Behaviour of advanced tritium breeder pebbles under simultaneous action of accelerated electrons and high temperature

The authors greatly acknowledge the technical and experimen-tal support of O. Valtenbergs and L. Avotina (Institute of Chemical Physics, University of Latvia). The work is performed in the frames of the University of Latvia financed project No. Y9-B044-ZF-N-300, “Nano, Quantum Technologies, and Innovative Materials for Eco-nomics”.Advanced lithium orthosilicate (Li4SiO4) pebbles with additions of lithium metatitanate (Li2TiO3) as a secondary phase are suggested as a potential source for tritium breeding in future nuclear fusion reactors. The advanced Li4SiO4 pebbles with different contents of Li2TiO3 were examined before and after simultaneous action of 5 MeV accelerated electron beam (dose rate: up to 10 MGy h−1) and high temperature (up to 1120 K) in a dry argon atmosphere. The accumulated radiation-induced defects (RD) and radiolysis products (RP) were studied by electron spin resonance (ESR) spectrometry and thermally stimulated luminescence (TSL) technique. The phase transitions were studied with powder X-ray diffraction (p-XRD). The microstructure and mechanical strength of the pebbles, before and after irradiation, were investigated by scanning electron microscopy (SEM) and comprehensive crush load tests. The obtained results revealed that the irradiation temperature has a significant impact on the accumulation of RD and RP in the advanced Li4SiO4 pebbles, and with an increasing content of Li2TiO3, the concentration of accumulated paramagnetic RD and RP decreases. Major changes in the mechanical strength, microstructure and phase composition of the advanced pebbles were not detected after irradiation.University of Latvia Y9-B044-ZF-N-300; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART