ENRICHMENT METER MEASUREMENTS WITH FALCON 5000

The Falcon 5000® is a portable Radionuclide Identifier (RID) based on a mechanically cooled High Purity Germanium (HPGe) detector. It has been previously demonstrated that the Falcon 5000® can be combined with the standard multi-group analysis method (MGAU) for measuring uranium enrichment. The standard MGAU analysis uses a set of peaks in the 100 keV region, which can be appreciably attenuated even by several millimeters of steel. This attenuation effect is especially noticeable when measuring uranium enrichment of solid state UF6, which is typically stored at enrichment facilities inside large metal cylinders. The wall thickness of large UF6 cylinders ranges from 8 mm to more than 12 mm, which complicates the use of the standard MGAU analysis method. In such cases the Enrichment Meter method, which is also available in MGAU, can be used. The Enrichment Meter approach utilizes a direct measurement of a single 186 keV line from 235U. The enrichment meter measurement involves using a collimated detector in a reproducible geometry, and requires initial calibration using one or more standards of known enrichment. An enrichment meter kit has been developed for use with the Falcon 5000®, which includes a special tungsten collimator and an enrichment meter software utility based on MGAU. The collimator design was optimized to ensure a reproducible measurement geometry and maximize the input count-rate. The software utility provides a simple easy-to-use user interface, which allows performing the enrichment meter measurement with minimal user interaction. This paper presents a description of the enrichment meter kit and provides some validation results, which were performed with uranium samples of known enrichment.