Simulation of detector efficiency for online liquid gamma monitor XH-3130A with MCNP

In order to study the influencing factors of detector efficiency and limitation of the liquid gamma monitor XH-3130A on the measurement of radioactive pipe of some nuclear plants, the detector efficiency of peak region and full spectrum region of gamma ray in the range of 0.08-1.5 MeV by XH-3130A is calculated with MCNP5. As for the measurement of Cs-137 gamma source, the calculated results are in line with the experimental data. Meanwhile the paper analyses effects of different sources of gamma ray energy and probe arrangement on the detection efficiency of activity concentration. The simulation results show that the limit of the modified monitor XH-3130A is 1.35103 Bq/cm3 and meets the engineering requirements.