SOME ASPECTS OF EFFECTS OF FISSION FRAGMENT IRRADIATION UPON OXIDATION OF AUSTENITIC STAINLESS STEELS BY OXYGEN AT 650 DEGREES AND 800 DEGREES C

The oxidation of an 18/8/Ti stainless steel by oxygen at 650 °C for varying periods up to 3760 h was enhanced by a fission fragment flux between 6.2 × 108 and 1.7 × 109 ff/cm2.sec but was not influenced by the associated incident reactor radiation. The enhancement increased with exposure, such that the magnitude of oxidation on the specimens irradiated with fission fragments was greater than on the controls by a factor of between 1.3-3.5 and 1.7-4.6 after 1000 and 3700 h respectively. There was no systematic correlation between the extent of the increased attack and the magnitude of the fission-fragment flux. The radiation-induced attack would appear to be primarily localised as mounds and is believed to be caused by displacement damage in the protective oxide film as a direct result of fission recoil bombardment. Fission-fragment irradiation did not influence significantly, however, either the magnitude of oxidation or the percentage of non-adherent oxide formed during the oxidation of a 20/25/Nb stainless steel at 800 °C. The exposure period varied up to 4252 h and the fission fragment flux was between 1.13 and 1.53 × 109 ff/cm2-sec. The absence of any irradiation effect at this temperature contrasts with the radiation-enhanced oxidation of this steel observed previously at 650 °C. © 1969.