Spiny Norman said:

Hey Captain S, I wanted to check the numbers on how much highly enriched uranium was needed for a modern nuclear bomb. I couldn’t immediately find a value for that but I did for plutonium – about 6 kg.

The Fat Man device specifically used 6.2 kg

Still looking for a number for uranium.

These tables came from the IAEA Safeguards Glossary 1980, which is still in use. It clarifies a lot of things.

https://inis.iaea.org/records/a801×-4nb39