High wettability of liquid caesium iodine with solid uranium dioxide

Area of Science:

• Nuclear Chemistry
• Materials Science
• Environmental Science

Background:

• The Fukushima Daiichi Nuclear Power Plant accident released volatile fission products, causing environmental contamination.
• Understanding the behavior of fission products like cesium and iodine is crucial for assessing public exposure and environmental impact.
• Specific mechanisms of fission product release and migration from molten nuclear fuel remain unclear.

Purpose of the Study:

• To experimentally investigate the interaction between liquid cesium iodide (CsI) and solid uranium dioxide (UO2).
• To elucidate the pathways and mechanisms governing the migration of volatile fission products from nuclear fuel.
• To introduce the concept of wettability for assessing fission product behavior.

Main Methods:

• Experimental analysis of liquid CsI interaction with solid UO2.
• Measurement of contact angles to determine wettability.
• Microscopic observation to identify CsI infiltration into UO2 pores.

Main Results:

• Liquid CsI exhibits favorable dispersion on solid UO2, with a contact angle near zero.
• CsI was observed infiltrating UO2 samples to depths of tens of micrometers.
• The infiltration is attributed to liquid CsI penetrating the porous network within the UO2 structure.

Conclusions:

• The wettability of liquid fission products on solid fuel surfaces significantly influences their migration and evaporation.
• Fission product behavior is dictated by the solid-liquid interface properties and fuel material characteristics.
• This study provides a framework for accurate assessments of volatile fission product release from nuclear fuel.