J. Plasma Fusion Res. SERIES, Vol. 9 (2010)

Basic Concept of JT-60SA Tokamak Assembly
K. Shibanuma1, T. Arai1, H. Kawashima1, K. Hoshino1, R. Hoshi1, K. Kobayashi1,
H. Sawai1, K. Masaki1, S. Sakurai1, Y. K. Shibama1, A. Sakasai1, K. Yoshida1,
Y. Kamada1, P. Barabaschi2, and G. Phillips2
1

Japan Atomic Energy Agency, Naka, Ibaraki-ken 311-0193, Japan2
Fusion for Energy, Boltzmannstr 2, Garching, 85748, Germany(Received: 30 October 2009 / Accepted: 25 February 2010)

The basic concept and approach for the assembly of the major components for JT-60SA are studied. The
absolute coordinate system for JT-60 SA assembly and the reference positions of the major components is defined
as a basis of the assembly, taking into account the different deformations of the vacuum vessel (VV) and toroidal
field coil (TFC) under the conditions of assembly and plasma operation. The conceptual assembly tools, such as theassembly frame and other jigs/fixtures, are also studied and proposed for effective assembly works for the majorcomponents, such as VV and TFC. The assembly of the last TFC is a critical issue due to the friction during
insertion between two adjacent TFCs in the narrow space of 20 degrees. To reduce the effect of friction, it issuggested that the opening angle for insertion of the last TFC is increased from 20 degrees to 60 degrees bycombining the last TFC with the adjacent two TFCs as a single body.
Keywords: JT-60SA, assembly, assembly frame, assembly jig and fixture, assembly scenario

In the present paper, therefore, the proposed basic
concept and approach for the assembly of the majorcomponents for JT-60SA are mainly described.
z Definition of the absolute coordinate system and thereference positions of the major components for
JT-60 SA assembly, taking into account thedifferent deformations of the VV and TFC between
assembly and plasma operationz Study of the basic scenario and sequence of themajor components for JT-60 SA assemblyz Study of the typical assembly tools such asassembly frame and jigs/fixtures for effective
assembly works for the major components such as
VV, TFC, lower EF coils and VV portsz Study of the assembly of the last TFC in the narrow

1. Introduction

The JT-60 SA project is a combined project ofJapan (JA) - EU satellite tokamak program under theBroader Approach (BA) agreement and JA domestic
program [1, 2]. The JT-60SA is planned to be constructedin the existing JT-60 tokamak building after disassemblyof the JT-60U facility. Major components of JT-60SA for
assembly are the vacuum vessel (VV); superconducting
coils, including the toroidal field coil (TFC), equilibrium
field (EF) coils and central solenoid (CS) coil; in-vessel
components, such as divertor; thermal shield(TS); andcryostat. The TS is composed of three parts, those being
the vacuum vessel thermal shield (VVTS), port thermalshield (PTS) and cryostat thermal shield (CTS). TheJT-60SA assembly also includes the re-installation of theneutral beam injector (NBI), electron cyclotron heatingsystem (ECH), VV-pumping system, etc., in the tokamakhall.
The assembly is planned to start in 2012, in order tomeet the schedule of the first plasma in March of 2016.
Based on this requirement, a collaborative conceptual
study for the JT-60SA assembly is ongoing between JAand EU. Assembly studies of the sub-components such aslayout of in-cryostat components and work space forpiping and connection of the feeders in the cryostat areunder way and preliminary level because the assembly ofthese components is planed around the end of 2014.

Origin (0,0,0)

8000 mmFig.1 Absolute coordinate system of JT-60SA

author’s e-mail:Shibanuma.kiyoshi@jaea.go.jp276©2010 by The Japan Society of Plasma
Science and Nuclear Fusion Research

K. Shibanuma et al., Basic Concept of JT-60SA Tokamak Assemblyrails are also provided in the assembly frame and used formainly transfer, support and positioning of the TFC. Inparticular, the assembly of the TFC contains the toroidal
movement along the pre-installed VV by the temporary
supports from the assembly frame. After movement, thespace of 20 degrees between two adjacent TFCs

2. Absolute Coordinate System for JT-60SA
Assembly

The absolute coordinate system of JT-60SA is basedon that of the JT-60 experimental building. The origin((X,Y,Z) = (0,0,0)) is defined to be 8000 mm from thefloor, which corresponds to a mid-plane position of theVV during plasma operation, as shown in Fig. 1.
Based on the this, the reference positions of themajor components such as VV and TFC of the JT-60SA
during assembly are required to be defined, taking into
account mainly the thermal deformation because theoperating temperature of the superconducting coils, suchas TFC, and VV are 4 K and 323 K, respectively. In
addition, the TS, which is an interface component
installed between VV and TFC, is also considered todefine the positions of VV and TFC. Figure 2 shows theresults of the deformations of VV and TFC duringassembly and plasma operation, respectively. Theposition (7998 mm) of the VV from the floor duringassembly at room temperature (293 K) is determinedconsidering the thermal expansion during plasma
operation at 323 K, based on the origin of the JT-60SA
device. The position (8018 mm) of the TFC from thefloor during assembly is also determined, considering not
only the thermal deformation at 4 K but also dead weight,
deformation during coil discharge and space for
installation of the TS.

Fig.3 Assembly frame
TFC is adjusted to a reference position and fixed by thetemporary supports from the assembly frame. Therefore,
the assembly frame also provides assembly tools and jigs
with jacks to temporarily support the components as wellas to adjust the components into their correct positions.
The assembly frame is installed on the floor of thetokamak hall in the JT-60 experimental building. The
existing base structures, which provide the available
connection bolts, are used for the installation of theassembly frame.

4. Reference Points for Metrology

The reference points (benchmarks) for JT-60SA
assembly in the tokamak hall can be defined based on
those for JT-60U assembly, as shown in Fig. 4. The six
reference points for JT-60U assembly were used as initial
positions. From these reference positions, the virtual
machine axes and the origin of the JT-60SA will bedefined in the center column located at the center of theFig.2 Positions of VV and TFC under assembly andplasma operation

3. Assembly Frame

An assembly frame, which is located around thetokamak device and provides the dedicated cranes fortransfer of the tokamak components, is adopted toeffectively carry out the assembly of tokamak
components in the tokamak hall, independently of thefacility cranes in the building for preparations such as
pre-assembly of the tokamak components in the assembly
hall before assembly at the tokamak hall. Figure 3 show aschematic concept of the assembly frame [3, 4]. The sizeof the assembly frame is approximately 16 m in heightand 17 m in diameter with 10 outer vertical columns andbeams between columns. The center column and guideY3 Wall

East Wall(X2)
FL+1000

Center of JT-60U
17000

18000

Floor

Fig.4 Reference points (benchmarks) for JT-60SA
assembly in the tokamak hall277

K. Shibanuma et al., Basic Concept of JT-60SA Tokamak Assembly(10) The lower cryostat body is installed.
(11) The CTS lid is installed after completion of piping,feeder connection, etc. in the upper space of thecryostat.
(12) The cryostat lid is installed. After that, the VV ports
are inserted and welded between VV and cryostat.

assembly frame by using the laser metrology device.
Additional reference positions will be also defined on thebuilding wall/floor and assembly frame, according to therequirements in the assembly process of the respective
JT-60SA components.

5. Global Assembly Scenarios and Sequences

6. Assembly Jig and Fixture

The basic assembly scenario and sequence of themajor tokamak components are illustrated in Fig. 5.
(1) The cryostat base is installed in the tokamak hall.
(2) The first 40 degree VV sector is installed.
(3) The VVTS is temporarily supported on the VV
sector (The VVTS is finally installed on the TFC
after completion of all TFC installation around VV).
(4) The first TFC is installed around the VV.
(5) The remaining VV sectors, VVTS and TFCs arecontinuously installed, respectively, according to thesame sequence of (2) to (4).
(6) The last TFC and VV sector covered by 20 degrees
with VVTS are installed together.
(7) Six EF coils and CS coil are installed on the TFCs.
The pre-loading of CS coil is under study, by wedge
or heating as examples.
(8) The PTS is connected to the VVTS, so that theVVTS is supported by the TFCs via the PTS.
(9) The CTS body is installed and connected to the PTS
after completion of piping, feeder connection, etc. inthe lower space of the cryostat.

6.1 Assembly Jig for VV Sector and TFC

For the assembly of the tokamak components, theassembly of the VV sector and TFC is the most criticalbecause the VV sector and TFC are installed under close
relationship in the assembly sequence. Therefore, theassembly scenario of the VV sector and TFC is describedin more detail, including some preliminary concepts ofjigs and fixtures for the assembly of VV sector and TFC.
Figure 6 shows a preliminary concept of theassembly jig and fixture, which is used not only for VV
sector installation but also TFC installation in theassembly frame. For this, the assembly jig and fixture
must be capable of:z Positioning the VV sector during installation for
welding between VV sectors
z Supporting the VV sector during TFC installation
around the VV sectorz Supporting the VV sector during installation of theVV gravity support
z Supporting the VV sector against possible
earthquake loads

Fig.6 Preliminary concept of the assembly jig and fixture
for VV assembly
To satisfy the above requirements, the assembly jig
provides six degrees of freedom for positioning
components, using jacks and support beams; clamp
mechanisms to grasp the VV sector; and removablestructure of the support beam, which avoids theinterference between the support beam and the TFC
during the toroidal movement of the TFC along the VVsectors.
Using this jig, the assembly sequence of the TFC
around the VV sector is shown in Fig. 7. After the lower

Fig.5 Basic assembly scenario and sequence of themajor tokamak components

278

K. Shibanuma et al., Basic Concept of JT-60SA Tokamak Assembly

supports the VV sector from the assembly frame. After
that, the lower leg of the support structure is reassembled
in stage (5).
As for the TFC assembly, a preliminary idea of thejig and some mechanisms for locating and supporting theTFC in the assembly frame is studied. Further detailed
study is necessary, after the clarification of therequirements of the TFC assembly. Figure 8 shows aschematic view of the assembly jig and mechanisms fortoroidal movement along the VV sectors, support andpositioning of the TFC in the assembly frame. The
toroidal movement is carried out using the toroidal moveralong the rail structures installed in the assembly frame inconjunction with the dedicated crane. The horizontal
support beams with jacks from the assembly frame andthe vertical support beams for temporary gravity support
at the inner and outer locations from the cryostat base areused for the positioning and fixture of the TFC, as shownin Fig.9. The reference points for the measurement andpositioning of the TFC in position will be adopted at theupper and lower parts of the inner wedge of the TFC.
Figure 9 also shows a combination and layout of thesupport beams between TFC assembly and VV sector
assembly. The optimized location and number of thesupport beams will be defined after more detailed study.

leg of the front side of the support beam is removed instage (3), the TFC is moved toroidally along the VV
sector and located at the center of the 40-deg. VV sector

Fig.7 Assembly sequence of the TFC around the VV
sector

6.2 Assembly Jig for Last TFC

The last TFC (18th TFC) has to be installed withVV sector and VVTS into the opening of 20 degree after
assembly of the VV sectors with 340 degrees and 17TFCs, as shown in Fig.10. The assembly jig and fixture
for the last TFC is required to be combined with that for
the VV sector and VVTS. Figure 11 shows an idea of thecombined jig and fixture, including the following
requirements and assumptions.
z The VV sector with VVTS is supported with the lastTFC.
z The last TFC is firstly installed and assembled bybolting adjacent TFCs.
z The support/fixture parts for the last TFC of thecombined jig and fixture are removed for thefollowing assembly of the last VVTS and VVsectors.
After removal of TFC support/fixture parts, thecombined jig and fixture after becomes the same
configuration as that for the assembly of the VV sector(see Fig.6).

Fig.8 Schematic view of the assembly jig andmechanisms for toroidal movement along theVV sectors, support and positioning of theTFC in the assembly framein stage (4). During this time, the other support beam

6.3 Assembly Scenario of Last TFC

According to the description in section 6.2, the last
TFC (18th TFC) has to be installed into the opening of 20
degree. However, the inner wedge, in particular the upperand lower crown areas, of the TFC is required to beconnected without gaps to the adjacent TFCs. It isdifficult to install the last TFC without a gap in the crownFig.9 Preliminary concept of the assembly jig andfixture for TFC assembly279

K. Shibanuma et al., Basic Concept of JT-60SA Tokamak Assembly

Therefore, this scenario can reduce the problem offriction during insertion of the last TFC in the narrow
opening space of 20 degrees.
Figure 12 shows the basic scenario and sequence ofthe last TFC installation.
(1) The installation of 17 TFCs and VV covering 340
degrees with the VVTS are assembled. At this stage,
it is noted that two adjacent TFCs located on bothsides of the last TFC are pre-assembled in position
using temporary bolts at the crowns.
(2) To customize the insulation shims between the last
TFC and adjacent TFC, the gap is measured after theinsertion and pre-assembly of the last TFC between
the adjacent TFCs. This pre-assembly is carried out
using the last TFC only, i.e. without the associatedVV sector and VVTS sector.
(3) After removal of the last TFC, the customized
insulation is attached on both sides of the inner wedgeof the last TFC in the assembly hall.
(4) The last TFC combined with VV sector and VVTS is
pre-assembled in the assembly hall and transfered tothe tokamak hall.
(5) The last TFC with VV sector is positioned shifted 10mm radially outward from the reference position
between the two adjacent TFCs. After that, the last
TFC is temporarily connected with two adjacent TFCs
by bolting at the crowns so as to form the last threeTFCs as a single body.
(6) The last three TFCs are installed in the reference
position in the opening space of 60 degrees. The
assembly of the last TFC is completed by bolt andshear pin connections at the crowns of the last TFC.
After the completion of all TFC installation, therespective connections of the last VVTS, by bolting;and VV sector, by welding; are carried out throughthe access gap between VV sectors from the inside ofthe VV.

areas due to friction between adjacent TFCs during
insertion. To solve this problem, it is propose that thefinal positioning and adjustment of the last TFC is carriedout together with the two adjacent TFCs. The
combination of the last three TFCs leads to the increaseof the opening angle to 60 degrees instead of 20 degrees.

Fig.10 Last TFC (18th TFC) has to be installed with VV
sector and VVTS into the opening of 20 degree
after assembly of the VV sectors with 340
degrees and 17 TFCs

Fig.11 Combined jig and fixture for last TFC assembly

6.4 Assembly Jigs for Lower PF Coils

Three lower EF coils need a special care for theinstallation in six EF coils. After installation of thecryostat base, three lower PF coils (EF4, EF5and EF6)
are pre-installed on the jack-up systems located on thecryostat base. Figure 13 (a) shows an example of EF5
installation. After completion of the assembly of TFC,
VV and VVTS, three EF coils are jacked up and installedin the right positions on the TFCs, respectively. Figure 13(b) shows the installation position of the EF5 lifted bysingle staged jack-up systems. Two-staged jack-up
systems will be used for the installation of EF6, whose
location is higher than that of EF5. After installation ofthe lower EF coils, three upper EF coils are installed by
the facility crane in the tokamak hall.

Fig.12 Basic scenario and sequence of the last TFC
installation

280

K. Shibanuma et al., Basic Concept of JT-60SA Tokamak Assembly

6.5 Assembly Jigs for VV Ports

Jack

There are many types of VV ports such as upper
vertical, upper oblique, horizontal, lower oblique andlower vertical ports. In addition, the assembly of the VVports is carried out in the restricted space between VV
and cryostat, although the precise installation is required.
To meet the requirements, a guide rail concept istherefore adopted. The guide rail is pre-installed between
VV and assembly frame as a base structure for thepositioning of the VV port, as shown in Fig. 14. In
addition, the precise adjustment and fixture of the VV
port are performed using the jack systems installed in theVV port, as shown in Fig.15. Installation of the VV porton the guide rail is carried out by the dedicated crane in
the assembly frame. After adjustment, the VV port iswelded from the inside of the VV.

Guide RailFig.15 Concept of adjustment mechanism for VV port
installation

7. Summary

The basic concept and approach on the assembly ofthe major components for the JT-60SA have been studied.
The conceptual assembly tools such as assembly frame
and jigs/fixtures have also been studied and a procedure
proposed for effective assembly of the major components,
including the VV and TFC. The critical issue ofovercoming friction during the assembly of the last TFC
could be reduced by combining the last TFC with two
adjacent TFCs as a single body, so that the opening spacebecomes wider up to 60 degrees for the insertion of thelast three TFCs.
Further to the above conceptual assembly study on
the major components, additional engineering works
including assembly of the in-cryostat components are
ongoing with the support from industry for the JT-60SA
assembly .

Jack-up System
EF5(a)(b)

Jack systems are already
pre-installed in the initial
phase of the assembly

EF5 is installed by the jacksystems to the rightposition

Roller

Fig.13 Basic scenario of the lower EF coil installation

3. References

Guide Rail
Upper Oblique
PortIn

[1]
[2]
[3]
[4]

nrtio
se

Horizontal Port

Upper ObliquePort

Fig.14 Basic scenario of the VV port installation

281

T. Fujita, et al., Nuclear Fusion 47 (2007).
S. Ishida, et al., Fusion Eng. Des., submitted.
Y. K. Oh, et al., J. Korean Physical. Society 49 (2006) p.S1
S. T. Wu, Fusion Eng. Des. 73 (2005) p.135.