分类： 物理学 >> 核物理学 提交时间： 2024-05-17
Yan Zhang
Hao-Ran Zhang
Ren-Bo Wang
Ming-Yu Li
Rui Chen
Hai-Tao Wang
Xiang-Ting Meng
Shu-Min Zhou
Bin Tang
摘要： A passive neutron multiplicity measurement device, FH-NCM/S1, based on field-programmable gate arrays(FPGAs), is developed specifically for measuring the mass of plutonium-240 (240Pu) in mixed oxide fuel. FHNCM/S1 adopts an integrated approach, combining the shift-register analysis mode with the pulse-positiontimestamp mode using an FPGA. The optimal effective length of the 3He neutron detector was determined tobe 30 cm, and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.After fabricating the device, calibration measurements were performed using a 252Cf neutron source; a detectionefficiency of 43.07% and detector die-away time of 55.79 μs were observed. Nine samples of plutoniumoxide were measured under identical conditions using the FH-NCM/S1 in shift-register analysis mode and aplutonium-waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency(ε) and double gate fraction (f d), resulting in corrected double rates (Dc), which were used to validate the accuracyof the shift-register analysis mode. Furthermore, the device exhibited fluctuations in the measurementresults, and within a single 20-s measurement, these fluctuations remained below 10%. After 30 cycles, therelative error in the mass of 240Pu was less than 5%. Finally, correlation calculations confirmed the robustconsistency of both measurement modes. This study holds specific significance for the subsequent design anddevelopment of neutron multiplicity devices.
分类： 物理学 >> 核物理学 提交时间： 2024-06-28
Yong Sun
Qi-Biao Wang
Peng-Cheng Li
Ming Xia
Bin Liu
He-Yong Huo
Wei Yin
Yang Wu
Sheng Wang
Chao Cao
Xin Yang
Run-Dong Li
Hang Li
Bin Tang
摘要： Nuclear energy is a vital source of clean energy that will continue to play an essential role in global energy production for future generations. Nuclear fuel rods are core components of nuclear power plants, and their safe utilization is paramount. Due to its inherent high radioactivity, indirect neutron radiography (INR) is currently the only viable technology for irradiated nuclear fuel rods in the field of energy production. This study explores the experimental technique of indirect neutron computed tomography (INCT) for radioactive samples. This project includes the development of indium and dysprosium conversion screens of different thicknesses and conducts resolution tests to assess their performance. Moreover, a pressurized water reactor (PWR) dummy nuclear fuel rods have been fabricated by self-developing substitute materials for cores and outsourcing of mechanical processing. Experimental research on the INR is performed using the developed dummy nuclear fuel rods. The sparse reconstruction technique is used to reconstruct the INR results of 120 pairs of dummy nuclear fuel rods at different angles, achieving a resolution of 0.8 mm for defect detection using INCT.
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