Reactor ceramic foils

Ceramic foils are produced continuously by tape-casting methods. These ceramic tapes consist of an organic binder and oxide powder material, for example, zirconia, titania or alumina. If it is possible to integrate the production process of a micro structured reactor into such a continuous process, production costs would decrease strongly. An early approach used unstructured ceramic foils to build up a micro reactor [159], The reactor consisted essentially of two functional layers, a reaction layer and a heating layer (Figure 4.102). 

The heater for the reaction chamber and the conductors were printed on the lowest layer and electrically contacted to the pads on the cover layer by vertical metal-filled vias in every intermediate layer. Still some manual work was necessary to shape the reaction channel from the pre-fired tapes. Also the soldering of clamp-type fittings to the cover layer is certainly difficult to automate. However, a manufacturing process for ceramic foil reactors seems to be within reach. 

Figure4.102 Micro structured reactor manufactured from a ceramic foil [159] (by courtesy of Kluwer Academic Publishers).

The VHTR has two typical reactor configurations, namely the pebble bed type and the prismatic block type. Although the shape of the fuel element for two configurations are different, the technical basis for both configuration is same, such as the TRISO-coated particle fuel in the graphite matrix, foil ceramic (graphite) core structure, helium coolant, and low power density, in order to achieve high outlet temperature and the retention of fission production inside the coated particle under normal operation condition and accident condition. The VHTR can support alternative fuel cycles such as U—Pu, Pu, mixed oxide (MOX), and U—thorium (Th). 

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