Thermal Predictions of the AGR 3/4 Experiment With Time Varying Gas Gaps

Abstract

A thermal analysis was performed for the Advanced Gas Reactor test experiment (AGR3/4) with timevarying gas gaps. The experiment was irradiated at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). Several fuel irradiation experiments are planned for the AGR Fuel Development and Qualification Program that supports the development of the VeryHighTemperature GasCooled Reactor (VHTR) under the NextGeneration Nuclear Plant (NGNP) project. AGR3/4 combines two tests in a series of planned AGR experiments to test tristructuralisotropic (TRISO)coated, lowenriched uranium oxycarbide fuel. Fortyeight TRISOfueled compacts were inserted into 12 separate capsules for the experiment (four compacts per capsule). The purpose of this analysis was to calculate the temperatures of each compact and graphite layer to obtain daily average temperatures using time (fast neutron fluence)varying gas gaps and to compare with experimentally measured thermocouple data. A finiteelement heat transfer model was created for each capsule using the commercial code ABAQUS. Model results are compared to thermocouple data taken during the experiment.