Effect of gamma radiation on CSN 422707.9 steel corrosion under anaerobic conditions

摘要

The 422707.9 steel is one of the candidate construction materials for spent nuclear fuel canister in Czech deep geological repository concept. Current canister design does not provide appropriate radiation shielding, it is expected that candidate steel corrosion under repository conditions would be affected by an ionizing radiation. Thus evaluation of corrosion rate under these conditions is important to estimate life time of steel in a deep geological repository. The contribution presents the study looking into the effect of gamma radiation on 422707.9 steel corrosion under anaerobic condition in simplified experimental system The steel samples were immerged into synthetic bentonite porewater solution in glass vials, sealed under anaerobic conditions and transferred into an irradiation facility.The vials were installed here in a furnace in order to attain elevated temperature 90 °C. An additional shielding was applied to gain low dose rate, being expected on canister surface, resembling proposed construction parameters. The .simultaneous heating and irradiation ((60)~Co gamma source) was performed for the period of 0.25 and 0.5 year duration. After the selected time, vials were transferred to the laboratory and dismantled in the glove box under argon atmosphere. Metal and solution samples were taken for the analyses. Obtained results provided information on corrosion rate under given conditions and will be used for development of more complex experiments in order to test potential candidate materials under ionizing radiation.