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MARKET SURVEY TECHNICAL NOTE
Fabrication of ITER First Wall Panel’s Beam structure by Additive Manufacturing Technology
The ITER Blanket-shield system is the innermost part of the reactor directly exposed to the plasma. Its basic function is to provide the main thermal and nuclear shielding to the vacuum vessel and external reactor components. The concept of the blanket shield system is modular and it is mechanically attached to the vacuum vessel. The Blanket modules consist of a water-cooled austenitic Stainless Steel (SS) Shield Block on which a separable First Wall Panel (FWP) is mechanically attached. The FWP is a component that consists of three main sub-components: Left Wing and Right Wing, which are connected to a Central Beam. Both Wings are joined to the Central Beam by Hot Isostatic Pressing Diffusion Bonding (HIP Diffusion Bonding). Conceptual views of the FWP and Central Beam are shown in Figures 1 and 2.
Figure 1. General illustration of the First Wall Panel and its main subcomponents
Figure 2. Cross Section of 316L(N)-IG FWP Central Beam
The material of the Central Beam is Austenitic Stainless Steel 316L(N)-IG (ITER Grade). The baseline design of the Central Beam is complex and requires lengthy and costly manufacturing steps. The main requirements for the Central Beam come from the operating conditions, which are:
· Providing structural support for the FWP at temperatures ranging from room temperature to 250°C.
· Being compatible with High Vacuum and Cleanliness in an experimental nuclear reactor.
· Resisting neutron irradiation up to 2dpa, which is the expected ITER accumulated dose.
The European contribution to ITER will consist in the delivery of 215 FWPs, in the period 2024-2027.
Figure 3 shows the shape of the beam part which is considered to be manufactured via Additive Manufacturing (AM).
Figure 3. General illustration of the Central Beam and its design features
Figure 4 gives general dimensions of the smallest and largest beam which shall be produced in the frame of the Series production. Thickness is in the range 70-100 mm.
Figure 4. Main dimensions of the smallest Central Beam variant (left) and largest Central Beam variant (right)
F4E is looking for information to assess the feasibility of building the FWP Central Beams by Additive Manufacturing and its potential benefits in terms of cost, time and performance. Preliminary studies on 316L(N) material produced via Additive Manufacturing indicate that the material properties are adequate for the application, and that the complex geometry is feasible for the AM technology. However, the feasibility to build a full scale component is one of the points which still remain open.
This market survey is published in preparation of a possible new procedure aimed at building a full scale beam of a representative FWP design by Additive Manufacturing Technology. Achieving a good understanding of the maximum build size is one of the main targets of this exercise. The parameters from this task will then be used to assess the feasibility for the series production of the FWPs.