Reassessing the melting temperature of PuO2

The melting behavior is a fundamental property of a material, closely related to its structure and thermodynamic stability, and has therefore been a crucial subject of research for ages. The melting point is also an important engineering parameter, as it defines the operational limits of a material in its application environment. This point becomes critical in nuclear engineering where the thermo-mechanical stability of a nuclear fuel element is a key factor determining fuel performance and safety. However, experimental difficulties stemming from the extreme temperatures, complex pressure-temperature-composition relations, and the high radioactivity make the study of melting of refractory actinide compounds particularly challenging. As a consequence, experimental data are rare and subject to large uncertainties, and more reliable experimental techniques are badly needed. A novel experimental approach is presented here, yielding new data and allowing a re-assessment of the PuO2 melting behaviour.