Zr-based alloys are used in nuclear power plants because of a unique combination of very low neutron absorption and excellent mechanical properties and corrosion resistance at operating conditions. However, Hydrogen (H) or Deuterium ingress due to waterside corrosion during operation can embrittle these materials. In particular, Zr alloys are affected by Delayed Hydride Cracking (DHC), a stress-corrosion cracking mechanism operating at very low H content (∼100–300 wt ppm), which involves the diffusion of H to the crack tip. H content in Zr alloys is commonly determined by destructive techniques such as inert gas fusion and vacuum extraction. In this work, we have used neutron imaging to non-destructively quantify the spatial distribution of H in Zr alloys specimens with a resolution of ∼5 wt ppm, an accuracy of ∼10 wt ppm and a spatial resolution of ∼25 μm × 5 mm x 10 mm. Non-destructive experiments performed on a comprehensive set of calibrated specimens of Zircaloy-2 and Zr2.5%Nb at four neutron facilities worldwide show the typical precision and repeatability of the technique. We have observed that the microstructure of the alloy plays an important role on the homogeneity of H across a specimen. We propose several strategies for performing H determinations without calibrated specimens, with the most precise results for neutrons having wavelengths longer than 5.7 Å.

基于Zr的合金由于在工作条件下具有非常低的中子吸收率和出色的机械性能以及耐腐蚀性能，因此在核电站中得到了广泛应用。但是，在操作过程中，由于水侧腐蚀而导致的氢（H）或氘进入，可能会使这些材料变脆。特别是Zr合金受延迟氢化裂纹（DHC）的影响，延迟氢化裂纹是一种在非常低的H含量（〜100–300 wt ppm）下运行的应力腐蚀开裂机制，其中涉及H扩散到裂纹尖端。Zr合金中的H含量通常通过破坏性技术（例如惰性气体熔融和真空萃取）来确定。在这项工作中，我们使用中子成像技术以无损方式量化了Zr合金样品中H的空间分布，其分辨率约为5 wt ppm，精度约为10 wt ppm，空间分辨率约为25μm×5 mm x 10 mm。在世界各地的四个中子设施上对一组Zircaloy-2和Zr2.5％Nb的校准标样进行的无损实验表明，该技术具有典型的精度和可重复性。我们已经观察到，合金的微观结构对整个试样中H的均匀性起着重要作用。我们提出了几种无需校准样品即可进行H测定的策略，对于波长超过5.7的中子，其结果最为精确。我们已经观察到，合金的微观结构对整个试样中H的均匀性起着重要作用。我们提出了几种无需校准样品即可进行H测定的策略，对于波长超过5.7的中子，其结果最为精确。我们已经观察到，合金的微观结构对整个试样中H的均匀性起着重要作用。我们提出了几种无需校准样品即可进行H测定的策略，对于波长超过5.7的中子，其结果最为精确。