"Formation of tetragonal gas bubble superlattice in bulk molybdenum under helium ion implantation"
Cheng Sun, David Sprouster, Khalid Hattar, Lynne Ecker, Lingfeng He, Y. Gao, Yipeng Gao, Yongfeng Zhang, Jian Gan,
We report the formation of tetragonal gas bubble superlattice in bulk molybdenum under helium ion implantation at 573 K. The transmission electron microscopy study shows that the helium bubble lattice constant measured from the in-plane d-spacing is ~4.5 nm, while it is ~3.9 nm from the out-of-plane measurement. The results of synchrotron-based small-angle x-ray scattering agree well with the transmission electron microscopy results in terms of the measurement of bubble lattice constant and bubble size. The coupling of transmission electron microscopy and synchrotron high-energy X-ray scattering provides an effective approach to study defect superlattices in irradiated materials.
"Infrastructure development for radioactive materials at the NSLS-II"
Eric Dooryhee, Lynne Ecker, G. Robert Odette, David Sprouster, Peter Wells, Randy Weidner, Sanjit Ghose, Theodore Novakowski, Tiberiu Stan, Nathan Almirall,
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
The X-ray Powder Diffraction (XPD) Beamline at the National Synchrotron Light Source-II is a multipurpose instrument designed for high-resolution, high-energy X-ray scattering techniques. In this article, the capabilities, opportunities and recent developments in the characterization of radioactive materials at XPD are described. The overarching goal of this work is to provide researchers access to advanced synchrotron techniques suited to the structural characterization of materials for advanced nuclear energy systems. XPD is a new beamline providing high photon flux for X-ray Diffraction, Pair Distribution Function analysis and Small Angle X-ray Scattering. The infrastructure and software described here extend the existing capabilities at XPD to accommodate radioactive materials. Such techniques will contribute crucial information to the characterization and quantification of advanced materials for nuclear energy applications. We describe the automated radioactive sample collection capabilities and recent X-ray Diffraction and Small Angle X-ray Scattering results from neutron irradiated reactor pressure vessel steels and oxide dispersion strengthened steels.
"Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels"
David Sprouster, Eric Dooryhee, John Sinsheimer, Sanjit Ghose, Peter Wells, Nathan Almirall, G. Robert Odette, Lynne Ecker, Tiberiu Stan,
Massive, thick-walled pressure vessels are permanent nuclear reactor structures that are exposed to a damaging flux of neutrons from the adjacent core. The neutrons cause embrittlement of the vessel steel that grows with dose (fluence), as manifested by an increasing ductile-to-brittle fracture transition temperature. Extending reactor life requires demonstrating that large safety margins against brittle fracture are maintained at the higher neutron fluence associated with beyond 60 years of service. Here synchrotron-based x-ray diffraction and small angle x-ray scattering measurements are used to characterize highly embrittling nm-scale Mn–Ni–Si precipitates that develop in the irradiated steels at high fluence. These precipitates lead to severe embrittlement that is not accounted for in current regulatory models. Application of the complementary techniques has, for the very first time, successfully identified the crystal structures of the nanoprecipitates, while also yielding self-consistent compositions, volume fractions and size distributions.
Crystallization and Phase-Separation in Melt-Derived Nuclear Waste Forms - FY 2020 RTE 2nd Call, #574
Synchrotron X-ray Characterization of the Microstructural Evolution of U Alloys Irradiated to Low Fluences - FY 2018 RTE 1st Call, #283
The study of local atomic structure and formation of ceramic phase in a simplified nuclear waste glassesl - FY 2018 RTE 2nd Call, #340