meltdown
1. [ noun ] (physics) severe overheating of the core of a nuclear reactor resulting in the core melting and radiation escaping
Synonyms: nuclear_meltdown
Related terms: overheating
2. [ noun ] a disaster comparable to a nuclear meltdown
Examples:

"there is little likelihood of a meltdown comparable to the American banking collapse in March 1933"

Related terms: calamity
Similar spelling:   melt_down
  Melton
  melting