RESIDUAL-STRESS OF A JACKET MATERIAL FOR ITER SUPERCONDUCTING COIL

The jacket material, Incoloy 908, of the superconducting coil for Inte rnational 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 a void the SAGBO fracture, a depth dependence of the strain in the jacke t sample was obtained from the [1 1 1] plane spacing measured with the neutron diffractometer, RESA, installed at JRR-3M in JAERI. A residua l stress distribution was calculated from the strain. The result shows that the tensile residual stress exceeds 200 MPa of the SAGBO conditi on in some areas inside the jacket. (C) 1998 Elsevier Science B.V. All rights reserved.