What is “Nuclear Material?”—The Devil is in the Details of the Various Definitions

The term “nuclear material” is used in the media, academia, and in international legal instruments, non-binding and binding guidelines, treaties, and conventions. However, there is no commonly accepted definition of the term “nuclear material,” and where definitions do exist they can be inconsistent, sometimes in very subtle ways. What is the significance of these differences? Is this a problem? If so, what is the solution? These are issues that are explored in this paper. While the International Atomic Energy Agency (IAEA) is undoubtedly the international leader in peaceful nuclear efforts involving “nuclear material,” the term itself does not appear in the Statute of the IAEA.1 The Statute does, however, provide definitions for the terms “special fissionable material” and “source material,” terms that are used by the IAEA in Agency documents to define “nuclear material” as described further below.