Calculation of radiation-induced deformation in the ITER vacuum vessel

Numerical calculation was carried out to evaluate the radiation induced def ormation at the blanket side of the vacuum vessel (120 degrees C) and the r ear portion of the blanket module (200 degrees C) in ITER. The calculation was performed for solution-annealed 316 stainless steel mainly at 1 x 10(-9 ) dpa/s and 100 MPa. Enhanced transient creep characteristic of the low tem perature irradiation is evident at 120 degrees C. However, the total accumu lated creep strain in the vacuum vessel is only below 0.01% for the lifetim e irradiation so that serious consequence would not be anticipated. At the rear portion of the blanket the creep strain would be about 0.01% and not s erious either. Radiation-induced stress relaxation at the vacuum vessel is only several per cent during the lifetime. At the rear portion of the blank et, on the other hand, the relaxation could be of the order of 10% and shou ld not be completely neglected. (C) 1998 Elsevier Science B.V. All rights r eserved.