JRP CALL information
Supported By

European Commission

Short description of the work
Six MOX samples were studied with different Pu content: 14, 24, 35, 46, 54 and 62 mol%. The starting materials were sintered stoichiometric disks cut from pellets. For each composition we have performed up to 4 laser melting experiments – two in pressurized Ar and two in Air, each consisting of four shots of different duration and intensity. During the experiments we recorded the temperature at the surface of the sample with a pyrometer. The normal spectral emissivity of the sample was also studied with the help of a multi-channel spectro-pyrometer. Phase transitions were also qualitatively identified with the help of a reflected blue laser.
We noticed interesting differences between the melting behaviour observed in different atmospheres.
In Argon, the observed melting/freezing temperatures for the investigated compositions seem to be consistent with the stable near-stoichiometric fluorite phase across the thermal cycles. In this case the experimental points match the Calphad optimized phase boundaries well.
In Air, the observed melting/freezing transitions occur at a systematically lower temperature, the lower is the Pu content. This observation is consistent with the fact that Uranium dioxide is easily oxidized on the surface forming new chemical species (like MO2+x, M3O8, M4O9 etc.), which melt at a lower temperature and are more volatile.
Preliminary Raman spectroscopy investigation confirms these trends.
Further characterisation of the treated samples will be done using HR-XAS, XRD and SEM in the upcoming months.
With these results we hope to enhance the understanding of the melting behaviour of near-stoichiometric MOX materials and also gain insight into the behaviour under an oxidizing atmosphere.

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

JRP Identification
JRP nr: TALI-C03-13
JRP title: Minimum melting temprature and HR-XANES of UPuO2 materials
JRP scope: Scope 3: Actinide materials

Visited Associated Pooled Facility
Visited APF during the stay: JRC-ITU - Labs & Hot-cells
Name of the APF Contact Person: Philippe Raison

Other APF and organisation involved in the JRP
Other organisations involved: CEA Cadarache
Other APF involved in the project:

Description of the work done at the associated pooled facility
Start date of the stay: 11/3/2014
End date of the stay: 11/14/2014
Quantity of access: 10
Access Unit: Days