Experimental study of the interaction of ceramic breeder pebble beds with structural materials under thermo-mechanical loads

This paper presents the first results obtained in a facility constructed at the University of California, Los Angeles to study the interaction of ceramic breeder pebble beds with structural materials in conditions relevant to fusion energy power plant blanket operations. The experiments study the thermo-mechanical performance of lithium meta-titanate oxide (Li2TiO3) pebbles and silicon carbide clad constrained by a low thermal expansion alloy in vacuum and He atmosphere. The results show that large deformations due to induced thermal stresses are present during the first heat cycle but afterward are accommodated by a combination of pebble re-arrangement within the bed and thermally induced creep deformation. Initial results of a numerical simulation of the experiments using a finite element code that includes creep deformation is also presented. Planned operation of the UCLA thermo-mechanics test facility is summarized to conclude the paper.