 0.6***** ; Weld : R=*****0.1,***** *****0.6***

**Crack growth curve**

**Comparison with the curve obtained for ITER Incoloy 908.****    (   : KSTAR Incoloy908)**

## Nondestructive test of Incoloy908 jacket

******* Russian standard for nuclear power stations (PNAEG-7-010-89)**

## Nondestructive test of Incoloy908 full size jacket

**Specimen**

**Specimen**

**Specimen for NDT and Fatigue test of Incoloy908 full size jacket**

**RT results of Incoloy908 full size jacket**

## Nondestructive test of Incoloy908 jacket

*** ****Background means change in colour due to certain roughness on surface**

**Nondestructive test of Incoloy908 jacket**

**DPT results of Incoloy908 full size jacket**

## Nondestructive test of Incoloy908 jacket

**Nondestructive test of Incoloy908 jacket**

**  ****UT image of ****base metal****. Focus adjusted to ****inner jacket surface****.**
** ****one artificial notch on inner jacket surface with total area less than ****0.3 mm****2****.**

**  ****UT images of jacket side with**** weld****. Focus adjusted to ****outer jacket surface****.**
**  ****one artificial surface notch on outer jacket surface**

**Artificial**
**notch**

**Artificial notch (0.3 mm****2****)**

**UT results of Incoloy908 full size jacket**
***No defects more than artificial notch of 0.3 mm******2****** ***