Well, in theory, the primary system would be sealed so that the fission products are extracted from the coolant. The gases and volatiles would certainly have to be collected and held up to decay, and then that stream would have to be processed.Well, you can always deport them back to Transurania or force them to stop cross dressing and remain uranium-atoms...
[Sorry, could not help it...please don't ban me!?]
Molten salt reactors would have issues with the release of volatile fission products (Xe, Kr, I, Cs and so fourth). In todays' solid fuel the leakage is quite small and does not cause serious concern as most fission products are locked in the oxide matrix. For MSR's the solution around this would require some form of double cotainment to stop significant leakage of fission products outside the plant.