a junction assembly with leak detection means comprising a pair of mating surfaces forming the junction of two fluid conduits , means forming an annular containment chamber in at least one of the surfaces circumscribing the conduit passageway , a pair of spaced apart o - ring seals respectively disposed on opposite sides of the containment chamber , a fluid sensor extending into the containment chamber for sensing the presence of unwanted fluids therein due to the failure of an o - ring seal and a control system for responding to an output signal generated by the sensor to deactivate the system in the event of failure .