1/3D Modeling of the Core of a PHWR Nuclear Power Plant

Abstract

A multi-dimensional CFD model to simulate the in-core coolant circuit of a Pressure Heavy Water Reactor (PHWR) of a nuclear power plant was performed. Three-dimensional (3D) detailed modeling of the upper and lower plenums, the downcomer and the hot-leg and cold-leg nozzles was linked with a finite volume one-dimensional (1D) one-phase code for modeling the behavior of all the 451 coolant channels. Suitable functions for introducing the distributed pressure drop (friction losses) and concentrated losses (spacer grids, inlet restrictors and outlet throttles) allowed to obtain the pressure variation along the channels. Moreover, the axial power distribution for each hydraulic zone was taked into account. Results were compared with the previously obtained with a zero-dimensional (0D) code getting more realistic temperature patterns at the upper plenum. Although the present model is one-phase, the prediction of the variation of pressure and temperature along the channels allow to a better identification of the location of incipient boiling by comparing with the local saturation temperature. This model is the previous step before perform a 1/3D two-phase model to evaluate in-channel subcooled boiling.