The grain size of tritium breeder pebbles should be
controlled at the level of less than 5 mm to have a good tritium release property. Results of the preliminary granulation
examined using novel combination methods indicate grain
sizes in excess of 5 mm in trial pebbles. Investigations for the
reason of grain sizes >5 mm suggest the predominant factor
affecting grain growth is the presence of binder in the gel
particles. This remaining binder gel reacts with the excess
lithium generating Li2CO3, which promotes grain growth. To
prevent the generation of Li2CO3, Li2
þxTiO3þy pebbles were
sintered under vacuum and subsequently in the atmosphere
of helium involving hydrogen (1% H2-He). The diameter of the
sintered Li2þxTiO3þy pebbles was approximately 1 mm, and
the average grain size was less than 5 mm .