Helium bubbles in 316L stainless steel irradiated with He+at 600℃ were investigated with TEM. Helium bubbles are formed preferentially at dislocation lines where helium concentration is low. As helium concentration increases

bubbles distribute homogeneously in the matrix. Bubbles are faceted both on grain boundary and in matrix

but bubble do not grow preferentially on the investigated grain boundary. Helium bubbles’ size and density were measured along the penetrating depth. With the help of u fluid mode"

helium depth distribution in visible bubbles were calculated with the measured bubble size and density. It is found that the depth distribution of helium in visible bubbles shifts to the surface as compared with the helium concentration calculated with TRIM code. Implanted helium is mostly confined to the visible bubbles.