Year
2014
Abstract
The Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) Project deployed a non-destructive assay (NDA) system called Passive Neutron Albedo Reactivity (PNAR) to measure the heavy-water moderated, light-water cooled Fugen reactor fuel assemblies in June 2013. The NDA system combines the following NDA techniques: (1) PNAR, (2) total neutron, (3) total gamma and (4) three sets of energy filtered fission chambers. The energy filtering of these fission chambers was achieved by surrounding each fission chamber with different materials, making each fission chamber set sensitive to neutrons in a different energy range. The measurement results of the four NDA techniques included have been analyzed and compared to Monteburns simulations of the Fugen fuel assemblies to assess the measurement capabilities of the PNAR system. Photon measurements matched the photon simulations performed by Fugen researchers. PNAR measurements showed a change in the PNAR signal that trended with multiplication. Future plans with this instrument include measuring a variety of fresh fuel assemblies comprised of differing numbers of low-enriched rods (3.2%, 0.7%, and 0.3% pins, as well as 3.2% pins with Gd) at Los Alamos National Laboratory. These experiments will be performed in water and be driven by neutrons from a Cf source placed inside the assembly.