Validation of the intermediate heat exchanger modelling for fast reactors with the CLAUDINA experimental data

The following thesis refers to the work carried out at the Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) in Saclay. This work aims to improve the modelling of the Intermediate Heat Exchanger for Sodium-cooled Fast Reactors. The purpose of the work was to assess various models and approaches for CLAUDINA, a sodium-sodium heat exchanger designed for civil applications. Chapter 1 provides a concise overview of the Generation IV scenario, with a particular focus on the Sodium-cooled Fast Reactors. The 2nd chapter introduces the CLAUDINA facility and compares it to the heat exchanger in Phénix. In the third chapter, the experiments studied are reported classified by set-up typology based on the several experiments that were conducted at the CLAUDINA facility during the late 1980s and early 1990s. These tests can be divided into two main families of experiments: standard and clogged tube tests. Finally, also a transient test was studied. Chapter 4 describes the CATHARE code and the results of the stand-alone calculations for each model, comparing new and experimental results. In the code, the EXCHANGER mode facilitates the definition of the heat exchange correlations on both the primary and secondary sides. There is also a comparison of the results obtained with CATHARE2 and CATHARE3 codes. The second code used is the MATHYS code, explained in Chapter 5. Validation of the MATHYS lead Trio_CFD and CATHARE coupling includes testing different heat exchange correlations compared against experimental data. For what concerns the transient test, a first attempt to run was not successful due to an error in the input deck. All of these results paved the way for Computational Fluid-Dynamics (CFD) calculations in Chapter 6, using Neptune_CFD. This aims for a more realistic exchanger description to enhance the precision of the coupled model. The singular pressure drop approach was the only approximation used.