Effects of stress on swelling and creep in irradiated Kh16N15M3B steels

Results are presented of investigation of gas-filled tubular samples irradiated in test packets at 350 deg C and 450 deg C. It is shown that from the onset od swelling (at 450 deg C this is a dose above 20 dpa) the strain on all the stress levels accelerates, that is not observed for samples at 350 deg C in the abscence of swelling. The high stress level in samples leads to their substantial strain describable by the linear dependence on a dose and stresses in the range 0...180 MPa. At stresses higher than 180 MPa the creep strain increases faster than that by linear law. Maximum strain at stress 320 MPa is 3.1 % at 450 deg C and 30 dpa irradiation. The results of irradiation creep investigations at high stresses have been used to analyse the deformation of fuel elements with envelops of the same steel irradiated in a fuel assembly in BOR 60 reactor