LIFE-ASSESSMENT TECHNIQUE FOR NUCLEAR-POWER-PLANT CABLES

The condition of polymer-based cable material can be best characterize d by measuring elongation at break of its insulating materials. Howeve r, it is not often possible to take sufficiently large samples for mea surement with the tensile testing machine. The problem has been conven iently solved by utilizing differential scanning calorimetry technique . From the tested cable, several microsamples are taken and the oxidat ion induction time (OIT) is determined. For each cable which is subjec t to the assessment of the lifetime, the correlation of Off with elong ation at break and the correlation of elongation at break with the cab le service time has to be performed. A reliable assessment of the cabl e lifetime depends on accuracy of these correlations. Consequently, sy nergistic effects well known at this time - dose rate effects and effe cts resulting from the different sequence of applying radiation and el evated temperature must be taken into account.