Advanced multi-step brazing for fabrication of a divertor heat removal component

Abstract

The advanced fabrication method named advanced multi-step brazing (AMSB) has been developed for fabrication of a tungsten (W)/copper alloy divertor heat removal component in a fusion reactor. The principle of AMSB is repetitive application of the advanced brazing technique (ABT). The ABT was originally developed in our previous work for jointing of W and oxide dispersion strengthened copper alloy (ODS-Cu: GlidCop®) with the BNi-6 (Ni-11%P) filler material. The special feature of the AMSB is that the leak-tight joint of GlidCop® (GlidCop®/GlidCop®) and of stainless steel (SUS) and GlidCop® (SUS/GlidCop®) can be realized by application of the ABT. Therefore, the AMSB enables production of a leak-tight sealing structure with the appropriate lid material such as GlidCop® or SUS for a pre-processed rectangle-shaped cooling flow path channel. The rectangle-shaped cooling flow path channel has an advantage regarding its heat removal capability. Another special feature of the AMSB is that the physical properties of the AMSB joint has strong tolerance against the repetitive brazing heat cycle. Thus, repetitive application of the ABT does not cause any undesired effects on the leak tightness of the GlidCop®/GlidCop® and the SUS/GlidCop®. The new AMSB type component with the rectangle-shaped fluid flow path and the V-shaped staggered rib structure were successfully produced; therein a pre-processed rectangle-shaped cooling flow path channel was sealed with a GlidCop® and SUS lid structure with leak-tight conditions. The component showed excellent heat removal capability under reactor-relevant conditions with ∼30 MW m−2.