Progress on the TAURO blanket system

TAURO is a self-cooled Pb-17Li blanket for Fusion Power Reactors (FPRs) using SiC(f)/SiC composites structures. It has been developed with the objective to achieve both passive safety and high thermal efficiency. The Pb-17Li outlet temperature exceeds 850 degreesC. A Brayton cycle is envisaged for power conversion and the possibility of hydrogen production is addressed. This paper recalls the main features of the TAURO blanket, and presents the performed investigations on a range of potential operations conditions with regard to plant thermal efficiency and H(2)-production. It also presents the recent advances made in the design methodologies of composite structures for fusion components involving the implementation in finite-element codes of material models capable of describing the complex non-linear mechanical behavior of these composites and the definition of new resistance criteria. It is possible with this new model to better treat the thermo-mechanical results. Indeed, stresses in each direction are compared directly with allowable limits for tension, compression and shear stresses in each orthotropic direction. Such a model has been implemented in the FEM code CASTEM 2000 developed at CEA. Fabrication aspects are discussed based on a brazing process currently under development and briefly presented. Moreover, the advantages of using newly-produced advanced fibers in SiC(f)/SiC composites in relation with the main issues (namely irradiation stability and thermal conductivity) are assessed. The potential of a liquid metal cooled divertor using SiC(f)/SiC as structural material, in line with the TAURO reactor characteristics is also investigated. A circuit in series could be envisaged, where the Pb-17Li flows at first in the divertor and then it passes in the blanket, which allows increasing the blanket inlet temperature. Calculations on a castellated square tube basic concept showed a reasonable maximum allowable heat flux of about 5 MW/m(2). (C) 2002 Published by Elsevier Science B.V.