核燃料元件模拟件的中子照相无损检测

Non-destructive testing dummy nuclear fuel rods by neutron radiography

中子照相可以对具有放射性的核燃料元件进行无损检测。本文采用核燃料元件模拟件在中国先进研究堆(CARR)中子束流水平孔道利用0.1mm厚的Dy中子转换屏配合工业X射线胶片获得成像,进行中子照相无损检测的模拟研究。利用检测成像发展了核燃料元件缺陷分析、包壳氢聚含量定量测量、芯块U-235富集度定量测量等成像分析方法,为真实核燃料元件的检测打下基础。

Background： The nuclear fuel rod is a key component of nuclear plants and reactors. It works in the extreme conditions, so it is easy to be broken. In order to be safe in operation, lots of testings have to be carried out from fabricating to operating of the fuel rod. Purpose： As a unique non-destructive testing technique, neutron radiography can be used to measure the nuclear fuel rods with radioactivity by an indirect neutron radiography method. Study the indirect neutron radiography method is the primary step of testing. Methods： Non-destructive testing experiments were carried out at China Advanced Research Reactor （CARR） by indirect neutron radiography method with dummy nuclear fuel rods as the samples. The 0.1 mm-thick Dy foil was used as the neutron converter. Results： The neutron images of dummy nuclear fuel rods were obtained. The resolution of testing was analyzed with the images. Through imaging analysis methods, the structure defections, the hydrogen accumulation in the cladding and the U-235 enrichment of pellet were studied and analyzed. Conclusions： The indirect neutron radiography method and the neutron image analysis method were studied. The work described in this paper provides a primary guideline for investigating actual irradiated fuel rods by the neutron radiography at CARR in the future.