The Canadian Nuclear Fuel Waste Management program is evaluating two basic supported-shell container concepts for used-fuel immobilization.
One concept uses a compacted particulate material within the container to sunport a thin, corroston-resistant shell. The other concept, called “the metal-matrix concept”, uses a cast-in-place metal matrix for shell support.
This paper describes corrosion studies on the candidate matrix materials, lead, zinc and aluminum-7 wt.7 Si (A1-7 wt.7 Si), in the temperature range 293 to 423 K and the dissolved oxygen content range 8 to 410 mg/L. Test specimens were analyzed for general and localized corrosion and the corrosion products were identified.
The results showed that, unlike lead, zinc and Al-7 wt.% Si are susceptible to localized corrosion. Lead showed only low general corrosion rates of 2 to 83 pm/a compared with zinc (36 to 15800 μm/a) and Al-7 wt.% Si (6 to 209 μm/a) in the above temperature and oxygen content ranges. Maximum pit depths of about 0.9 mm on Al-7 wt.% Si and 0.6 mm on zinc were observed. These results indicate that, of the candidate matrix metals studied, lead has the greatest potential to retard radionuclide release from used-fuel disposal containers.