Use of chemical and isotopic tracers as part of an improved safeguards approach in uranium conversion facilities

The existence and operation of undeclared uranium conversion facilities (UCFs) that produce purified UF₆, or other enrichment feedstocks from yellow-cake, is a significant issue for international safeguards, since the existence of such plants could indicate a broader network of undeclared uranium enrichment activity in the State as a whole. Similarly, undeclared processing of uranium in a declared plant could be used to produce feedstock for an undeclared enrichment program. Historically, the International Atomic Energy Agency (IAEA) has not had legal authority to apply rigorous safeguards to uranium until it has reached the state of purity suitable for enrichment or for direct fabrication into nuclear fuel. Consequently, UCFs that use impure feedstock are not rigorously safeguarded from beginning to end. In order to more capably detect undeclared processing in a declared UCF, the use of feedstock with added chemical or uranium isotopic tracer materials is proposed. This might give the inspectorate the ability to detect undeclared use of a declared facility. This paper outlines and conceptually explores how chemical and uranium isotopic tracers might be employed as part of an approach to address this issue and improve safeguards on UCFs in a safeguards resource efficient manner.