Surface chemistry of neutron irradiated tungsten in a high-temperature multi-material environment

• Published in: Nuclear materials and energy 2023-03, Vol.34, p.101323, Article 101323
• Main Authors: Taylor, Chase N., Shimada, Masashi, Nobuta, Yuji, Kobayashi, Makoto I., Oya, Yasuhisa, Hatano, Yuji, Koyanagi, Takaaki
• Format: Article
• Language: English
• Subjects: Deuterium retention; Neutron irradiated tungsten; Surface chemistry; X-ray photoelectron spectroscopy
• ISSN: 2352-1791; 2352-1791
• DOI: 10.1016/j.nme.2022.101323

•XPS of neutron irradiated tungsten reveals multi-material interactions that occur during months-long reactor irradiations.•The state of surface chemistry is shown to affect deuterium retention in neutron irradiated tungsten.•Neutron enhanced diffusion is likely responsible for surface interactions. Deuterium retention was measured on neutron irradiated tungsten samples where one side of the samples had a visually clean metallic luster and the opposite side appeared to have a reacted surface film. Deuterium plasma exposure and subsequent thermal desorption from the reacted surface side produced spectra with larger total deuterium desorption at lower temperatures than from the clean surface side. For neutron irradiation, these W disk samples were installed in an irradiation capsule in such a way that one side of W sample was in contact with the surface of another W sample, and the opposite side was in contact with a SiC temperature monitor. The composition of the reacted surface was investigated using X-ray photoelectron spectroscopy and showed that SiC had interdiffused into the W samples. Neutron enhanced diffusion likely contributed to this as SiC and W are stable at temperatures exceeding the irradiation temperature. Results highlight the need to consider the surface chemistry of samples in drawing conclusions on hydrogen isotope retention of W materials and also illustrate the complexity of multi-material nuclear environments expected in fusion devices.