Power Conversion System (PCS) Options for Generation IV Nuclear Plant Available to Purchase

The next stage of Generation IV High Temperature Gas-Cooled Reactor (HTGR) is currently under development for production of electricity and process heat. High outlet temperature of the helium coolant makes it possible to use gas turbines in future power conversion systems. This paper compares the costs and risks of various direct and indirect power conversion systems to evaluate the best commercial electricity generation option. It concludes that, although a direct cycle was predicted to be more efficient, a significant cost and risk reduction will be achieved for an indirect cycle for the near term commercial electricity generating plant. The indirect Combined Cycle Gas Turbine (CCGT) cycle offers excellent efficiency, together with lowest risk and cost for the near term commercial plant. This combines a gas turbine of low-risk design with a current technology steam system. However, the intermediate heat exchanger (IHX) represents a major development item and also introduces some major risks. The implications of the IHX risks have not been fully assessed. In the longer term, when development of high risk and high cost components such as electro-magnetic bearings are more mature, a direct cycle may merit reconsideration on the grounds of elegance and simplicity, in particular a direct Brayton cycle.