Cable life extension for plant license renewal

Cables are important to safety during both normal operation and under accident conditions. Cables will, therefore, be a major consideration in determining plant life extension. Cabling as defined by the Nuclear Regulatory Commission consists of conductor cables, connectors, splices, terminal blocks and penetrations that constitute the path between sensors and monitors and between equipment and power source used for reactor control and protection. This study is limited to life extension for conductor cables only. There is a strong motivation to extend cable life rather than replace cables as part of an overall plant life extension strategy. New research on cable aging has identified areas of both conservatism and non-conservatism in determining the cable qualified life. The areas of conservatism are: (1) plant normal and accident temperature profile, (2) cable loading, (3) equal does equal damage assumption, and (4) Arrhenius methodology; and the areas of non-conservatism are: (1) combined environment effect, (2) jacket integrity, (3) presence of oxygen during accident testing, (4) fire retardation properties of cables and jackets after aging. Since plant life extension is the ultimate goal of utilities and the US Department of Energy (DOE), cable life extension studies to address the areas of conservatism and nonconservatism are ongoing cable manufacturer, utility, DOE and Electric Power Research Institute programs. A strategic plan for determining cable life extension is to develop a cable life extension management program that will consist of an outline for (1) a plant specific cables data base, (2) a generic cable qualification data base, and (3) guideline that uses the above as input for extending cable qualified life