(Verbatim from Annex I to the Convention on the Physical Protection of Nuclear Material)
(a) Levels of physical protection for nuclear material during storage incidental to international nuclear transport include:
(1) For Category III materials, storage within an area to which access is controlled;
(2) For Category II materials, storage within an area under constant surveillance by guards or electronic devices, surrounded by a physical barrier with a limited number of points of entry under appropriate control or any area with an equivalent level of physical protection;
(3) For Category I material, storage within a protected area as defined for Category II, to which, in addition, access is restricted to persons whose trustworthiness has been determined, and which is under surveillance by guards who are in close communication with appropriate response forces. Specific measures taken in this context should have as their objective the detection and prevention of any assault, unauthorized access, or unauthorized removal of material.
(b) Levels of physical protection for nuclear material during international transport include:
(1) For Category II and III materials, transportation shall take place under special precautions including prior arrangements among sender, receiver, and carrier, and prior agreement between natural or legal persons subject to the jurisdiction and regulation of exporting and importing States, specifying time, place and procedures for transferring transport responsibility;
(2) For Category I materials, transportation shall take place under special precautions identified for transportation of Category II and III materials, and in addition, under constant surveillance by escorts and under conditions which assure close communication with appropriate response forces;
(3) For natural uranium other than in the form of ore or ore residue, transportation protection for quantities exceeding 500 kilograms U shall include advance notification of shipment specifying mode of transport, expected time of arrival and [shall provide for] confirmation of receipt of shipment.
Category I is a formula quantity of strategic special nuclear material;
Category II is special nuclear material of moderate strategic significance or irradiated fuel; and
Category III is special nuclear material of low strategic significance.
10 C.F.R. 73 app E to Part 73