The proposed internship will be realized within the framework of an international OECD/NEA project, called ATRIUM (Application Tests for Realization of Inverse Uncertainty quantification and validation Methodologies in thermal-hydraulics): https://www.oecd-nea.org/jcms/pl_83562/application-tests-for-realisation-of-inverse-uncertainty-quantification-and-validation-methodologies-in-thermal-hydraulics-atrium.

The thermal-hydraulic code CATHARE is the reference code for the safety analysis of French nuclear reactors. It is based on a set of six conservation equations (mass, momentum and energy for the liquid and vapor phase) complemented by appropriate closure laws. The validation of these semi-empirical laws and the associated uncertainty quantification is a fundamental issue. The validation is based on experiments at different scales covering the operating domain of nuclear reactors. In particular, the global validation of the code is carried out using the experimental data coming from reactor-scale thermal-hydraulic loops, also called Integral Effect Tests (IETs). These loops are representative of the primary and secondary circuits of nuclear reactors. Different scenarios can be reproduced to improve the understanding of the physical phenomena occurring during an accident.

The internship consists in studying the impact of uncertainties on an accidental scenario in the LSTF IET facility. In details, the candidate will:

• Understand the physics of the experiment;

• Improve its existing CATHARE modelling, if needed;

• Perform propagations of uncertainties and sensitivity analyses to different physical models using appropriate statistical methods;

• Comparing the impact of different statistical hypotheses/methodologies on the results

• Present and discuss his/her work during international technical meetings and write a final report.

The candidate should have a good knowledge of fluid-dynamics/thermal-hydraulics, ideally applied to nuclear reactors. A basic knowledge of Linux, Excel and Python/Matlab is desired. A good knowledge of English is a must. French would be a plus.