The Effect Of Irradiation On The Corrosion Of Carbon Steel In Alkaline Media

This paper presents the results of an experimental programme that was carried out to investigate the possible effects of radiation on the anaerobic corrosion of the carbon steel overpack that will surround high level waste (HLW) and spent fuel containers in the Belgian Supercontainer Concept. The anaerobic corrosion rates of carbon steel were measured by monitoring hydrogen evolution rates using a manometric gas cell technique. The electrochemical behaviour of anaerobically corroding carbon steel was investigated by measuring open circuit potential, linear polarisation resistance and AC impedance. Experiments were carried out in an artificial porewater that simulated the cementitious buffer material selected for use in the Supercontainer concept. The programme took account of gamma-irradiation dose dose rate (0 Grays hr(-1) and 25 Grays hr(-1)), temperature (25 degrees C and 80 degrees C) and chloride concentration (0 and 100 mg/l). The paper will summarise the results obtained. It was found that radiation at a dose rate of 25 Grays hr(-1) had a negligible effect on gas generation rates compared to the unirradiated situation. The possible effect of radiation on the electrochemical behaviour will be discussed and the future programme will be outlined.