Browsing by Author "Vernaz, E"

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    Alteration of cold crucible melter titanate-based ceramics: comparison with hot-pressed titanate-based ceramic
    (Materials Research Society, 1997) Advocat, T; Leturcq, G; Lacombe, J; Berger, G; Day, RA; Hart, KP; Vernaz, E; Bonnetier, A
    Synroc ceramics were synthesized in an induction-heated cold crucible at laboratory scale (1 kg) from an oxide mixture, and at industrial prototype scale (45 kg) from Synroc previously produced by sintering under load at high temperature. After melting, both materials contained the major phases of Synroc-C. The chemical durability of both melted materials, as determined by static leaching of powder samples in initially pure water at 90°C with an SA/V ratio of 20000m−1, was equivalent to that of conventional hot-pressed Synroc-C. Cerium, used in this investigation to simulate the presence of tri-and tetravalent actinides, was found in steady-state concentrations on the order of 1 ppb (i.e. NL(Ce) ≤ 10−6 g·m−2). The concentration in the leachates was independent of the initial CeO2 content of the Synroc (at least up to 10 wt%); moreover, it is similar to the results obtained with hot-pressed Synroc-C specifically formulated for conditioning long-lived actinides. © Materials Research Society 1997
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    Materials science of high-level nuclear waste immobilization
    (Materials Research Society, 2009-01) Weber, WJ; Navrotsky, A; Stefanovsky, S; Vance, ER; Vernaz, E
    With the increasing demand for the development of nuclear power comes the responsibility to address the issue of waste, including the technical challenges of immobilizing high-level nuclear wastes in stable solid forms for interim storage or disposition in geologic repositories. The immobilization of high-level nuclear wastes has been an active area of research and development for over 50 years. Borosilicate glasses and complex ceramic composites have been developed to meet many technical challenges and current needs, although regulatory issues, which vary widely from country to country, have yet to be resolved. Cooperative international programs to develop advanced proliferation-resistant nuclear technologies to close the nuclear fuel cycle and increase the efficiency of nuclear energy production might create new separation waste streams that could demand new concepts and materials for nuclear waste immobilization. This article reviews the current state-of-the-art understanding regarding the materials science of glasses and ceramics for the immobilization of high-level nuclear waste and excess nuclear materials and discusses approaches to address new waste streams. © 2009, Materials Research Society