ITER divertor cassette body fabrication

The International Thermonuclear Experimental Reactor (ITER) divertor cassette body is a large (20+ ton) 316 LN stainless steel cast structure that supports the plasma facing components (PFCs) and provides shielding for the vacuum vessel and magnets. The cassette body must be robust to accurately position the PFCs in the magnetic volume that confines the plasma while withstanding intense electromagnetic loads generated during disruptions. It is intended to be a full life component, accommodation several successive sets of PFCs. It must also be compatible with the high-vacuum conditions necessary for fusion plasma. Cooling water must be routed throughout the cassette body to remove nuclear heating. Machined side coolant channels and cross-over holes accomplish the routing of the cooling water through the body. The machined side coolant channels are closed with welded cover plates to contain the 4.5 MPa, 150/spl deg/C water coolant. The cover plate welds must be able to withstand a lifetime of exposure to the water coolant without development of leaks.