Cost-effective shield designs for environmentally attractive fusion power plants

Vanadium alloys and SiC/SiC composites offer significant advantages in their low activation characteristics and high thermal performance capability. However, a design based entirely on these advanced structures would be expensive. Therefore, it is essential to limit the use of such advanced materials to highly irradiated components such as plasma facing components and blanket. The cost savings for replacing the V and SiC structures of the massive shield with steel are significant. This will degrade the thermal conversion efficiency of the system somewhat since steel cannot operate at temperatures as high as V or SiC. The dividing boundary between the high temperature and low temperature zones will therefore depend on how much power could be dumped as low grade heat without significantly reducing the useful thermal power. This novel approach for designing the shield of V- and SiC-based fusion power plants, along with other innovative ideas that improved the shield performance, reduced the overall cost of electricity by 10%, which is significant. 8 refs., 2 figs., 4 tabs