UNREPORTED PLUTONIUM PRODUCTION AT LARGE RESEARCH REACTORS

Unreported production is defined here as the production of plutonium (ie ^'Pu) at a research reactor by means of irradiation of targets containing undeclared fertile material (ie 2MU). A study of unreported production by F T Binfordll) concluded that an absolute minimum reactor power level of 40 MW(th) is required to produce a significant quantity (SQ), ie 8 kg, of plutonium per year. Binford recommended that reactor specific calculations would be necessary if accurate unreported production estimates were to be obtained. These calculations were the focus of a multinational Member State Support Programme (MSSP) task organized by the International Atomic Energy Agency (IAEA). This task included reports RH\" from Russia, Belgium, Indonesia/Australia and the UK on unreported production at six separate research reactors (see Table 1). The validity of Binford's analysis was confirmed by these reactor specific calculations (see Table 2 and Figure 1). Unfortunately, there exists no straightforward method to detect unreported production by simply monitoring the values of observable reactor parameters. There may, however, be a number of distinguishable differences between normal reactor operation and operation during unreported production. Observation of these differences may provide evidence of a diversion. A full summary I8] of this work has been produced jointly between the IAEA and the MSSPs.