What is(was) the worst radiation????????

Question: What is(was) the worst radiation????????
- Keywords:
  radiation
Asked by 699nveg23 to Sarah on 10 Nov 2016.
- Sarah Hunak answered on 10 Nov 2016:
  
  All radiation can be harmful, it depends how much there is of it.
  I suppose the worst nuclear disaster was at Chernobyl in the Ukraine where the reactor exploded. This was the worst disaster in history and sadly people died from it.
  We’ve learned a lot from this accident and hopefully it would never happen again.

Question: What is(was) the worst radiation????????