A nuclear bomb in a dream is read as fear of a change so large it would leave nothing as it was, and often mirrors anxiety about the world rather than personal events.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.