Heat dissipation in transportation of nuclear materials is strongly dependant of radiation exchanges from the external faces of the protective caisson, surrounding nuclear material packaging. However, the thermo-optical properties of the external paint, total hemispheric emissivity and solar absorbance factor, are degraded during transportations. This degradation is due to the dirtying, and does not permit to fully use high emissive and low absorbent paint.
Commercial “easy-to-clean” coating has been tested on epoxy-based paint. This transparent varnish is hydrophobic and release dirt out of the treated surface.
Laboratory dirtying tests with “carbon black” solution simulate penalizing dirt exposure. And different measurements (colour lightness, total hemispheric emissivity and solar absorbance factor), made before and after dirtying and cleaning steps, permit to quantify the “easy-to-clean” property of this coating.
The commercial coating tested in this study does not modify the initial thermo-optical properties of the paint, and is very efficient to maintain them after dirtying and simple cleaning steps. So, the addition of this coating could be an easy way to improve the heat release during nuclear material transportations.
Dirt exposure test on real caisson are in progress to confirm the conclusions of this laboratory study.