Gamma ray multiplicity of a ^240 Pu solid sphere simulated by JMCT

Determining the mass of plutonium metal is an important research objective in the field of nuclear material accounting and control. Based on the 3D neutron and photon transport code JMCT (Jointed Monte Carlo Transport), the gamma ray multiplicity of ^240 Pu was simulated in this study, and the average number of gamma rays leaking from ^240 Pu solid spheres with different masses was also obtained. The simulation results show that there is a one-to-one correspondence between the average number of gamma rays and the mass of ^240 Pu solid spheres in the range of 0.50–3.00 kg. This result provides a basis for using the average number of gamma rays to account for the mass of ^240 Pu.