An Australian nuclear scientist working for the UK Rutherford (New Zealander) labs | Tube Alloys | MAUD program told them how to.
It took a while to convince the US scientists who were mainly interested in making big hot piles for power.
The actual building of atomic weapons (Trinity, Fat Man and Little Boy) took place under a fully authoritarian ultra secret State directed militarily controlled program that cost a significant chunk of national GDP.
The example you chose appears to be both incorrect and the very opposite of whatever point you wanted to make.