Year
2014
Abstract
Californium - Interrogation with Prompt Neutron detection (CIPN) is an active interrogation technique developed under the Next Genera tion Safeguards Initiative Spent Fuel (NGSI - SF) effort to improve capability to quantify the plutonium (Pu) mass in, and detect the diversion of pins from, spent nuclear fuel assemblies with non - destructive assay (NDA) techniques as well as estimate the initial enrichment, burnup and cooling time of the fuel . The C IPN detector consist s of four neutron and two gamma - ray detectors in a compact, waterproof case. It is deployed on a pole and placed adjacent to an assembly in the spent fuel pool. A capsule of neutron - emitting californium - 252 (Cf) is placed near the fuel assembly to induce fissions. The instrument is capable of measuring passive neutron background from the assembly as well as operating in the active - mode with the Cf source to analyze the fissile material content. Ion chambers can also provide a gross gamma count rate tha t can be related to the assembly burnup. Performance of the CIPN detector was evaluated with the Monte Carlo N - Particle transport code MCNP X using realistic spent fuel assembly libraries developed at Los Alamos National Laboratory (LANL). A large number of simulations provided data to correlate the detector response to specific assembly characteristics. These included the initial U - 235 enrichment, irradiation history, and post - irradiation cooling time for each assembly. Future work will focus on integra ting the CIPN detector signals to improve spent fuel assembly characterization and quantification of Pu mass.