Orange Herald

Common card · No. 406154

Orange Herald was a British nuclear weapon, tested on 31 May 1957. It used 117 kg of highly enriched uranium, more than any other nuclear weapon built or tested, and yielded 720 kilotons. It was intended as a boosted fission weapon, using a small quantity of lithium deuteride and tritide in the core, but it is thought this contributed either nothing or a very small fraction to the yield. This would make it either the largest ever pure fission weapon, exceeding the US Ivy King test, or the largest boosted fission weapon.

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