Conservativeness of the Accelerated Aging Method for Nuclear Power Cables

A low‐voltage cable was retrieved after being laid for an extended period in the primary containment vessel of a boiling water nuclear power plant (NPP). A new cable of the same type underwent accelerated artificial aging using the ‘superposition of time‐dependent data’ method to simulate a slightly milder degree of age‐induced deterioration than the retrieved cable would have undergone. Subsequently, both cables were subjected to radiation and water steam exposure, anticipated during two types of accidents: severe and loss‐of‐coolant accidents. Following this, the leakage current passing through the insulation of each cable was measured using the current integration method while a DC voltage was applied. The results showed that, in most instances, the newly artificially aged cable demonstrated insulation properties nearly identical to or slightly inferior to those of the retrieved cable. This indicates that the artificial accelerated aging method is suitably conservative.