ATHENA Integral Test Facility: Secondary System Design and Thermal-Hydraulic Assessment with RELAP5 Code

In support to the development of ALFRED reactor , FALCON consortium identified within the envisaged experimen tal infrastructures, two main facilities to address the pool thermal hydraulic issues and progressively demonstrate the performances of the revised ALFRED configuration and of its main components: the Advan c ed Thermo Hydraulics Experiment for Nuclear Appli cation facility (ATHENA) and the European Lead Fast facility ( In particular, ATHENA is a large pool type lead cooled multi-purpose experimental infrastructure that features a large size vessel (3.2 m diameter, 10 m in height), which is conceived to host and to test single and coupled ALFRED full scale components . The test section to be installed in the main vessel includes an electrically heated fuel pin simulator which delivers to the primary coolant (lead) a total thermal power of 2.21 MW , a main coolant pump and a counter current shell and tubes main heat exchanger. The heat exchanger bundle is of bayonet tubes type and it is fed by pressurized water provided by a dedicated secondary system. Thermal-hydraulic system codes are currently employed as numerical tools to support the design phase and the safety analysis of nuclear related technologies. In this paper, RELAP5/Mod3.3 code has been used to realize a numerical model of the main heat exchanger o f the ATHENA facility along with its secondary system. The simulations carried out provide feedback on the thermal hydraulic performances of the component, as well as information relevant for the design of the secondary loop and the definition of its operational phases.