Water/Pb-Bi Interaction Experiments in LIFUS5/Mod2 Facility Modelled by SIMMER code

The new generation Heavy Liquid Metal Reactors (HLMRs) are characterized by a pool type configuration having high pressure steam generators set inside the reactor vessel. The primary (hot low pressure LBE melt) and secondary (high pressure sub-cooled water) coolant could come into contact as consequence of Steam Generator Tube Rupture (SGTR) phenomenon, that cannot be considered negligible. The structural integrity of the reactor internals, steam generators in particular, could be affected by the SGTR scenario consequences. The pressure wave propagation, cover gas pressurization, domino effect on the surrounding tubes, reactivity feedback due to steam dragged into the core, primary system pollution and slug formation constitute the most hazardous effects of the SGTR accident. Therefore, this accidental scenario constitutes a safety issue in the design and in the preliminary safety analysis. A key issue in the SGTR analysis for HLMRs is constituted by the availability of qualified experimental data, suitable to be extrapolated to full scale plant and to support the computer code development and demonstrating the code reliability in the phenomena prediction (qualified code). In this paper, part of the experimental campaign performed in the LIFUS5/Mod2 facility at ENEA CR Brasimone (in the frame of the THINS project), investigating the water-LBE interaction, is reported. The experimental activity aimed to provide high-quality measurement data for supporting the development and validation phase of computer codes for SGTR numerical simulation. The reported experimental test has been numerically simulated by SIMMER III code. The pressure, temperature and injected water mass flow rate time trends have been computed during the water-LBE interaction in the reaction vessel. The work aims to evaluate the prediction capability of the two-dimensional SIMMER III code and to determine the suitability of the SIMMER code physical models.