An atomic bomb in a dream is read as fear of total, irreversible change, and often reflects anxiety about the wider world more than anything personal.
Where in your waking life have you met something like this lately?
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.