Nuclear instrumentation cable end seal

An improved coaxial end seal for hermetically sealed nuclear instrumentation cable exhibiting an improved breakdown pulse noise characteristic under high voltage, high temperature conditions is described. A tubular insulator body has metallized interior and exterior surface portions which are braze sealed to a center conductor and an outer conductive sheath. The end surface of the insulator body which is directed toward the coaxial cable to which it is sealed has a recessed surface portion within which the braze seal material terminates