There is an episode where Accelerator mentions to Last Order if I recall correctly (it could be another character) that he/she shouldnt worry about someone who can't be killed even by a nuclear bomb. But in the other hand, his brain has been overwhelmed with information sometimes, when he had to kill the virus for example, and I think there were other moments where he received many vectors and couldnt fight back 100%. I assume a nuclear bomb has many vectors to process. Since he appears in several series/media (3 different animated series, mangas and light novels) plus there could be data in official databooks if they exist, I thought this question might have been probably answered.
Can Accelerator be killed by a nuclear weapon?