Study on the Influence of Different Neutron Source on the Active-well Neutron Coincidence Method by MCNPX

The model of Active-Well Coincidence Counter(AWCC) was established by MCNPX, meanwhile, with two types of induced neutron source (Am-Li and Am-Be), the neutron coincidence count rate of low enriched uranium was simulated, and the comparison of the measurement accuracy between the two simulations was also demonstrated. It was found that the coincidence count rate induced by Am-Be source was lower than that induced by Am-Li source, and the fitting degree of scaled mass curve under Am-Be source was better than that under Am-Li source, the corresponding relative error was also lower than that of under Am-Li source. The relative error range of uranium mass corresponding to the inspection point under Am-Li source is 0.3%~13%. The relative error range under Am-Be source is 0.1%~4.5%. According to the results, for the measurement of the mass of low enriched uranium by AWCC, it could be better to choose Am-Be source for reducing measurement relative error.