When ceramic breeder research was initiated in the 1970s, relevant data for lithium-based ceramics were scarce or nonexistent. Initial screening of candidates was mainly based on examination of the physical and chemical characteristics and neutronic behavior. An extensive R&D effort focused on determining the properties of unirradiated materials and on designing irradiation experiments to understand and quantify the effect ofneutron irradiation on material properties and on recovery ofgenerated tritium. With the publication of these data, the relative merits of the candidates became known and interest changed accordingly. With the evolution of the INternational TOkamak Reactor (INTOR) and International Thermonuclear Experimental Reactor (ITER) projects, much of the international R&D effort was focused on the opportu­nities for implementing breeding units or driver blan­kets in such a device and its role in the technological development ofpower reactor blanket systems.

Several breeder blanket design options had been developed such as high-temperature water-cooled and helium-cooled concepts for DEMO and power reactors, and low-temperature water-cooled concepts for ITER.2-21 The ceramics under consideration exhibit different characteristics, which can make one ceramic more adaptable to a specific blanket concept. In this chapter, the issues being addressed in R&D in support ofcurrent blanket design studies are high­lighted. In this chapter no reference is made to R&D for other fusion systems like inertial confinement.

Two major types ofceramic breeder material con­figurations have been developed based on pressed and sintered pins or pellets or as a collection of packed spheres or pebble beds. The actual arrange­ment of pebbles though may be in tube, which may lead to some confusion when ‘breeder-in-tube’ (BIT) is mentioned. The paper by Ihli et a/.21 provides an overview of blanket design developments and refer­ences ongoing work by various parties.

Until 2010, pebble-bed concepts were the preferred options for all parties involved in ceramic breeder test blanket module (TBM) programs for ITER as reported by Giancarli and coworkers.23,24 Typically, inert gas with hydrogen addition, whose characteristics are dis­cussed later in this chapter, is used for the extraction of the tritium produced from lithium ceramics.25-2