About fifty-eight Blue Danube bombs were produced. The first bombs had plutonium cores, but all service models were modified to use a composite core which used both uranium-235 and plutonium. The bomb had a yield of . The cores were stored separately from the high explosive components in concrete "igloos" at RAF Barnham in Suffolk and RAF Faldingworth in Lincolnshire. Some casings were stored elsewhere in the UK and in Cyprus for "second strike" use. It remained in service until 1962, and was replaced by Red Beard, a smaller tactical nuclear weapon. The Blue Danube cores were recycled, and the plutonium used in other nuclear weapons.