In the 1990s, the NRC had to “take repeated actions to address defective welds on dry casks that led to cracks and quality assurance problems; helium had leaked into some casks, increasing temperatures and causing accelerated fuel corrosion”.[11]

With the zeroing of the federal budget for the Yucca Mountain nuclear waste repository in Nevada in 2011, more nuclear waste began being stored in dry casks. Many of these casks are stored in coastal or lakeside regions where a salt air environment exists, and the Massachusetts Institute of Technology posited that corrosion in these environments could occur in 30 years or less, while the NRC was studying whether the casks could be used for 100 years as some hoped.[12]

Impervious to absolutely anything, except a little helium, or slightly salty air.