NUCLEAR TECHNIQUES, Volume. 48, Issue 5, 050401(2025)
Passive fast neutron multiplicity counting system based on liquid scintillation detectors
Quick and accurate detection of the effective quality of 240Pu in special nuclear materials (SNM) is of great significance for preventing nuclear proliferation whilst traditional thermal/epithermal neutron multiplicity counting systems based on 3He tubes have relatively low measurement accuracy and high development costs. Fast neutron multiplicity counting (FNMC) technique based on liquid scintillation detectors has become a research hotspot. However, FNMC systems currently built are still in the experimental research stage.
This study aims to develop a passive FNMC system that can be used for practical measurement.
Firstly, a passive FNMC system was built using 32 self-developed EJ-309 liquid scintillation detectors. To improve the uniformity of neutron detection efficiency of the system, these detectors were arranged in a spherically symmetrical geometry. A self-designed and developed 32-channel high-voltage power supply and a user-friendly application software were integrated for the system. Then, the Doubles parameter fitting method and the three-parameter fast neutron multiplicity analytical method were employed to evaluate the spontaneous fission rates of the 252Cf neutron sources respectively. Finally, the performance of the system under different neutron radiation backgrounds (with Singles rates of 111.42±0.46, 73.97±0.28, and 47.27±0.29, respectively) was also investigatted.
The experimental results show that the Doubles parameter fitting method can accurately evaluate the spontaneous fission rates of 252Cf neutron sources. The relative differences of the spontaneous fission rates of the 252Cf neutron sources evaluated by using the fast neutron multiplicity analytical method are less than ±4%. The measurement results under different neutron radiation backgrounds are basically consistent with those under natural environment background (the Singles rates were 0.51±0.02).
The FNMC system developed in this study can accurately determine the spontaneous fission rate of the 252Cf neutron source (with an equivalent 240Pueff mass range of 5.37~209.62 g), and has very good anti-background interference capabilities.
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Yuezhuang LIU, Shaodong ZHANG, Yuanjiang YOU, Xurun LIN, Zhibo ZHOU, Duohong LI, Xingyu ZHOU, Mengyuan LI, Baoliang JIN, Meng LI, Lin MA, Qi ZHANG, Da LI, Zhaohui WU, Xiaodong ZHANG. Passive fast neutron multiplicity counting system based on liquid scintillation detectors[J]. NUCLEAR TECHNIQUES, 2025, 48(5): 050401
Category: NUCLEAR ELECTRONICS AND INSTRUMENTATION
Received: Sep. 14, 2024
Accepted: --
Published Online: Jun. 26, 2025
The Author Email: Xiaodong ZHANG (张小东)