Fabrication Of Mock-ups Research Articles

Fabrication and testing of small mock-ups for helium cooled ceramic reflector breeding blanket development

Korea has developed a helium cooled ceramic reflector test blanket module (TBM) for fusion reactors. An advanced reduced activation alloy has been developed as a structural material and various joining methods such as E-beam welding, tungsten inert gas (TIG) welding, laser welding, and hot isostatic pressing have been applied to establish its fabrication method and procedure. Based on the current design of the TBM and breeding blanket, TIG welding was selected as the main joining method, and the U-shaped first wall (FW) was adopted. For welding of the breeding blanket, a special joining technique without a permanent backing strip with simultaneous full penetration welding in accordance with the design rules of class N2RX of RCC-MRx is required for the pressure vessel. For the U-shaped FW, distortion of the drilled cooling hole during the bending should be limited. Three small mock-ups were fabricated in this study to investigate these issues. The joints and bending parts were visually observed after cutting, and the hydrostatic pressure test was performed for regions with low thickness. The results show that the proposed fabrication methods are applicable in the fabrication procedure development for the breeding blanket.

Development of IN-RAFM steel and fabrication technologies for Indian TBM

India has indigenously developed its own Indian Reduced Activation Ferritic Martensitic Steel (IN-RAFM steel) which, it is proposed to use for fabrication of Indian TBM to be installed in ITER. With an objective of qualifying this material for use in ITER, extensive testing of this material to generate the necessary data required to offer this material for Particular Material Appraisal of ITER has been undertaken. Accordingly, data generation on creep, fatigue and physical properties of this steel is in progress. Physical properties like thermal diffusivity, heat capacity and thermal expansion coefficient for this steel at various temperatures have been measured and thermal conductivity estimated from the measured physical properties. Values obtained for these physical properties are comparable with those reported for other RAFM steels. Results of creep tests that are in progress also indicate that creep is comparable to that of other RAFM steels. Low cycle fatigue (LCF) behaviour of this steel has been studied in air with total strain control in the strain amplitude range of ±0.25–1% and temperatures range of 300–873K at a constant strain rate of 3×10−3s−1. Results confirm that fatigue life of IN-RAFM steel is at par with that of the European Union grade Eurofer 97 RAFM steel.During production of IN-RAFM steel plates of different thicknesses, it is observed that processing parameters have a major role in ensuring consistency in the property of the steel. Accordingly, processing map for this steel has been generated from compression tests conducted at various strain rates and temperature. Safe processing zone of temperature and strain rate has been identified from this map.During technology development for electron beam (EB) welding of IN-RAFM steel, it is found that ductile brittle transformation temperature (DBTT) for the weld metal is higher than that of the base metal and this is attributed to high W content in the steel and consequent formation of delta-ferrite in the weld metal. A welding procedure that produces weld metal with DBTT comparable to that of the base metal has been developed. IN-RAFM filler wires with matching composition to that of the base metal have been produced for TIG and NG-TIG (narrow gap-TIG) welds and the qualification of this consumable is in progress.For fabrication of TBM first wall, which is ‘C’ shaped plate with internal channels, hot isostatic pressing (HIP) of grooved plates which are pre-bent and assembled with ceramic core to produce channel is being adopted. Curved ceramic core and procedure to join this with straight core have already been developed and production of channel plate is in progress. Further, fabrication of three mock up ceramic breeder cassettes each using EB, laser and TIG welding techniques respectively has also been initiated. Fabrication of these mock ups is expected to help in finalizing the fabrication procedures for the actual breeder cassettes to be used in Indian TBM.Details of these developments in material, data generation and fabrication of mock ups of different components of TBM towards realization of the Indian TBM are being presented in this paper.

The European ITER Test Blanket Modules: Current status of fabrication technologies development and a way forward

The paper reviews fabrication technologies and procedures applied for manufacturing of the TBM sub-components, like, HCLL and HCPB cooling plates, HCLL/HCPB stiffening plates, and HCLL/HCPB first wall and side caps. The used technologies are based on fusion and diffusion welding techniques taking into account specificities of the EUROFER-97 steel. Development of a standardized procedure complying with professional codes and standards (RCC-MRx), a preliminary fabrication/welding procedure specification (pF/WPS), is described as well as a fabrication and characterization of feasibility mock-ups (FMU) aimed at assessing the suitability of a fabrication process for fulfilling the design and fabrication specifications. Also, fabrication procedures for the TBM box assembly are presently under development through collaboration between European Fusion Laboratories and Industry for the establishment of an optimized assembly sequence/scenario and development of standardized welding procedure specifications. Selection of optimized assembly scenario takes into accounts not only the design requirements and fabrication possibilities/constraints but also maximum accessibility to the welds for sound non-destructive examination in compliance with welds classification. A future approach towards qualification of the developed fabrication technologies and procedures, through a number of medium to full-size qualification mock-ups according to European standards, is outlined before construction of the first TBMs.

An Ergonomics-oriented Product Development and Evaluation Process: A Case Study of Children's Pointing Device

This study proposes a process for the development and evaluation of ergonomic-oriented products. This process comprises three phases: (1) establishing design requirements, (2) developing the design concept, and (3) ergonomic evaluation of the prototype. In the first phase, a comprehensive collection of existing devices is assembled from which a small number of representative products are selected. Usability testing of these devices enables the establishment of design requirements. In the second phase, rough sketching is used to develop conceptual designs, followed by 3-D modeling and the fabrication of mockups and functional prototypes. In the third phase, ergonomic evaluation of the prototype includes evaluation of participants, setting up experimental apparatus, outlining experimental procedures, and producing an evaluation report. A case study involving the design of a pointing device for children is provided to demonstrate the practical implementation of the product development process.

Fabrication of small mock-ups reflecting the design features of the ITER semi-prototype

The ITER semi-prototype was designed to qualify the manufacturing technology for the ITER blanket first wall. However, its fabrication is expected to face great difficulty due to a design complexity. Even though joining technology for different materials such as beryllium, CuCrZr, and stainless steel (SS) was developed during the first stage of qualification, the joining is still a key issue for the fabrication of the semi-prototype. In this study, small mock-ups (SMU) were fabricated to realize and verify the manufacturing of the semi-prototype reflecting the described design features. The joining of multiple beryllium tiles on the angled CuCrZr surface was confirmed with SMU#1. Six beryllium tiles were joined using hot isostatic pressing (HIP), and slitting was then performed to form multiple tiles. In SMU#2, HIP was performed two times in order to facilitate the cooling channels at the CuCrZr/SS interface, and to join the beryllium tiles on CuCrZr/SS. The method used to form a pressure boundary for the complex cooling channels was also developed by fabricating the SMU#3. The SMUs confirmed the applicability of the HIP for the manufacturing of the semi-prototype.

Validation of welding technology for ITER TF coil structures

Japan Atomic Energy Agency (JAEA), acting as the Japan Domestic Agency (JADA) in the ITER project is responsible for the procurement of 9 Toroidal Field (TF) coil winding packs (WPs), structures for 19 TF coils (including one spare), and assembly of the WPs and the coil structures for 9 TF coils [1]. The TF Coil structures which support large electromagnetic force generated in TF coils under the cryogenic temperature (about 4 K), are very large welded structures composed of a coil case and structural attachments made of high strength and high toughness stainless steel. JAEA has been performing welding trials for heavy thickness materials since 2008 and is planning fabrication of full-scale mock-ups of main sub-components (1 set for the inboard side and 1 set for the outboard side) in 2011 in order to investigate the technical issues for manufacturing the TF coil structures. This paper presents the results of welding trials and the status of full scale mock-ups fabrication to confirm the validity of welding technology and manufacturing design before fabricating the actual products.

Development of welding technologies for the manufacturing of European Tritium Breeder blanket modules

Europe has developed two reference Tritium Breeder Blankets concepts for a DEMO fusion reactor: the Helium-Cooled Lithium–Lead and the Helium-Cooled Pebble-Bed. Both are using the reduced-activation ferritic–martensitic EUROFER-97 steel as structural material and will be tested in ITER under the form of test blanket modules. The fabrication of their EUROFER structures requires developing welding processes like laser, TIG, EB and diffusion welding often beyond the state-of-the-art. The status of European achievements in this area is reviewed, illustrating the variety of processes and key issues behind retained options, in particular with respect to metallurgical aspects and mechanical properties. Fabrication of mock-ups is highlighted and their characterization and performances with respect to design requirements are reviewed.

Helium-cooled divertor for DEMO: Manufacture and high heat flux tests of tungsten-based mock-ups

A helium-cooled divertor concept for DEMO has been investigated extensively at the Forschungszentrum Karlsruhe under the EU power plant conceptual study, the goal being to demonstrate performance under heat flux of 10 MW/m 2 at least. Work covers different areas ranging from conceptual design to analysis, materials and fabrication issues to experiments. Meanwhile, the He-cooled modular divertor concept with jet cooling (HEMJ) has been proposed as reference design. In cooperation with the Efremov Institute, manufacture and high heat flux testing of divertor elements was performed for design verification and proof-of-principle. This paper focuses on the technological study of the fabrication of mock-ups from W/W alloy and Eurofer steel supporting structure material. The high heat flux test results of 2006 and 2007 are summarised and discussed.

ITER vacuum vessel, in-vessel components and plasma facing materials

The vacuum vessel (VV) design is being developed in more detail considering manufacturing and assembly methods, and cost. Incorporating manufacturing studies being performed in cooperation with ITER Parties, the regular VV sector design has been nearly finalized. Design of the neutral beam (NB) ports including duct liners has been developed. Design of the in-wall shielding has been developed in more detail considering the supporting structure and the assembly method. Additional ferromagnetic inserts to be installed in the outboard midplane region will minimize the maximum ripple and the toroidal field flux line fluctuation. Detailed studies were carried out on the ITER vacuum vessel to define appropriate codes and standards in the context of ITER licensing in France. The blanket module design has progressed in cooperation with participant teams. Fabrication of mock-ups for qualification testing is under way and the tests will be performed in 2007–2008. The divertor activities have progressed with the aim of launching the procurement according to the ITER project schedule.

Status of the EU R&D programme on the blanket-shield modules for ITER

A research and development (R&D) programme for the ITER blanket-shield modules has been implemented in Europe to provide input for the design and the manufacture of the full-scale production components. It involves in particular the fabrication and testing of mock-ups and full-scale prototypes of shield blocks and first wall (FW) panels. This paper summarises the main achievements obtained so far and presents the latest results of this R&D programme. In particular, it reports the status of the shield fabrication development programme with the manufacture of a full-scale shield prototype. It also reports the latest results of high heat flux and thermal fatigue tests of FW mock-ups. It describes the preparation of irradiation experiments of Be coated FW mock-ups. Finally, it presents the outline of a possible qualification programme that each contributing participant teams should pass prior to the procurement of the blanket-shield modules for ITER.

Manufacture of blanket shield modules for ITER

A research and development programme for the ITER blanket shield modules has been implemented in Europe to provide input for the design and the manufacture of the full-scale production components. It involves in particular the fabrication and testing of mock-ups (small scale and medium scale) and full-scale prototypes of shield blocks (SB) and first wall (FW) panels. The manufacturing feasibility of FW panels has been demonstrated for two copper alloy candidates. Two designs have been developed for the manufacture of the SB, one for a conventional fabrication route and one for a fabrication route based on the hot isostatic press technology. This paper presents the fabrication routes developed in Europe for the manufacture of the ITER Shield modules.

Development of the plasma facing components for the dome-liner component of the ITER divertor

On the basis of the design and the specification of the dome-liner elaborated by EFDA, a manufacturing route based on high temperature brazing has been developed and proved by means of the fabrication and testing of several samples and mock-ups. The dome is protected with tungsten armour tiles joined onto heat sinks obtained from a bimetallic plate made of precipitation hardened copper–chromium–zirconium alloy and stainless steel realized by explosion bonding. The brazed joint between the tungsten tiles and the heat sink has been qualified by means of thermal fatigue tests on small-scale mock-ups in reactor relevant conditions. The properties of the explosion bonding joint between the front copper alloy plate to the rear steel backing has been assessed by means of an extensive metallurgical and mechanical test program according to the specification provided by EFDA. The dimensional stability during the fabrication route has been investigated by means of the realization of a relevant curved component that has been dimensionally tested after the completion of each step of the manufacturing route. The results of the experimental activity are presented and discussed in this paper.

Thermo-mechanical testing of Li–ceramic for the helium cooled pebble bed (HCPB) breeding blanket

The helium cooled pebble bed (HCPB) Test blanket module (TBM) for the DEMO Reactor foresees the utilization of lithiate ceramics as breeder in form of pebble beds. The pebbles are organized in several layers alternatively stacked among couples of cooling plates (CP). ENEA has launched an experimental programme for the out-of-pile thermo-mechanical testing of mock-ups simulating a portion of the HCPB-TBM. The programme foresees the fabrication and testing of different mock-ups, to be tested in the HE-FUS3 facility at ENEA Brasimone. The paper describes the HELICHETTA III campaign carried-out in 2003. In particular, the test section layout, the pebble filling procedure, the experimental set-up and the results of the relevant thermo-mechanical test are herewith presented.

The development of divertor and first wall armour parts at JAERI, Sandia N.L. and KFA Jülich

The development of new armour materials, and fabrication and testings of the divertor and first wall mock-ups have worldwidely been carried out during the Conceptual Design Activities (CDA) of ITER. This paper is a review of the activities on the divertor and first wall armour components which has been performed by JAERI, Sandia National Laboratory, and KFA Jülich. The design requirements have instantly been reflected in material development. For instance, carbon fiber composites (CFC's) have already been developed to have a thermal conductivity as high as copper at room temperature. Further modification of CFC's has been made. Based on the extensive progress in armour materials, the fabrication and testings of mockups have been started. Divertor mock-ups which are able to endure a stationary heat flux of 8 to 15 MW/m 2 have already been developed. Some new high heat flux test facilities have been constructed and are able to simulate a heat load of plasma disruption. Extensive understanding on disruption erosion of the armour materials has been obtained by experiments with these facilities. Some mock-up tests and disruption simulating tests have been performed under international collaboration.