Manufacture of a stainless steel primary first wall panel using an innovative hip technique

Abstract

Hot isostatic pressing (HIP) techniques are being considered by the ITER project as one of the fabrication routes to produce ITER primary first wall panels (PFW). HIP techniques have been identified as promising as they assume to overcome drawbacks associated with cast products, to enhance the properties of foundry parts and to lower the fabrication cost through a strong reduction of the machining and the number of welds. To demonstrate the potential and the availability of such techniques, material development, innovative mock-ups fabrication and numerical modeling for the production of components are currently studied by CEA-Grenoble in collaboration with the EFDA-CSU Garching. The aim of this work was to investigate the manufacturing feasibility of advanced PFW panel concepts, without copper heat sink thus lowering the fabrication cost while still keeping good mechanical and thermal fatigue performances. In order to select the best fabrication route, two different HIP techniques have been considered. The first technique consists in HIP forming. Mock-ups have been made from serpentine tubes expanded into a proper matrix. The second technique is based on powder HIPping. Mock-ups have been made from serpentine tubes embedded into stainless steel (SS) powder. In both cases, the objective was to obtain the minimum pitch between the SS tubes and between the SS tubes and the front face. The principal conclusion of this development work was that solid/powder forming route, consisting in a combination of the two techniques, appeared to be the best method, and was therefore selected for the manufacture of a 316L SS panel prototype. The dimensions of this panel prototype are 900 mm long, 250 mm wide and 70 mm thick. This paper presents the main results of the development work and the main fabrication steps for the manufacture of this panel.