A strong electric power industry having diverse generation sources is a key for advances in the industry, agriculture, technology and standards of living for any nation. In the last few decades, the nuclear power industry has emerged as a strong competitor in the electric power production market due to its less carbon oxide emission, high capacity, and efficiency. The reliable operation of nuclear power plants is heavily dependent on the safe operation of the low voltage instrumentation and control and power cables, which are mostly installed in the containment area and are under thermal and radiation stresses which may decrease the expected life of the cable. In this research work, the behavior of Choloro-Sulfonated Polyethylene/Cross-Linked Polyethylene based low voltage nuclear power plant power cable samples under thermal stress have been studied with the help of non-destructive extended voltage response method. The effect of the thermal stress on the expected life of the cable are also discussed.