Orange Herald

Having said that, a design for a pure fission warhead based on Orange Herald was later pressed into service as a megaton warhead for the RAF under the code name of Green Grass. This was reduced in size so as to economise in fissile material, and was installed in the Blue Danube bomb casing. The new bomb was known as Violet Club. 

TNA PRO EG 1/312. Cost of UK atomic weapons programme. Revised Calculation Of Charges To The Ministry Of Aviation Year 1960/61. 3 January 1961. TNA PRO AVIA 65/1193. Warhead for a medium range missile Air Staff requirement OR 1142 Orange Herald (DAW plans action). 

This option would become available once the high enrichment section of the gaseous diffusion plant at Capenhurst had come into full-scale production. Most of the highly enriched was used in high yield nuclear weapons - in particular, the Orange Herald and Green Grass warheads. 

There were other limitations imposed on the reactor design. One early design decision was that the core should not exceed five feet in diameter. Another constraint was the supply of U — 80 kg were made available for the project, and further supplies would be hard to come by. (The Orange Herald device which was tested in the Pacific in 1957 used 120 kg of U, which went up in smoke.)... 

The Admiralty were charged 1,400,000 for the 46 kg of uranium used in the Neptune reactor — which works out as roughly 30,000 per kilogram (the 120 kg of in Orange Herald was noted in one air staff memo as having a value of 2.5 million — only 20,000 per kilogram ). 

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