Year
2011
Abstract
Active measurements were performed using a 10-MeV electron linear accelerator with custom inspection objects containing various nuclear and nonnuclear materials available at the Idaho National Laboratory’s (INL) Zero Power Physics Reactor (ZPPR) facility. The inspection objects were assembled from unirradiated ZPPR fuel plate materials to evaluate a photonuclear inspection technology for the characterization of plutonium or highly-enriched uranium materials shielded by other nuclear and/or non-nuclear materials. A series of pulsed photonuclear, time-correlated measurements were performed with known quantities of unshielded calibration materials and with unknown quantities of nuclear material having more complex composite shield configurations. The measurements used multiple 3He detectors that are designed to detect delayed neutrons between interrogation pulses of an electron linear accelerator. The accelerator produced 10-MeV bremsstrahlung X-rays at a repetition rate of 125 Hz (8 ms between pulses) with a 4- ?second pulse width. All inspected objects were positioned on beam centerline and 100 cm from the X-ray photon source. The time-correlated data was collected using a Los Alamos National Laboratory (LANL)- designed, list-mode acquisition system. A combination of different experimental configurations and data analysis methods enabled the successful material detection/characterization of each inspection object. This paper describes the experimental configuration, the ZPPR inspection objects used, the various measurement types, and overall results for each unknown inspection object.