Extend the Emission concept

[AhlemRhayem]

Hello,

We need to add the following concepts as sub-classes of the emission concept:

• Hydrogen permeation: Diffusion of hydrogen ions through the thin metal isolation in valves and instruments either through interstitial or substitutional (vacancy) mechanisms.

• Boil off gas: Boil of gas (BOG) is the natural evaporation of a cryogenic fluid (LH2, LNG, LPG...) inside a tank due to the admission of external heat into the tank.