Blue Danube ( nuclear weapon ) Blue Danube was the first operational British nuclear weapon . It also went by a variety of other names , including Smallboy , the Mk . 1 Atom Bomb , Special Bomb and OR . 1001 , a reference to the Operational Requirement it was built to fill . The RAF V bomber force was initially meant to use Blue Danube as their primary armament at a time when the first hydrogen bomb had not been detonated , and the British military planners still believed that an atomic war could be fought and won using atomic bombs of similar yield to the Hiroshima bomb . For that reason the stockpile planned was for up to 800 bombs with yields of approx . 10 - 12 kilotons . V - bomber bomb bays were sized to carry Blue Danube , the smallest - size nuclear bomb that was possible to be designed given the technology of the day ( 1947 ) when their plans were formulated . Initial designs for the Blue Danube warhead were based on research derived from Hurricane , the first British fission device ( which was not designed nor employed as a weapon ) , tested in 1952 . The actual Blue Danube warhead was proof - tested at the " Marcoo " ( surface ) and " Kite " ( air - drop ) nuclear trials sites in Maralinga , Australia , by a team of Australian , British and Canadian scientists in late 1956 . Blue Danube added a ballistically shaped casing to the existing Hurricane physics package , with four flip - out fins to ensure a stable ballistic trajectory from the planned release height of 50 , 000 ft . It initially used a plutonium core , but all service versions were modified to use a composite plutonium / U - 235 core , and a version was also tested with a uranium - only core . The service chiefs insisted on a yield of between 10 - 12 kt for two reasons : firstly , to minimise usage of scarce and expensive fissile material ; and secondly , to minimise the risk of predetonation , a phenomenon then little understood , and the primary reason for using a composite core of concentric shells of plutonium and U - 235 . Although there were many plans for versions with higher yields , some up to 40 kt , none were developed , largely because of the scarcity of fissile materials , and there is no evidence that any were seriously contemplated . The first Blue Danube was delivered to stockpile at RAF Wittering in November 1953 although there were no aircraft equipped to carry it until the following year . No . 1321 Flight RAF was established at RAF Wittering in April 1954 as a Vickers Valiant unit to integrate the Blue Danube nuclear weapon into RAF service . The Short Sperrin was also able to carry the Blue Danube and had been ordered as a fall - back option , in case the V - bomber projects proved unsuccessful . Declassified archives show that 58 were produced before production shifted in 1958 to the smaller and more capable Red Beard weapon , which could accept the Blue Danube fissile core and also could be carried by much smaller aircraft . It seems unlikely that all 58 Blue Danube weapons were operational at any given time . Blue Danube was retired in 1962 . Bomb storage facilities for the weapon were built at RAF Barnham in Suffolk and RAF Faldingworth in Lincolnshire . These sites were built specifically to store bomb components in small building called ' hutches ' with the high explosive elements of the weapons stored in dedicated storage areas . The storage facilities were probably closed in 1963 and put up for sale in 1966 , the Barnham site becoming an industrial estate . The site at Barnham is a scheduled monument . Major deficiencies with Blue Danube included the use of unreliable lead - acid accumulators to supply power to the firing circuits and radar altimeter s . Later weapons used the more reliable ram - air turbine - generators or thermal batteries . Blue Danube was not really engineered as a weapon equipped to withstand the rigours of service life . It was really a scientific experiment on a gigantic scale , which needed to be re - engineered to meet service requirements . That re - engineered weapon became Red Beard . A similar account could be written of the first U . S . atomic bomb , Fat Man , which was quickly re - engineered after World War II . Parts of a Blue Danube can be viewed by the public at Sellafield Visitors Centre in Cumbria .