Service lifetime estimates for nuclear medium voltage(MV) cables in nuclear power plants often do notmatch the actual performance lifetime in serviceconditions, particularly under immersion. With themajority of submerged MV cable insulation in NPPsbeing EPR and XLPE, a study was done to determinethermally aged EPR lifetime. However, with 34 EPRinsulation failures reported within 30 years ofinstallation, their 300-year predicted lifetime does notmatch the later survey. Current lifetimes areestimated using various accelerated ageing testsmostly dry, but these tests are not tuned for thematerial in its specific application, which mayexperience a range of environmental factors thatchange the modes or kinetics of degradation. Thispaper outlines a testing procedure utilizing differentenvironments to expand more accurate life estimateson the effects of cyclic and permanent immersion inwater, Harrison solution, and copper sulfate onpolypropylene and polyethylene at elevatedtemperatures. Current results after 16 weeks suggestimmersion and cycling show greater UTS impact.After further analysis and more tests, this research willpropose either a correlation between the lifetimeestimate of dry-aged polypropylene and polyethyleneto cycled and immersed polypropylene andpolyethylene or advocate for additional time orresearch correlated with electrical properties.
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