A319 Captain reported during walk around finding fuel leaking from the lower fuselage area and after discussing with maintenance decided to refuse aircraft.

Narrative

While doing a walk around with my trainee FO; we discovered fuel on the ground which was coming from multiple locations on the ram air temperature doors.Discrepancy was written up. Maintenance responded and eventually found a leak from some sealant external of the left main tank. Leak was deferred for a ferry to ZZZ due to it being 1 drop per two minutes at the source; however the external presentation of the leak was at least 3 drops per minute from the ram air temperature area and from at least two locations on the ram air temperature doors. This indicates to me that what maintenance found wasn't the only source of the leak; or that fuel was pooling in the aircraft fuselage somewhere.Either of those situations makes the aircraft unsafe for flight given that the location of the fuel potential pooling or unfounded leak. There is no fire warning or suppression for that area of the aircraft and there are hydraulic and electrical potential sources of ignition in that area. Crew would have been potentially subject to a loss of aircraft control due to a fire that they would never have known about and could not fight; even if they had. The Jet crash in the Everglades immediately comes to mind.In addition; Maintenance Control mentioned that we don't seal tanks externally; but yet I was shown pictures of external sealant on the left main tank to include the point of the leak; which leads me to believe that there has been undocumented maintenance performed on this aircraft.Aircraft was refused for the ferry flight as it was determined that the location and amount fuel leaking made it unsafe to fly.