SF old movie with bald people, a radiation and mysterious cave

My friend remembers only scene, in which immortal people are after radiation. They are probably gray or silver color, they are bald completely and hidden in caves. They are reached by people from the top of the planet who have become immune to radiation or survived it. A scene similar to that of Planet of the Apes, where there they meet these old people in the underground.

It isn't "Time Machine" (1960), although Morlocks are some similar, but they aren't bald.

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The are the underground people and the above ground people friendly or enemies?

There's a quite a few old sci fi flicks with this premise. Maybe The Mole People?

Rather enemies. Every guess is good.

I remember a 1950s era movie similar to yours. I think it was an alien planet where human astronauts landed, about 4-5 men. They were friendly with the above ground people(AGP). The humans had a pistol and maybe a rifle. The humans and some of the friendlies were captured and taken by the UGP. I don't remember if the UGP were bald, but they were dressed nicer and had nicer living spaces. The AGP had simpler clothes.

It's not The Phantom Planet

Perhaps it is my movie, but I didn't find a title.

That's because I don't remember the title. Ask your friend if he remembers human astronauts.

His description didn't have a lot, so I'm trying to see if we can add additional search criteria.

Okay, back in the day, "Planet of the Apes" was a franchise with several movies. Your description sounds a lot like one of the movies "Beneath the Planet of the Apes"

He remembers that people which survived an apocalypse, were immortal, they had gray or silver faces and they were genetically modified (because it was necessary for life in new conditions). I found "Journey to the Center of Time" (1967), but I'm not sure.