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Fusion Engineering and Design 83 (2008) 1294–1299

Contents lists available at ScienceDirect

Fusion Engineering and Design

journa l homepage: www.e lsev ier .com/ locate / fusengdes

anufacture of a shield prototype for primary wall modules

. Boudota,∗, B. Boireaua, A. Cottina, P. Lorenzettob, P. Bucci c, O. Giliac

AREVA NP, Technical Centre, Porte Magenta, 1 rue B. MACET, 71200 Le Creusot, FranceEFDA, Close Support Unit, Boltzmannstr. 2, D-85748 Garching, GermanyCEA DRT, Liten, DTH 38054 Grenoble, France

r t i c l e i n f o

rticle history:vailable online 11 July 2008

eywords:hieldigh isostatic pressure

a b s t r a c t

In the frame of the blanket module (BM) development for ITER, an R&D programme was implementedfor the manufacture of a shield prototype by powder hot isostatic pressing (HIPping). The manufacturedshield is a full-scale module No. 11a. Starting from a forged block of 1350 mm × 1300 mm × 450 mm, themain machining steps as deep drilling (1200 mm), 3D machining and sawing were performed. Tubes were3D bent and large number of small parts were designed and machined. By welding together all the sub-parts we erected the main part of the water coolant circuit. Once the water circuit was built; the shield wascompleted using powder HIPping together with forged block embedding the tubes in a final solid part.The powder/solid HIP is used to minimize the number of BM seal welds in front of plasma. It increasesthe reliability of the components during operation. About 300 kg of stainless steel powder was densified

together with the forged block. 3D measurement was done before and after the HIP cycle to collect thedata to be compared with theoretical model. It allows to predict the main distortions of the solid bulk.Ultrasonic examination of the densified powder on the stainless steel bulk and around the bended tubeswas performed as well as mechanical characterization of the samples. The recess for stub key attachmenton the vacuum vessel side, the hydraulic connector, the key for the primary wall panel attachment on thefront side and the link between the four parallel water coolant circuits were then machined to achieve

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the shield prototype.

. Introduction

The R&D program related to the manufacturing of the shieldrototype was carried out in two stages. The first one, which con-isted in manufacturing of the small and medium size mock-ups,as followed by the second one, devoted to the manufacturing of

he full-scale ITER shield prototype for primary wall (PW) modules1].

The contract to manufacture the above quoted shield waswarded to AREVA NP.

This paper aims to describe the manufacturing programxpected to be use for fabrication of the ITER SHIELD No. 11A. Thehield prototype for PW modules is fabricated by a process basedn hot isostatic pressing (HIP-ing) of steel powder with solid parts.IP-ing is used to minimize the number of seal welds in the PW

odules increasing thereby the reliability of the components dur-

ng operation. The goal is not to have any single seal weld in theompleted Shield. All the seal welds being HIP-ed, the risk of leakue to a weld defect is decreased [2].

∗ Corresponding author. Tel.: +33 3 85806103.E-mail address: cecile.boudot@areva.com (C. Boudot).

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920-3796/$ – see front matter © 2008 Elsevier B.V. All rights reserved.oi:10.1016/j.fusengdes.2008.05.036

© 2008 Elsevier B.V. All rights reserved.

Manufacturing of a shield involves many different techniques athigh level of complexity.

. General machining of the forged part

The rough material as close as possible to ITER Grade (IG)tainless steel are: a forged block (1350 mm × 1300 mm × 450 mm)heets 20 mm, 2 mm, 3 mm, tubes and SS (IG) powder.

The first step is to machine the forged block to its almost finalimensions. This operation is not considered as a complex one, butue to the large size of the part, it requires large machine tool.

The second step is the machining of four facets on the forgedlock corresponding to the location of the four panels later attachedn the shield. This operation aims to give the shape of the shield toollow the toroidal profile of the vacuum vessel.

Once the machining of facets is completed, the deep drillingperation is launched (Fig. 1).

. Deep drilling

157 holes are drilled between the topside and the bottomside.hey are located as follows:

C. Boudot et al. / Fusion Engineering an

Fig. 1. Forged block.

Fig. 2. Deep drilling.

Fig. 3. Water collector machining.

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11 holes Ø10 mm corresponding to the ends of the slots machinedlater.8 holes Ø16 mm and 6 holes Ø30 mm corresponding of the twoaisles of the shield: the right and left lateral side.6 holes Ø22 mm are located just under the rear face. The 9 rowsof 14 holes Ø22 mm each complete the set of the top/bottomsideholes.

The location tolerances for all these holes are tight for two rea-ons:

The next step of the manufacturing consists in machining of thewater collector. Each water box is machined around a set of holesat the closest. If the required theoretical location of the hole is notrespected, the drawings of the water collector need to be modifiedas well as the machining program.At the latest stages of the manufacturing, the perpendicular holesused for the attachment of the primary first wall (PFW) panelon the shield will be drilled. The machining tolerances are verysevere to avoid any damaging between the toroidal and poloidalholes crossing very closely.

Some other difficult manufacturing issues are the connections

etween the holes and special tooling had to be designed and man-factured.

A drilling sequence was defined to monitor potential distortionsnd ensure the precision.

Fig. 4. Slots machining.

1296 C. Boudot et al. / Fusion Engineering and Design 83 (2008) 1294–1299

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Fig. 5. 3D bending of tubes.

Once, the operation of drilling completed, the dimensional con-rols of the holes location and axis on both faces of shield are doneFig. 2).

. Water collector and slots machining

The third step of the manufacturing consists in machining of theater collector on both (bottom and top) sides. This machining step

s not complex and can be done easily.After water collector, 11 slots of 3 mm width have been

achined from the front side. Their depth is varying from 100 mmo 170 mm. The machining of these grooves needs a tool speciallydapted for this operation. The axe of machining is located betweenhe holes drilled previously between the top and bottom face. Theepth of the central groove implies a tool of Ø500 mm (Figs. 3 and 4).

. Rear face machining

The fourth step is the machining of the rear face. 3D bent tubes

ill be HIP-ed within a powder layer on that face and to monitor

heir distortions, an adapted design had to be completed and tested.his design was studied through several mock-ups validating theubes displacement and distortions that occur during HIP process

Fig. 6. Assembly verification.

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Fig. 7. Water collector welding.

nd are related to the supports design. This work has been reportedn Soft 2006 proceedings.

. 3D bending

In parallel to the above machining sequence, the cooling tubes

re 3D bent. The design principle is to avoid as much as possiblehe welded connections between the tubes in view to minimizehe possible metal excess generated inside the tube during weldingrocess and also reduce the risk of weld defect. The reason of this

Fig. 8. Container before sealing.

C. Boudot et al. / Fusion Engineering and Design 83 (2008) 1294–1299 1297

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Fig. 9. He leak testing.

estriction is dictated by the conditions of ultrasonic examination ofhe HIP bonded area between tube and surrounding powder. Thisxamination being performed from inside to outside of the tube,he ultrasonic probe has to move freely inside required minimumiameter.

Manufacturing of many small parts used for tubes/bulk connec-

ion was also carried out through the design studies validated with

ock-ups (Fig. 5).

Fig. 10. Installation for HIP.

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Fig. 11. After HIP.

. HIP preparation

This is one of the most critical operations during all manufac-uring process of the prototype because of the huge technical andnancial risk. If one of the single sub-operation is missed, the con-equence can be a total non-conformity of the whole shield withoutny way to repair. Therefore, this manufacturing stage is done withery high attention applying the repetitive control and examina-ion program. All parts are carefully etched and cleaned to ensurehat no impurities such as oxides or grease should make impossiblehe completion of the HIP process.

The preparation and the welding of all small parts are done in alean environment.

All the welds are He leak tested. When the water coolant circuits built, all free space between the constituent parts inside the con-ainer is filled up with SS powder. The amount of powder to fulfilhe free space is calculated using CATIA model. To avoid any risk ofefects during the HIP process, so predicted weight of powder has

o be fully introduced into container. To ensure a good filling ratio,he filling is done on a vibrating table capable of carrying 5 tons ofeight.

Fig. 12. Ultrasonic examination.

1298 C. Boudot et al. / Fusion Engineering and Design 83 (2008) 1294–1299

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It consists in several very complex operations:The castellation that have been done in an early stage of the

manufacturing can now be completed.

Fig. 13. Distor

After the powder filling operation, the container is under vac-um conditioned for HIP operation using appropriate vacuumump system (Figs. 6–9).

. HIP cycle

The dimensions of the shield No. 11A exceed the largest, avail-ble in Europe HIP furnace. For this reason, its external dimensionsere reduced and adapted to the dimension (diameter 1280 mm)

f the Bodycote Surrahammar facility where the HIP cycle was per-ormed.

To be located in the right position in the furnace, the shieldould not lay on the one of its planned surface. The appropriateool able to support the shield weight (4.5 tons) inside the HIPurnace at 1400 ◦C was studied, designed and manufactured. Theupporting tool behaviour during the HIP cycle has been calculatedo ensure that potential distortions cannot lead to a damage of theurnace.

The space between the shield and the furnace wall was notxceeding few millimetres.

The HIP cycle, 1400 ◦C and 1200 bar was carried out without anyroblem and the general shape of the HIP-ed part was only slightlyistorted even if on the rear side, the reduction of the volume dueo the densification of the powder was reached about 30%.

3D measurements done before and after the HIP cycle deter-ines the distortion ratio and relocates the internal water circuit

rom external references.This is an important aspect of solid powder HIP cycle, the part

as several distortions in 3D but the mechanical references have toe replaced to continue the next machining steps.

An intermediate step is therefore an ultrasonic examination toheck the joining efficiency between all parts and also to measurend record the tubes location inside the rear face.

easurement.

The HIP was successful; all tubes are properly joined andetected at their expected position.

The above statement gave the “green light” to pursuit the nexttage of the shield prototype manufacturing, i.e. final machiningFigs. 10–13).

. Final machining

Fig. 14. Front face final machining.

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The key corresponding to the panel location are machined andhe holes for the studs and nuts of the panel attachment are drilled.ll these operations are of the high risk because the holes are

ocated extremely close (3.92 mm) to theoretical location of theeighbour tube. To be sure that any overlapping defect, betweenoles for panel attachment and cooling circuit tubes will occur dur-

ng manufacturing, the complex examination is performed beforetarting the machining (Fig. 14).

Once the part is on the drilling machine and once all theimensional measurement and identification of the drilling axis

s identified, an ultrasonic verification is performed checking thathe tubes are at a minimum distance from the hole.

The next machining stage is the machining of the rear keys forhe shield attachment on the vacuum vessel and the machiningf the hydraulic connector that ensure the water inlet and outletonnection. This final stage is also highly complex because the cur-ently existing machining tools employed for the related operationsork in extreme conditions and may induce the heavily reparableefects.

0. Final equipment

After this final machining, the connections between the inlet andutlet of the rear face cooling tubes are done by external pipes weld-ng. This operation completes the water circuit erection and finalise

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d Design 83 (2008) 1294–1299 1299

he manufacturing of the shield. To validate the shield fabrication,eception tests as hydraulic flow and pressure test are performed.

1. Conclusion

This first shield prototype fabricated from forged and powderIP SS shows that this component which is very complex to manu-

acture is feasible. The main manufacturing steps have been realisedithin the required tolerances. Fabrication operation like deeprilling, slots machining, 3D bending, monitoring of HIP distortionsas been successfully anticipated and prepared. This manufacturehows how to proceed to monitor the risk by the constant improve-ent of the manufacturing program consisting in real time analysis

f the constraints, fabrication of the small mock-ups validatingncertainties, adaptation and designing of the appropriate tools.

The close collaboration between designers and manufacturerseads to a final part which fulfils the product specification.

eferences

1] O. Gillia, B. Boireau, C. Boudot, A. Cottin, P. Bucci, F. Vidotto, J.M. Leiboltd, P.

Lorenzetto, Modelling and computer simulation for the manufacture by powderHIPping of blanket shield components for ITER, Fusion, Engineering and Design82 (2007) 2001.

2] A. Furmanek, P. Lorenzetto, A conceptual design proposal for blanket modulein the neutral beam injector region of ITER, Fusion, Engineering and Design 82(2007) 1664.