Transient Simulation of a Steam Rankine Cycle using CATHARE-3 System Thermal-hydraulic Code: Application to Superphenix Fast Reactor

Abstract

In this paper, a simplified model of the Superphénix (SPX) steam Rankine cycle is drawn and implemented in the CATHARE-3 transient two-phase thermal-hydraulic system code. First, a comparison of several levels of simplification of the Superphénix Rankine cycle is made using the CYCLOP steady-state pre-conceptual design tool. Then, the most simplified thermodynamic cycle that reproduces accurately the physical parameters at key points of the cycle at the nominal state is modeled using CATHARE-3. The model is compared with the nominal state of the Rankine cycle simulated by CYCLOP. It is observed that physical parameters at nominal state are consistent with CYCLOP results (within 10% discrepancy for 15/17 parameters analyzed). The model is then used to simulate a transient of reactor normal operation: a power decrease from 100 to 40% of Nominal Power (NP) by acting on the secondary sodium flow rate in the Steam Generator (SG). The model shows an expected physical behavior since the whole system adapts itself well to a change in the power exchanged in the SG, physical parameters in the cycle such as pressure and temperature stabilizes at lower values which is what occurs in an actual Rankine cycle at partial load. In the next future, it will be necessary to use transient experimental data of the SPX Rankine cycle in order to evaluate more quantitatively the model under dynamic conditions.