Hello you all!
You guessed, said zirconium is the cladding of fissile fuel rods... Which produces hydrogen when not cooled properly and getting in contact with vapour.
First, could you confirm that this is a banal metal-water reaction, leading to metal oxide and hydrogen? Following a bizarre article in Wikipedia, many people imagine water being dissociated by moderate heat and staying dissociated until the mixture explodes, which would look like a double miracle to me.
Then, could this reaction be avoided if water were alkaline, for instance through a volatile amine? Or does PH rather play no role more at such temperatures, which I believe to be red hot? Could some other inhibitor be added to water?