Simulation study on neutron multiplicity of plutonium based on liquid scintillation detector

Fast neutron multiplicity counting (FNMC) is a new method of non-destructive analysis for nuclear materials. Using fast neutron detector array to detect the neutrons emitted from a sample, it obtains measurements according to the multiple counting method and analyzes the mass of plutonium in the sample. In this paper, A FNMC measuring device model has been constructed for simulation study in reference to the most advanced FNMC experimental device in the world. A series of typical plutonium sample models, including samples of plutonium metal and samples of plutonium oxide with different isotopic abundance and in different mass, have been designed. The correctness of the newly established fast neutron multiplicity measuring equation and the necessity of modifying the classical measuring equation have been verified by the computer simulated measurements. Compared with the calculation result from the equation developed in this paper and the calculation result from the classical NMC model, the simulated result shows that the new method is better than the classic method in result deviation.