Thermal analysis of supercritical CO2 power cycles: assessment of their suitability to the forthcoming sodium fast reactors

Abstract

.

Sodium fast reactors (SFRs) potential to meet Gen. IV requirements is broadly acknowledged worldwide. The scientific and technological experience accumulated by operating test reactors and, even, by running commercial reactors, makes them be considered as the closest Gen. IV option in the near future. In the past their balance of plant has been always based on Rankine cycles. This paper investigates the potential use of supercritical recompression CO2 cycles (S-CO2) in SFRs on the basis of the working parameters foreseen within the European Sodium Fast Reactor (ESFR) project. A wide range of configurations have been explored, from the simplest one to combined cycles (with organic Rankine cycles, ORC), and a comparison has been set in terms of thermal efficiency. As a result, it has been found out that the most basic configuration could reach a thermal efficiency as high as 43.31%, which is comparable to that obtained through super-critical Rankine cycles proposed elsewhere. A sensitivity analysis together with an exergy study of this configuration, pointed the pre-cooler and IHXNa CO2 as key components in the cycle performance. These results highlight a main conclusion: the potential use in SFRs of recompression S-CO2 cycles for their balance of plant, whenever a sound and extensive database is built-up on S-CO2 turbo-machinery and IHX performance.