An Interfacing Systems Loss-Of-Coolant Accident (ISLOCA) is a breach in a system that interfaces with the reactor coolant system (RCS) and could cause a loss of coolant accident, if the breach is not isolated from the RCS. Such a breach could be caused if valves fail to isolate the RCS from an interfacing system not designed for the high RCS pressures. When portions of an interfacing system are located outside the containment, particular concern arises because an unisolated system breach outside containment can result in a release of radionuclides that bypasses the containment.