Letters from a Dead Man (1986) IMDb
Konstantin Lopushansky (director).
A poetic look at the consequences of nuclear exchange. A Nobel laureate tends to his radiation-sickened wife in the ruins of a grand museum, somewhere on Earth in a black winter of fallout and desperate shortages. A small group of scarcely sane intellectuals in the museum are the only ones attending the wake of humanism. The last trace of civilization with any real hope of survival is moving far underground, planning to emerge after some 30 to 50 years, free of the old world’s crippling altruism. The scientist is not going with them.
Science fiction. In addition to directing, Konstantin Lopushansky did the writing, with Vyacheslav Rybakov and Boris Strugatsky.
This is what Threads (1984) might have been like if Tarkovsky had directed it. It adds the humanist lament of O-Bi, O-Ba – The End of Civilization (1985) and it is The Sacrifice (1986) done right. Indeed, this is probably second only to Threads as a cinematic depiction of nuclear apocalypse, and it’s supposed to have been hugely popular. Unfortunately, the special effects are weak and it is, on the whole, a less gripping take.
References here: Visitor of a Museum (1989).