PASSIVE TIME COINCIDENCE MEASUREMENTS WITH HEU AND DU METAL CASTINGS

A Department of Energy sponsored Oak Ridge National Laboratory/Y-12 National Security Complex program of passive time coincidence measurements has been initiated at Y-12 to evaluate the ability to determine the presence of highly enriched uranium (HEU) and distinguish it from depleted uranium (DU). This program uses the Nuclear Materials Identification System (NMIS) without an active interrogation source. Previous passive NMIS measurements with Pu metal and Pu oxide have been successful in determining the Pu mass, assuming a known 240Pu content. The spontaneous fission of uranium metal is considerably lower than that of Pu, and time coincidence measurements have been performed on Pu at Lawrence Livermore National Laboratory [1]. This work presents results of measurements of HEU and DU metal castings using moderated 3He detectors.