The UK has, as part of measures to strengthen the global safeguards regime, agreed with International Atomic Energy Agency (IAEA) and Euratom a protocol in addition to its other safeguards agreements.
Although the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) does not require its five nuclear-weapon states (NWS) parties to adopt safeguards agreements, the five states concerned (China, France, Russia, the UK and the US) have each concluded what are known as voluntary offer safeguards agreements with the IAEA – in part to allay concerns expressed by non-nuclear weapons states (NNWS) that their nuclear industry could be at a commercial disadvantage. The agreements follow the basic structure of the standard full scope/comprehensive agreement for NNWS but are based on fundamentally different safeguards undertakings which, in effect, recognise that the NWS continue to have nuclear activities outside the scope of IAEA safeguards and thus limit IAEA activities to all or part of the NWS’ civil nuclear activities as specified ('volunteered') by the NWS in question.
The UK voluntary offer safeguards agreement with the IAEA and Euratom came into force in 1978 and specifies the UK’s acceptance of the application of IAEA safeguards:
"On all source or special fissionable material in facilities or parts thereof within the United Kingdom, subject to exclusions for national security reasons only"
The UK therefore provides the IAEA with a list of its civil nuclear facilities. Nuclear materials accountancy reports and basic design information for all these facilities is supplied to the IAEA via the European Commission and the IAEA is free to designate any of them for inspection. The UK facilities currently designated and inspected by the IAEA include parts of the Sellafield facility containing separated plutonium product from the reprocessing of irradiated fuel and the gas centrifuge enrichment facility at Capenhurst.
The agreement also allows for the UK to remove facilities and/or withdraw material from the scope of the agreement for reasons of national security. But such withdrawals from safeguards now involve only small quantities of material for use in instrument calibration or radiological detectors, or as analytical tracers or radiological shielding. Details of withdrawals since 2001 are available here, and information on withdrawals prior to then has previously been made available to Parliament.
The UK is also committed to publishing information each year on inventories of civil plutonium and uranium in the UK.
The figures are published here and by the IAEA as part of its Information Circular number 549 on internationally agreed guidelines for the management of plutonium.