Plutonium except that with isotopic concentration exceeding 80% in plutonium-238; uranium233; uranium enriched in the isotope 235 or 233; uranium containing the mixture of isotopes as occurring in nature other than in the form of ore or ore-residue; any material containing one or more of the foregoing. Nuclear material is necessary for the production of nuclear weapons or other nuclear explosive devices. Under comprehensive safeguards agreements, the IAEA verifies that all nuclear material subject to safeguards has been declared and placed under safeguards. Certain non-nuclear materials are essential for the use or production of nuclear material and may also be subject to IAEA safeguards under certain agreements. The Statute of the IAEA uses the term special fissionable material, with the meaning essentially of nuclear material as defined here, but explicitly excluding source material. For the purposes of IAEA safeguards agreements, nuclear material is defined as "any source material or special fissionable material as defined in Article XX of the Statute of the IAEA". The meaning is essentially the same as that of nuclear material as defined here. See: The Safeguards Glossary (2001 edition). The Paris Convention on Third Party Liability in the Field of Nuclear Energy uses the term nuclear substances, which means nuclear fuel (other than natural uranium and depleted uranium) and radioactive products or radioactive waste