Study on structural response of reactor vessel under direct safety injection

An emergency core cooling system for a pressurized water reactor adopts direct safety injection with reactor pressure vessel. In this design, a special flow guide device is introduced in order to minimize the heat effects on the reactor internals. But this design makes the pressure vessel bear stronger heat and current impact. To investigate the dynamic response of the pressure vessel during safety injection, the law of dynamic distribution of the heat and flow load are studied using three experiments: In the visualization experiment, the relationship between injection condition and distribution pattern in the downcomer is obtained. In the heat mixing experiment, measuring the temperature and pressure near the inner wall of the pressure vessel, enables us to find out the law that governs dynamic distribution of the heat and pressure load as well as the main distribution area of these loads, and analyze how the temperature oscillation generated. In the structural response experiment, the strain response of the pressure vessel to temperature and pressure is obtained. Moreover, the frequency range of its response to hot oscillation under safety injection is also obtained by analysis. This study provides support to recognize the action law of heat, pressure and structural response in the reactor during safety injection.