Alessio Pesetti

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.Copyright

Test Section Design for SGTR Experimental Investigation in CIRCE Facility for HLMRS Supported by SIMMER-III Code

In the framework of MAXSIMA project, the design of a large-scale Test Section (TS), aiming to experimentally investigate the Steam Generator Tube Rupture (SGTR) postulated event in a relevant configuration for Gen IV MYRRHA reactor, was carried out. The TS will be implemented in the large pool CIRCE facility, at ENEA CR Brasimone. The TS is composed of four tube bundles representing a full scale portion of the Primary Heat eXchanger (PHX) of MYRRHA plant. They allow the execution of four SGTR tests, one at a time, excluding the necessity to extract the TS from the facility after each test. Water is foreseen to be injected at 16 bar and 200°C in the pool, partially filled by LBE at 350°C with a cover gas of argon at about 1 bar.The pressurization transients of CIRCE vessel and the sizing of the discharge lines and relative rupture disks were numerically predicted by SIMMER-III code on the base of a preliminary simplified configuration of the TS. The obtained results showed that the design pressure of CIRCE main vessel was not reached during more than 10 s of water injection, implementing a singular rupture disk having a diameter of 2 inch activated at 6.5 bar. It appears more than enough to notice, in a real reactor, the occurrence of the SGTR event and stop the water supply, interrupting the accidental scenario. These numerical results were adopted to support the design of the presented TS.Copyright