Instant release EOS7R
To simulate an instant release of a radionuclide in eos7r, we have to insert a no-zero value of the component in the INCON block. This value should be the mass fraction of the component that will be released. My doubt is how to calculate this mass fraction. If there is only the single phase liquid, is the radionuclide mass fraction the ratio between the mass of the radionuclide released and the total mass of the brine in the system?
The aqueous phase mass fraction is a local, grid-block-specific concentration, defined as the mass of radionuclide dissolved in aqueous phase in the grid block divided by the total mass of aqueous phase in that same grid block. The aqueous phase mass includes the mass of all dissolved components.
Somehow I think you may be asking a question different from how I interpreted it, so please feel free to follow up.
If I well understood, the release rate in GENER block constitues a flow-through conditions (kg/s), but using the INCON block it constitues an instant release expressed in mass fraction. Apparently, as Curt says, this mass fraction corresponds to the total mass of Rn dissolved in aqueous phase divided by the total mass of the aqueous phase in the considered grid block.