Numerical evaluation of crack propagation of ITER first wall with an initial interfacial defect

Suzuki, Satoshi; Enoeda, Mikio; Matsuda, Hirokazu*; Hiramatsu, Hideki*; Kuroda, Toshimasa*

The first wall of ITER will be fabricated by means of HIP method for the bonding of cooling tubes and a copper alloy heat sink. A ultrasonic testing (UT) is adopted as a non-destructive inspection method for the bonding interface as one of acceptance tests of the first wall components. Therefore, clarification of defect size criteria is one of critical issues for the soundness of the first wall. Thermo-mechanical behavior of an initial defect at the bonded interface of the first wall was numerically analyzed. J-integral was calculated to evaluate the propagation behavior of the interfacial defects under thermal loading. As a result, it was found that the initial defect size of 10mm 20mm in semi-elliptic shape was unlikely to propagate. This defect size is more than ten times larger than a detection limit of present UT techniques, and it can be resulted that the UT method presently available is sufficient to detect such harmful initial defects of the ITER first wall.