AP 600 - In containment refueling water storage tank (IRWST) hydrodynamic analysis

The AP600 is a 600 MWe Advanced Light Water Reactor that is being designed with passive safety features including an automatic depressurization system (ADS). During emergency conditions some of the ADS valves discharge into the in-containment refueling water storage tank (IRWST) under water through a sparger, producing hydrodynamic loads on the tank walls and equipment. The purpose of this paper is to present the IRWST hydrodynamic analyses, jointly performed by Ansaldo and Westinghouse, as part of the AP600 program, under Westinghouse's overall leadership, in conjunction with sparger tests conducted on a test tank model. An analytical procedure to predict hydrodynamic loads imposed on the AP600 IRWST tank from ADS discharges has been validated by a comparison with test tank measurements; the appropriate inclusion of fluid structure interaction effects allows significant pressure attenuations from the discharge region and indicates that relatively low structural effects are produced on tank main structures from induced wall pressures