Synthesis & fabrication of lithium-titanate pebbles for ITER breeding blanket by solid state reaction & spherodization

(6)Li produces tritium by (n, alpha) nuclear reaction, (6)Li + (1)n -> (4)He + (3)H. Lithium titanate (Li(2)TiO(3)) enriched with (6)Li, is the most promising candidate for solid test blanket module (TBM) material for fusion reactors. Various processes are reported in literature for the fabrication of Li(2)TiO(3) pebbles for its use as TBM material. A process has been developed based on the solid state reaction of lithium-carbonate and titanium-dioxide for the synthesis of lithium titanate and pebble fabrication by extrusion, spherodization and sintering. This paper discusses the sequence of steps followed in this process and the properties obtained. Analytical grade titanium-dioxide and lithium-carbonate were taken in stoichiometric ratio and were milled to ensure thorough intimate mixing and obtain fine particles less than 45 mu m before its calcination at 900 degrees C. Following calcination, the agglomerated product was again milled to fine particles of size less than 45 mu m. Aqueous solution of ploy-vinyl-alcohol was added as binder prior to its feeding in the extruder. The extruded strips were spherodized and spherical pebbles were dried and sintered at 900 degrees C for different duration. Pebbles of desired density and porosity were obtained by suitable combination of sintering temperature and duration of sintering. Properties of the prepared pebbles were also characterized for sphericity, pore size distribution, grain size, crushing load strength, etc. The values were found to be conforming to the desired properties for use as solid breeder. The attractive feature of this process is almost no waste generation. (C) 2010 Elsevier B.V. All rights reserved.