Abstract
Among the envisaged experimental infrastructures supporting ALFRED reactor development [1][2], FALCON consortium identified two main facilities (named ATHENA and ELF) to address the pool thermal-hydraulic challenges and progressively demonstrate the feasibility of the revised ALFRED configuration [3], along with the thermal-hydraulic performances of its main components. In particular, the Advanced Thermo-Hydraulics Experiment for Nuclear Application facility (ATHENA) is a large pool-type lead-cooled multi-purpose experimental facility featuring a large size vessel (3.2 m diameter, 10 m in height), conceived to host almost 800 tons of lead to test ALFRED relevant scaled components. The test section to be installed in the main vessel includes an electrically heated core simulator, made of 7 FAs, which delivers to the primary coolant (lead) a nominal thermal power of 2210 kW, a main coolant pump for lead circulation and a counter-current shell and tubes main heat exchanger. The heat exchanger bundle is of double wall bayonet tubes type, and it is fed by pressurized water by a dedicated secondary circuit. A preliminary analytical calculation has been performed to identify the most suitable configuration for the ATHENA heat exchanger, as well as to achieve a preliminary sizing of the component. The final layout foresees a bundle of 91 bayonet tubes, arranged in a cylindrical geometry, having an active length of 5000 mm and adopting an external double wall tube geometry with a pressurized helium gap. A numerical model of the heat exchanger has been developed using the thermal-hydraulic system code RELAP5/Mod3.3, and a numerical sensitivity analysis on the geometrical and operating parameters has been carried out to verify the performances of the component.
