An yi amfani da maɓallin maɓallin maɓalli don aikin shine uranium, wanda aka yi amfani da shi azaman man fetur ga masu sarrafawa, a matsayin abincin da aka canza zuwa plutonium, kuma, a cikin nau'in da aka wadatar da shi, a cikin bam din nukiliya kanta. Akwai manyan wuraren ajiyar uranium guda hudu da aka sani a 1940: a Colorado, a arewacin Kanada, a Joachimsthal a Czechoslovakia, da kuma a cikin Congo na Belgium. Duk amma Joachimstal sun kasance a hannun abokan haɗin gwiwa. A cikin Nuwamba 1942 binciken ya ƙaddara cewa akwai wadataccen uranium don biyan bukatun aikin. Nichols ya shirya tare da Ma'aikatar Harkokin Waje don sarrafa fitarwa da za a sanya a kan uranium oxide kuma ya yi shawarwari don sayen tan 1,200 na ɗan gajeren lokaci (1,100 t) na uranium ore daga Congo na Belgium wanda aka adana a cikin sito a Staten Island da kuma ragowar ragowar ma'adinai na ma'adinai da aka adana a cikin ma'adinai.
Shekara ta 1942