Simulation of three-dimensional hydrodynamic components with a one-dimensional transient analysis code

Significant multidimensional pressure gradients occur in the water plenum region of the reactors at the Savannah River Site (SRS). A multi-dimensional RELAP5 input model of the L-Reactor was developed and benchmarked against SRS data. Although RELAP5 is a one-dimensional code, its cross-flow junction allows a multidimensional analysis capability. RELAP5 and the model of L-Reactor calculated water plenum pressures that were in good agreement with measured values for tests with symmetric and asymmetric flow patterns within the plenum. The results included in this paper indicate that a one-dimensional code such as RELAP5, in conjunction with a carefully designed input model, can be used to predict hydraulic response even when large multidimensional effects are present