Residual stress of a jacket material for ITER superconducting coil

Abstract

The jacket material, Incoloy 908, of the superconducting coil for International Thermonuclear Experimental Reactor (ITER) has a possibility of fracture due to stress-accelerated grain boundary oxidation (SAGBO) in the region of tensile residual stress above 200 MPa. In order to avoid the SAGBO fracture, a depth dependence of the strain in the jacket sample was obtained from the (1 1 1) plane spacing measured with the neutron diffractometer, RESA, installed at JRR-3M in JAERI. A residual stress distribution was calculated from the strain. The result shows that the tensile residual stress exceeds 200 MPa of the SAGBO condition in some areas inside the jacket.