Rhinoplasty, Stalker.

[Dave Monroe]

A clarification.  Apparently, the problem in shooting Stalker was with
the filmstock itself.  Other films shot at the same time were affected
as well, but Stalker was further along when the problem was discovered.
However, it seems Tarkovsky might have taken advantage of the situation
to relieve himself of some footage he wasn't happy with as well, so ...
see ...

Tarkovsky, Andrei.  Collected Screenplays.
    Trans. William Powell and Natasha Synessios.
    Boston: Faber and Faber, 1999.

As well as ...

Johnson, Vida T. and Graham Petrie.
    The Films of Andrei Tarkovsky: A Visual Fugue.
    Bloomington: Indiana UP, 1994.

Also appears that Stalker was shot (in both its shootings) outside
Talinn, Estonia, rather than at Chernobyl in the Ukraine.  I guess once
you've seen one Soviet power plant, you've seen 'em all ...