Enhanced fabrication process for lithium orthosilicate pebbles as breeding material

Abstract

The solid breeder blanket concept proposed by the European Union features the tritium breeding ceramics as pebble beds inside several breeder units. The pebble bed will not take part in the structural rigidity of a breeder unit. Still the pebbles need to withstand forces originating from thermal expansion mismatches and neutron irradiation. A designated breeder ceramic for this concept is lithium orthosilicate with a slight surplus of silica. It has been demonstrated that lithium orthosilicate can be processed by melt spraying, which is favorable to other processes in terms of recycling. This work summarizes changes to the process and investigations of the current limitations that have to be overcome to enhance not only the mechanical properties of the pebbles, but also the yield of the process. A key feature of the improvements is to control the forming of the single pebbles more precisely than in the past. Thereby, not only the generation of pores should be avoided, but also the size distribution of the pebbles should be more accurately controlled.