Experimental studies of the effect of irradiation on the anaerobic corrosion of carbon steel in relation to the Belgian supercontainer concept

Abstract

Abstract. This paper describes recent results from an investigation of the effects of -radiation on the anaerobic corrosion of carbon steel in cement, in relation to the Belgian Supercontainer Concept for radioactive waste disposal. Anaerobic corrosion rates were measured by monitoring hydrogen evolution and the corresponding electrochemical behaviour was investigated by measuring open circuit potential and linear polarisation resistance. The test medium was alkaline simulated porewater, at -irradiation dose rates of 0 and 25 Gy hr −1 , temperatures of 25• C and 80• C and chloride concentrations of 0 and 100 mg/l. The effects of radiation on the corrosion behaviour were found to be small.

The anaerobic corrosion of carbon steel in alkaline media – Phase 2 results

“…For the unirradiated experiments ( Figure 1) the peak corrosion rate on pickled surfaces was higher at 80°C compared to 25°C. This is comparable to previous measurements [2][3][4] in similar conditions. The corrosion rates decreased with time; at both 25°C and 80°C the corrosion rate after 17,000 hours was approximately 0.1 µmyr -1 .…”

“…Similarly, electrochemical measurements were carried out in two phases. The results from Phase 1 are described in references [2] to [4]. In Phase 2 electrochemical behaviour was studied using sealed glass cells, for the irradiated experiments, or sealed stainless steel autoclaves with electrical feedthroughs for the unirradiated experiments.…”

“…Figure 3 shows that within the normal statistical experimental variation, radiation at 25 Gyhr -1 did not increase the rate of hydrogen production, in fact it appears to reduce the long-term corrosion rate compared to unirradiated specimens. This may be because radiation appears to shift the corrosion potential to more negative values [4].…”

“…An experimental programme is being conducted to investigate (i) the possible effect of gamma radiation on the anaerobic corrosion rate of carbon steel in cementitious porewaters and on the nature of the corrosion products formed, and (ii) the effect of radiation on the electrochemical and corrosion behaviour of carbon steel corroding anaerobically in simulated concrete porewater conditions, including the effects of sulphur species. Previous publications have described the experimental arrangements and reported earlier results from this programme [2][3][4] for both gas generation and electrochemical measurements; this programme follows from previous work in the field [5][6][7][8]. The aim of the present paper is to present some recent results from Phase 2 of the programme.…”

Further studies on the anaerobic corrosion of carbon steel in alkaline media in support of the Belgian supercontainer concept

“…[4] A programme of research has been carried out to investigate and measure the rate of anaerobic corrosion of carbon steel in an artificial alkaline porewater that simulates the aqueous phase in the cementitious buffer material and also in solid cement matrices. Much of the work carried out to date is described in previous studies, [5][6][7][8][9][10] and full details are available in a research report. [11] This study presents recent results from the programme covering a range of different aspects that extend the previously published work.…”