JRP CALL information
Supported By

European Commission

Short description of the work
During this stay, the first X-ray Absorption Spectroscopy measurements on transuranium-bearing samples at high temperature and under controlled atmospheres were performed. The data were collected using an experimental set-up especially developed for this experiment.
XANES (X-ray Absorption Near Edge Structure) measurements were performed on uranium-gadolinium and uranium-americium samples from 300 to 1400 K at both U and Am L3 edges. The samples were WAR (Weak Acid Resin) microspheres loaded with U and Am or Gd. These compounds are used as potential new precursor for the fabrication of mixed oxide nuclear fuels and transmutation targets for fast neutrons reactors. Using this new in-situ XAS set-up, the calcination under air of these amorphous compounds to an oxide was monitored through the determination of the cation oxidation states and local symmetry at different temperatures.
The first results highlight the oxidation of uranium during the oxide formation while americium remains mostly trivalent. Once calcination was completed, the reduction of the same sample under Ar-H2(4%) was then performed in-situ and monitored. It was shown that a reduced U(+IV)/Am(+III) mixed oxide is obtained at high temperature. After cooling down to room temperature in 10 minutes, a slight oxidation of uranium was observed, leading to a mixed +IV/+V oxidation state in the final mixed oxide. A final sample close to what was previously observed with our past ex-situ XAS was thus obtained. This TALISMAN-JRP therefore allowed the achievement of the main objective of this project: performing high temperature XAS measurements on transuranium-bearing samples. Moreover, the developed experimental setup is now fully validated and would be available for the study of other actinide systems.

Main visitor contact data
Name: Florent Lebreton
Organisation: CEA Marcoule - DEN/DTEC/SDTC/LEMA + Université de Limoges

JRP Identification
JRP nr: TALI-C02-09
JRP title: In-situ XAS measurements at high temperature on transuranium-bearing oxide fuels and precursors
JRP scope: Scope 3: Actinide materials

Visited Associated Pooled Facility
Visited APF during the stay: KIT-INE - Beamline
Name of the APF Contact Person: Kathy Dardenne – Joerg Rothe

Other APF and organisation involved in the JRP
Other organisations involved: CEA Cadarache - DEN/DEC/SESC/LLCC (Philippe Martin);; IPGP (Daniel Neuville), ; Université de Limoges (Florent Lebreton); ; Université Montpellier 2 (Marie Caisso)
Other APF involved in the project:

Description of the work done at the associated pooled facility
Start date of the stay: 6/1/2014
End date of the stay: 6/13/2014
Quantity of access: 6
Access Unit: Days

Other APF visitors of the JRP during the stay
Visitor 2: Marie Caisso, Ph.D student (CEA Marcoule - DEN/DTEC/SDTC/LEMA + Université Montpellier 2)
Visitor 3: Dr Philippe Martin (CEA Cadarache - DEN/DEC/SESC/LLCC)
Visitor 4: Dr Laure Ramond (CEA Marcoule - DEN/DTEC/SDTC/LEMA)
Visitor 5: Michal Strach, Ph.D student (CEA Cadarache - DEN/DEC/SPUA/LMPC)