FRACTURE-MECHANICS OF A POSTULATED CRACK IN ITER VACUUM VESSEL

A vacuum vessel wall with a postulated crack is modeled by using the t wo-dimensional solid finite elements. The J-integral value, a criterio n of fracture mechanics, is calculated to estimate the integrity of th e vacuum vessel wall with a postulated crack. The analytical results s how that the J-integral value of a crack having a quarter depth of the wall width is considerably less than the fracture toughness JIC when the membrane stress is less than the 0.2% proof stress of the unirradi ated material, even if the vacuum vessel is irradiated to 3 dpa. This means that a shallow crack in the vacuum vessel wall does not become c ritical in the design load.