Demonstration of JK2LB Jacket Fabrication for ITER Central Solenoid

The Japan Atomic Energy Research Institute developed a jacket material called JK2LB (0.03C-22Mn-13Cr-9Ni-1Mo-0.2N-B) for the Central Solenoid (CS) conductor in the International Thermonuclear Experimental Reactor (ITER). To demonstrate production feasibility of CS conductor jacket, trial fabrication of a full size jacket using hot extrusion followed by cold drawing of the JK2LB billets was performed. As a result of dimensional measurement, the ITER dimensional requirement for circle-in-square jacket has been achievable. We achieved the requirement of 0.2% yield strength >1000 MPa and K_IC(J)ges130 MParadicm for solution treated + aged jacket. It has been observed that applied cold work strongly affects the toughness of jacket before and after aging. We estimate that C and N reduction will be required to achieve the required strength and fracture toughness for ITER CS jacket. The fabrication R&D has prepared us for mass production of jacket for the ITER CS conductor procurement