AbstractThe gas desorption properties of low-activation ferritic steel (F82H) were evaluated by thermal desorption spectroscopy (TDS), and compared with those of austenitic steels (316SS and 316LSS). The major desorbed gas species of F82H were CO, H2O, CO2 and H2. The fraction of oxygen-containing species such as CO, CO2 and H2O to the total outgassing amount was 98%. The gas desorption behavior was very similar to the case of 316SS. The gas desorption spectra for F82H show the required prebaking temperature becomes higher than 700 K. For the F82H sample exposed to atmosphere, the gas desorption properties were examined. As the time of exposure increase, desorption amounts of H2O and CO largely increased. This increase may be due to the corrosion in atmosphere.