Nuclear safeguards are measures to verify that countries comply with their international obligations not to use nuclear materials for nuclear explosives.
Nuclear materials include:
A fundamental principle of the safeguards regime is that the verification is independent of the country, and is performed by international inspectorates.
Global recognition of the need for such verification is reflected in the Treaty on the Non-Proliferation of Nuclear Weapons (the NPT). Under the NPT, the nuclear weapons states (China, France, Russia, UK and US) undertake not to transfer nuclear weapons or any other nuclear explosive devices, and not to support manufacture or acquisition of such weapons or devices by any non-nuclear weapons states. More than 180 non-nuclear weapons states are now party to the treaty, which means they have agreed that the International Atomic Energy Agency (the IAEA) must apply safeguards on all their nuclear material - according to what are known as full-scope or comprehensive safeguards agreements.
These comprehensive safeguards agreements are, in many cases, now supplemented by an Additional Protocol agreement to strengthen the safeguards system, in particular by improving the IAEA's ability to detect undeclared nuclear activities.
Alongside the IAEA safeguards requirements, civil nuclear material in the Member States of the European Union is also subject to the safeguards provisions of Chapter VII of the Treaty establishing the European Atomic Energy Community (the Euratom Treaty). The safeguards are applied by the European Commission to provide confidence that nuclear materials in the EU are not diverted from their declared end uses.
Until the last decade of the 20th century, implementation of safeguards arrangements focused on nuclear materials accountancy measures (sometimes termed classical safeguards~). These measures involved the state providing the IAEA with declarations of its nuclear material (i.e. how much material there is and where it is, in nuclear materials accountancy reports), and information on relevant aspects of the design and the nuclear facilities concerned.
The IAEA's verification activities were directed at confirming nuclear material was present as declared, through regular inspections to confirm that records and supporting information at the facility were consistent with the declarations to the IAEA and to perform checks on the material itself, either by means of direct measurement/sampling of by so-called containment and surveillance measures.
The European Commission's approach to safeguards verification has been largely the same as that of the IAEA.
Following the Gulf War in the 1990s, it was discovered that despite having signed the NPT as a non-nuclear weapons state and the IAEA having implemented a comprehensive safeguards agreement, Iraq had nevertheless managed to pursue a substantial nuclear weapons programme. This prompted major efforts to strengthen the safeguards system, in particular to increase the IAEA's capability to detect undeclared nuclear material and activities.
A key part of the output from this strengthening process is what is known as the Additional Protocol - additional that is to existing safeguards agreements.
The main features of the Protocol are that it:
This extended information and access, together with collection and analysis of a wide range of information from other sources, provides the IAEA with a more comprehensive picture of a state's nuclear activities. This means that they are better placed to spot and pursue indicators of possible undeclared activities.
More information on safeguards implementation and how the global and European regimes have developed can be found at the websites of the IAEA and the European Commission.
Maybe use the 'plain(er) English' summary provided for the article in Regulation Matters (the nuclear materials subject to safeguards requirements are those essential to nuclear explosives. They are defined in terms of special fissionable or fissile materials (eg plutonium-239 or enriched uranium or uranium-233) which may be in forms that require only limited further processing to make them usable for explosive purposes, and source materials (eg natural or depleted uranium, or thorium) from which special fissionable materials can be produced. Full definition of the terms is included in the Euratom Treaty and the Statue of the IAEA.) with the formal definitions accessed by drop-down options.