An X-ray absorption spectroscopy study of an oxide dispersion strengthened steel

Oxide dispersion strengthened (ODS) steels are being investigated as possible structural material for components of future nuclear power plants. The dispersoids in the matrix (yttria particles) serve as pinning points for moving dislocations, and thereby improve the creep behavior of the material. Depending on the product, the dimension of the particles is in the range from a few nm up to 100 nm. The material properties depend on the size distribution. It is also expected that other parameters of the dispersoids may influence the materials behavior. An extended X-ray absorption fine structure (EXAFS) study has been conducted on PM2000 (ferritic ODS steel) samples, in order to determine the structure of the yttria inclusions. A PM2000 sample, which had been irradiated with He ions of 1.5 MeV up to a matrix-damage of not, vert, similar1 displacement per atom (dpa) in a surface layer of 2.7 μm in depth was measured. A multi angle implantation was performed, in order to avoid damage peaks as function of depth. A direct comparison of the EXAFS spectra and of the Fourier transformations shows no major difference between the irradiated samples and the non-irradiated one. Therefore any potential radiation induced damage or phase transformation of the dispersoids must be minor, which indicates good radiation stability under the given circumstances

Characterization of Alloy Particles Extracted from Spent Nuclear Fuel

We characterized, for the first time, submicro- and nanosized fission product-alloy particles that were extracted nondestructively from spent nuclear fuel, in terms of noble metal (Mo-Ru-Tc-Rh-Pd-Te) composition, atomic level homogeneity and lattice parameters. The evidences obtained in this work contribute to an improved understanding of the redox chemistry of radionuclides in nuclear waste repository environments and, in particular, of the catalytic properties of these unique metal alloy particles

A scalable membrane electrode assembly architecture for efficient electrochemical conversion of CO2 to formic acid

Abstract The electrochemical reduction of carbon dioxide to formic acid is a promising pathway to improve CO2 utilization and has potential applications as a hydrogen storage medium. In this work, a zero-gap membrane electrode assembly architecture is developed for the direct electrochemical synthesis of formic acid from carbon dioxide. The key technological advancement is a perforated cation exchange membrane, which, when utilized in a forward bias bipolar membrane configuration, allows formic acid generated at the membrane interface to exit through the anode flow field at concentrations up to 0.25 M. Having no additional interlayer components between the anode and cathode this concept is positioned to leverage currently available materials and stack designs ubiquitous in fuel cell and H2 electrolysis, enabling a more rapid transition to scale and commercialization. The perforated cation exchange membrane configuration can achieve >75% Faradaic efficiency to formic acid at <2 V and 300 mA/cm2 in a 25 cm2 cell. More critically, a 55-hour stability test at 200 mA/cm2 shows stable Faradaic efficiency and cell voltage. Technoeconomic analysis is utilized to illustrate a path towards achieving cost parity with current formic acid production methods