Speaker
Description
In order to most efficiently produce tritium from a high energy neutronic reaction, lithium dense tritium breeding materials (TBMs) are required. TBMs must operate under high temperatures and neutron radiation, whilst producing extractable tritium and being compatible with the surrounding materials. Ceramic TBMs offer material compatibility and do not suffer from magnetohydrodynamic (MHD) effects, however, traditionally they have lower tritium breeding ratios (TBRs) in addition to concerns over radiation damage.
With the current industrial interest in spherical tokamak arrangements with less space for TBMs, materials with higher TBRs are required. Neutronics simulations suggest that the octalithium compounds, with their high lithium densities, offer significantly higher TBRs than Li4SiO4 and Li2TiO3 which are designated for use in ITER – however most of these compounds lack basic physical data (melting points, phase stability, mechanical properties) and none have been subject to micro mechanical and ion irradiation testing.
This work presents the mechanical properties (Youngs modulus, hardness and fracture toughness) of dense octalithium ceramics (Li8MO6, M = Zr, Pb, Sn and Ce) from nanoindentation, how these experimental values correspond with those predicted using density functional theory modelling (DFT), and the impact of high energy (12 MeV, 1e17cm-2) He ion irradiation on these properties. Further we examine how the octalithiums will perform in the hostile environment of a future reactor, by exploring the phase stability at high temperatures (500°C, 700°C and 900°C) using X-ray diffraction and mass loss.
| Speaker affiliation | University of Oxford |
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