CRACK-PROPAGATION IN FIRST WALL OF FUSION-REACTOR BY CYCLIC THERMAL-STRESS

To clarify the crack propagation behavior of first wall materials unde r high thermal load cycles, cyclic high heat flux loading tests were c arried out on SUS316. A specimen with a thickness of 5 mm was used, an d the tests were performed under three types of external load conditio ns in order to investigate the effect of stationary tensile stress, si mulating gravitational load on the first wall. To get rid of the effec t of creep, the duration time of the beam was limited to 0.5 s in ever y 30 s high heat flux loading cycle. Two-dimensional thermal and elast o-plastic stress analyses and non-linear fracture mechanics analysis w ere carried out, and the fatigue crack propagation lengths were evalua ted using (J) over cap-integral amplitude Delta (J) over cap(eff). Thr ough this study, it was concluded that crack propagation lengths were decreased by applying stationary moderate tensile load, and that the e valuated crack lengths roughly agreed with experimental ones. (C) 1998 Published by Elsevier Science S.A. All rights reserved.