NONDESTRUCTIVE ANALYSIS OF IMPURE HEU-CARBON SAMPLES USING AN AWCCa

Highly enriched uranium-containing graphite-based material from the Los Alamos National Laboratory (LANL) is currently stored at the Idaho National Engineering and Environmental Laboratory (INEEL). Measurements to verify the uranium content of these samples are required prior to their disposition to the Y-12 facility in Tennessee. The stored materials vary significantly in their matrix purity and in their 235U content and enrichment. A set of 26 samples selected from the LANL material inventory were analyzed nondestructively using an Active Well Coincidence Counter (AWCC) calibrated versus pure UO3 standards. A correction, calculated from published data and the approximate carbon-to-uranium atom ratios of each sample, was applied for the response enhancement from the carbon matrix. In some cases this correction was as high as 30%. Eight of the 26 sample that had been analyzed in the AWCC were destructively analyzed to provide a benchmark for the nondestructive analyses. The average recovery (NDA/Destructive results) was 0.997±0.115. One sample had a destructive result that lay outside a 3-sigma interval about the NDA result.