Importers must hold a specific NRC import license authorizing receipt of source material (defined as uranium or thorium in any form). The license application requires disclosure of the material's origin, quantity, intended use, and storage arrangements. CBP coordinates with the NRC at entry, and shipments without proper licensing will be refused. Importers should also confirm whether any applicable Section 232 or other trade-remedy measures affect the specific origin.

Raw uranium ore is typically classified at the ore stage when it has not undergone chemical concentration, while yellowcake (U₃O₈ or ammonium diuranate) results from milling and chemical processing that substantially increases uranium content. The concentrate form is the standard traded commodity in the nuclear fuel cycle. Precise chemical composition and uranium assay documentation are essential for correct classification and NRC compliance.