Manufacturing aspects in the design of the breeder unit for helium cooled pebble bed blankets

Abstract

The breeding blanket programme has been the focus of European fusion research for more than two decades. One central goal in this present status is to ensure all manufacturing processes for these blankets to allow functional operation while integrating in ITER. Two kinds of blankets are established for this first run of ITER: One is the helium cooled pebble bed (HCPB) blanket and the other is the helium cooled liquid lead (HCLL) blanket. Both the designs employ three different cooling plate (CP) dimensions, which are forming the test blanket module (TBM). Namely, the first one is the U-shaped first wall (FW) with two similar dimensioned caps. The second type is the cross section of stiffening grids (SG) that separates the equally spaced breeder unit (BU) region. The third type is the U-shaped CP of each BU canister. Different processes for hot isostatic pressing (HIP) are presently focused to be most successful for the fabrication of all cooling plates. It will be shown that the extension of already verified HIP processes is in need of further optimization for the production of real scaled TBM components. This paper will additionally present an alternative manufacturing by spark erosion (SE) process for the U-formed cooling plates (U-CP) of the breeder unit assembly combined with conventional electron beam (EB) welding technology.