A comparative study of alternative power cycles for small modular reactors

To combat safety concerns and poor economics, research and commercialization of new nuclear power plants has focused on the development of small modular reactors. NuScale Power has developed a small modular reactor design based on natural convection cooling inside the reactor core. The energy conversion is provided by a regenerative Rankine cycle. This comparative study provides a research review of alternative power cycles designs suited for small modular pressurized water reactors. The candidate cycles are analyzed for overall thermal efficiencies (1st law) and their primary exergy destruction sources. To compare with the baseline regenerative Rankine cycle, key design variables for each cycle are optimized using a penalty method. Results reveal that the two alternative cycles of regenerative reheat Rankine and transcritical ethanol have promise as potential alternative replacements. The regenerative reheat Rankine cycle would be the simplest cycle to integrate into the current small modular design due to being similar to the current regenerative Rankine cycle. Conversely, the transcritical ethanol cycle shows higher thermal efficiency but would requires more research to assess the viability through better understanding of its cycle design, component development and costs, and safety implications.