Corrosion studies on POLLUX cask material

Within the POLLUX engineering concept, the material concept for safe containment of radioactive materials includes corrosion resistance, reproducible quality, material reliability, and controlled component quality. These requirements with regard to material and applied technology are optimally satisfied within the POLLUX concept, where the selected steel grade, 15 MnNi 6.3, for the cask body and plasma hot-wire surfacing (PHS) combine a base material with a proven surfacing welding process. Metallographic examinations of Inconel and Hastelloy C4 layers have been performed for characterizing the structure and determining the thickness of the applied layers. Microprobe analyses are conducted for examining the layered structure achieved with the transition zones between the layers, as well as for confirming the attainment of Hastelloy quality in the uppermost layer. The Hastelloy C4 specimens employed for the corrosion tests were surface-welded and originated from the topmost layer of the cladding surfaced with the use of the PHS process. MgCl2 was used in most of the studies as the corrosive media. It was concluded that the microstructure and purity of the weld layer is important in regard to corrosion resistance; and that higher temperatures in the corrosive media influence resistance