Introduction

Europe is currently spearheading the development of Lead-cooled Fast Reactors (LFRs)—a next-generation nuclear technology that uses molten lead as a coolant instead of water. Because lead has a very high boiling point and excellent natural cooling properties, LFRs offer enhanced safety, sustainability, and the potential for modular, cost-effective energy production. SCK CEN is a key member of the European consortium dedicated to bringing this technology to market, focusing on the design and licensing of these innovative systems.

A critical hurdle in the licensing and safety assessment of LFRs is the accurate prediction of fission product behavior. To ensure these reactors meet modern safety standards, it is essential to understand how radionuclides are released and transported from the source into the reactor hall. This requires a transition from simplified models to advanced numerical frameworks capable of simulating complex reactive transport processes, including evaporation and deposition, in a dynamic environment.

This research project focuses on bridging the gap between chemical thermodynamics and fluid mechanics. By coupling a chemical equilibrium model with professional-grade Computational Fluid Dynamics (CFD) codes, we aim to create a robust tool for predicting fission product transport and release. This work will provide the high-fidelity simulations necessary for code validation and the development of safety-related experimental platforms, ultimately supporting the viability of LFR technology.

Objective

The primary objective of this thesis is to develop and evaluate a coupled numerical approach for simulating the reactive transport of fission products. The student will gain proficiency in both thermodynamic modeling (HSC, GEMS) and CFD transport codes (T-Flows, Fluent, and/or COOL-M). The work involves building a functional interface between these codes (leveraging a modern programming language such as Python) and evaluating the reliability of the integrated system by comparing results against commercial benchmarks and experimental data.

Research questions

• Do different chemistry databases offer a comparable and accurate description of radionuclide chemistry?
• Do different CFD codes offer equivalent functionality and performance?
• How can chemistry and CFD codes be efficiently coupled?
• How accurately can the coupled CFD-chemistry approach be validated against experimental results regarding the evaporation and transport of fission products?
• What are the main challenges in terms of calculation time when running high-fidelity chemical simulations within a 3D fluid environment, and how can they be managed?