Enhanced Techniques and Improved Results in 235U Enrichment Measurement of Large UF6 Cylinders by Portable Germanium Spectrometer

Enrichment measurements to determine the hexafluoride (UF portable gamma spectrometry via the enrichment meter method. However, previously demonstrated uncertainties associated with the method using small germanium detectors are poor, at best. In this work, control of certain analytical parameters has resulted in improvements to the measurement leading to what is believed to be the highest precision and lowest bias currently reported for this type of analysis. These parameters include: 235U content in uranium6) cylinders are easily performed utilizing Detector Placement Utilization of a positioning bracket to which the detector was mounted provided stability for analysis at any point on the cylinder. This is very important because in large cylinder storage areas there are many configurations of rows and stacks of cylinders. It is expedient to be able to perform the necessary analysis in the region of the cylinder that lends itself to approach. This versatility was necessary in order to allow thickness measurements to be performed at any location on the cylinder and to avoid surface anomalies and UF 6 void areas. More Rigorous Cylinder Wall Thickness Measurements Multiple thickness measurements at the exact location of gamma analysis were averaged for an accurate thickness. Areas of nonreproducible thickness were avoided. Avoidance of Cylinder Surface Anomalies Areas of obvious corrosion, roughness, etc. were avoided. Likewise, internal areas of corrosion were avoided when detected. Avoidance of Large Interrogation Void Areas Regions within the cylinder void of UF detected. For example, if the UF could be determined. Also, cylinder position with respect to the sun was utilized to determine migrational characteristics of the contained UF The types of cylinders involved in the measurements were 30B, 48X, 48Y, and 48G cylinders ranging from 1/4 thickness. As would be expected due to a loss of signal strength in the 185.7 keV region, the uncertainty of the measurements increased with increasing cylinder wall thickness and decreasing enrichment. Even so, the results for all cylinder types and enrichment ranges measured were excellent with respect to those reported previously for other nondestructive analyses. 6 were avoided when6 mass was known, the fill height6. to 5/8 wall