B. Riccardi et al./ Fusion Engineering and Design 51-52(2000)11-22 The design activities have been focussed on the about 1.5 MPa). Stiffeners have also the functions blanket outboard segments. In the most recent of Pb-17Li flow separators design version [7 each outboard segment is di- Because of the low pressure of the coolant fle vided in the poloidal direction in four straight 2.5 FW thickness of 3 mm could be acceptable m high modules, attached on a common thick However, plasma erosion has to be taken into back plate but cooled independently(Fig. 1). Pre- account and the minimum thickness has still to be liminary estimation of the back plate thickness present at the submodule end of life. At this stage leads to the choice of 80 mm. The feasibility of of the design uncertainties are present concerning such a structure has not been analysed in detail the erosion rate of SiC/SiC and the acceptability but a possible solution could be the use of a of direct exposure of Sic/sic to the plasma multilayer plate of SiC/Sic or, because of the regarding the last point the use of protective lower neutron flow at the back plate location, the coatings or monolithic Sic armour could be use of composites with lower resistance to neutron envisaged dose such as the carbon-SiC composites. Each A preliminary fabrication sequence was deter modulus is divided in the toroidal direction in five mined for the TAURO submodule. The different submodules and each of them is supported by the basic components to be manufactured and then back plate and cooled in parallel through a com assembled are shown in Fig. 2. The joining tech mon top horizontal collector formed by two let nique require relatively large contact surfaces els. one for the inlet and one for the outlet flow possible technologies are textile assembling by stitching and co-infiltration during manufacturing module. Within each submodule. the Pb_ILi or brazing. The use of half finished product T flows, at first, poloidally downwards (U=lm )in a thin channel (1.25 cm thickness) located Joints and to improve the stiffness of the module 2-D neutronic analysis was performed by means just behind the FW (6 mm thickness), at the of Montecarlo code TRIPOLI 4, by using the bottom turns in a second channel and flows up, ENDBF-VI transport cross section library [8] then down and up again(at gradually reduced The analysis was aimed at evaluating the overall elocity down to 0.06 m s-) for entering in the performance of the blanket in terms of tritium outlet collector. Toroidal stiffeners plates are re breeding ratio TBR), power density deposition quired for reinforcing the submodule box in order and coolant temperature at the outlet. The results to enable it to withstand the Pb-17Li hydrostatic obtained have shown that the tauro blanket pressure (whose maximum estimated value with 90% enrichment Li can widely fulfil TBR and that lower enrichment can be envisaged. The power density deposition distribution has been used for successive thermal-mechanical analysis For the initial TaURo blanket version [4, the design criteria used were those defined in the ARIES reactor studies [2]. More more severe criteria has recently be defined based mental results on 2D-CERASEPs N2-1 composite [9]. These new criteria take into ac count the orthotropic characteristics of the com- osite and do not distinguish between primary (mechanical) and secondary (thermal)stresses. The assumed limits, which depends on the specific composite and, therefore, are likely to change when more advanced composites will be evalu- Fig. I. The TAURO blanket concept. ated. are 145 MPa for the von mises stresses inB. Riccardi et al. / Fusion Engineering and Design 51–52 (2000) 11–22 13 The design activities have been focussed on the blanket outboard segments. In the most recent design version [7] each outboard segment is di￾vided in the poloidal direction in four straight 2.5 m high modules, attached on a common thick back plate but cooled independently (Fig. 1). Pre￾liminary estimation of the back plate thickness leads to the choice of 80 mm. The feasibility of such a structure has not been analysed in detail but a possible solution could be the use of a multilayer plate of SiC/SiC or, because of the lower neutron flow at the back plate location, the use of composites with lower resistance to neutron dose such as the carbon–SiC composites. Each modulus is divided in the toroidal direction in five submodules and each of them is supported by the back plate and cooled in parallel through a com￾mon top horizontal collector formed by two lev￾els, one for the inlet and one for the outlet flow (Fig. 1). The feeding pipes are located behind the module. Within each submodule, the Pb–17Li flows, at first, poloidally downwards (6=1 m s−1 ) in a thin channel (1.25 cm thickness) located just behind the FW (6 mm thickness), at the bottom turns in a second channel and flows up, then down and up again (at gradually reduced velocity down to 0.06 m s−1 ) for entering in the outlet collector. Toroidal stiffeners plates are re￾quired for reinforcing the submodule box in order to enable it to withstand the Pb–17Li hydrostatic pressure (whose maximum estimated value is about 1.5 MPa). Stiffeners have also the functions of Pb–17Li flow separators. Because of the low pressure of the coolant flow, a FW thickness of 3 mm could be acceptable. However, plasma erosion has to be taken into account and the minimum thickness has still to be present at the submodule end of life. At this stage of the design uncertainties are present concerning the erosion rate of SiC/SiC and the acceptability of direct exposure of SiC/SiC to the plasma: regarding the last point the use of protective coatings or monolithic SiC armour could be envisaged. A preliminary fabrication sequence was deter￾mined for the TAURO submodule. The different basic components to be manufactured and then assembled are shown in Fig. 2. The joining tech￾nique require relatively large contact surfaces: possible technologies are textile assembling by stitching and co-infiltration during manufacturing or brazing. The use of half finished product (T and L shape) is useful to reduce the number of joints and to improve the stiffness of the module. 2-D neutronic analysis was performed by means of Montecarlo code TRIPOLI 4, by using the ENDBF-VI transport cross section library [8]. The analysis was aimed at evaluating the overall performance of the blanket in terms of tritium breeding ratio (TBR), power density deposition and coolant temperature at the outlet. The results obtained have shown that the TAURO blanket, with 90% enrichment 6 Li can widely fulfil TBR and that lower enrichment can be envisaged. The power density deposition distribution has been used for successive thermal-mechanical analysis. For the initial TAURO blanket version [4], the design criteria used were those defined in the ARIES reactor studies [2]. More realistic and more severe criteria has recently be defined based on experimental results on 2D-CERASEP® N2-1 composite [9]. These new criteria take into ac￾count the orthotropic characteristics of the com￾posite and do not distinguish between primary (mechanical) and secondary (thermal) stresses. The assumed limits, which depends on the specific composite and, therefore, are likely to change when more advanced composites will be evalu￾Fig. 1. The TAURO blanket concept. ated, are 145 MPa for the von Mises stresses in