A Review of ITER Blanket Designs

Changes in ITER requirements and conditions in the Engineering Design Activity (EDA), and the desire to obtain greater operating flexibility, led to a reconsideration of the ITER Conceptual Design Activity (CDA) blanket designs. The current strategy is to follow a two-tiered development approach: The reference design blanket is non-breeding, and satisfies only the basic performance phase (BPP) functional requirements. This blanket would need to be changed out for the extended performance phase (EPP). A lower level development effort is also underway on an tritium-breeding blanket. The decision as to which of the two designs to adopt will be made at the end of a two-year development effort. This paper describes the present candidate blankets and the issues associated with each of them. The reference design is a non-breeding, low temperature, low pressure, water cooled, austenitic stainless steel (316SS) blanket/shield (BS). The first wall (FW), which may be integral with or separate from the BS, is a bonded copper-alloy/SS structure with a beryllium coating. Critical issues here are copper-SS bonding, fabricability, and radiation damage and stress corrosion cracking of the SS. The breeding blanket utilizes vanadium alloy structural material, with lithium as the breeder. The coolants are either lithium (self-cooled) or high pressure helium. The primary issues here are the need to electrically insulate the flow channels, the qualification of vanadium as a structural material, and the fabrication of large vanadium structures.