Review of Passive Corrosion Studies of Carbon Steel in Concrete in the Context of Disposal of HLW and Spent Fuel in Belgium

Abstract

The Supercontainer (SC) design is the preferred option for the final disposal of high level nuclear waste and spent fuel in Belgium. The SC consists of a carbon steel overpack surrounded by a very thick concrete buffer, contained within a stainless steel envelope. In this highly alkaline environment of the annulus and under normal conditions (without the ingress of aggressive species), the carbon steel overpack will be protected by a passive oxide film, which is believed to result in very low and almost negligible uniform corrosion rates. This paper discusses the modeling efforts simulating the evolution of various parameters that can potentially influence the corrosion processes (temperature, pH, saturation degree and concentration of aggressive species). The outcome of the Belgian experimental program to study the passive uniform corrosion of carbon steel in concrete is also addressed. Long-term uniform corrosion rates are determined using different independent techniques (hydrogen gas measurements by means of manometric gas cells or pressure transducers, long-term passive current density measurements).

Transport- and surface reaction-controlled SON68 glass dissolution at 30°C and 70°C and pH=13.7

“…The overpack with a lifetime about 100,000 years will prevent the waste glass from being contacted by the cementitious pore water at least during the thermal phase (about 600 years). Once the overpack will be locally perforated, cementitious pore water will contact vitrified waste (Kursten et al, 2013). Very few glass alteration studies have been reported for hyperalkaline media.…”

Overview of anaerobic corrosion of carbon steel radioactive waste packages in alkaline media in support of the Belgian supercontainer concept

“…The results from the cells containing steel wires are adjusted by deducting any pressure fluctuations that occur in the control cells and are normalised to standard temperature and pressure. [ 26–30 ] The setup of the barometric gas cell measurements is shown in Figure 2.…”

“…The tensile specimens are strained at a constant slow strain rate of 5 × 10 −7 s −1 at open‐circuit potential (OCP). [ 27,37–40 ]…”

Corrosion issues of carbon steel radioactive waste packages exposed to cementitious materials with respect to the Belgian supercontainer concept

“…By measuring the height of the mercury, it was possible to calculate the volume of gas produced and hence to derive the corrosion rate (based on the formation of magnetite as the final corrosion product). The results were corrected for temperature and external atmospheric pressure fluctuations [14][15][16].…”