Impact of SEM acquisition parameters on the porosity analysis of irradiated U-Mo fuel

•Scanning electron microscopy (SEM) is usually employed to analyze fission gas porosity in irradiated U-Mo fuel.•In back-scattered electron (BSE) mode, the electron beam voltage, among various acquisition parameters, strongly affects the way fission gas bubbles are imaged and, as such, characterized.•The difference is attributed to different electron penetration depths, as corroborated by Monte Carlo simulations, and geometry relations between bubbles and the polished sample surface.•The same, and possibly low (<10 kV), SEM voltage must be employed in order to increase the robustness of porosity analysis performed in different laboratories.