B. Riccardi et al./ Fusion Engineering and Design 51-52(2000)11-22 The SiC SiC composites have been conceived ous design studies which differ on the assumed and developed mainly for aerospace applications safety strategy [2-4]. within the eu the TAURO The optimisation of such material for fusion blanket concept [4] has been proposed by the needs a strong coordination of R&D efforts Commissariat a l' Energie Atomique (CEA).In among research institutes, including participation this concept the chosen safety strategy is based on of industry through all the development stages the minimisation of the energy available within The development of more advanced fibres and the reactor so that the amount of radioactive the enhancement of composites processing meth- material released. in case of severe accident. can ods as well as alternative solutions for fibre -ma e limited. This passive safety concept, which has trix interphase lead to improved thermo- to be applied to all in-vessel components, leads to mechanical characteristics at elevated tempera the use of low pressure coolants with reduced tures. Nevertheless critical issues related to chemical reactivity in air. Liquid Pb-17Li is the nuclear environment are still present; these issues most promising candidate. The main objectives of are mainly connected to the fibres and matrix the TAuRo Study were to find a credible alterna- stability under neutron irradiation, to the poor tive to existing high-pressure He-cooled blanket thermal properties and to the residual porosity In designs, to develop models and design criteria parallel, technology issues must be addressed, e.g. joining methodology and definition of design adapted MC) structural materials. to determine the main issues In parallel to the manufacturing development for a self cooled Pb-17Li using SiC/SiC materials and materials characterisation. fusion reactors de- and to evaluate the limit for fusion application of sign studies using SiCr Sic composites as struc the existing industrial SiCr/SiC composites tural material have been undertaken. These The tauro design is based on the reactor studies, relying on currently available materials specifications defined for the SEAFP Study [5]: 3 data. provide also guidelines for improvements of Gw of fusion power, neutron and heat wall load- ceramic composites, ranking the priorities of fu- Ing of, respectively, 2 and 0.5 MW m-2 and 5 ture developments years of full power continuous operation. The The present overview reports the main achieve- SEAFP conceptual reactor has 6 toroidal field ments of the European R&D activities on Sic/ coils and 48 outboard and 32 inboard segments SiC composites. a description of the design study (about 10 m high) of a SiCr/Sic composites blanket which uses liq The tauRo blanket consists essentially of a uid lithium lead as coolant is discussed. advances SiCSic box containing the Pb-17Li which in manufacturing routes dealing with chemical works as coolant. tritium breeder. neutron multi vapour infiltration(CVI) and polymeric infiltra plier and tritium carrier. The maximum velocity tion and pyrolysis(PIP)are also presented includ- of Pb-17Li is about I m s-l in the channel ing recent results on joining and coating located just behind the Fw. The design is based techniques. Studies on radiation effects on ther- on the assumption, to be experimentally verified, mal conductivity and mechanical properties in that the Sic Sic has enough low electrical con- cluding irradiation creep and compatibility with uctivity to avoid large magneto-hydro-dynamic some solid breeders for long exposure time (MHD) induced pressure drops. Recent studies (10 000 h)are also reported carried out at JRC Ispra [6] indicate, for commer- cially available Sicr/Sic composites, a measured electrical conductivity ranging from 350(@2m) 2. Design at 200oC to 550(Q2m)at 1000C. Therefore, the item need further investigations taking into ac The use of SiC/SiC composite as structural count that the neutron irradiation tends to in- material for fusion power reactor has been pro- crease the electrical conductivity, being the design posed by different institutions by means of vari- reference value 500(Q2m)12 B. Riccardi et al. / Fusion Engineering and Design 51–52 (2000) 11–22 The SiCf /SiC composites have been conceived and developed mainly for aerospace applications. The optimisation of such material for fusion needs a strong coordination of R&D efforts among research institutes, including participation of industry through all the development stages. The development of more advanced fibres and the enhancement of composites processing meth￾ods as well as alternative solutions for fibre–ma￾trix interphase lead to improved thermo￾mechanical characteristics at elevated tempera￾tures. Nevertheless critical issues related to the nuclear environment are still present; these issues are mainly connected to the fibres and matrix stability under neutron irradiation, to the poor thermal properties and to the residual porosity. In parallel, technology issues must be addressed, e.g. joining methodology and definition of design criteria. In parallel to the manufacturing development and materials characterisation, fusion reactors de￾sign studies using SiCf /SiC composites as struc￾tural material have been undertaken. These studies, relying on currently available materials data, provide also guidelines for improvements of ceramic composites, ranking the priorities of fu￾ture developments. The present overview reports the main achieve￾ments of the European R&D activities on SiCf / SiC composites. A description of the design study of a SiCf /SiC composites blanket which uses liq￾uid lithium lead as coolant is discussed. Advances in manufacturing routes dealing with chemical vapour infiltration (CVI) and polymeric infiltra￾tion and pyrolysis (PIP) are also presented includ￾ing recent results on joining and coating techniques. Studies on radiation effects on ther￾mal conductivity and mechanical properties in￾cluding irradiation creep and compatibility with some solid breeders for long exposure time (10 000 h) are also reported. 2. Design The use of SiCf /SiC composite as structural material for fusion power reactor has been pro￾posed by different institutions by means of vari￾ous design studies which differ on the assumed safety strategy [2–4]. Within the EU the TAURO blanket concept [4] has been proposed by the Commissariat a l’Energie Atomique (CEA). In this concept the chosen safety strategy is based on the minimisation of the energy available within the reactor so that the amount of radioactive material released, in case of severe accident, can be limited. This passive safety concept, which has to be applied to all in-vessel components, leads to the use of low pressure coolants with reduced chemical reactivity in air. Liquid Pb–17Li is the most promising candidate. The main objectives of the TAURO Study were to find a credible alterna￾tive to existing high-pressure He-cooled blanket designs, to develop models and design criteria adapted to ceramic matrix composites (CMC) structural materials, to determine the main issues for a self cooled Pb–17Li using SiCf /SiC materials and to evaluate the limit for fusion application of the existing industrial SiCf /SiC composites. The TAURO design is based on the reactor specifications defined for the SEAFP Study [5]: 3 GW of fusion power, neutron and heat wall load￾ing of, respectively, 2 and 0.5 MW m−2 and 5 years of full power continuous operation. The SEAFP conceptual reactor has 16 toroidal field coils and 48 outboard and 32 inboard segments (about 10 m high). The TAURO blanket consists essentially of a SiCf /SiC box containing the Pb–17Li which works as coolant, tritium breeder, neutron multi￾plier and tritium carrier. The maximum velocity of Pb–17Li is about1ms−1 in the channel located just behind the FW. The design is based on the assumption, to be experimentally verified, that the SiCf /SiC has enough low electrical con￾ductivity to avoid large magneto-hydro-dynamic (MHD) induced pressure drops. Recent studies carried out at JRC Ispra [6] indicate, for commer￾cially available SiCf /SiC composites, a measured electrical conductivity ranging from 350 (Vm)−1 at 200°C to 550 (Vm)−1 at 1000°C. Therefore, the item need further investigations taking into ac￾count that the neutron irradiation tends to in￾crease the electrical conductivity, being the design reference value 500 (Vm)−1