Designs of Corrosion Modules for Long-Term Corrosion Tests of Canister Materials in Aerobic and Anaerobic Underground Water

Abstract

Corrosion modules simulating the engineered barrier system were designed in this study for long-term-corrosion (LTC) testing of canister materials under aerobic and anaerobic conditions. The LTC module for aerobic conditions was designed as a bath-type container with flowing underground water extracted from the Korea Underground Research Tunnel. Five types of metallic disks, that is, rolled Cu, Type 304 stainless steel (SS), Titanium Grade 2 (Ti-G2), cast iron (CI), and Cu coating, were embedded into bentonite and maintained at different temperatures. After 3 years of testing under aerobic conditions, the corrosion rates of CI and Cu were estimated to be 1.9 μm/year and 550 nm/year, respectively. The SS and Ti-G2 exhibited a better corrosion rate of 6 nm/year. The LTC module for anaerobic conditions was developed in a vessel-type cylindrical container to allow it to settle in the boreholes. Four coin-shaped disks of each metal were embedded in bentonite, which was subsequently stacked in the cylindrical vessel. The vessels were placed in boreholes at a depth of 300 m. The Cu corrosion rate after 6 months of LTC testing under anaerobic conditions was 280 nm/year. Longer LTC tests will provide a more exact corrosion rate.

Keywords:

• Copper
• corrosion
• aerobic underground water
• anaerobic underground water
• long-term test module

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Institute for Korea Spent Nuclear Fuel (iKSNF) and a National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT, MSIT) (2021M2E1A1085193 and 2021M2E3A2041351).