On 20 & 21 February 2020, the first irradiations of neptunium-237 (237-Np) in solution by high-energy alpha particles from the ARRONAX cyclotron (67.4MeV) took place. This kind of irradiation by an alpha emitter, external moreover, had never been performed before.

Emeline Craff, PhD student in the Radiochemistry team of the Subatech laboratory, conducted during the irradiation an in situ monitoring of the modifications of the 237-Np oxidation states and speciation by UV-Visible-NIR absorption spectroscopy.

The absorption spectra obtained in this way allow species hypotheses to be formulated. The next step will be to isolate these species for analysis by EXAFS (Extended X-Ray Absorption Fine Structure) spectroscopy on the SOLEIL synchrotron.

This work was carried out in collaboration with the University of Nevada, Las Vegas (UNLV), the Institute of Separative Chemistry at Marcoule (ICSM, UMR 5257), IPN-Orsay and the SOLEIL synchroton (MARS light line), as part of Emeline Craff’s thesis, funded by the University of Nantes, on the hydrolysis of Np under alpha/gamma radiation.

Contacts : Emeline Craff et Johan Vandenborre, Subatech laboratory