Study on the corrosion resistance of welded zone of carbon steel overpack

Kobayashi, Masato*; Takahashi, Rieko*; Asano, Hidekazu*; Taniguchi, Naoki ; Naito, Morimasa 

Overpack is one of the components of EBS (Engineering barrier system) and is required to contain the radioactive waste at least for 1000 years. It has been evaluated that carbon steel overpack can be achieved lifetime of over 1000 years in expected deep underground environment by securing 40mm corrosion allowance. However, since the welded zone have different characteristics from the base metal in chemical composition and microstructure, its corrosion behavior would possible to be different from that in base metal. Concerning such background, corrosion tests to evaluate the corrosion resistance of welded zone (including heat affected zone and welded metal) were carried out and the effects of welding on the corrosion properties were investigated.