The radioactive gases are quite short-lived. The worst one is Nitrogen (I think it is N-18), but it literally decays in minutes. The hydrogen is so chemically reactive (and has such a small neutron absorption rate) that it would never escape the primary coolant. Hydrogen gas is really only a problem during a continuous control rod withdrawal casualty (don't worry it's too late for this to happen), where control rods withdrawal so fast that hydrogen explodes.
I only know all this crap because it was crammed down my throat at gunpoint at Navy Nuclear Power School