Modelagem Computacional da Convecção Natural no Reator IEA-R1

Abstract

This work presents a three-dimensional modelling of natural convection in the IEA- R1 reactor using the porous media technique with Computational Fluids Dynamics (CFD). Experimental data from a primary pump trip accident were used to validate the models. This accident was selected due to the availability of experimental data from a test performed with an Instrumented Fuel Assembly. Two CFD techniques were used to model the accident to compare against experimental data. The first approach modeled the accident with a fuel channel analysis using a CFD tool. Subsequently, a full fuel element was modeled with the porous media technique with input data from the previous channel simulation. In both cases, the flow decay in the core was determined with RELAP5 code. In the final stage of the study, the porous model of the fuel element was applied to simulate the full IEA-R1 reactor during natural convection conditions. Both transient simulations accurately reproduced the experimental data reported in the literature. Although, the models responded well throughout the transient, the peak temperature was overestimated. The channel model overestimated this peak by only 1.6 °C, while the porous media model overestimated it by of 10,5°C. Despite this larger discrepancy, attributed to the simplified nature of the model, the porous media technique was considered a reliable and feasible tool to simulate the reactor core in its complete form. The full porous model of the reactor during natural convection phase allowed to visualize temperature and velocity fields in the reactor. The model developed can be used to couple neutronic and thermal-hydraulics phenomenon in future studies.