Analysis of spent fuel assemblies using a lead slowing down spectrometer

Abstract We analyze the potential of using Lead Slowing Down Spectrometer technology for assaying spent fuel. This initial study demonstrates that it may be feasible to design a system that will provide approximately 1% statistical precision in the determination of the 239 Pu concentration in a pressurized water reactor spent-fuel assembly, for intermediate-to-high burnup levels, using commercial neutron sources, and an array of ultra-high-purity 238 U threshold fission detectors. LSDS technology can also determine the concentration of 241 Pu and 235 U. There is indication that missing pins can be detected, as can asymmetry in the fuel bundle. The analytical model used to perform the viability assessment is described, as are the systematic effects that were not incorporated in this analysis, but could significantly degrade actual performance. These results provide the justification and impetus for the initiation of followup studies that will incorporate the complete suite of effects that impact the accuracy of LSDS measurements.