France research pioneered the discovery of radioactivity and nuclear research. However looking at the names of non-US Americans in the Manhattan project there are very few French names (maybe just Bertrand Goldschmidt?) so I wonder what the famous French nuclear scientists were doing at the time. Were the French developing their own nuclear weapons project during World War II or were they discouraged from making one due to the cost of war? Any good sources on the status of nuclear weapon research in France during the war would be welcome.