Violet Club
Violet Club was a nuclear weapon deployed by the United Kingdom during the Cold War; the name was chosen in adherence to the Rainbow code system.
In 1953, shortly after the Americans tested a thermonuclear device in 1952, followed by the Soviets with Joe 4,[A 1] the Atomic Weapons Research Establishment (AWRE) at Aldermaston was asked about the possibilities for a very large pure fission bomb with a yield of one megaton.
A true thermonuclear design, one that would derive a large amount of its total energy from fusion reactions, was referred to as "Type B".
Development of the Type A design was carried out under Green Bamboo, which weighed about 4,500 lb (2,045 kg), and its spherical shape measured about 45 inches (115 cm) diameter, with a 72-point implosion system.
[3] This was intended as the warhead for all projected British strategic delivery systems of the period; the Yellow Sun Stage 1 air-dropped bomb, and the Blue Steel air-launched stand-off missile.
This led to a reduced-size design, later known as Orange Herald, which was made smaller largely by reducing the size and complexity of the implosion system.
[8] Ultimately the decision was made to abandon Green Bamboo in favour of the true thermonuclear devices, being developed as the "Granite" series.
[11] The Green Grass warhead containing perhaps 70–86 kg of HEU (although there are no reliable declassified sources for this figure) was therefore hurriedly produced and installed in a modified Blue Danube casing, to be known as Violet Club, until a better solution based on the Yellow Sun casing could be produced, known then with Green Grass installed, as Yellow Sun Mk.1.
[12] Only five Violet Club weapons were produced, known by the RAF description of Bomb, Aircraft, HE 9,000 lb HC, and they were stripped of their Green Grass warheads for transfer to the better casings when these became available.
[13] The HEU core was greater than one uncompressed critical mass and to maintain it in a sub-critical condition AWRE fashioned it into a hollow thin-walled sphere.
However, a fire in the bomb store or a traffic collision on the airfield could easily lead to a partial crushing or collapse of the unremovable uranium shell, and in turn a spontaneous nuclear chain reaction.
AWRE responded by inserting (through a hole in the shell) a rubber bag, and filled this with 20,000 steel ball bearings of 0.375 inches (9.5 mm), weighing around 70 kilograms (150 lb).
[17] At least one accident, dated 1960, was reported in the press when the plastic bung was removed and 133,000 steel ball bearings spilled onto the aircraft hangar floor, leaving the bomb armed and vulnerable.
[18] The Royal Air Force were so nervous of the outcome of a fire in storage that permission was sought to store the bombs inverted, so that a loss of the plastic bung could not end with the steel balls on the floor, leaving the HEU unprotected against a subsequent explosion.
Violet Club could be loaded into a bomber for up to thirty days on standby while parked overnight on a remote base where the bomb could get very cold.
Other design flaws centred on a requirement for a strip-down and inspection at six-monthly intervals, this took three weeks per weapon using AWRE civilian staff.
The unstable nature of the bomb required that the work be done in-situ at RAF facilities, causing considerable disruption to operational duties.
The engines must not be started until the weapon is prepared for an actual operational sortie [to prevent the steel balls vibrating like a bag of jellybeans].[29]...
By 1958 Britain's accumulated production of plutonium was only 472.2 kg[34] and a proportion of that was bartered to the United States in exchange for HEU and other items.
