The assessment of fissile material mass is a key requirement to enhance radioactive waste management and to ensure a high level of safety in the nuclear industry. The assessment of plutonium fissile mass by passive coincidence measurements is usually obtained by detecting the neutrons generated by the spontaneous fissions of Pu isotopes. The detection and the quantification of a fissile mass in the radioactive waste can also be carried out using active neutron interrogation with a pulsed D-T neutron generator. The 14-MeV neutrons are moderated to induce fissions in the uranium and plutonium-contaminated waste. The emitted neutron signal can be analyzed by considering their detection time after the generator pulse. Data are measured according to the principles of the neutron measurement techniques. As proportional counters filled with 3He gas display high neutron detection efficiency and good gamma-ray immunity, they are the reference detector for passive neutron coincidence counting. A charge preamplifier or a current amplifier, depending on applications, collects the electric pulse produced by neutron interaction in the 3He gas, and a threshold discriminator produces a logic pulse used for neutron counting. This article describes the performance assessment of different commercially-available electronics from Mirion Technologies, Precision Data Technology (PDT), Mesytec, as well as MONACO electronics originally developed by CEA LIST for fission chamber measurements in experimental reactors. Comparative passive neutron measurements are carried out with these electronics at CEA/DEN Nuclear Measurement Laboratory in Cadarache. Overall, PDT and Mesytec electronics show similar detection efficiency as the ACH-NA98 charge amplifier, which is commonly used in our laboratory for such applications. However, MONACO electronics have a lower detection efficiency, similar to the Mirion 7820 current amplifier used in specific high-count rate applications. An optimization of MONACO settings would probably be necessary to adapt to 3He counters instead of fission chambers.

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用于无源中子测量的放大和鉴别电子设备的性能评估

裂变材料质量评估是加强放射性废物管理和确保核工业高水平安全的关键要求。通过被动符合测量对钚裂变质量的评估通常是通过检测钚同位素自发裂变产生的中子来获得的。放射性废物中裂变物质的检测和量化也可以使用脉冲 DT 中子发生器的主动中子询问来进行。14-MeV 中子被减速以在铀和钚污染的废物中引起裂变。可以通过考虑发生器脉冲后的检测时间来分析发射的中子信号。根据中子测量技术的原理测量数据。由于充满 3He 气体的正比计数器显示出较高的中子探测效率和良好的伽马射线抗扰度，它们是无源中子符合计数的参考探测器。根据应用，电荷前置放大器或电流放大器收集 3He 气体中中子相互作用产生的电脉冲，阈值鉴别器产生用于中子计数的逻辑脉冲。本文介绍了 Mirion Technologies、Precision Data Technology (PDT)、Mesytec 以及最初由 CEA LIST 开发的用于实验反应堆裂变室测量的 MONACO 电子设备的不同商用电子设备的性能评估。比较被动中子测量是在 Cadarache 的 CEA/DEN 核测量实验室使用这些电子设备进行的。全面的，PDT 和 Mesytec 电子设备显示出与 ACH-NA98 电荷放大器相似的检测效率，我们实验室通常将其用于此类应用。但是，MONACO 电子设备的检测效率较低，类似于特定高计数率应用中使用的 Mirion 7820 电流放大器。可能需要优化 MONACO 设置以适应 3He 计数器而不是裂变室。