Study on the corrosion assessment of overpack welds, 2 (Joint research)

Mitsui, Hiroyuki*; Taniguchi, Naoki ; Otsuki, Akiyoshi*; Kawakami, Susumu; Asano, Hidekazu*; Yui, Mikazu

The corrosion experiments for welded carbon steel were planed to contribute to an assessment of long-term integrity of carbon steel overpack welds considering corrosion damage specific to overpack welds. Based on this plan, electrochemical tests for welded carbon steel using the samples welded by EBW and TIG were carried out, and the corrosion behavior of welded zone was compared with that of base metal. The results of anodic polarization tests in 0.01M and 0.1M carbonate aqueous solutions for base metal, heat affected zone and welded metal indicated that; -As for EBW, the anodic polarization curves were not affected by welding although the metallurgical structures vary with base metal, heat affected zone and welded metal. -As for TIG, the current density of welded metal was larger than that of base metal and of heat affected zone, and local dissolution with immediate increase in current density was observed in 0.01M-pH10 carbonate aqueous solution.