Pre-Test Analysis of a PLOFA Scenario for CIRCE-THETIS Facility by Means of Coupled STH/CFD Calculations

In the context of GEN IV fission power reactors, the Liquid Metal Fast Reactors (LMFRs) stand out as a promising solution, introducing a better radioactive waste management and new safety features with respect to previous NPPs generations. Numerous EU projects have been started to support the development of such kind of reactors. This work is in support of the CIRCE-THETIS experimental campaign foreseen at the ENEA Brasimone Research Centre (RC), in the framework of the EU project PATRICIA. This paper focuses on the pre-test analyses of one of the postulated Protected Loss Of Flow Accident (PLOFA), foreseen during the experimental campaign, investigating the safe cooling strategies for such kind of scenarios: in the considered case, the SG was used as decay heat removal system. The facility was represented using a coupled CFD/STH approach with an explicit time advancing scheme. The model was deeply examined to ensure the best representation of reality, aligning with the preliminary evaluation from the experimentalists. Particular attention was paid to the SG heat transfer prediction due to the new helical geometry that provides heat transfer enhancement and to the thermal-hydraulics phenomena occurring inside the pool during the postulated transients.