The Chernobyl accident was the worst disaster in the history of nuclear power. Radioactive debris spread in a massive cloud that stretched throughout Western Europe, and ultimately reached the eastern seaboard of the United States. 200,000 had to be relocated from badly contaminated regions of Soviet controlled Ukraine and Belarus. It is estimated that as many as 4,000 people may die from the deadly exposure they received that day. Chernobyl displayed the kind of staggering incompetence that came to reflect Soviet bureaucratic decision-making towards the close of the Cold War.
Time: Late War
Removed after event: Yes
Not a particularly fearsome event if you draw it, since playing it on the last Action Round is no big deal (though remember to announce that your Operations go before the event!).
Chernobyl is one reason to overprotect your European assets a bit more. If you only control East Germany and Poland at 0/3, then it costs the US 14 Ops to take them over and win with Europe Control (and this is without considering events like East European Unrest or Tear Down This Wall). But if you have been diligent in using your free eastern Europe influence from US-triggered plays of Comecon and Warsaw Pact Formed to double- or triple-overprotect East Germany/Poland, then you are effectively immune to a Chernobyl assault on Europe. (Of course, holding Warsaw Pact is an even better defense against US intrusion into eastern Europe.)
If the US headlines Chernobyl, the response is similar to the response to Nuclear Subs — you try to distract them with threats elsewhere, such that the US is never able to take advantage of the Chernobyl ban.
Chernobyl works best as a headline. Most players tend to headline it immediately and go gung-ho for Europe, but I think this is in error. The USSR almost always overprotects East Germany/Poland, meaning you might not have enough Ops to take them over. So unless those battlegrounds are weakened, or if you have strong Europe events to help you, you’re unlikely to land that knockout blow (especially considering potential USSR events like The Reformer and Warsaw Pact Formed).
I think Chernobyl is most effective when you line it up with any scoring card. If you can combine it with Asia Scoring and make use of Chernobyl’s prohibition to swing Domination from one side to the other, then Chernobyl is effectively a 8+VP swing for 3 Ops plus whatever board position you lost elsewhere by focusing on Asia. (Assuming, of course, that the USSR lacks events that affect that region.) This is much more feasible and less costly than trying to go for instant wins in Europe.
Of course, if you do draw Chernobyl with the right events, then by all means use it for the Europe win. I usually hold it from turn to turn, trying to line it up with either a European opportunity, good Europe events, or a high-value scoring card. Just be mindful that while you focus on the Chernobyl-blocked region you don’t lose too much board position elsewhere. This is especially true for Europe — it’s not uncommon to see people losing while controlling Europe, because they’ve sacrificed so much of the rest of the world that they lose to autovictory before Europe was scored.
Rules clarifications: the prohibition applies only to “the play of Operations points to place influence”. Coups, realignments, and events like The Reformer are unaffected.