气冷微堆核测系统布置研究及其在堆芯监测中的应用
Research on Nuclear Detecting for Gas-cooled Micro Reactor and Its Application in Core Monitoring
气冷微堆受限于紧凑布置及堆内高温运行环境，仅能布置少量堆外探测器用于堆芯监测。提出耦合中子源和堆外探测器的微堆核测系统布置方案，并通过物理实验模拟验证可行性。研究结果表明，微堆无源启动要求堆内临时探测器和堆外源量程探测器灵敏度不低于290和980 cm^2，而耦合较低源强启动中子源、较低灵敏度堆外涂硼中子管、γ 补偿电离室的有源核测系统更适宜移动式微堆的长寿期、无人化智能运营；中子源需布置在活性区才能使裂变中子占比大于95%，探测器通过镉和聚乙烯套筒测量高能量中子以提高堆芯监测准确性。首次临界实验的外推临界装载量与理论值一致，单棒外推临界棒位仅偏差-2 cm，keff偏差在6×10^-4以内；探测器刻度实验的功率水平和轴向功率偏移AO绝对偏差在0.2%和0.4%以内。研究结果为气冷微堆堆芯监测提供参考。
核反应堆工程粒子探测技术、辐射探测技术、核仪器仪表
气冷微堆无源启动有源核测系统布置首次临界实验堆外探测器刻度实验
张成龙,袁媛,刘国明,张鹏,肖会文,董建华,管婧宇,贺楷,易璇.气冷微堆核测系统布置研究及其在堆芯监测中的应用[EB/OL].(2025-04-17)[2025-10-19].https://chinaxiv.org/abs/202504.00225.点此复制
[Background] The gas-cooled micro reactor is one of advanced reactor types that can be used as movable intelligent micro nuclear power sources. The nuclear detecting has been a main challenge for its development due to the compact layout and the harsh service environment inside the core, this is to say, only a small number of ex-core detectors can be deployed for core monitoring. [Purpose] A method and scheme for the layout of micro reactor nuclear detecting system, was proposed in this study to tackle this problem. [Methods] It was explored through the coupling of neutron source and ex-core detectors, based on the detailed three-dimensional model of core and external structure, using Monte Carlo procedure RMC. Its feasibility was verified by the calculating simulations of first critical experiment and ex-core detector calibration experiment. [Results] The results show that its feasible to startup without external neutron sources if 3He detectors with sensitivities of no less than 290 and 980 cm^2 are used as in-core temporary detector and ex-core source range detector. The requirements for scenarios with long-time operation and few personnel on duty can be met by the detecting system including an Am-Be neutron source with strength as low as possible, ex-core boron coated neutron counting tubes with low sensitivity, ex-core gamma compensation ionization chambers with wide range. The Am-Be neutron source can only be arranged at the front of active core to ensure that the proportion of fission neutrons meets the requirement. By installing cadmium and polyethylene sleeve structures outside detectors to monitor high-energy neutrons, more accurate nuclear measurement signals can be obtained. In the simulation of the first critical experiment, the number of extrapolated critical fuel assembly columns was consistent with theoretical value, and the deviation of extrapolated critical position for a single control rod was only -2cm, and the deviation of keff was within 610^-4. In the simulation of ex-core detector calibration experiment, the absolute deviation of the power level and the axial power offset were within 0.2% and 0.4%. [Conclusions] The layout of nuclear detecting system has been verified to be reasonable and feasible. These results can provide guidance for core monitoring of various advanced micro reactors, and promote the development of movable intelligent micro nuclear power source products.
Gas-cooled micro reactorStartup without external neutron sourcesLayout of core detecting system with external neutron sourceFirst critical experimentEx-core detector calibration experiment
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