if those tubes are exposed to the air, the metal oxidizes and starts to breakdown. it is like the idea of rusting, it is not rusting, it is oxidi seepation. if the bottom of your car looks like this, like mine does, you worry about whether you have to replace it, whether you need framework done, or whether you need a new car. rust. sir cone yum doesn't rust but it does objection diez when exposed to air. the combination of heat and the objection did iization, it is like super fast rusting. exposing those fuel rods to the air causes that. it is like super fast rusting on steroids and that's trouble.