Annulus pressurization load evaluation after high energy line break

In Light Water Reactor design, it is required by the US Nuclear Regulatory Commission (NRC) that a conservative method must be used to estimate the loads on the Reactor Pressure Vessel (RPV) and components in the analysis of the loss of coolant accident (LOCA). As part of the safety design of the containment for light water reactors, jet forces resulting from the postulated rupture of high-pressure piping are accounted for in the design of internal structures. Traditionally, the jet force was estimated using ANS 58.2. However, it does not address the compressibility, reflection, and feedback amplification of the pressure forces as directed by NRC. In this paper, a numerical method is developed to estimate the annulus pressurization caused by the high-energy line break in the Economic Simplified Boiling Reactor (ESBWR). The pressure loading time history caused by the blast wave was predicted by the method. From the prediction, the maximum pressure loading was obtained. The method and the results have been submitted to the NRC as the supporting documents for the ESBWR certification.