[en] Particle analysis of environmental swipe sample is used by the International Atomic Energy Agency (IAEA) to detect the presence of undeclared nuclear activities. Swipe samples from uranium enrichment plant typically contain fluorine. U_O2F₂ is known to lose fluorine over time, which may be accelerated by exposure to UV-light and elevated temperatures. Of particular interest is the assessment of the reduction of fluorine by UV-light. For this, the uranyl-fluoride (UO₂F₂) particles are formed from the reaction between the uranium hexafluoride and the steam in air. The relative a mount of fluorine was measured from UO₂F₂ particles after different exposure to UV-light by scanning electron micros copy combined with energy-dispersive X-ray spectrometry (SEM-EDX). Appropriate working parameters were selected by conditional experiments. The results from SEM/EDX show no significant fluorine reduction trend on UO₂F₂ particles after different exposure to UV-light, which may be improved by adjusting working conditions or be completed by other measurement techniques. (authors)