EMREL Awarded $3.99M Project from Department of Energy to develop technologies to
improve environmental impact of Nuclear Graphite
A 3.99 million dollar Stony Brook University project led by Lance Snead of EMREL to develop a materials-science understanding of irradiation graphite and to develop new technologies to reduce both its volume and impact in repositories has been awarded. This project, which was one of eight large Integrated Research Programs awarded by DOE-Office of Nuclear Energy, assembles a team which included the Massachusetts Institute of Technology, University of California-Berkeley, the Idaho and Oak Ridge National Laboratories and a number of commercial entities. Link HERE
Streit and Sean's paper, "Unraveling Thermodynamic and Kinetic Contributions to the
Stability of Doped Nanocrystalline Alloys using Nanometallic Multilayers" published
in Advanced Materials.
Here, thermodynamic modeling is implemented to select the Mo–Au system for exploring the interplay between thermodynamic and kinetic contributions to nanostructure stability. Using nanoscale multilayers and in situ transmission electron microscopy thermal aging, evolving segregation states and the corresponding phase transitions are mapped with temperature. The microstructure is shown to evolve through a transformation at lower homologous temperatures (<600 °C) where solute atoms cluster and segregate to the grain boundaries, consistent with predictions from thermodynamic models. An increase in temperature to 800 °C is accompanied by coarsening of the grain structure via grain boundary migration but with multiple pinning events uncovered between migrating segments of the grain boundary and local solute clustering. Direct comparison between the thermodynamic predictions and experimental observations of microstructure evolution thus demonstrates a transition from thermodynamically preferred to kinetically inhibited nanocrystalline stability and provides a general framework for decoupling contributions to complex stability transitions while simultaneously targeting a dominant thermal stability regime. The full text may be found HERE.
Bin's paper, "Ceramic composite moderators as replacements for graphite in high temperature
microreactors" published in Journal of Nuclear Materials.
Here, we explore neutronics driven selection of entrained moderating phases in MgO-based ceramic composites with a focus on the MgO-BeO system given its exceptional moderating power and high temperature stability. Using lithium-bearing salts as sintering aids, fully dense MgO-BeO composites with BeO loading up to 40 vol.% are produced through direct current sintering at markedly reduced temperatures relative to phase-pure MgO. Thermophysical properties mapped as a function of the BeO concentration are shown to align with various composite models, thus revealing the influence of underlying defects on the thermophysical property trends. From microreactor neutronics and thermal hydraulic calculations, the MgO-40BeO moderator is shown to increase both cycle length and fuel utilization relative to graphite and with steady-state temperature distributions remaining within specification. The ceramic composite moderators outperform graphite for all metrics considered with significant potential demonstrated for reducing energy costs while enabling novel microreactor designs through the replacement of graphite. The full text may be found HERE.
EMREL awarded $3.4M from Department of Energy for project to reduce Nuclear Waste
A Stony Brook University project led by Jason Trelewicz of EMREL aimed at reducing nuclear waste has received $3.4 million from the U.S. Department of Energy (DOE), one of 11 nationwide projects seeking to increase the deployment, and use of, nuclear power as a reliable source of clean energy and limit the amount of waste produced from Advanced Nuclear Reactors (AR).
More information may be found HERE.
Nick's paper, "Microstructural Transitions during Powder Metallurigcal Processing
of Solute Stabilized Nanostructured Tungsten Alloys" published in Metals
Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders. The full text may be found HERE.
Prof. Snead's article, "Development and potential of composite moderators for elevated
temeperature nuclear applications" published in Journal of Asian ceramic Societies
This paper discusses historic reactor moderator materials, which are relatively simple monolithic materials each having intrinsic benefits and limitations. Additionally, a new class of engineered composite moderators is presented for which two examples are fabricated: magnesia-matrix composite systems with either beryllium-based or metal-hydride entrained phases. In additions to presenting their route to fabrication effectiveness as advanced moderators is discussed. The full text may be found HERE.