One disadvantage of zirconium alloys is that zirconium reacts with water at high temperatures , producing hydrogen gas and accelerated degradation of the fuel rod cladding : This exothermic reaction is very slow below 100 °C , but at temperature above 900 °C the reaction is rapid . Most metals undergo similar reactions . The redox reaction is relevant to the instability of fuel assemblies at high temperatures . This reaction was responsible for a small hydrogen explosion first observed inside the reactor building of Three Mile Island nuclear power plant in 1979 , but at that time , the containment building was not damaged . The same reaction occurred in the reactors 1 , 2 and 3 of the Fukushima I Nuclear Power Plant ( Japan ) after the reactor cooling was interrupted by the earthquake and tsunami disaster of March 11 , 2011 , leading to the Fukushima I nuclear accidents . After venting the hydrogen in the maintenance hall of those three reactors , the mixture of hydrogen with atmospheric oxygen exploded , severely damaging the installations and at least one of the containment buildings . To avoid explosion , the direct venting of hydrogen to the open atmosphere would have been a preferred design option . Now , to prevent the risk of explosion in many pressurized water reactor ( PWR ) containment buildings , a catalyst-based recombiner is installed that converts hydrogen and oxygen into water at room temperature before the hazard arises
earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Zirconium