Precautions were taken after bomb dogs and electronic scans indicated possible explosive residue on a delivery truck, the Savannah River Site nuclear reservation said in a statement Monday.
But "an offsite law enforcement investigation has found no explosive residue or device on the truck that was inspected this afternoon at the Savannah River Site," near Aiken, the plant said in a Facebook posting, according to AFP.
South Carolina and Georgia law enforcement agencies were assisting site security contractor Centerra.
The massive facility, which does waste processing, is owned by the US Department of Energy.