Full Scale Mock-up Trial Fabrication of B3 Segment for ITER-TF CoilStructures
ITER TFコイル構造物 実機大B3セグメント試作
Toshiaki Hanaoka, Hiroshige Ogata, Tsuyochi Ogawa, Toshiyuki Minemura, Ikuo Senda,*Masahide Iguchi, *Yutaka Chida, *Hideo Nakajima
花岡敏成, 小方大成, 小川剛史, 峯村敏幸, 仙田郁夫, *井口将秀, *千田 豊, *中嶋秀夫
Toshiba Corporation
8, Shinsugita-Cho, Isogo-Ku, Yokohama 235-8523, Japan (Yokohama Complex)
株式会社 東芝 〒235-8523 横浜市磯子区新杉田町8 (横浜事業所)*Japan Atomic Energy Agency
801-1 Mukoyama, Nala-shi, Ibaraki 311-0193, Japan*日本原子力研究開発機構 〒311-0193 茨城県那珂市向山801-1
Full scale mock-up of B3 segment of TF coil structures has been fabricated to investigate welding
deformation. B3 segment has complicate welding deformation because of the complicate cross sections
along welding. The full penetration weld, one side weld has been performed by narrow gap Tungsten Inert
Gas (TIG) weld using pressing to control the deformation. As the result, the control procedure of welding
deformation are obtained for the fabrication of the actual B3 segment.

1. Introduction
ITER Toroidal Field coil (TF coil) consists of awinding pack and structures [1]. The dimensions ofthe structures are 16.5m in height, 9m in width, andthe weight is about 200 ton, made of stainless steel
FM316LN [2]. The seven segments of the structures
are A1-A3, B1-B4 and two plate segments of AP,
BP as shown in Fig.1. As the fabrication of a fullscale mock-up, B3 segment which is 5.8m incurved length, 2.7m in width, 35 ton in weight, hasbeen selected to investigate the weld deformation.
This paper describes the results of trail
fabrication of B3 segment, in which an attempt tocontrol the deformation was tried.
Side plate

9mA1

B1

16.5m

B2BPA3AP

B3B4TF Coil Structures

Outer PlateWing

Side plate

BCA

Fig.2. B3 segment

Winding

A2maximum width between the wing edges is2740mm, as shown in Fig.2. The side plates
including the wings were manufactured by forging
and outer plate by bending a flat plate.

Outer plate
B3 Segment

Fig.1. TF Coil
2. Full Scale Trial Fabrication of B3 Segment
2.1 Composition of B3 Segment
B3 segment has two side plates and one outerplate. The side plates were welded at the both edgesof the outer plate, witch is shown in Fig.1. Outersurface of the side plate has a massive structure
called “wing” to join to neighboring TF coils.
Typical width of B3 segment is 1065mm, and the2.2 Welding Method
Welding of B3 segment is full penetration of120mm in depth and about 5800mm in curved
length. One side weld was selected because of thenarrow space inside B3 segment inside. Narrow gap
TIG welding and simultaneous welding of two sideplates are used for controlling welding deformation
which includes shrinkage and angular deformation.
To compensate the estimated shrinkage, thewidth of outer plate was widened. For the angulardeformation, the off-set displacement was given to
the side plates by hydraulic jack, as shown in Fig.3
a. The pressure of hydraulic jack was adjusted atevery pass, comparing the estimated spring backafter release of welding jig and the measured
deformation during welding.

Shrinkage(Inside)Hydraulicjack

Direction of welding

120882220(Outside)WUWDAngular Deformationa) Welding deformation and pressing

Target of WD, WU: 848.6b) Cross section

Fig.3. Outline of cross section and welding restraint
2.3 Full Scale Trial Fabrication of B3 Segment
Before the trial fabrication, curved mock-up of
1m length was manufactured to investigate theshrinkage and the angular deformation. Theshrinkage (ΔWU) was the difference at WU
between before and after welding, as shown inFig.3 b. The difference between WU and WD,
which is described by ΔWD, was used as ameasure of the angular deformation.
From the result of the curved mock-up, the widthof the outer plate was widened by 6mm for theshrinkage, and the off-set displacement given to theside plates edges was 10mm.

longitudinal direction.
Table I. ΔWU and ΔWD after release of welding jig(mm)MeasuredpointAB
C

Initial distance
betweenside plates
855.2
855.0
854.3

Angulardeformation
ΔWD
15.0
12.5
13.8

Shrinkage
ΔWU
3.9
5.4
6.0

Measured angular deformation changes at every
weld pass and those at constraining by jigs areshown in Fig.5. For first 12 passes, deformations
with and without hydraulic jack were measured.
The angular deformation from 1st to 12th pass canbe controlled well because the deformation is lower
than zero. After 12 pass, the deformation gradually
increases due to insufficiency constraint of jigs. The
angular deformation after release of the welding jig
at the completion of welding is up to 15mm.
However the angular deformation could be reducedby the sufficient constraint of welding jig, when thejig controls the value of the angular deformation as
much as the compensation for the spring back.
mm Hydraulic jackRelease of welding jig

Constraining welding jiga) Welding between Side
plate and Outer plateb) After welding andrelease of welding jig

Fig.4. Fabrication of B3 SegmentWelding deformation in the trial fabrication weremeasured at the both the edges (A, C) and at thecenter (B), as shown in Fig.2. The welding wasperformed from position A to position C, measuring
the welding deformation at every weld pass. The
angular deformation (ΔWD) reached about -10mm
at 12th pass. Then the hydraulic jack was removed
and the side plates were constrained by welding jigs.
Up to 12th pass, deformation was measured after
welding each pass by releasing jack press
2.4 Result
The results of the welding deformation are shownin Table I. Comparing values of shrinkage, ΔWU
at A is smaller than those at points B, C. The long
length and the curvature of B3 segment cause theconstraint at point C which is the welding end.
ΔWD at point B is smaller than the others. This isbecause stiffness of wing constraints welding
deformation. This shrinkage is about the same as
the estimated value, though shrinkage varies in theAngular Deformation

15

ΔWU at A, B, C
without pressure

105C0B-5-10-15

Spring back
ΔWD in constraining

A12

Number of Welding Pass40Fig.5. Welding angular deformation
3. Conclusion
Full scale mock-up of B3 segment for ITER-TF
coil has been fabricated by full penetration one side
weld with hydraulic jack and jig restraining,measuring welding deformations. The welding
shrinkage was controlled to be almost the estimatedvalue. The angular deformation was controlled byhydraulic jack and welding jig. Although thesufficient constraint of welding jigs is necessary tocompensate the spring back, the control method ofwelding deformation was demonstrated for thefabrication of the actual segment.
References[1] M.Iguchi, et al., Development of structures for ITER
Toroidal Field Coil in Japan, MT-22, to be published[2] Codes of Fusion Facilities -Rules on
Superconducting Magnet Structure -, JSME, JSME S
KA 1-2008, Maruzen (2008)