Modeling of Interconnected UF6 Entrichment Cascades for Non Proliferation Analysis

The activities of the Safeguards Authorities for the monitoring and the surveillance of a nuclear plant, include the estimation of the probability of events like breaks and violations of Non Proliferation (NP) treaties. In this context the use of “ad hoc” numerical models represents a very useful tool for analyzing the Gas Centrifuge Enrichment Plants (GCEP) performance and outlines some possible break out scenarios. At JRC ITU the Non Proliferation analyses make regular use of the available modeling techniques: for example, GCEP performances are estimated using advanced numerical modeling techniques supported and/or validated with data acquired during on field inspections. By adopting this approach, normal and/off normal conditions can be tested at an early stage improving the odds of a timely detection of eventual misuses or diversions. For this reason a numerical model of a gas centrifuge enrichment cascade was developed using the software tool Simulink which is a multi - domain simulation tool for dynamic and embedded systems. The model, which can simulate single and/or interconnected cascades, assumes a “quasi” ideal cascade structure where a single stage mixing coefficient that can be varied and eventually adapted to the supplied experimental data when available. For the current NP analyses of the enrichment activities, following the information supplied by IAEA, a large use of single cascade or of the two interconnected cascades model has been done. This paper illustrates some characteristics of the model and its applications to some plant configurations at different enrichment stage. This numerical tool demonstrated to be very useful to integrate and add confidence to the data acquired “on site” and to predict some possible timelines for the production of 1 or more significant quantities of weapon grade Uranium. In conclusion the comparison between the model results with the available data, shows that the model is able to estimate in a reliable way the plant performance provided that a correct choice of the inter stage mixing coefficient is made.