Failure and Intentional Off-Normal Operation in a Gas Centrifuge Cascade

The increasing size and complexity of gas centrifuge enrichment plants have created many challenges for IAEA safeguards. Unattended on-site process monitoring systems have been proposed as a solution to reduce inspection effort and to aid in reaching timeliness goals, making safeguards more effective and ef?cient. One such technology, continuous enrichment monitoring, has been used in the past as a way to detect if HEU was present in a cascade. Recently, more interest has been placed in quantitative assay measurements from online enrichment monitors. Computational modeling can offer insight into how different cascade operations affect the cascade external streams. In this paper, a transient enrichment and ?uid dynamics model of a generic gas centrifuge cascade is used to study the effects of various cascade operations on the cascade external enrichment. Speci?cally, we investigate the difference in cascade streams between unintended off-normal scenarios such as centrifuge failure and intentional misuse scenarios such as the addition of undeclared material in the cascade. The effects of cascade size and centrifuge are also considered. The results of this study show clear, key differences in the predicted enrichment pro?les due to periodic, legitimate anomalies versus those that might arise from proliferant activities. This sort of information can help to reduce the necessary amount of on-site inspection activities.