Fast Neutron Multiplicity Simulation of Nuclear Material Based on Geant4

Fast neutron multiplicity counting (FNMC) analysis method is a new nondestructive method for nuclear materials, which defines sample plutonium quality by the fast neutron detection array with multiplicity counting technique. Referring to the most advanced FNMC experimental device, fast neutron multiplicity counter model was constructed in this paper. A series of typical plutonium material sample models were designed, which includes the plutonium metal with different isotopic abundance and different quality and the plutonium oxide. The correctness of the equations and the necessity to amend the original equation were verified by computer simulated measurement through C++ language programming with the help of Geant4 simulation toolbox, fission software library function by Lawrence Livermore National Laboratory, and the IAEA provided neutron reaction data in Geant4 format. The simulation results showed the advantage of the new equation calculations than original equation calculations and the error of the new equations is less than half of that of the original equations.