LBE-Water Interaction in LIFUS 5 Facility to Study a SGTR Event Under ELSY Reactor Conditions

In the framework of the research activities of the EURATOM FP6 project named ELSY (European Lead-cooled System), aimed at demonstrating the possibility of designing a competitive and safe fast critical reactor based on the Generation IV Lead Fast Reactor (LFR) concept, the study of the lead-water interaction following an incidental SGTR (Steam Generator Tube Rupture) event is an important issue to address. To simulate such event, an experimental test has been carried out on the LIFUS 5 facility at the ENEA Brasimone Research Centre, in order to assess the physical effects and the possible consequences connected to this kind of interaction. The experiment has been conducted by injecting water at the pressure of 185 bar and with a temperature of 300 °C into a volume of 80 l of Lead Bismuth Eutectic (LBE) kept at atmospheric pressure and at a temperature of 400 °C. The experimental facility has been suitably modified in order to reproduce as close as possible the operating conditions of the ELSY Steam Generator Unit (SGU), in which a free volume of cover gas (argon) is foreseen at the top of the system, with the objective to dampen the pressure waves inside the SGU itself. The experimental test has been supported through a numerical modelling campaign performed at the University of Pisa by means of the SIMMER code within both 2-D (SIMMER III) and 3-D (SIMMER IV) models. Pre-test simulations have been carried out to aid the design of the new facility configuration and to select the test conditions which could better reproduce the behaviour expected for ELSY. In addition, a post-test analysis has also been accomplished, allowing to compare the numerical and experimental results, so as to validate and assess the performance of the code when employed for this kind of applications.