Ceramic breeding blanket development for experimental fusion reactor in JAERI

The ceramic breeding blanket is a promising breeding blanket concept for experimental fusion reactors, and worldwide efforts have been devoted to their design and R&D. A layered pebble bed type ceramic breeder blanket with water cooling was proposed by JAERI during ITER/CDA, and has been improved based on detailed analysis and consideration of fabricability. In this concept, beryllium and ceramic breeder pebble bed layers are arranged alternately, in which the beryllium layer works as a thermal resistance layer between the breeder layer and a cooling panel as well as a neutron multiplier. The use of the breeding material and beryllium in the form of small pebbles has been proposed to accommodate dimensional changes by irradiation effects. variety of R&D has also been conducted on the design progress. The development of the fabrication technology for the blanket box structure and its mechanical testing, elementary testing on the thermal performance of the pebble bed, and engineering-oriented material tests of breeder and beryllium pebbles, such as compatibility with structural materials and thermal cycle durability, are the main recent achievements. esent paper outlines recent progress in the design of the ceramic breeder blanket in JAERI and the major results of R&D on box structure fabrication and elementary out-of-reactor testing are also described.