Modelling of the DIADEMO Experiment with the CATHARE Code for ASTRID Gas Power Conversion System Studies

International audienceThe Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) is a French Sodiumcooled Fast Reactor developed by the CEA and its partners. For safety reasons, a gas Power Conversion System based on a nitrogen Brayton cycle is investigated for the tertiary circuit. One of the key issue is the design of an innovative Sodium Gas Heat Exchanger (SGHE) that transfers heat from the sodium secondary loops to the nitrogen Brayton cycle. The safety demonstration of this new option will require the thermohydraulic calculation of a wide range of normal and accidental situations that will be performed using the CATHARE-3 code. The first qualification step of the SGHE is to validate the thermo-hydraulic performances of the component and is carried out at low scale (40kW) on the DIADEMO loop currently in operation in Cadarache. This paper presents in details the modelling of the whole DIADEMO experiment with the CATHARE-3 code. The focus is made on the modelling of the SGHE but the modelling of the sodium and nitrogen loops and their components is also presented. The comparison between the experimental data and the CATHARE calculations is performed on a Loss Of Flow Accident (LOFA). For this LOFA, the blower's rotational speed is reduced and a bypass line is open in the nitrogen loop. Thisstudy extends the validation of the CATHARE code and justifies the modelling choices of the SGHE used for ASTRID transient studies