Premise: Chernobyl disaster . The Chernobyl accident dominates the Energy accidents sub-category , of most disastrous nuclear power plant accident in history , both in terms of cost and casualties . The accident motivated safety upgrades on all remaining Soviet-designed reactors in the RBMK ( Chernobyl No. 4 ) family , of which eleven continued to power electric grids as of 2013 .
Hypothesis: The Chernobyl disaster was an accident.
Label: ENTAILMENT