Developing the Californium Interrogation Prompt Neutron Technique to Measure Fissile Content and to Detect Diversion in Spent Nuclear Fuel Assemblies

252Cf Interrogation with Prompt Neutron (CIPN) detection isone of the fourteen nondestructive assay (NDA) techniques researchedunder the Next Generation Safeguards Initiative effort.CIPN is a relatively low-cost and lightweight instrument, and itlooks like a Fork detector combined with an active interrogationsource. The study of CIPN evaluates its capability of measuringfissile content and detecting diversion of fuel pins in commercialspent nuclear fuel assemblies. The design and the underlyingphysics of the CIPN detector are described. The response ofCIPN to a series of virtual spent fuel assemblies were quantifiedusing MCNPX simulations. The net signal of CIPN is mainlydue to multiplication of the Cf source neutrons; this multiplicationis dependent on both the fissile content and the neutronabsorbers present in spent fuel. Two novel corrections have beenintroduced to account for the absorption caused by neutron absorbers.With the help of empirical fitting developed in this work,the fissile content in a target spent fuel assembly can be determinedfrom the CIPN signal. CIPN is also tested in a series ofhypothesized diversion cases. Preliminary results show that CIPNcan detect the replacement of at least eight fuel pins (3 percentof total mass) with depleted uranium provided the count rate ofbaseline case was previously measured. In short, CIPN showspromising capability for measuring fissile content.