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M. Isobe, K. Matsuhiro, Y. Ohtsuka, Y. Ueda,
M. Nishikawa
Graduate School of Engineering, Osaka Univerisity, Suita, Osaka, Japan
Abstract. A pebble drop divertor concept is proposed for
future fusion reactor. The marked feature of this system is the use of
multi-layer pebbles that consists of a central kernel and some coating layers,
as a divertor surface component. By using multi-layer pebbles, pebble drop
divertor have the advantages such as steady state wall pumping with low bulk
tritium retention. The performance of whole divertor system depends on the
characteristics of the multi-layer pebble. Particularly the maximum heat load
of the system is determined by the dimensions, the layer structure and the
material of a kernel. A kernel also has an important role to determine surface
temperature, which affects the wall pumping efficiency. This paper presents
the numerical results of the maximum allowable heat load and the surface
temperature of the divertor pebble. From the numerical estimation of thermal
stress and surface temperature, it is found that the radius of divertor pebble
with ceramic kernel should be 0.5 - 1 mm.
IAEA 2001
