Yan Zhang, Hao-Ran Zhang, Ren-Bo Wang, Ming-Yu Li, Rui Chen, Hai-Tao Wang, Xiang-Ting Meng, Shu-Min Zhou, Bin Tang
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引用次数: 0
Abstract
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. FH-NCM/S1 adopts an integrated approach, combining the shift register analysis mode with the pulse-position timestamp mode using an FPGA. The optimal effective length of the 3He neutron detector was determined to be 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 detection efficiency of 43.07% and detector die-away time of 55.79 \({\upmu }\)s were observed. Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift register analysis mode and a plutonium waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency (\(\varepsilon\)) and double gate fraction (\(f_{\rm d}\)), resulting in corrected double rates (\(D_{\rm c}\)), which were used to validate the accuracy of the shift register analysis mode. Furthermore, the device exhibited fluctuations in the measurement results, and within a single 20 s measurement, these fluctuations remained below 10%. After 30 cycles, the relative error in the mass of 240Pu was less than 5%. Finally, correlation calculations confirmed the robust consistency of both measurement modes. This study holds specific significance for the subsequent design and development of neutron multiplicity devices.
期刊介绍:
Nuclear Science and Techniques (NST) reports scientific findings, technical advances and important results in the fields of nuclear science and techniques. The aim of this periodical is to stimulate cross-fertilization of knowledge among scientists and engineers working in the fields of nuclear research.
Scope covers the following subjects:
• Synchrotron radiation applications, beamline technology;
• Accelerator, ray technology and applications;
• Nuclear chemistry, radiochemistry, radiopharmaceuticals, nuclear medicine;
• Nuclear electronics and instrumentation;
• Nuclear physics and interdisciplinary research;
• Nuclear energy science and engineering.