A relatively minor, yet annoying alternate history cliché.
Anything strange or disastrous happening in the Soviet Union will almost exclusively take place on the Ukraine-Belarus border, sort of to the north of Pripyat.
Project Koschei in Charles Stross's A Colder War, the Race's nuclear stockpile in the Worldwar series - they all go off in Chernobyl…
While an infrequent use of this veiled reference to the OTL Chernobyl disaster can be implemented into an AH story in a subtle and clever way to amuse the reader, it has been unfortunately overused by too many authors, to the point of irrelevance. Outside of the overuse, the problem of this cliché is that it becomes a tired shorthand for “weird things happening in Ukraine can only happen in and around Chernobyl and Pripyat”. It basically counts as a failure on part of the author's imagination, or his unwillingness to research Ukrainian geography for other possibilities concerning “places for spooky and/or ominous events”.
The name of this cliché references the conspiracy theory that the Revelation of St. John alludes to the Chernobyl catastrophe with the word “wormwood” - in reality, the Ukrainian term for “wormwood” is not “chernobyl”, but “polyn”.