EGU2020-6356
https://doi.org/10.5194/egusphere-egu2020-6356
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Corrosion behavior of low carbon steel under different water conditions in compacted bentonite of China-Mock-Up

Xin Wei1, Yuemiao Liu2, and Junhua Dong1
Xin Wei et al.
  • 1Institute of Metal Research Chinese Academy of Sciences, Shenyang , China
  • 2Research Institute of Uranium Geology, Beijing, China

In some countries, low carbon steel has been considered as the candidate material of the disposal container for high-level radioactive wastes (HLWs) due to its excellent anti-irradiation, high strength, low cost and fine processing performance. However, during the long-term geological disposal, the steel disposal container will suffer from the threat of corrosion damage under the coupled THMC conditions.

This work focused on the corrosion behavior of low carbon steel under different water conditions in compacted bentonite of China-Mock-Up by in situ electrochemical impedance spectroscopy (EIS) with the infiltration of groundwater from outside to inside. Based on the EIS results, the corresponding equivalent circuit models were proposed to interpret the evolution of electrochemical characteristics of low carbon steel with the increase of water content in compacted bentonite. In the initial stage of EIS measurement, water in bentonite around the electrochemical sensors from outside to inside was hygroscopic water and chemical bonding water successively. With the running of China-Mock-Up, water in outer bentonite transformed from hygroscopic water to free water. Meanwhile, the water in the inner bentonite blocks transformed from chemical bonding water to hygroscopic water, which caused a slight corrosion of low carbon steel. After China-Mock-Up running for 1202 days, the instantaneous corrosion rate of low carbon steel located in the inner bentonite blocks was just 0.002 mm/a. While in the outside bentonite blocks, the corrosion rate reached to 0.58 mm/a after 1155 days, indicating that the free water could cause a serious corrosion of low carbon steel.

How to cite: Wei, X., Liu, Y., and Dong, J.: Corrosion behavior of low carbon steel under different water conditions in compacted bentonite of China-Mock-Up, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6356, https://doi.org/10.5194/egusphere-egu2020-6356, 2020