20181022 27 th IAEA Fusion Energy Conference Ahmedabad India M NAKAHIRA M IGUCHI T SAKURAI H OZEKI E FUJIWARA K TAKANO YS HONG M INO M NISHINO N KOIZUMI QST ID: 1048551
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1. 1COMPLETION OF THE FIRST TF COIL STRUCTURE OF ITER2018.10.22 27th IAEA Fusion Energy ConferenceAhmedabad, IndiaM. NAKAHIRA, M. IGUCHI, T. SAKURAI, H. OZEKI, E. FUJIWARA, K. TAKANO, Y.S. HONG, M. INO, M. NISHINO, N. KOIZUMI (QST)N. SAWA, D. HARA, T. INAGAKI (MHI) S.Y. KIM, J.H. CHOI, S.S. HWANG (HHI) C. LUONGO (IO)FIP1-1 / CN258
2. ITER Toroidal Field Coil224m18mTF Coils (18)16mGreat Stupa (16m high, Sanchi, India)~300 tonWater in 25mx12m pool (~300ton)
3. TF Coil Structure (TFCS)The biggest super conducting coil structures The procurement responsibility :100% Japan Domestic Agency (JADA).3Winding Pack (WP)AUAPBPBUTFCS65 ton105 ton8 ton12 tonA1A2A3B1B2B3B4Basic Segments (BS)Sub-Assembly (SA)
4. Challenges4Material:Control yield strength at 4KControl fracture toughness at 4K(ii) Welding deformationControl welding deformationControl segments welding(iii) Partial Penetration Welding (PPW)PPW crack initiationPPW crack growth(iv) Ultrasonic testing (UT) Attenuation compensation methodAttenuation compensation factorUT for PPW(v) Fitting testFitting test for AU-AP and BU-BPFitting test for AU-BUas-weld notchMark LineControlled deformationReference LineSection at welding lineAU/BUAP/BP
5. Challenge (i) Control yield strength at 4KSpecial material is required with total amount about 5000 ton5Ensure Huge magnetic force (Static analysis) Measured valuePrediction curve (1)Prediction curve by (C+N)Figured out correlation between yield strength at 4K and C+N contentsHuge amount of 4K test is neededActual materials (total about 5000 ton)In beginning of 2018, material procurement for TFCS was completed.C+N contentsYield strength at RTSpecimenYield strength at 4KPredictCN
6. Challenge (i) Control fracture toughness at 4KIn the work to improve control fracture toughness, JADA discovered the strong correlation between Md30 and fracture toughness at 4K.6Figured out correlation between fracture toughness at 4K and Md30Found martensite at edge of cracked areaThe Md30 has improved the quality of fracture toughness.y = αx+βLow fracture toughness(ex. Glass: Hard but fragile)High fracture toughness(ex. Metals)Chemical contents (9 elements)Grain sizeFracture toughness at 4KPredict
7. Challenge (ii) Control weld deformationJADA performed 1) welding qualification using mock-ups, Mechanical properties of welding joints were confirmed, 2) Basic segment mock-ups. Control method of welding deformation was improved.7① Outer groove welding (1st)② Inner groove welding (1st)③ Outer groove welding (2nd)④ Inner groove welding (2nd)Welding with monitoring welding deformation (Balance welding)B3 segment mock-upThe deformation converges to 0mm.Welding qualificationImprove by sequence
8. Challenge (ii) Control segments weldingSegments welding is the most difficult to control. Through trial, amount of deformation and tendency are figured out to implement to actual manufacturing.8Segment-to-segment welding (A1+A2)Example of welding deformation controlWelded Sub-assemblies (AU)Mark LineControlled deformationReference Line4mWelding LineA2A1~180mm~80mmSide PlateOuter PlateSection at welding lineWelding trial (A1+A2(3m))Target PositionThe actual manufacturing, deformation is well controlled
9. Challenge (iii) Partial Penetration Welding (PPW)9Narrow work space FPW: Invisible welding PPW: Visible weldingPlate shape attachments FPW: Impractical weld joint design PPW: Practical weld joint designFull Penetration welding (FPW) is better. But…Application of PPW is necessaryas-weld notchorS-N?LEFM?
10. 101: Confirmation of crack initiation behaviorBase: 316LN (N~0.21%)Weld: JJ1 (12Cr-12Ni-10Mn-5Mo-0.13N)Method: TIG weldUnweldedWeldedWeldedAs-weld notchCT specimen (As-weld notch)CT specimen (EDM notch)Test condition: Load control Frequency: 10HzStress ratio: 0.1a)b)Challenge (iii) PPW crack initiation12,6981,898As-weld notch (no artificial treatment)EDM notch (R0.1mm is remained on edge.)=> Behavior like Crack=> Propagation in weld
11. 11Challenge (iii) PPW crack growthCT specimen (Weld metal/EDM notch)d)FEM analysis and assessment allowable weld joint and maximum initial defect sizeFEM analysis (total 133 weld joints) Allowable maximum initial defect size =>100mm2 of semi-elliptical at root① Slow crack growth③Application of common region to assessmentBase metal①②③c) Crack growth rate parameter②Stress redistribution when sampling Method of “Design by analysis” for PPW was successfully established!11
12. Challenge (iv) Ultrasonic Testing (UT)Principle of Ultrasonic Testing12TransducerCrackCrackEchoBack surfaceEchoInitial pulseAttenuation of weld metal was evaluated.Ultrasonic waveWeld metalBasemetalWave decreases in the weld
13. Challenge (iv) UT attenuation compensate methodDAC curves* were prepared byCalibration block using base metalReference block including weld metal13*: DAC curves (Distance Amplitude Characteristic curves)The difference were quantified.
14. Challenge (iv) UT attenuation compensation factorUltrasonic attenuation (dB) vs. Weld metal path(mm) “y = ax” (a: 0.2 ~ 0.4) 14Weld metal attenuation of TFCS was Properly corrected.
15. 15Challenge (iv) UT for PPWEstablishment inspection method for PPWNoise!High quality weld joint ← Inside defect inspectionWeld depth& initial crack size ← weld depth Confirmation Ultrasonic Testing (UT) methodNoise near root → Low accuracy on depth measuring?Verification test by actual size PPW mock up.UT procedure was defined.+/-1mm accuracy for depth measuring.
16. Challenge (v) Fitting Test16AP/BPAU/BUMisalignmentGapMis-alignmentGap: 0.5±0.25mmMisalignment:±0.3mmReq. groove tolerances (inner)Misalignment: ±1.3mmReq. groove tolerances (outer)AU/BUAP/BPReq. 2): AU-BUGap: 0.5±0.25mmMisalignment:±0.7mmGap: 0.5±0.25mmMisalignment:±0.3mmGap: 0.5±0.25mmMisalignment:±0.3mmBack plateSide plateSide plateReq. 1): AU-AP, BU-BPUpperLower- Strict alignment accuracy requested on welding groove to assure welding quality- Actual AU, AP, BU, BP were tested
17. Challenge (v) Fitting Test for AU-AP/BU-BP17Nylon wedgesStainless SteelwedgesHydraulic JackProtectionJigJigs used to fit up AP to AUAU and AP after fit-up Difficulty: To control the precise position of AP and BP. To control the flexibility of AP and BP shape. Solution: Several types of guide jigs to adjust their position. Lever hoist to control their axial flexibility Result: Tests were successfully completed.
18. Challenge (v) Fitting Test for AU-BU18Aligned groovesAU and BU after fitting up for the first EU products tested in horizontal position AU and BU after fitting upfor the first JA coil tested in vertical position Difficulty: To find the exact position of actual AU and BU to achieve the target criteriaSolution: Virtual fitting based on the dimension survey data by laser tracker Find the optimum position of AU and BUResult: Tests were successfully completed utilizing the above
19. CONCLUSIONSolving the difficult challenges, TFCS became feasible.Two TFCSs has been completed in 2018, and another one will be completed soon. The first Japan-manufacturing TF coil will be assembled TFCS and WP from the fourth quarter of 2018 as the very first TF Coil of ITERAll the TF coils will be delivered to ITER in 202119
20. आपका ध्यान के लिए धन्यवाद20