The tritium trick technique was used to build-up radiogenic helium inside stainless steel 12Cr18Ni10Ti (SS). A great quantity of defects with a mean diameter of 20 nm, most probably platelet-like bubbles with 3He atoms, was observed in 3He-containing samples. The mean density of these bubbles in SS samples containing ~75 appm of 3He is estimated to be 61020 m-3. Much larger helium bubbles were observed in SS after annealing the samples at T1170 K. Thermal release of radiogenic helium occurs at T>1500 K. The presence of 3He in structural materials causes the formation of an additional state for hydrogen sorption.