The Preliminary Thermo-hydraulics Calculation of Unfolding Process of the Lotus Reactor

The LOTUS reactor is a kind of water-cooled pool-type reactor, with the purpose of city heat supply, which can automatically unfold along-centerline-split-parts of its core radially into several parts when the water in the pool is lost, only driven by gravity and buoyancy. The heat can be better conducted out of the core into the water of the pool to avoid a meltdown risk in such a dynamic evolution. In order to find out the temperature distribution of the core, the tool STAR-CCM+ was used to carry out the thermo-hydraulics calculation. The results shows that the temperature changed as a function of the unfolding process. In this process, the overset grid technique was adopted to simulate the large-scale motion, and the required heat source was provided by the transient calculation of the Monte Carlo code SERPENT. At the same time, except for the sensitivity analysis of mesh and time step settings, we also finished the calculation of different unfolding velocities to ensure sufficient cooling performance of unfolding design for the core.