Hyperalkaline Cement Leachate-Rock Interaction and Radionuclide Transport in a Fractured Host Rock (HPF Project)

ABSTRACTThe HPF project (Hyperalkaline Plume in Fractured rock) at the Grimsel Test Site comprises an underground long-term field experiment in a shear zone, in-situ radionuclide transport experiments, two laboratory core infiltration experiments, sophisticated reactive transport modeling exercises, studies on radionuclide stability and solubility, innovative on-line measurement techniques and development of equipment for high-pH conditions (K-Na-Ca-OH, pH = 13.4 at 15 °C). Results to date indicate a decrease in the overall transmissivity of the tested shear zone over a duration of 2 years accompanied by channeling of flow as evidenced by repeat dipole tracer testing with Na-fluorescein, 82Br, 131I, 24Na, and 85Sr. The associated evolution in fluid chemistry indicates the in situ formation of Ca-Si-hydrates. Tracer transport modeling of dipole tests are based either on a heterogeneous porous medium approach or on discrete fracture models. Reactive transport modeling is achieving reasonable agreement with a laboratory core infiltration experiment. Integral to the project are supporting sorption / stability studies, colloid measurements, and development of analytical and measurement techniques.</jats:p

Influence of the benzoquinone sorption on the structure and electrochemical performance of the MIL-53(Fe) hybrid porous material in a lithium-ion battery

Among the metal-organic frameworks (MOFs), MIL-53(Fe) or Fe III(OH) 0.8F 0.2[O 2C-C 6H 4-CO 2] was the first ever reported member to reversibly insert Li + electrochemically. A variety of electroactive sorbents has been investigated in an attempt to increase its electrochemical capacity vs Li +/Li 0. Here, we describe the synthesis and characterization of a new composite hybrid material involving MIL-53(Fe) as the host for the guest electroactive 1,4-benzoquinone molecule in a 1:1 molar ratio, using complementary highresolution X-ray diffraction (XRD), differential scanning calorimetry (DSC), and magic angle spinning nuclear magnetic resonance (MAS NMR) measurements. Its room-temperature structure has been solved and shows that the quinone molecules are located within the channels nearly parallel to each other, and to the benzene rings of the skeleton, in order to maximize π-π interactions. When heated in a sealed container, a flip-flop reorganization of the quinone molecules occurred above 140 C°, whereas in an open environment, desorption of the quinone was shown near 120 C° giving rise to a new phase having solely 0.5 quinone molecules/MIL-53(Fe) formula unit. Enhancement of the electrochemical performances, due to the redox properties of the quinone molecules, was observed during the first 2 cycles. An exchange between both the quinone and the electrolyte molecules is proposed to account for the capacity decay in subsequent cycles. © 2009 American Chemical Society

Graphite and Carbon Fiber Composite for Fusion

2siGraphite and carbon fiber composites have been an historic material for plasma facing components for fusion devices. While the use of this material enhances plasma performance, the harsh plasma and nuclear environment gives rise to a range of physical property changes and materials interactions. High-energy plasma ions can react with and remove the carbon atoms to the plasma. Neutron produced by the fusion reaction will cause structural damage drastically alter the thermophysical properties of the material and enhance tritium trapping. As discussed in this chapter, these factors inherently limit both the lifetime of the plasma facing components and the performance of the devices in which they are applied.reservedmixedFerraris, Monica; Snead, LanceFerraris, Monica; Snead, Lanc