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Manufacturing progress on the first sector and lower ports for ITER vacuum vessel
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Manufacturing progress on the first sector and lower ports for ITER vacuum vessel H.J. Ahn a,∗ , H.S. Kim a , G.H. Kim a , C.K. Park a , G.H. Hong a , S.W. Jin a , H.G. Lee a , K.J. Jung a , J.S. Lee b , T.S. Kim b , J.G. Won b , B.R. Roh b , K.H. Park b , J.W. Sa c , C.H. Choi c , C. Sborchia c a
National Fusion Research Institute, Daejeon 305-333, South Korea Hyundai Heavy Industries Co. Ltd., Ulsan 682-792, South Korea c ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-lez-Durance, France b
h i g h l i g h t s • • • •
All manufacturing drawings of the first sector of VV have been completed. Full scale mock-ups have been constructed to verify fabrication procedure. Qualifications for welding and forming are done and for NDE are ongoing. Manufacturing progress is around 40% for the sector and LPSE up to the end of 2015.
a r t i c l e
i n f o
Article history: Received 9 November 2015 Received in revised form 20 January 2016 Accepted 1 February 2016 Available online xxx Keywords: Vacuum vessel Sector Port Nuclear Manufacturing Welding distortion
a b s t r a c t Manufacturing design of Korean sectors and ports for the ITER Vacuum Vessel (VV) has been developed to comply with the tight tolerance and severe inspection requirements. The first VV sector and lower ports are being fabricated slowly under strict regulations after verification using several real scale mock-ups and qualifications for welding, forming and NDE. During three years after start of fabrication, manufacturing progress on four poloidal segments of the first sector is that (1) all inner shells were welded, (2) forgings for complicate components have been machined, (3) port stubs and poloidal T-ribs were assembled, and (4) machined components are welded on the inner shells by narrow-gap TIG welding and electron beam welding. The progress of lower ports is that (1) inner shells of stub extensions were bent and treated with heat, (2) T-ribs were fabricated and examined by qualified phased array UT, (3) supporting pads and gussets have been machined, and (4) inner shells are assembled with T-ribs and machined forgings. The progress rate of manufacturing is around 40% up to the end of 2015 for the first sector and lower port stub extensions. © 2016 Elsevier B.V. All rights reserved.
1. Introduction The ITER Vacuum Vessel (VV) is a torus shaped double wall structure and consists of nine sectors and several ports. Main functions of the VV are to provide high vacuum for plasma operation and to prevent radioactive contamination as a Protection Important Component (PIC). ITER is a Nuclear Facility INB-174 [1]. Korea Domestic Agency (KODA) is responsible for procurement of two VV sectors, nine lower ports and seventeen equatorial ports. KODA contracted with Hyundai Heavy Industries Co., Ltd. (HHI) to produce the VV
sectors and major ports including the first sector which will be delivered before others. The VV shall be designed and fabricated as nuclear equipment in accordance with the RCC-MR code [2] and regulations of nuclear pressure equipment in France (ESPN). The manufacturing design was developed to fabricate the VV sector and port structures based on the design requirements. All manufacturing sequences including welding and inspection methods were also introduced to comply with the tight tolerance and severe inspection requirements [3,4]. 2. Manufacturing design
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (H.J. Ahn).
The ITER VV is a double walled torus structure and consists of nine sectors with forty four main ports like long nozzles of a pressure vessel. The main material is 316L(N)-IG, ITER grade austenitic
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The manufacturing design of Korean sectors has two special design concepts to minimize welding distortion. One is a selfsustaining welded IWS support rib which is designed to keep strong contact with FSH at unwelded area. The other is cup-and-cone type segment joints which can be directly welded to poloidal ribs without splice plates. The special joint designs will mitigate the risk of sector tolerance mismatch [7]. All manufacturing drawings of the sector have been completed. 2.2. Lower port design
Fig. 1. Composition of a VV Sector.
stainless steel. Nitrogen contents and limited impurities such as boron, cobalt and niobium shall be controlled for the ITER grade stainless steel. The heavy welded VV sector is composed of double shells, T-shape ribs and flexible support housings (FSH). The height and outer diameter of the VV are 11.4 m and 19.4 m, respectively. Its gross weight is more than 5200 ton. The in-wall shielding (IWS) and cooling water fill the interspace between double walls of the VV. The IWS occupies 60% of the interspace and provides efficient neutron shielding [5,6].
At the lower level of the VV, there are nine lower ports located for the vacuum pumping (Cryopump) or remote-handling of divertor cassettes and diagnostic (RH/D) at every 40◦ sector. A typical lower port structure consists of a port extension (PE) and a port stub extension (PSE) connected to the port stub in the main vessel as shown in Fig. 3. The ports are rigid double-wall structure with Trib stiffeners between the shells for supporting the main vessel. To enhance the port bearing capacity, the support pad of the VV gravity supports and heavy gussets are integrated into the stub extensions. The splice plates are also adopted to connect PSE and PE as well as PSE and VV sector. The end part of the PE is normally equipped with a closure plate for the high vacuum boundary. Total length, width and weight of the lower RH/D port are 6.97 m, 3.63 m and 52 ton, respectively. Those of the Cryopump port are 6.34 m, 3.68 m and 45 ton, respectively [8]. 2.3. Fabrication sequence and assembly scheme
2.1. Sector design Nine 40◦ sectors are to be fabricated in the factory and finally to be assembled in the ITER Tokamak pit. The weight of each sector including IWS is about 400 ton and the width and the height are 6 m and 13 m, respectively. A sector is composed of four poloidal segments (PS) with segment splice plates (SP) which are PS1 (inboard segment), PS2 (upper segment), PS3 (equatorial segment) and PS4 (lower segment) as shown in Fig. 1. Each segment consists of inner and outer shells with 60 mm thickness, poloidal and toroidal ribs with 40 mm thickness, and FSHs of 275 mm diameter. All poloidal segments except PS1 have port stubs and in-vessel coil (IVC) supports on the inner shell. Several components such as a triangular support, pipe penetrations, divertor rails and gussets are attached to the lower segment. The welding joints of outer shell and rib are designed as T-shape adapter to satisfy the code requirements of the minimum distance between welds and full penetration weld. Typical details of major welding joints are illustrated in Fig. 2. Double U-type groove joint was adopted for butt welding of inner shells and it can be examined by radiographic testing (RT) by the aid both sides accessibility. Narrow U-type groove joint and ultrasonic testing (UT) are applied to the outer shell welding because of lack of back side accessibility.
The fabrication sequences of VV segments and lower port have been developed based on the welding distortion analyses to meet the tolerance requirement. Electron beam welding (EBW) and narrow-gap tungsten inert gas (TIG) welding techniques are fully refined through the manufacturing of mock-ups. All segments for VV sector are to be fabricated independently according to the following common sequence. 1 2 3 4 5 6 7 8 9 10 11 12
Marking and cutting of plates for each component Forming and machining of plates for inner shells Inner shell assembly by butt welding on the jig Installation of T-ribs on the inner shell Machining of the holes on the inner shell for keys, FSHs and port stubs Welding of keys, port stubs and FSH into the shell Welding of IWS support ribs between FSHs Installation of IWS on the support ribs Forming and custom-machining of outer shells Cover welding of the outer shells 3-Dimensional (3-D) measurement of segment Final machining of interfacing areas of segment
Fig. 2. Typical details for major weld joints.
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Table 1 Forming qualification list.
Fig. 3. Composition of a lower port (RH/D type).
Item
Thickness
Elongation
Applicable component
1 2 3 4
40 mm 60 mm 80 mm 60 mm
11.8% 16.8% 22.2% 33.3%
Inner shell of LPE Inner shell of LPSE Inner flange of LPSE Triangular support
impacts of IVC/manifold rail welding on global distortions for the D-shape and on local distortions that might affect the inner wall shape. A partial mock-up for the triangular support was fabricated to confirm the machinability of complicated shapes and the welding distortion of small sub-components with optimized sequence. Through a mock-up fabrication of lower port stub extension (LPSE) which has double walls with very narrow interspace, manufacturing feasibility and design were verified and several technical issues have been solved. However the tolerance requirement seems to be very challenging with comparison of 3-D inspection results of the fabricated mock-ups. 3.2. Qualifications for welding, forming and NDE
Fig. 4. Real scale mock-ups for PS1, PS2, triangular support and LPSE.
Four poloidal segments are to be assembled simultaneously by welding with segment SP in the factory according to the baseline fabrication scheme of a VV sector. For the final machining of the segment, 3-D inspection should be performed to determine and adjust machining quantities at cup-and-cone type segment joints. The segment joint has several scallops to avoid welding overlap in the cross welding lines and to provide the space for non-destructive examination (NDE) on inner shell weld [7]. For the lower port, the fabrication sequence is basically the same as the sequence of segment except FSH and IWS. The port shell has a lot of formed parts which have more than 10% elongations. These formed components shall be treated by solution annealing heat treatment at 1105 ◦ C after cold forming operation due to corrosion concerns.
Major manufacturing activities can be started only after relevant qualification according to the design requirement and RCC-MR code. For the welding activity, thirteen welding procedure specifications (WPS) have been approved with lots of supporting welding procedure qualification records. In parallel, welder performance qualification and filler material acceptance test were completed. Cold forming process is applied to make 3-D shaped shells using 10,000 ton press, 1500 ton press and 4000 ton bending roller. One step or multistep die forming method is used for inner and outer shells of VV sectors depending on their sizes. V-Block bending method is for locally high elongation parts such as the shell of triangular support and shells of ports. In case of the elongation is larger than 10%, solution annealing heat treatment and forming qualification are mandatory. Four critical cases of forming conditions are summarized in Table 1 and have been qualified including heat treatment operation. Even though ITER VV is heavy welded double wall structure which has very complex configuration, all welding joints have to be verified by 100% volumetric examination. However the radiographic examination is only applicable to the butt weld joint of inner shell with both sides accessibility. The ultrasonic examination is an alternative NDE method for all weld joints except the double side accessible butt weld joint. The qualification has been conducted rigorously to apply the ultrasonic examination with phased array probe to the thick weld joints of real product, because the attenuation and dispersion of the ultrasonic signal is generally high on the austenitic welds. The 1st group qualification was completed for the regular T-type joints. The 2nd group is just completed for butt joints and special joints. The 3rd one is in progress for the tilted butt joint between FSH and outer shell.
3. Mock-ups and qualifications 4. Progress on the first sector manufacturing 3.1. Full scale mock-ups Several mock-ups have been constructed to verify fabrication feasibility and to develop the manufacturing design and procedures as shown in Fig. 4. The PS1 mock-up was built to develop and stabilize EBW techniques regarding dense welding lines for FSHs and induced weld distortions. Through the manufacturing of 20◦ PS2 mock-up, HHI ensured that narrow-gap TIG welding, 3-D inspection and NDE procedures are applicable to the final production. The empirical testing on the PS2 mock-up has been conducted to assess
All plates (480 ton) and forgings (341 ton) for two KO sectors have been produced and delivered from Industeel and R. Kind, respectively. The fabrication of the first sector (VV sector #6) was started in early 2012 from cutting of the 60 mm thick stainless steel plates for PS2 inner shell at first. The inner shells of all segments consist of 3-D shaped plates which were produced by 10,000 ton press using cold forming method without post heat treatment because the permanent elongation is less than 3%. Quite strong and heavy fit-up jigs of all segments were fabricated for exact assem-
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Fig. 5. Manufacturing progress of all segments for the first sector.
bly of the inner shells. The assembly jigs were also made to be mounted on the inside surface of inner shell and to minimize the weld distortions. All poloidal segments for the first sector are being fabricated simultaneously to meet the procurement schedule in HHI factory. Manufacturing progress of the first sector is shown in Fig. 5. The inner shells of each segment were assembled by butt-weld using manual gas tungsten arc welding (GTAW) with the help of the setting jigs and the welding jigs. Heavy machining of many forging blocks is almost completed for lots of FSHs, triangular support, divertor support rail and local penetrations. The centering and inter-modular keys for blankets have been welded into the assembled inner shells of PS1 and PS2 by EBW and manual GTAW, respectively. NDE works are conducted for inner shell welds and no defect was detected. Port stubs of PS2, PS3 and PS4 are almost completed. The port stubs will be welded into the inner shells before installation of FSHs
for minimizing welding deformation. Poloidal T-ribs for all segments are under the fabrication in parallel. EBW was performed to divertor stop body on inner shell of PS4 and to subcomponents of the triangular support. Fabrication of the triangular support is a critical path because it requires heavy machining, welding and NDE works. All plates for the triangular support have been cut and bent using cold forming method according to the qualified forming procedure. Because the permanent elongation of these pieces is more than 30%, solution heat treatment has been applied in accordance with the RCC-MR Code requirement.
5. Progress on the lower port manufacturing The plates (1273 ton) and forgings (627 ton) for the lower and equatorial ports have been produced and delivered from Industeel and FAV, respectively. The port fabrication was started in November 2012 with cutting of the 40 mm thick stainless steel plate
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of 316L(N)-IG using a water jet cutting machine for the T-ribs of the LPSE. For the inner shells of the LPSE, plates with 60 mm thickness have been cut, cold bent using V-block bending method according to the qualified forming procedure and heat treated. Heat treated parts have been cleaned and then inspected using 3-D. The manufacturing progress of the LPSEs is shown with real photographs in Fig. 6 which also shows fabrication sequence of LPSE. Two bent plates for the inner shell were combined as an upper or a lower part with many strong jigs. Assembly of the upper and lower shell parts is on-going after machining of weld joints based on the result of dimensional measurement. Front and rear part assemblies are being combined for the inner shell completion. All T-ribs are fabricated with manual and auto-welding machines and inspected by phased array UT. Gussets, T-ribs and water stopping flange will be attached to the shell. Finally outer shell will be covered between T-ribs and tested for NDE, pressure and leak. 6. Summary The manufacturing design has been completed to fabricate the VV sectors and ports based on IO’s detail design in accordance with the RCC-MR code and regulation of nuclear pressure equipment in France. After a long time for preparation activities since a contract with HHI, the first sector and lower ports have been manufacturing slowly at the front of ITER project as a nuclear component under strict regulations. Nevertheless the fabrication was started for all segments of the sector and all LPSEs, the progress rate of manufac-
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turing is around 40% up to the end of 2015. The fabrication speed could be getting better because important technical issues and risks are almost solved or mitigated. Acknowledgments This research was supported by the Ministry of Science, ICT and Future Planning of Republic of Korea under an ITER Contract. The view and opinion expressed herein do not necessarily reflect those of ITER Organization. References [1] ASN Decision 2013-DC-0379 dated 12 November 2013, private communication (2013). [2] Design and Construction Rules for Mechanical Components of Nuclear Installation, RCC-MR, AFCEN, Edition 2007. [3] ITER System Design Description (DDD) 1.5 Vacuum Vessel, private communication. [4] H.J. Ahn et al., Fabrication Design and Code Requirements for the ITER Vacuum Vessel, ASME 2011 Pressure Vessels and Piping Conference, Volume 1: Codes and Standards, Baltimore, Maryland, USA, July 17–21 (2011). [5] B.C. Kim, et al., Fabrication design progress of ITER vacuum vessel in Korea, Fusion Eng. Design 88 (2013) 1960–1964. [6] C.H. Choi, et al., Status of the ITER vacuum vessel construction, Fusion Eng. Design 89 (2014) 1859–1863. [7] H.J. Ahn, et al., Manufacturing Design and Progress of the First Sector for the ITER Vacuum Vessel, Presented at 25th IAEA FEC, St. Petersburg, Russia, 2014. [8] H.S. Kim, et al., Fabrication results of full scale mock-up for ITER VV port in Korea, Fusion Eng. Design 89 (2014) 1779–1783.
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Fig. 6. Manufacturing progress (real photograph) of lower port stub extension (LPSE) based on the fabrication sequence.
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Manufacturing progress on the first sector and lower ports for ITER vacuum vessel H.J. Ahn a,∗ , H.S. Kim a , G.H. Kim a , C.K. Park a , G.H. Hong a , S.W. Jin a , H.G. Lee a , K.J. Jung a , J.S. Lee b , T.S. Kim b , J.G. Won b , B.R. Roh b , K.H. Park b , J.W. Sa c , C.H. Choi c , C. Sborchia c a
National Fusion Research Institute, Daejeon 305-333, South Korea Hyundai Heavy Industries Co. Ltd., Ulsan 682-792, South Korea c ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-lez-Durance, France b
h i g h l i g h t s • • • •
All manufacturing drawings of the first sector of VV have been completed. Full scale mock-ups have been constructed to verify fabrication procedure. Qualifications for welding and forming are done and for NDE are ongoing. Manufacturing progress is around 40% for the sector and LPSE up to the end of 2015.
a r t i c l e
i n f o
Article history: Received 9 November 2015 Received in revised form 20 January 2016 Accepted 1 February 2016 Available online xxx Keywords: Vacuum vessel Sector Port Nuclear Manufacturing Welding distortion
a b s t r a c t Manufacturing design of Korean sectors and ports for the ITER Vacuum Vessel (VV) has been developed to comply with the tight tolerance and severe inspection requirements. The first VV sector and lower ports are being fabricated slowly under strict regulations after verification using several real scale mock-ups and qualifications for welding, forming and NDE. During three years after start of fabrication, manufacturing progress on four poloidal segments of the first sector is that (1) all inner shells were welded, (2) forgings for complicate components have been machined, (3) port stubs and poloidal T-ribs were assembled, and (4) machined components are welded on the inner shells by narrow-gap TIG welding and electron beam welding. The progress of lower ports is that (1) inner shells of stub extensions were bent and treated with heat, (2) T-ribs were fabricated and examined by qualified phased array UT, (3) supporting pads and gussets have been machined, and (4) inner shells are assembled with T-ribs and machined forgings. The progress rate of manufacturing is around 40% up to the end of 2015 for the first sector and lower port stub extensions. © 2016 Elsevier B.V. All rights reserved.
1. Introduction The ITER Vacuum Vessel (VV) is a torus shaped double wall structure and consists of nine sectors and several ports. Main functions of the VV are to provide high vacuum for plasma operation and to prevent radioactive contamination as a Protection Important Component (PIC). ITER is a Nuclear Facility INB-174 [1]. Korea Domestic Agency (KODA) is responsible for procurement of two VV sectors, nine lower ports and seventeen equatorial ports. KODA contracted with Hyundai Heavy Industries Co., Ltd. (HHI) to produce the VV
sectors and major ports including the first sector which will be delivered before others. The VV shall be designed and fabricated as nuclear equipment in accordance with the RCC-MR code [2] and regulations of nuclear pressure equipment in France (ESPN). The manufacturing design was developed to fabricate the VV sector and port structures based on the design requirements. All manufacturing sequences including welding and inspection methods were also introduced to comply with the tight tolerance and severe inspection requirements [3,4]. 2. Manufacturing design
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (H.J. Ahn).
The ITER VV is a double walled torus structure and consists of nine sectors with forty four main ports like long nozzles of a pressure vessel. The main material is 316L(N)-IG, ITER grade austenitic
http://dx.doi.org/10.1016/j.fusengdes.2016.02.012 0920-3796/© 2016 Elsevier B.V. All rights reserved.
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The manufacturing design of Korean sectors has two special design concepts to minimize welding distortion. One is a selfsustaining welded IWS support rib which is designed to keep strong contact with FSH at unwelded area. The other is cup-and-cone type segment joints which can be directly welded to poloidal ribs without splice plates. The special joint designs will mitigate the risk of sector tolerance mismatch [7]. All manufacturing drawings of the sector have been completed. 2.2. Lower port design
Fig. 1. Composition of a VV Sector.
stainless steel. Nitrogen contents and limited impurities such as boron, cobalt and niobium shall be controlled for the ITER grade stainless steel. The heavy welded VV sector is composed of double shells, T-shape ribs and flexible support housings (FSH). The height and outer diameter of the VV are 11.4 m and 19.4 m, respectively. Its gross weight is more than 5200 ton. The in-wall shielding (IWS) and cooling water fill the interspace between double walls of the VV. The IWS occupies 60% of the interspace and provides efficient neutron shielding [5,6].
At the lower level of the VV, there are nine lower ports located for the vacuum pumping (Cryopump) or remote-handling of divertor cassettes and diagnostic (RH/D) at every 40◦ sector. A typical lower port structure consists of a port extension (PE) and a port stub extension (PSE) connected to the port stub in the main vessel as shown in Fig. 3. The ports are rigid double-wall structure with Trib stiffeners between the shells for supporting the main vessel. To enhance the port bearing capacity, the support pad of the VV gravity supports and heavy gussets are integrated into the stub extensions. The splice plates are also adopted to connect PSE and PE as well as PSE and VV sector. The end part of the PE is normally equipped with a closure plate for the high vacuum boundary. Total length, width and weight of the lower RH/D port are 6.97 m, 3.63 m and 52 ton, respectively. Those of the Cryopump port are 6.34 m, 3.68 m and 45 ton, respectively [8]. 2.3. Fabrication sequence and assembly scheme
2.1. Sector design Nine 40◦ sectors are to be fabricated in the factory and finally to be assembled in the ITER Tokamak pit. The weight of each sector including IWS is about 400 ton and the width and the height are 6 m and 13 m, respectively. A sector is composed of four poloidal segments (PS) with segment splice plates (SP) which are PS1 (inboard segment), PS2 (upper segment), PS3 (equatorial segment) and PS4 (lower segment) as shown in Fig. 1. Each segment consists of inner and outer shells with 60 mm thickness, poloidal and toroidal ribs with 40 mm thickness, and FSHs of 275 mm diameter. All poloidal segments except PS1 have port stubs and in-vessel coil (IVC) supports on the inner shell. Several components such as a triangular support, pipe penetrations, divertor rails and gussets are attached to the lower segment. The welding joints of outer shell and rib are designed as T-shape adapter to satisfy the code requirements of the minimum distance between welds and full penetration weld. Typical details of major welding joints are illustrated in Fig. 2. Double U-type groove joint was adopted for butt welding of inner shells and it can be examined by radiographic testing (RT) by the aid both sides accessibility. Narrow U-type groove joint and ultrasonic testing (UT) are applied to the outer shell welding because of lack of back side accessibility.
The fabrication sequences of VV segments and lower port have been developed based on the welding distortion analyses to meet the tolerance requirement. Electron beam welding (EBW) and narrow-gap tungsten inert gas (TIG) welding techniques are fully refined through the manufacturing of mock-ups. All segments for VV sector are to be fabricated independently according to the following common sequence. 1 2 3 4 5 6 7 8 9 10 11 12
Marking and cutting of plates for each component Forming and machining of plates for inner shells Inner shell assembly by butt welding on the jig Installation of T-ribs on the inner shell Machining of the holes on the inner shell for keys, FSHs and port stubs Welding of keys, port stubs and FSH into the shell Welding of IWS support ribs between FSHs Installation of IWS on the support ribs Forming and custom-machining of outer shells Cover welding of the outer shells 3-Dimensional (3-D) measurement of segment Final machining of interfacing areas of segment
Fig. 2. Typical details for major weld joints.
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Table 1 Forming qualification list.
Fig. 3. Composition of a lower port (RH/D type).
Item
Thickness
Elongation
Applicable component
1 2 3 4
40 mm 60 mm 80 mm 60 mm
11.8% 16.8% 22.2% 33.3%
Inner shell of LPE Inner shell of LPSE Inner flange of LPSE Triangular support
impacts of IVC/manifold rail welding on global distortions for the D-shape and on local distortions that might affect the inner wall shape. A partial mock-up for the triangular support was fabricated to confirm the machinability of complicated shapes and the welding distortion of small sub-components with optimized sequence. Through a mock-up fabrication of lower port stub extension (LPSE) which has double walls with very narrow interspace, manufacturing feasibility and design were verified and several technical issues have been solved. However the tolerance requirement seems to be very challenging with comparison of 3-D inspection results of the fabricated mock-ups. 3.2. Qualifications for welding, forming and NDE
Fig. 4. Real scale mock-ups for PS1, PS2, triangular support and LPSE.
Four poloidal segments are to be assembled simultaneously by welding with segment SP in the factory according to the baseline fabrication scheme of a VV sector. For the final machining of the segment, 3-D inspection should be performed to determine and adjust machining quantities at cup-and-cone type segment joints. The segment joint has several scallops to avoid welding overlap in the cross welding lines and to provide the space for non-destructive examination (NDE) on inner shell weld [7]. For the lower port, the fabrication sequence is basically the same as the sequence of segment except FSH and IWS. The port shell has a lot of formed parts which have more than 10% elongations. These formed components shall be treated by solution annealing heat treatment at 1105 ◦ C after cold forming operation due to corrosion concerns.
Major manufacturing activities can be started only after relevant qualification according to the design requirement and RCC-MR code. For the welding activity, thirteen welding procedure specifications (WPS) have been approved with lots of supporting welding procedure qualification records. In parallel, welder performance qualification and filler material acceptance test were completed. Cold forming process is applied to make 3-D shaped shells using 10,000 ton press, 1500 ton press and 4000 ton bending roller. One step or multistep die forming method is used for inner and outer shells of VV sectors depending on their sizes. V-Block bending method is for locally high elongation parts such as the shell of triangular support and shells of ports. In case of the elongation is larger than 10%, solution annealing heat treatment and forming qualification are mandatory. Four critical cases of forming conditions are summarized in Table 1 and have been qualified including heat treatment operation. Even though ITER VV is heavy welded double wall structure which has very complex configuration, all welding joints have to be verified by 100% volumetric examination. However the radiographic examination is only applicable to the butt weld joint of inner shell with both sides accessibility. The ultrasonic examination is an alternative NDE method for all weld joints except the double side accessible butt weld joint. The qualification has been conducted rigorously to apply the ultrasonic examination with phased array probe to the thick weld joints of real product, because the attenuation and dispersion of the ultrasonic signal is generally high on the austenitic welds. The 1st group qualification was completed for the regular T-type joints. The 2nd group is just completed for butt joints and special joints. The 3rd one is in progress for the tilted butt joint between FSH and outer shell.
3. Mock-ups and qualifications 4. Progress on the first sector manufacturing 3.1. Full scale mock-ups Several mock-ups have been constructed to verify fabrication feasibility and to develop the manufacturing design and procedures as shown in Fig. 4. The PS1 mock-up was built to develop and stabilize EBW techniques regarding dense welding lines for FSHs and induced weld distortions. Through the manufacturing of 20◦ PS2 mock-up, HHI ensured that narrow-gap TIG welding, 3-D inspection and NDE procedures are applicable to the final production. The empirical testing on the PS2 mock-up has been conducted to assess
All plates (480 ton) and forgings (341 ton) for two KO sectors have been produced and delivered from Industeel and R. Kind, respectively. The fabrication of the first sector (VV sector #6) was started in early 2012 from cutting of the 60 mm thick stainless steel plates for PS2 inner shell at first. The inner shells of all segments consist of 3-D shaped plates which were produced by 10,000 ton press using cold forming method without post heat treatment because the permanent elongation is less than 3%. Quite strong and heavy fit-up jigs of all segments were fabricated for exact assem-
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Fig. 5. Manufacturing progress of all segments for the first sector.
bly of the inner shells. The assembly jigs were also made to be mounted on the inside surface of inner shell and to minimize the weld distortions. All poloidal segments for the first sector are being fabricated simultaneously to meet the procurement schedule in HHI factory. Manufacturing progress of the first sector is shown in Fig. 5. The inner shells of each segment were assembled by butt-weld using manual gas tungsten arc welding (GTAW) with the help of the setting jigs and the welding jigs. Heavy machining of many forging blocks is almost completed for lots of FSHs, triangular support, divertor support rail and local penetrations. The centering and inter-modular keys for blankets have been welded into the assembled inner shells of PS1 and PS2 by EBW and manual GTAW, respectively. NDE works are conducted for inner shell welds and no defect was detected. Port stubs of PS2, PS3 and PS4 are almost completed. The port stubs will be welded into the inner shells before installation of FSHs
for minimizing welding deformation. Poloidal T-ribs for all segments are under the fabrication in parallel. EBW was performed to divertor stop body on inner shell of PS4 and to subcomponents of the triangular support. Fabrication of the triangular support is a critical path because it requires heavy machining, welding and NDE works. All plates for the triangular support have been cut and bent using cold forming method according to the qualified forming procedure. Because the permanent elongation of these pieces is more than 30%, solution heat treatment has been applied in accordance with the RCC-MR Code requirement.
5. Progress on the lower port manufacturing The plates (1273 ton) and forgings (627 ton) for the lower and equatorial ports have been produced and delivered from Industeel and FAV, respectively. The port fabrication was started in November 2012 with cutting of the 40 mm thick stainless steel plate
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of 316L(N)-IG using a water jet cutting machine for the T-ribs of the LPSE. For the inner shells of the LPSE, plates with 60 mm thickness have been cut, cold bent using V-block bending method according to the qualified forming procedure and heat treated. Heat treated parts have been cleaned and then inspected using 3-D. The manufacturing progress of the LPSEs is shown with real photographs in Fig. 6 which also shows fabrication sequence of LPSE. Two bent plates for the inner shell were combined as an upper or a lower part with many strong jigs. Assembly of the upper and lower shell parts is on-going after machining of weld joints based on the result of dimensional measurement. Front and rear part assemblies are being combined for the inner shell completion. All T-ribs are fabricated with manual and auto-welding machines and inspected by phased array UT. Gussets, T-ribs and water stopping flange will be attached to the shell. Finally outer shell will be covered between T-ribs and tested for NDE, pressure and leak. 6. Summary The manufacturing design has been completed to fabricate the VV sectors and ports based on IO’s detail design in accordance with the RCC-MR code and regulation of nuclear pressure equipment in France. After a long time for preparation activities since a contract with HHI, the first sector and lower ports have been manufacturing slowly at the front of ITER project as a nuclear component under strict regulations. Nevertheless the fabrication was started for all segments of the sector and all LPSEs, the progress rate of manufac-
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turing is around 40% up to the end of 2015. The fabrication speed could be getting better because important technical issues and risks are almost solved or mitigated. Acknowledgments This research was supported by the Ministry of Science, ICT and Future Planning of Republic of Korea under an ITER Contract. The view and opinion expressed herein do not necessarily reflect those of ITER Organization. References [1] ASN Decision 2013-DC-0379 dated 12 November 2013, private communication (2013). [2] Design and Construction Rules for Mechanical Components of Nuclear Installation, RCC-MR, AFCEN, Edition 2007. [3] ITER System Design Description (DDD) 1.5 Vacuum Vessel, private communication. [4] H.J. Ahn et al., Fabrication Design and Code Requirements for the ITER Vacuum Vessel, ASME 2011 Pressure Vessels and Piping Conference, Volume 1: Codes and Standards, Baltimore, Maryland, USA, July 17–21 (2011). [5] B.C. Kim, et al., Fabrication design progress of ITER vacuum vessel in Korea, Fusion Eng. Design 88 (2013) 1960–1964. [6] C.H. Choi, et al., Status of the ITER vacuum vessel construction, Fusion Eng. Design 89 (2014) 1859–1863. [7] H.J. Ahn, et al., Manufacturing Design and Progress of the First Sector for the ITER Vacuum Vessel, Presented at 25th IAEA FEC, St. Petersburg, Russia, 2014. [8] H.S. Kim, et al., Fabrication results of full scale mock-up for ITER VV port in Korea, Fusion Eng. Design 89 (2014) 1779–1783.
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Fig. 6. Manufacturing progress (real photograph) of lower port stub extension (LPSE) based on the fabrication sequence.
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