Answer: atombomb

AnswerCrossword Clue
ATOMBOMBManhattan Project project
ATOMBOMBMushroom-making weapon
ATOMBOMB1940s Los Alamos development
ATOMBOMBIt was used to discover fermium
ATOMBOMBLittle Boy, e.g.
ATOMBOMB14-year-old invention.
ATOMBOMBModern weapon.
ATOMBOMBPhenomenon of our time.
ATOMBOMBEnola Gay's load
ATOMBOMBMushroom cloud producer
ATOMBOMBFat Man or Little Boy