Thermal-hydraulic analysis of the LORELEI test design by means of CATHARE2 V2.5

LORELEI (Light Water One-Rod Equipment for LOCA Experimental Investigation) test device is currently under design in the framework of the planned experimental facilities of the Jules Horowitz Reactor. The objective of this devise is to analyze the thermal-mechanical behavior of the fuel rod and the radiological consequences during a Loss of Coolant Accident (LOCA). This paper deals with an accurate modeling of the LORELEI test device by means of the system code CATHARE2 V2.5. The experimental device and its geometry is described together with the experimental parameters and the different phases of the test planned accident. The modeling and testing are dedicated to the study of the re-irradiation and the dry phase. The re-irradiation phase is not a part of the LOCA accidental sequence but it is modeled to provide a study concerning the nominal and abnormal conditions by finding out the device thermal-hydraulic limits. In this first phase, aiming at creating a detectable fission product inventory, the device is filled with water and the fuel rod is cooled by a convection loop. During the dry-phase, the device simulates the first part of a LOCA accidental scenario. The fuel cladding temperature is increased up to 1200 °C and a small amount of water is set in the bottom of the device to produce steam needed to investigate the exothermic reaction with the fuel cladding. The object of this last part is to plan the operating test sequences and determine the best thermal conditions to reach an acceptable fuel cladding temperature profile.