# Where did Fermi get the U235 for the first nuclear pile?

I am puzzled as to where or who produced the U235 for the first nuclear pile. I read that graphite was used as a neutron moderator but only .7 % of natural uranium is U235.

He must have gotten it from Oak Ridge?. But I always thought that Oak Ride's uranium production came after the feasibility study that a pile was even possible. So where did the original batch come from ? Maybe from mass spectroscope or cyclotron but that wouldn't make enough uranium would it?

• This reactor used natural uranium. See en.wikipedia.org/wiki/Chicago_Pile-1 – Alexandre Eremenko Jun 6 '18 at 20:27
• Yes...interesting...50 tons uranium oxide and 6 tons uranium.....but now were both the uranium oxide and uranium .7 % U235 ? I thought maybe Fermi separated the U235 for the fast neutron source....but maybe he just used it as is and moderated it only ? and there lies the mystery ... – Sedumjoy Jun 6 '18 at 21:49

## protected by HDE 226868♦Aug 8 at 21:32

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