§ Llew Smith
To ask the Secretary of State for Trade and Industry what the reactors of origin were of the 1061W plutonium used in the MOX fuel sent to Japan and Switzerland from Sellafield; and what safeguards arrangements apply to this plutonium. 
§ Mr. Wilson
It is not possible to identify definitively the individual reactors in which specific batches of plutonium allocated to the ownership of specific customers might originally have been produced. Reprocessing customers receive back separated plutonium based on that contained in the fuel they originally supplied. This is assessed before the fuel is reprocessed. The nature of commercial reprocessing in large-scale bulk chemical processing facilities means that the plutonium contained in the fuel becomes blended with that contained in fuel from other reactors.
International safeguards arrangements for MOX fuel assemblies include measurement of the nuclear material content of the fuel before its shipment from the fabrication plant and then the application of seals to the transport flasks into which the assemblies have been loaded. On receipt at a reactor facility seals are checked and removed before the fuel is placed in storage or loaded into the reactor. Such fuel storage and reactor loading is monitored by safeguards inspections combined with the use of containment and surveillance equipment (e.g. cameras and seals). Safeguards measures continue to be applied after MOX fuel has been loaded in a reactor.