OVERSIGHT BY MEANS OF FLOWSHEET VERIFICATION

The IAEA Board of Governors has tasked the Secretariat with maintaining oversight of neptunium and americium such that the Board can be informed in the event there is acquisition or prospective acquisition by a non-nuclear-weapon State (NNWS) of substantial quantities of either material in separated form. A key consideration in such oversight is the scope for possible diversion and separation of neptunium or americium during the processing of materials which contain them (e.g. in the reprocessing of irradiated nuclear fuel, or wet processes for the production of MOX powder). The Flowsheet Verification (FSV) approach has been developed as a cost-effective means of providing assurance that undeclared recovery or separation is not taking place during such processing. In line with the decision taken by the IAEA's Board of Governors this can be achieved directly for neptunium and indirectly for americium (i.e. using information already available related to the processing of other nuclear materials). Application of the FSV approach is illustrated by means of a study of what its implementation would involve firstly and in detail at a large-scale reprocessing plant, secondly and in principle at a plutonium fuel plant. The conclusion from the study is that, even for a large and complex plant, only relatively modest effort in addition to that required for the application of safeguards to plutonium and uranium (combined with small modifications to plant and operational practice) would provide sufficient confidence in the conclusion that no diversion of neptunium or americium had taken place.