After the blueprint has been placed, it will request from the logistic network if possible. uranium and iron can be also supplied by belt. secondary items are locked from importing the 'good' uranium until the first 40 are imported into the first kovarex proces or when extra items (like rocket fuel) are present. fuel cells are als put back on the belt if there are to many in the system. The uranium ore belt is blocked when the storage is almost full, the request for the ore is blocked later so the logistic system can be cleared of ore until the storage is completly full. providers will be filled only when more the one side is backed up.
when placing with limited centrifuges make sure the correct one is placed first for the kovarex proces.