Weick Sarah, Grosse Mirco
Institute for Applied Materials-Applied Materials Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
Materials (Basel). 2024 Feb 6;17(4):781. doi: 10.3390/ma17040781.
Neutrons interact with the magnetic moment of the atomic shell of an atom, as is common for X-rays, but mainly they interact directly with the nucleus. Therefore, the atomic number and the related number of electrons does not play a role in the strength of an interaction. Instead, hydrogen that is nearly invisible for X-rays has a higher attenuation for neutrons than most of the metals, e.g., zirconium, and thus would be visible through dark contrast in neutron images. Consequently, neutron imaging is a precise, non-destructive method to quantify the amount of hydrogen in materials with low attenuation. Because nuclear fuel cladding tubes of light water reactors are made of zirconium (98%), the hydrogen amount and distribution in metallic claddings can be investigated. Even hydrogen concentrations smaller than 10 wt.ppm can be determined locally with a spatial resolution of less than 10 μm (with a high-resolution neutron microscope). All in all, neutron imaging is a very fast and precise method for several applications. This article explains the basics of neutron imaging and provides samples of investigation possibilities, e.g., for hydrogen in zirconium alloy cladding tubes or in situ investigations of hydrogen diffusion in metals.
中子与原子的原子壳层磁矩相互作用，这与X射线的情况类似，但主要是它们直接与原子核相互作用。因此，原子序数和相关的电子数在相互作用强度中不起作用。相反，对X射线几乎不可见的氢对中子的衰减比对大多数金属（如锆）更高，因此在中子图像中会通过暗对比度显示出来。因此，中子成像 是一种精确的、非破坏性的方法，用于量化低衰减材料中的氢含量。由于轻水反应堆的核燃料包壳管由锆（98%）制成，因此可以研究金属包壳中的氢含量和分布。即使氢浓度小于10 wt.ppm，也可以使用空间分辨率小于10μm的高分辨率中子显微镜在局部确定其浓度。总之，中子成像对于多种应用来说是一种非常快速且精确的方法。本文解释了中子成像的基础知识，并提供了一些研究可能性的示例，例如用于研究锆合金包壳管中的氢，或对金属中氢扩散进行原位研究。
