Reactor Cavity Cooling System (RCCS)

The Reactor Cavity Cooling System (RCCS) is a new passive safety system designed for the next generation of nuclear power plants, and it will be incorporated into High Temperature Gas-Cooled Reactors (HTGR), which is one of the proposed Generation IV reactor designs. This system was conceived to guarantee the integrity of the fuel, the reactor vessel, and the structures inside the reactor cavity by removing heat from the cavity during both normal operation and accident scenarios. 


Typical HTGR plant Configuration


Two different RCCS designs are currently under discussion. The design proposed by General Atomic is a natural convection, air-based cooling system with no pumps, circulators, valves, or other active components and is designed to operate continuously in all modes of plant operation. The second configuration, proposed by AREVA, is a constant flow, water-based cooling system that operates at low-temperature and low pressure. Water temperatures are below 30°C during normal active operation, reaching the boiling point only during emergency passive operation.

The thermal-hydraulic laboratory has worked on both designs, designing, constructing, and operating a water-cooled RCCS experimental facility and an air-cooled experimental facility.

The experimental data produced have been compared with simulations results generated using systems codes (RELAP5-3D) and CFD codes (STARCCM+).


CFD (left) and RELAP5 (right) representations


CFD Simulation (Reactor Cavity)


Water-Cooled RCCS Glass Manifold


Water-Cooled RCCS - Flow Visualization Technique