To be more clear, I heard an opinion on the matter, by a friend who lives in the U.S. He told me that one reason they did those drills, was to protect the children from watching their impending doom. So any thoughts on the and any clear answers?
The basis for duck and cover is addressed in this previous answer by u/restricteddata:
To directly address your friend's idea — no, that was not one of the motivations for "Duck and Cover." That sort of nonsense is, however, common of to a strand of non-serious Civil Defense critiques that sprung up in the 1950s-1980s. (There are serious critiques of Civil Defense; this is not one of them.)
One can certainly say that Civil Defense drills, aside from the technical aspects addressed in the linked-to thread, had ideological aspects. They tried to propagate an idea of government control over an uncontrolled situation; they tried to reassure; they tried to imagine a world in which nuclear war was to some degree survivable; they tried to project a vision of what a sort of collective citizenship would look like. (Whether they succeeded at these goals is a separate question, and whether these goals should be considered insidious is another one.) But "keeping children from watching their impending doom" is not a motivation nor is it even what "Duck and Cover" would accomplish from a strictly technical viewpoint.