Multispectral Active Neutron Interogation Analysis

2013 J. D. Williams Student Paper 1st Place<br>The non-destructive assay (NDA) of spent nuclear fuel is an increasinglyimportant research area due to the need in internationalsafeguards for a direct and independent method of determiningplutonium mass in spent fuel. A new method has been developedthat iteratively determines the isotopic masses of fissionable isotopesin a fuel sample from the fission rates induced in the fuelsample at different interrogating neutron energies using readilyavailable neutron generators and neutron sources. This method,called MANIA (Multispectral Active Neutron InterrogationAnalysis), uses the fission rates from the active neutron interrogationin a system of linear equations that is solved using a convexoptimization algorithm that allows for a variety of constraints tobe placed on the sought after solution. To compensate for the effectsof self-shielding, iteration occurs between the measured fissionrates and the simulated fission rates from an MCNP modelof the irradiation setup. This method has been tested with syntheticfission rates generated in MCNP for a variety of sample geometries,dimensions, and isotopic compositions; and convergesto the correct isotopic composition.