Speaker
Description
Pedr Charlesworth1*, Ben Phoenix2, Samuel Murphy3, Mohamad Abdallah4, David Kingham4,
David Armstrong1, Chris Grovenor1
1Department of Materials, University of Oxford, U.K.
2Department of Physics and Astronomy, University of Birmingham, U.K.
3 Engineering Department, Lancaster University, U.K
4Tokamak Energy, Abingdon, U.K
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.
