This work uses an external alpha beam to irradiate an uranium oxide/water interface and investigates the release of uranium in aerated deionized water under alpha irradiation. A high energy alpha beam delivered by a cyclotron (CERI-CNRS) goes through the oxide and emerges in the water with a 20 MeV energy. First results are reported here showing that the uranium mass loss rate increases by three orders of magnitude in aerated deionized water under high flux (≥3.3×1010 α.cm−2s−1).