AbstractIn the frame of the conceptual design of ITER, Ansaldo DNT and ENEA Frascati have brought foreward the design of a ceramic blanket. At the present state of the design, a module consists of two tube bundles containing breeder rod segments; the tubes are topped by helium/water manifolds and constrained to the back-plate by ten supporting grids.One fundamental objective of the work was to study the feasibility, in the near term, of this pin-type blanket. In particular, the feasibility of the thermal barrier between the sintered pellets (LiA1O2) and the low-temperature cooling water, was a matter of uncertainty. To reach the aforecited objective means the possibility of realizing a component with technologies which are currently used in the nuclear field. The main problems and solutions related to the mechanical design and construction of the blanket subcomponents are now briefly presented.From a theoretical approach, the problem of breeder temperature control has been solved: relatively short straight cladding segments keep the pellets centered inside the internal water pipe with the help of inconel spacers.An investigation has shown that an industrial effort is needed to develop a technology able both to produce long thin pipes, which constitute the water channel, with very tight tolerances and to bent them to the desired radius.Two different version of manifolds have been proposed. In each case, care was taken to reduce the number and length of welds needed to connect the tubes to the relative tube sheets.The supporting grids of the egg-crate type are such to minimize the pitch between the pipes, have a relatively high stiffness and make possible differential thermal elongation between the bundles and the back-plate. Their feasibility has already been assessed since similar grids have been used in steam generators.
Design and technology development of solid breeder blanket cooled by supercritical water in Japan