Year
2000
Abstract
International safeguards for gas centrifuge facilities does not normally require extensive inspection of the cascade hall. Because the inventory contained in the process equipment is minimal, cascade hall measurements are not normally necessary. Visual inspections of the centrifuge hall are also performed and are generally adequate to identify any anomalous conditions. However, a centrifuge plant has recently come under International Atomic Energy Agency (IAEA) safeguards that eliminates the possibility for adequate visual inspections because the cascade equipment has been secluded from view of the inspector by opaque panels. The operator of the facility does not permit visual inspections by IAEA inspectors because the operator feels that the design and layout of the facility is proprietary information. A method that utilizes a combination of nondestructive assay measurement techniques has, therefore, been developed that can effectively identify moderately enriched uranium (MEU) that could potentially be secluded within the cascade hall. This method is also designed to detect shielding material that could be used to effectively reduce the passive gamma rays and neutrons emanating from undeclared and potentially secluded enriched uranium. This method utilizes a combination of passive and active gamma and neutron measurement techniques. Measurement methods tested include (1) passive -ray scanning, (2) passive neutron measurements, (3) neutron transmission measurements, and (4) detection of gamma rays emitted during neutron capture. Studies performed to date indicate that, if applied properly, this method can successfully locate an attempt to divert MEU into shielded storage containers located behind panels that cover the sensitive components within the centrifuge cascade.