So water-cooled reactors are built inside of big, thick concrete buildings called containment buildings, which are meant to hold all of the steam that would come out of the reactor if you had an accident where you lost pressure.
Assim, esses reatores são construídos dentro de enormes edifícios de betão chamados edifícios de contenção concebidos para aguentar todo o vapor que sairia do reator no caso de um acidente com perda de pressão.