Energetics of typical radiation defects observed in austenitic stainless steel of 304L type has been characterized in the model FeNi10Cr20 alloy by means of atomistic simulations employing a set of interatomic potentials specially derived to reproduce main features of 304L steel. The following defects have been considered: dislocation loops of both interstitial and vacancy nature, stacking fault tetrahedron, perfect loops and voids. The formation energy of these defects has been calculated at 0 K and the obtained results have been compared with the prediction of the elasticity theory. A good agreement has been found in all the cases except for the hexagonal Frank loop, whose sides have splitted into 1/6〈1 1 2〉 partial dislocations, thus lowering the total formation energy. High temperature annealing, performed using molecular dynamics simulations, has proven that the considered defects are thermally stable in the temperature range 300–1200 K.