Up to 1940, the total amount of uranium metal produced in the USA was not more than a few grams, and even this was of doubtful purity; of metallic beryllium not more than a few kilograms; and concentrated deuterium oxide (heavy water) not more than a few kilograms.
Indtil 1940, var den totale mængde af uran metal produceret i USA ikke mere end nogle få gram, og det var endda af tvivlsom renhed; metallisk beryllium var kun produceret i nogle få kilogram; og koncentreret deuterium oxid (tungt vand) også kun i størrelsesordenen af nogle få kilogram.