Chernobyl goes critical. Three Mile Island barely escapes a similar fate. The unhappy bottom line is that you can never plan for everything.
=== RMS Titanic ===
The [https://en.wikipedia.org/wiki/RMS_Titanic Titanic] is the iconic symbol of disaster. It was considered to be unsinkable despite obvious design flaws that were only admitted retrospectively. They combined with initial human error before and after the collision with an iceberg to create a full-fledged disaster.