JRP CALL information
Supported By

European Commission

Short description of the work

Post-mortem examinations (XRD, Raman, XAS etc.) after laser melting experiments are needed to study the changes induced in the sample’s properties. We performed several melting experiments at ITU Karlsruhe on MOX samples with six compositions (Pu/U+Pu at% = 14, 24, 35, 46, 54 and 62). Two series of experiments were carried out – one in Ar and one in air (pressurized to 3.5 bars). The post-mortem examination at the ANKA synchrotron was divided in two parts. First, we collected data at the L edges, mainly to study local structure and electronic properties around each cations. Four pairs of samples were chosen (MOX14, MOX46, MOX54, MOX62), each with the same composition, with one sample melted in air and the other in Ar. We recorded spectra at room temperature at the UL3, UL2 and PuL3 edges.
In the case of the samples treated in Ar, slight changes were observed in the XANES spectra (at the PuL3 and UL3 edges) as compared to the stoichiometric references UO2 and PuO2. The results of linear combination fitting hint towards slight oxidation of U cations in MOX14 and slight reduction of Pu cations in MOX62. MOX46 and MOX54 contained both oxidized U and reduced Pu.
Uranium spectra collected on samples treated in air show strong deviations from UO2. It appears that in each case the white lines could be placed between those of U4O9 and U3O8 references. Data found in literature suggests that oxidation will readily occur in MOX in the considered temperature range (300-3000 K) under air. Thus, linear combination fitting using U3O8 and U4O9 was done to estimate the composition of each sample. With increasing Pu content, the level of oxidation decreased. Also, for samples rich in Pu (MOX54 and MOX62) the PuL3 spectra are shifted towards lower energies, indicating a slight reduction of Pu.

Main visitor contact data
Name: Michal Strach
Organisation: CEA Cadarache

JRP Identification
JRP nr: TALI-C03-13
JRP title: Minimum melting temperatures and HR-XANES studies of (Ux,Pu1-x)O2 with varying plutonium content
JRP scope: Scope 3: Actinide materials

Visited Associated Pooled Facility
Visited APF during the stay: KIT-INE - Beamline
Name of the APF Contact Person: Thorsten Schaefer

Other APF and organisation involved in the JRP
Other organisations involved:
Other APF involved in the project: JRC-ITU - Labs & Hot-cells

Description of the work done at the associated pooled facility
Start date of the stay: 2/5/2015
End date of the stay: 2/6/2015
Quantity of access: 2
Access Unit: Days

Other APF visitors of the JRP during the stay
Visitor 2: Philippe Martin (CEA Cadarche)
Visitor 3: Dario Manara (ITU Karlsruhe)
Visitor 4: Damien Prieur (ITU Karlsruhe)
Visitor 5: