Development of aluminum alloy coating for advanced nuclear systems using lead alloys

Kurata, Yuji; Yokota, Hitoshi*; Suzuki, Tetsuya*

Small and medium reactors using lead alloys as coolant are one of the promising reactor concepts with improved safety. This paper focuses on development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). Since corrosion attack becomes severe against steels at high temperatures, it is necessary to improve corrosion resistance. An Al-alloy coating method using Al, Ti and Fe powders, and laser beam heating has been developed. Main defects formed in an Al-powder-alloy coating process are surface defects and cracks. Conditions required to avoid these defects were found. According to results of the corrosion tests at 550 C in liquid LBE, the Al-alloy coating layers on 316SS protect severe corrosion attack observed in 316SS without coating. From the viewpoints of the soundness of coating layers and preservation of their corrosion resistance, it is estimated that the range of the adequate Al concentration in the coating layer is from 4 to 12 wt%.