NUCIRC Simulation of a Large Header for the CANDU Type Nuclear Reactor Heat Transport System

Abstract

A header manifold model for the NUCIRC code has been developed for the large scale CANDU type nuclear reactor. NUCIRC's header manifold model was originally designed for the CANDU 6 heat transport system (HTS) [1,2], but is modified in this work to extend it to a large scale system. The large scale CANDU system uses parallel core passes with a common reactor outlet header (ROH), and is designed to accommodate 100 more fuel channels than the CANDU 6 design [3,4]. Two different reactor header models can be employed in the NUCIRC code: the nonmanifold and the manifold model. The non-manifold model simulates the reactor headers as constant pressure reservoirs [5]. The manifold model possesses the ability to capture the differences in the header designs, and the axial pressure gradients in the reactor headers due to the flow distributions along the headers. As a result, the manifold model should provide a more accurate predictions on the flow channels header-to-header pressure drops. This paper will demonstrate the ability of the header manifold model to better simulate the large scale CANDU reactor by generating a more detailed representation of the HTS when compared to the nonmanifold model.