Also, at the Children of the Cathedral in the Hub there is a locked room in the northwest corner you can pick. On the shelf of a bookcase you can steal Rad-X as well as Rad-Away.
The effects of Rad-X are stackable up to two subsequent doses, but taking an immediate third dose of Rad-X has no effect. This is due to the fact that in the original Fallout, taking two doses of Rad-X granted 100% radiation resistance, enough to survive the most irradiated place on the map for several hours.
