Progress on a corrosion study of low carbon steel for HLW container in a simulated geological disposal environment in China

Abstract

In a multi-barrier system of geological disposal for high-level radioactive waste (HLW), it is considered that the disposal container is the first layer of protective barrier to HLW. Low carbon steel is considered as the most promising candidate material for geological disposal container given its mechanical performances and cost-effectiveness. In a long-term geological disposal process, corrosion resistance and corrosion evolution law of low carbon steel in a deep geological environment determine the service life of the disposal containers. Based on a large number of electrochemical corrosion experimental results in a simulated groundwater environment in Beishan, a candidate site for geological disposal of HLW in China, this paper reviews corrosion behavior of low carbon steel from the principles of chemical thermodynamics and kinetics respectively. The effects of environmental factors such as deaeration, aeration, chemical compositions of groundwater on the evolution of corrosion products with immersion time were explored, and the secondary effect of corrosion product on the change of corrosion mode was proposed. In addition, by evaluating corrosion rate as a function of exposure time duration and simulated environment, the feasibility of manufacturing the geological disposal container with low carbon steel was introduced.

Keywords

• Deep geological disposal of high-level radioactive waste
• Low carbon steel
• Corrosion evolution
• Simulated groundwater
• Bentonite