Dynamic simulation of the CEFR control rod drop experiments with the Monte Carlo code Serpent

The China Experimental Fast Reactor (CEFR) is the first SFR operated in China. The CEFR physical start-up tests, conducted in 2010, included control rod (CR) worth (CRW) measurements by the rod drop method. In this study, the transient simulations of the actual course of eigth CR drop experiments have been performed with the Monte Carlo code Serpent using a detailed 3D heterogeneous CEFR core model. For each of the eight cases, the calculated time-depended neutron population, dynamic reactivity, and CRW have been compared to the measurements. The experimental and calculated reactivity curves have shown a very close behavior for the entire simulated time interval. With regard to the CRW results, a very good compliance between the experiment and simulations as well as among the applied computational approaches has been observed. The obtained results indicate that Serpent can be routinely applied to transient simulations, the area which until recently was limited to deterministic methods.