Glossary letter V

Vacuum Tube Collector (Solar)

A panel made up of glass vacuum tubes containing a heat transfer fluid for optimal thermal insulation. The vacuum significantly reduces heat loss. The heat transfer fluid carries the heat generated to its point of use, such as a radiator or water heater.

Vitrification (Nuclear)

The process of converting a substance into an amorphous glass or slag material through high-temperature melting followed by rapid cooling. In the nuclear industry, this technique is used to stabilize and contain radioactive waste.


In physics and chemistry, the tendency of a substance to change from a liquid to a gas (vaporization) or from a solid to a gas (sublimation). A fuel's volatility is a key property when determining its quality.