基于中子IP板的核燃料元件间接中子CT实验方法研究

中子照相作为一种无损检测技术是分析和确定核燃料元件缺陷的重要手段。中国原子能科学研究院中子照相团队依托中国先进研究堆（CARR）中子照相测试平台，搭建了核燃料元件间接中子CT装置，并开展核燃料元件模拟件的间接三维中子成像技术研究。本文首先采用蒙特卡罗模拟方法优化确定了样品环境转移屏蔽容器的关键参数并研制出屏蔽容器，并基于该装置开展了核燃料元件模拟件的间接中子CT照相实验，从获得的三维实验数据可观测到尺寸约0.35 mm模拟芯块缺陷。实验结果表明，该装置可满足核燃料元件的间接中子CT实验检测。同时初步研究了基于IP板的间接中子成像数据处理的制约因素和方法，为后续进一步利用金属转换屏替代中子IP板等技术，真正实现乏燃料元件无损检测应用提供实验指导。

Study on Indirect Neutron CT Technology of Nuclear Fuel Element Based on Neutron IP Plate

Neutron radiography, an effective non-destructive testing technology, is an important means to analyze and determine the defects inside nuclear fuel elements. Based on the neutron radiography platform located at China Advanced Research Reactor (CARR), the neutron radiography group at China Institute of Atomic Energy has carried out the research on the simulated nuclear fuel elements using the developed indirect three-dimensional neutron imaging device for nuclear fuel elements. The key parameters of sample transfer container for nuclear fuel elements were optimized and the container was designed based on the Monte Carlo simulation method. As a result, the study on simulated sample of nuclear fuel elements was performed using the developed indirect three-dimensional neutron imaging device, and the defects with the size of about 0.35 mm can be clearly observed in the obtained reconstructed 3D images. Therefore, the experimental results indicate that this developed device at CARR can meet the demand of studying nuclear fuel elements. Besides, several factors and processing methods for indirect neutron CT experimental digital images during data processing were also studied simultaneously, and this study can provide some invaluable advice for practical application of real nuclear fuel elements using metal conversion screen to replace the neutron image plate (IP) in this study in future.