LAUSR

Abstract Fast neutron multiplicity counting have (FNMC) is a new method of non-destructive analysis for nuclear materials. The new measurement equations of the fourth-order FNMC was established for plutonium samples. Based on the analysis of equations, a set of FNMC with three layers and six liquid scintillations in each layer is set up considering crosstalk, and the single crosstalk rate κ is determined to be 5.68‰. In addition, the quality of Pu and the measurement deviation correction under the different shell materials conditions were analyzed respectively. Finally, the third-order polynomial fitting equations under the condition of multiplication coefficient and (α, n) reaction rate are obtained by modifying the solution quality of Pu. Within the mass range of 500 g Pu, the corrected deviation was less than ±6%. The results show that the combination of FNMC and the coefficient correction method can achieve a more accurate measurement of Pu properties.