Carlos CIFUENTES will defend his PhD thesis entitled : “Laser micro macro-machining of nuclear fuels: towards a multiscale approach of material properties”, which will take place on Tuesday, December 16th at 02:00 p.m., in the salle des thèses, campus St. Jérôme, Marseille.
A Zoom link will be provided later. The presentation will be given in French.
Members of the Jury :
- Florence GARRELIE, Laboratoire Hubert Curien, Université Jean Monnet, Rapporteuse
- Rodrigue LARGETON, EDF Lab les Renardières, Rapporteur
- David GROJO, LP3 – CNRS, President of the Jury
- Alexandre SEMEROK, CEA Saclay, Examinateur
- Laurent GALLAIS, Institut Fresnel – Centrale Méditerranée, Thesis Director
- Yves PONTILLON, CEA Cadarache, Thesis Co-Director
- Thomas DOUALLE, CEA Cadarache, encadrant CEA invited
Abstract : Safe operation and the development of current and next-generation reactors re-quire an in-depth understanding of materials properties and, consequently, sample-preparation routes that do not alter the fuel microstructure while remaining com-patible with local analyses. Laser micro/macro-machining is investigated here as a potential solution for cutting fuel materials, with the aim of reducing the impacts and potential damage associated with fabrication processes. In this context, this dissertation establishes an integrated strategy for ultrashort-pulse laser micro/macro-machining of nuclear fuels, applied to fresh uranium dioxide, combining the development of a dedicated experimental platform with associated thermal modelling. Complementary in-situ infrared thermography is employed to quantify and interpret the extent of the heat-affected zone. Prior to the study of the nuclear ceramic, an assessment step was carried out on a test material, graphite, in order to validate and establish the experimental and analysis protocols. This work constitutes the first demonstration of cutting UO2 with an ultrashort laser at 1030 nm using 300 fs pulses in the MHz regime. The main results identify an operating window that limits thermal effects and thereby preserves specimen integrity. Under the identified conditions, the Heat-Affected Zone is on the order of 5 µm and sub-millimetre cuts display regular edges. In conclusion, the coupled measurement–modelling approach provides operating rules from single-pulse to cutting regimes, together with a framework transferable to other nuclear ceramics and, ultimately, to irradiated fuels where control of thermal effects is even more critical.
Keywords : Laser macro/micromachining, Uranium dioxide (UO2), heat-affected zone, infrared thermography, thermal modelling
