Try wrapping the chips in foil or use wood chunks instead on the skillet. Chips directly on the skillet will burn out quickly I would imagine. Your UDS is almost like a gas grill with open vents for the burner. Wood chips should be wrapped in foil.
Also, be extra cautious to make sure you have no trapped gas in the drum prior to lighting.
....UDS....Mini-WSM....Midi-WSM....Mod-ECB....22.5-OTG....34"wood fired pizza oven....