The microstructure of nuclear fuel undergoes significant changes under irradiation, necessitating access to specific areas within fuel pellets for post-irradiation examinations, particularly for studying the release of fission gases resulting from post-accidental reactions in events such as Reactivity Initiated Accidents (RIA) and/or Loss of Coolant Accidents (LOCA), or for studying material properties. The objective of developing a micro-machining approach preserving the physicochemical integrity of the worked piece while minimizing thermal and mechanical effects is essential. We propose a high-resolution and non-destructive method, ultrafast laser ablation micro-machining, as an innovative solution for this application. We present experimental and numerical studies aimed at evaluating the feasibility of applying this process to the preparation of irradiated UO2 samples of various dimensions (ranging from μm to cm). Our preliminary work on graphite, as a model material, validates the feasibility of this approach, and we intend to transfer the technique to non-irradiated UO2 and eventually apply it to irradiated material.
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