Abstract
B4C is widely used as control rods in light water reactors, such as the Fukushima Daiichi nuclear power plant, because it shows excellent neutron absorption and has a high melting point. However, B4C can melt at lower temperatures owing to eutectic interactions with stainless steel and can even evaporate by reacting with high-temperature steam under severe accident conditions. To reduce the risk of recriticality, a precise understanding of the location and chemical state of B in the melt core is necessary. Here we show that a novel soft X-ray emission spectrometer in electron probe microanalysis can help to obtain a chemical state map of B in a modeled control rod after a high-temperature steam oxidation test.
Highlights
The spatial distribution of B in B4C after severe accidental simulation tests has been analyzed mainly by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and by electron probe microanalysis (EPMA) with wavelength-dispersive X-ray spectroscopy (WDS)[1,5]
The change in the spectral shape is attributed to the bonding of B and C
The spectra of the iron borides FeB and Fe2B depict clear shoulders, designated as Sat.[2] in the upper horizontal axis of Fig. 1, near 187 eV. These shoulders relate to the Fermi level of the material, as the electron behavior of B in iron borides is more metallic than that in the pure element[11]
Summary
The B-Kαpeak of B4C shifts to a slightly higher energy at 184 eV and shows a characteristic shape with decreased intensity at lower-energy. The spectra of the iron borides FeB and Fe2B depict clear shoulders, designated as Sat.[2] in the upper horizontal axis of Fig. 1, near 187 eV. These shoulders relate to the Fermi level of the material, as the electron behavior of B in iron borides is more metallic than that in the pure element[11]. We consider that EPMA-SXES has a sufficiently high energy resolution to determine the chemical state of B from the changes in the spectral shape of the B-Kαpeak. EPMA-SXES permits the visualization of the chemical state of elements in various materials at the micro-scale
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
