Radiochemistry / Theme "Physical Chemistry of Irradiated Materials"

The radiolysis is the set of chemical transformations in materials caused by absorption of energy from ionizing radiation. Radiolysis is present at every stage of the nuclear fuel cycle: the reactor core, fuel reprocessing, waste storage ... The consequences of alpha- and gamma- radiolysis of the systems studied are very different and involve parallel studies along several complementary directions. They were initiated in SUBATECH through collaboration with the LCP d’Orsay as part of a doctoral thesis in 2006. They continue today closely associated with the cyclotron ARRONAX. These research projects are well structured and constitute part of an interdisciplinary collaborative efforts involving several laboratories.

The studies in Nantes are particularly focused on the effect of alpha radiation. We are interested in speciation in solution and at solid/solution interfaces. In addition to the post-irradiation analysis, the project now has two coupled instruments: an UV-visible spectrophotometer and a Raman spectrometer.

These research activities are grouped now around three projects:

• Radiolytic yields - the measurements in order to quantify the formation of radical species or molecular species in water as function of the beam parameters (intensity, energy, dose, ... ) and as function of chemical parameters (pH, solution composition, solvents, gas partial pressure, temperature, ...). For these studies, a system of pulsed alpha radiolysis synchronized with a light probe is being developed.

• Radiolysis and corrosion at the solid/liquid interface - This project focuses on the study of the effect of alpha radiolysis on materials of interest in the nuclear fuel cycle (storage, reprocessing, ...) . We are currently especially interested in the UO2 matrix.

• Irradiated materials : This project develops in collaboration with DAHER and concerns the effects of radiation on the structure of materials in the context of decommissioning of nuclear reactors.