Bulk porous materials as an alternative to pebble beds in tritium breeding blankets

Abstract

• A new porous Li 4 SiO 4 bulk breeder was prepared by prefabricated in mold followed by removal of the organic binder. • The porous Li 4 SiO 4 bulk breeder contains an interconnected tritium release channel structure (K g ∼107 m 3 /m 2 h kpa). • The new porous Li 4 SiO 4 bulk breeding material has substantially higher density (∼72 %) compared with pebble beds. • Mechanical strength tests demonstrated good structure integrity and low elastic modulus (0.575 GPa). In this work, a new porous Li 4 SiO 4 bulk breeder was prepared by a novel synthesis method of compression molding-sintering technique based on organic binder. This process results in a denser bulk configuration breeder with an interconnected channel structure for tritium release, following prefabricated in mold the organic binder is removed by volatilization. we also studied in detail the effects of sintering temperature on the morphology, porosity, permeability and mechanical properties of porous bulk breeder. The results show that with the sintering temperature increasing from T = 0.7 T m to T = T m , the porosity of the bulk breeder decreases continuously, accompanied with an increase of compressive strength except for in the range of T ≥ 0.9T m . The main reason is that thermal stress leads to micro-cracks in Li 4 SiO 4 material under higher cooling rate. In summary, the as-prepared porous bulk material at 0.9 T m , aside from the increased density relative to pebble beds (Packing factor ∼71.62 % vs ∼ 63 %), it also has high phase purity, satisfactory air permeability (107 m 3 /m 2 h kPa), the excellent mechanical properties (2.89 MPa) and increased thermal durability, which will be a good candidate for the fusion reactor breeding blanket.